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NASA Technical Memorandum 4677 


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Microgravity Science & Applications 

Program Tasks and Bibliography 
for FY1994 


March 1995 


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National Aeronautics and 
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Office of Life and Microgravity 
Sciences and Applications 

Microgravity Science and Applications Division 


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NASA Technical Memorandum 4677 


Microgravity Science & Applications 

Program Tasks and Bibliography 
for FY1994 


Microgravity Science and Applications Division 
NASA Headquarters, Code UG 
Washington, DC 20546-0001 


National Aeronautics and 
Space Administration 

Office of Management 

Scientific and Technical 
Information Program 

March 1995 




MSAD Program Tasks & 

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Bibliography — FY 1994 

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Table of Contents 




I. INTRODUCTION 


II. MICROGRAVITY SCIENCE & APPLICATIONS PROGRAM TASKS 


Flight: Benchmark Science 

Critical Dynamics in Microgravity (Dr. Robert V. Duncan) 7 

Statellite Test of the Equivalence Principle (Prof. C.F. Everitt) 11 

Critical Dynamics of Fluids (Prof. Richard A. Ferrell) 13 

Critical Fluid Light Scattering Experiment (ZENO) (Prof. Robert W. Gammon) 15 

Heat Capacity Measurements Near the Lambda Point of Helium (Prof. John A. Lipa) 17 

Confined Helium Experiment (CHeX) (Prof. John A. Lipa) 19 

Critical Fluid Thermal Equilibrium Dynamics (Dr. R. Allen Wilkinson) 21 


Flight: Biotechnology 

Protein Crystal Growth Vapor- Diffusion Flight Hardware and Facility (Dr. Daniel C. Carter) 23 

Advanced High Brilliance X-Ray Source (Dr. Daniel C. Carter) 25 

Protein Crystal Growth in Microgravity (Dr. Lawrence J. Delucas) 27 

Electrophoretic Separation of Cells and Particles from Rat Pituitary (Dr. Wesley C. Hymer) 29 

An Observable Protein Crystal Growth Flight Apparatus (Dr. Alexander McPherson, Jr.) 31 

Electrophoresis Technology (Dr. Robert S. Snyder) 34 


Flight: Combustion Science 

Scientific Support for an Orbiter Middeck Experiment 

on Solid Surface Combustion (Prof. Robert A. Altenkirch) 36 

Low-Velocity, Opposed- Flow Flame Spread in a 

Transport-Controlled, Microgravity Environment (Prof. Robert A. Altenkirch) 38 

Reflight of the Solid Surface Combustion Experiment with 

Emphasis on Flame Radiation Near Extinction (Prof. Robert A. Altenkirch) 41 

Gravitational Effects on Laminar, Transitional, and Turbulent 

Gas-let Diffusion Flames (Dr. M. Yousef Bahadori) 43 

Sooting Effects in Reduced Gravity Droplet Combustion (SEDC) (Prof. Mun Y. Choi) 46 

Candle Flames in Microgravity (Dr. Daniel L. Dietrich) 48 

Investigation of Laminar jet Diffusion Flames in Microgravity: 

A Paradigm for Soot Processes in Turbulent Flames (Prof. Gerard M. Faeth) 50 

Unsteady Diffusion Flames: Ignition, Travel, and Burnout (Dr. Frank Fendell) 54 

Fundamental Study of Smoldering 

Combustion in Microgravity (Prof. A. Carlos Femandez-Pello) 56 

Ignition and the Subsequent Transition to 

Flame Spread in Microgravity (Dr. Takashi Kashiwagi) 59 


PRECEDING 


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iii 



MSAD Program Tasks & Bibliography 


— FY1994 

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Table of Contents 

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Studies of Premixed Laminar and Turbulent 

Flames at Microgravity (Prof. Paul D. Ronnev) 

Ignition and Flame Spread of Liquid Fuel Pools (Dr. Howard Ross) 

Combustion of Solid Fuel in Very Low Speed Oxygen Streams (Prof. James S. T'ien) 
Droplet Combustion Experiment (Prof. Forman A. Williams) 


Flight: Fluid Physics 

Surface Controlled Phenomena (Dr. Robert E. Apfel) 

Critical Viscosity of Xenon (Dr. Robert F. Berg) 

The Dynamics of Disorder-Order T ransitions in 

Hard Sphere Colloidal Dispersions (Prof. Paul M. Chaikin) 

Kinetics of Diffusional Droplet Growth (Dr. Donald O. Frazier) 

Microscale Hydrodynamics Near Moving Contact Lines (Prof. Stephen Garoff) 

Plasma Dust Crystallization (Dr. John A. Goree) 

Evaporation from a Meniscus within a Capillary Tube in Microgravity (Prof. Kevin P. Hallinan) 

Geophysical Fluid Flow Cell (Dr. John E. Hart) 

Interfacial Phenomena in Multilayered Fluid Systems (Prof. Jean N. Koster) 

Extensional Rheology of Non-Newtonian Materials (Prof. Gareth H. McKinley) 

Pool Boiling Experiment (Prof. Herman Merte, Jr.) 

Surface Tension-Driven Convection Experiment (STDCE-I, STDCE-2) (Prof. Simon Ostrach) .. 

Modeling and New Experiment Definition for the VIBES (Prof. Robert L. Sani) 

Studies in Electrohydrodynamics (Dr. Dudley A. Saville) 

Mechanics of Granular Materials (Dr. Stein Stu re) 

Thermocapillary Migration and Interactions of 

Bubbles and Drops (Prof. R. Shankar Subramanian) 

Drop Dynamics Investigation (Dr. Taylor G. Wang) 

Colloid Physics in Microgravity (Dr. David A. Weitz) 

Study of Two Phase Flow Dynamics and Heat 

Transfer at Reduced Gravity (Prof. Larry Witte) 


72 

74 

76 
78 
80 
83 
. 85 
87 
89 
, 91 
. 93 
. 96 
. 99 
101 
103 

105 

107 

109 

110 


Flight: Materials Science 

In Situ Monitoring of Crystal Growth Using MEPHISTO (Prof. G.J. Abbaschian) 

Coupled Growth in Hypermonotectics (Dr. J. Barry Andrews) 

Effects on Nucleation by Containerless Processing (Prof. Robert J. Bayuzick) 

Alloy Undercooling Experiments in 

Microgravity Environment (Prof. Merton C. Flemings) 

Compound Semiconductor Growth in Low-g Environment (Dr. Archibald L. Fripp) 

Melt Stabilization ofPbSnTe in a Magnetic Field (Dr. Archibald L. Fripp) 

Gravitational Role in Liquid-Phase Sintering (Prof. Randall M. German) 

Isothermal Dendritic Growth Experiment (Prof. Martin E. Glicksman) 


112 

115 

117 

119 

120 
122 
124 
126 


iv 


Bibliography — FY1994 Table of Contents 

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Evaluation of Microstructural Development in 

Undercooled Alloys (Dr. Richard N. Grugel) 129 

Thermophysical Properties of Metallic Glasses and 

Undercooled Alloys (Dr. William L. Johnson) 131 

Orbital Processing of High Quality Cadmium Telluride (Dr. David J. Larson) 133 

Crystal Growth of 11- IV Semiconducting Alloys by 

Directional Solidification (Dr. Sandor L. Lehoczky) 137 

Growth of Solid Solution Single Crystals (Dr. Sandor L. Lehoczky) 139 

GaAs Crystal Growth Experiment (Dr. David H. Matthiesen) 141 

Diffusion Processes in Molten Semiconductors (Dr. David H. Matthiesen) 142 

The Study of Dopant Segregaton Behavior 

During the Growth of GaAs in Microgravity (Dr. David H. Matthiesen) 144 

Temperature Dependence of Diffuswities in Liquid Metals (Prof. Franz Rosenberger) 145 

Double Diffusive Convection during Growth of Lead Bromide Crystals (Dr. N.B. Singh) 147 

Particle Engulfment and Pushing by Solidifying Interfaces (Dr. Doru M. Stefanescu) 149 

Crystal Growth of ZnSe and Related Ternary Compound 

Semiconductors by Physical Vapor Transport (Dr. Ching-Hua Su) 151 

Measurement of Viscosity and 

Surface Tension of Undercooled Melts (Dr. Julian Szekely) 153 

Test of Magnetic Damping of Convective Flows in Microgravity (Dr. Frank R. Szofran) 155 

Vapor Growth of Alloy-Type Semiconductor Crystals (Dr. Heribert Wiedemeier) 157 

Ground: Benchmark Science 

Superfluid Transition of 4 He in the Presence of a Heat Current (Prof. Guenter Ahlers) 159 

Microgravity Test of Universality and Scaling Predictions 

Near the 3 He Critical Point (Dr. Martin B. Barmatz) 161 

Measurement of the Heat Capacity of Superfluid 

Helium in a Persistent Current State (Dr. Taiso C. P. Chui) 163 

Nonequilibrium Phenomena Near the Lambda 

Transition of 4 He (Dr. Taiso C. P. Chui) 165 

Determination of the Correlation Length in 

Helium II in a Microgravity Environment (Prof. Russell Donnelly) 166 

Nucleation of Quantized Vortices from Rotating Superfluid Drops (Prof. Russell J. Donnelly) 168 

Kinetic and Thermodynamic Studies of Melting-Freezing of 

Helium in Microgravity (Prof. Charles Elbaum) 170 

Theoretical Influence of Microgravity on Critical 

Fluid Measurements (Prof. Richard A. Ferrell) 172 

Condensate Fraction in Superfluid Helium Droplets (J. Woods Halley) 173 

Ultra-Precise Measurements with Trapped 

Atoms in a Microgravity Environment (Dr. Daniel J. Heinzen) 176 

Dynamic Measurement Near the Lambda-Point in a 
Low-g Simulator on the Ground (Dr. Ulf E. Israelsson) 


MSA D Program Tasks & 


178 



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Turbidity of a Binary Mixture Very Close to the Critical Point (Prof. Donald T. Jacobs) .. 

Atom Interferometry in a Microgravity Environment (Dr. Mark A. Kasevich) 

Effect of Confinement on Transport Properties by Making 

Use of Helium Near the Lambda Point (Prof. John A. Lipa) 

Theoretical Studies of the Lambda Transition of Liquid 4 He (Efstratios Manousakis) 

Dynamics and Morphology of Superfluid 

Helium Drops in a Microgravity Environment (Prof. Humphrey J. Maris) 

Critical Transport Phenomena in Fluid Helium Under Low Gravity (Prof. Horst Meyer) 
Equilibration in Density and Temperature near the 

Liquid-Vapor Critical Point (Prof. Horst Meyer) 

Nonlinear Dynamics and Nucleation Kinetics 

in Near-Critical Liquids (Prof. Alexander Z. Patashinski) 

Precise Measurements of the Density and Thermal Expansion 

of 4 HeHear the Lambda Transition (Dr. Donald M. Strayer) 


180 

182 

184 

185 

188 

190 

192 

195 

196 


Ground: Biotechnology 


Evaluation of Ovarian Tumor Cell Growth and Gene Expression (Jeanne L. Becker, Ph.D.) 198 

Crystallographic Studies of Proteins Part II (Dr. Daniel C. Carter) 200 

Microgravity Studies of Cell-Polymer Cartilage Implants (Lisa E. Freed, M.D., Ph.D.) 202 

Excitable Cells and Growth Factors under Microgravity Conditions (Charles R. Hartzell, Ph.D.) .... 205 

Sensitized Lymphocytes for Tumor Therapy Grown in Microgravity (Marylou Ingram, M.D.) 208 

Three-Dimensional Modeling of Human Colon Tissues (J. Milbum Jessup, M.D.) 211 


Three-Dimensional Tissue Interactions in 

Colorectal Cancer Metastasis (J. Milbum Jessup, M.D.) 

Applications of Atomic Force Microscopy to Investigate 

Mechanisms of Protein Crystal Growth (Dr. John H. Konnert) 

Neuro-endocrine Organoid Assembly in Vitro (Peter I. Lelkes, Ph.D.) 

Formation of Ordered Arrays of Proteins on Surfaces (Prof. Abraham M. Lenhoff) 

Crystallization Studies in Microgravity of an Integral Membrane Protein: 

The Photosynthetic Reaction Center (Dr. James R. Norris) 

Shear Sensitivities of Human Bone Marrow Cultures (Bernhard O. Palsson, Ph.D.) 

Microgravity Crystallization of Avian Egg White Ovostatin (Dr. Marc L. Pusey) 

Study of Crystallization and Solution Properties of 

Redesigned Protein Surfaces (Prof. David C. Richardson) 

Convective Flow Effects on Protein Crystal Growth and 

Diffraction Resolution (Prof. Franz E. Rosenberger) 

Enhancement of Cell Function in Culture by Controlled Aggregation (W. M. Saltzman) .. 
Culture of Porcine Islet Tissue : Evaluation of 

Microgravity Conditions (David W. Scharp) 

Automation of Protein Crystallization Experiments: 

Crystallization by Dynamic Control of Temperature (Dr. Keith B. Ward) 

Thermal Optimization of Groiuth and Quality of Protein Crystals (Dr. John M. Wiencek) 


213 

216 

218 

223 

225 

228 

229 

231 

233 

236 

239 

241 

243 


vi 



MSAD Program Tasks & Bibliography — 

""‘It min 


FY1994 Table of Contents 

I hid 


Search for Dilute Solution Prq?erty to Predict Protein Crystallization (Dr. W. William Wilson) 246 

Characterization of Solvation Potentials Between Small Particles (Dr. Charles F. Zukoski) 248 


Ground: Combustion Science 

Effects of Energy Release on Near Field 

Flow Structure of Gas jets (Prof. Ajay K. Agrawai) 250 

Radiative Extinction of Diffusion Flames (Prof. Arvind Atreya) 252 

Multicomponent Droplet Combustion in Microgravity : Soot Formation , Emulsions, 

Metal-Based Additives , and the Effect of Initial Droplet Diameter (Prof. C.T. Avedisian) 254 

Development of Advanced Diagnostics for Characterization 

of Burning Droplets in microgravity (Dr. William D. Bachalo) 255 

Ignition and Combustion of Bulk Metals in Microgravity (Prof. Melvyn C. Branch) 256 

Ignition and Combustion of Bulk Metals in Microgravity (Prof. Melvyn C. Branch) 258 

Modeling of Microgravity Combustion Experiments (Prof. John C. Buckmaster) 259 

Buoyancy Effects on the Structure and Stability 

of Burke-Schumann Diffusion Flames (Prof. L.D. Chen) 263 

Gravitational Effects on Premixed Turbulent Flames (Dr. Robert K. Cheng) 266 

Gravitational Effects on Premixed Turbulent Flames : 

Microgravity Flame Structures (Dr. Robert K. Cheng) 268 

Combustion of Interacting Droplet Arrays in 

a Microgravity Environment (Dr. Daniel Dietrich) 269 

Internal and Surface Phenomena in 

Heterogeneous Metal Combustion (Dr. Edward L. Dreizin) 271 

Flame-Vortex Interactions Imaged in Microgravity (Prof. James F. Driscoll) 273 

Aerodynamic, Unsteady , Kinetic, and Heat Loss Effects on the Dynamics and 

Structure of Weakly- Burning Flames in Microgravity (Prof. Fokion N. Egolfopoulos) 275 

Effects of Gravity on Sheared and Nonsheared 

Turbulent Nonpremixed Flames (Prof. Said E. Elghobashi) 276 

Combustion of Electrostatic Sprays of Liquid Fuels in 

Laminar and Turbulent Regimes (Prof. Alessandro Gomez) 278 

Three-Dimensional Flow in a Microgravity Diffusion Flame (Prof. Jean R. Hertzberg) 280 

Chemical Inhibitor Effects on Diffusion Flames in Microgravity (Prof. Simone Hochgreb) 282 

Time-Dependent Computational Studies ofPre-Mixed Flames (Dr. K. Kailasanath) 285 

Radiative Ignition and Transition to Flame Spread in Microgravity (Dr. Takashi Kashiwagi) 288 

Sooting Turbulent jet Diffusion Flames (Prof. Jerry C. Ku) 291 

Soot and radiation Measurements in Microgravity 

Turbulent Jet Diffusion Flames (Prof. Jerry C. Ku) 293 

Studies of Flame Structure in Microgravity (Prof. Chung K. Law) 294 

Structure and Dynamics of Diffusion Flames in Microgravity (Prof. Moshe Matalon) 296 

Filtration Combustion for Microgravity Applications : (V Smoldering, (2) Combustion 

Synthesis of Advanced Materials (Prof. Bernard J. Matkowsky) 298 


vii 



MSAD Program Tasks & 




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Table of Contents 


Combustion of PTFE: The Effect of Gravity on the Production 

ofUltrafine Particles Generation (Prof. J.T. McKinnon) 

Premixed Turbulent Flame Propagation in Microgravity (Prof. Suresh Menon) 

A Fundamental Study of the Combustion Syntheses of Ceramic-Metal Composite Materials 
Under Microgravity Conditions (Prof. John j. Moore) 

Flow and Ambient Atmoshere Effects on 

Flame Spread at Microgravity (Prof. Paul D. Ronney) 

Combustion Research (Dr. Howard Ross) 

Combustion of Solid Fuel in Very Low Speed Oxygen Streams (Kurt R. Sacksteder) 

Reduced Gravity with 2-Component Miscible Droplets (Prof. Benjamin Shaw) 

Quantitative Measurement of Molecular Oxygen 

in Microgravity Combustion (Dr. Joel A. Silver) 

Numerical Modeling of Flame-Balls in Fuel-Air Mixtures (Prof. Mitchell D. Smooke) .... 

Combustion of Solid Fuel in Very Low Speed Oxygen Streams (Prof. James S. T'ien) 

Interactions Between Flames on Parallel Solid Surfaces (Dr. David L. Urban) 

Gasless Combustion Synthesis from Elements Under Microgravity: 

A Study of Structure-Formation Processes (Prof. Arvind Varma) 

Studies of Wind- Aided Flame Spread Over Thin 

Cellulosic Fuels in Microgravity (Prof. Indrek S. Wichman) 

High Pressure Droplet Combustion Studies (Prof. Forman A. Williams) 

High-Pressure Combustion of Binary Fuel Sprays (Prof. Forman A. Williams) 

Laser Diagnostics for Fundamental Microgravity 

Droplet Combustion Studies (Dr. Michael Winter) 

Combustion of a Polymer (PMMA) Sphere in Microgravity (Dr. Jiann C. Yang) 


300 

302 

304 

307 

309 

315 

317 

320 

322 

323 
325 

327 

. 329 
. 330 
. 331 

. 333 
. 335 


Ground: Fluid Physics 

Study of Two-Phase Flow and Heat Transfer in Reduced Gravities (Dr. Davood Abdollahian) 

Colloids & Nucleation ( Prof. Bruce J. Ackerson) 

Stability Limits and Dynamics of Nonaxisymmetric Liquid Bridges (Dr. lwan D. Alexander) 

Investigation of Multiple-Layer Convection (Prof. C.D. Andereck) 

Electrokinetic Transport of Heterogeneous Particles in Suspensions (Prof. John L. Anderson) 
Experimental Study of Liquid jet Impingement 

in Microgravity: The Hydraulic Jump (Prof. C.T. Avedisian) 

Studies on the Response of Emulsions to Externally-Imposed Electric and Velocity Fields: 
Electrohydrodynamic Deformation and Interaction of a Pair of Drops (Dr. James C. Baygents) 

Marangoni Effects in Boiling of Binary Fluid 

Mixtures Under Microgravity (Prof. Van P. Carey) 

Marangoni Instability Induced Convection in Evaporating Liquid Droplets (Dr. An-Ti Chai) . 

Rewetting of Monogroove Heat Pipe in Space Station Radiators (Prof. S. H. Chan) 

Marangoni and Double-Diffusive Convection in a 

Fluid Layer under Microgravity (Prof. Chuan F. Chen) 


337 

339 

340 
342 
344 

346 

347 

349 

350 
352 

354 


viii 



MSAD Program Tasks & Bibliography 

mm until mini in n 


FY1994 Table of Contents 




Transport Phenomena in Stratified Flow in the 

Presence and Absence of Gravity (Dr. Norman Chigier) 356 

Bubble Dynamics, Two-Phase Flow , and Boiling 

Heat Transfer in Microgravity (Prof. Jacob N. Chung) 358 

Reactive Fluids Experiment: Chemical Vapor Deposition (Dr. Ivan O. Clark) 360 

Microgravity Particle Dynamics (Dr. Ivan O. Clark) 362 

Studies of Freely Suspended Liquid Crystal Bubbles (Prof. Noel A. Clark) 364 

Fluid Interface Behavior Linder Low- and Reduced -Gravity Conditions (Prof. Paul Concus) 365 

Convection and Morphological Stability During Directional Solidification (Prof. Sam R. Coriell) .... 369 
Microphysics of Close Approach and Film Drainage 

and Rupture During Drop Coalescence (Prof. Robert H. Davis) 371 

Phase Segregation Due to Simultaneous Migration and Coalescence (Prof. Robert H. Davis) 373 

Interaction and Aggregation of Colloidal Biological 

Particles and Droplets in Electrically-Driven Floras (Prof. Robert H. Davis) 375 

Theory of Solidification (Prof. Stephen H. Davis) 377 

Microgravity Foam Structure and Rheology (Prof. Douglas J. Durian) 378 

The Influence of Gravity on Nucleation, Growth, Stability 

and Structure in Ordering Soft-Spheres (Prof. Alice P. Gast) 380 

Fluid Mechanics of Capillary Elastic Instabilities 

in the Microgravity Environment (Prof. James B. Grotberg) 382 

Effects of Convection on the Thermocapillary Motion of 

Deformable Drops (Prof. Hossein Haj-Hariri) 383 

Interfacial Transport and Micellar Solubilization Processes (Prof. T. Alan Hatton) 385 

Critical Phenomena, Electrodynamics, and Geophysical Flows (Dr. John Hegseth) 387 

Thermocapillary Instabilities and g-Jitter Convection (Prof. George M. Homsy) 388 

Kinetic and Transport Phenomena in a Microgravity Environment (Prof. David Jasnow) 390 

Surfactant Based Critical Phenomena in Microgravity (Dr. Eric W. Kaler) 392 

Instability of Velocity and Temperature Fields in the 

Vicinity of a Bubble on a Heated Surface (Dr. Mohammad Kassemi) 394 

Stabilization of Thermocapillary convection by Means of 

Nonplanar Flow Oscillations (Prof. Robert E. Kelly) 396 

Microgravity Heat Transfer Mechanisms in the Nucleate Pool Boiling and Critical 

Heat Flux Regimes Using a Novel Array of Microscale Heaters (Prof. Jungho Kim) 398 

Molecular Dynamics of Fluid-Solid Systems (Dr. Joel Koplik) 400 

Fluid Dynamics and Solidification of Metallic Melts ( FDSMM ) (Prof. Jean N. Koster) 402 

Thermocapillary Convection in Floating Zones Under 

Simulated Reduced Gravity (Prof. Sindo Kou) 404 

Analysis of Phase Distribution Phenomena in 

Microgravity Environments (Prof. Richard T. Lahev) 406 

Nonlinear Drop Dynamics and Chaotic Phenomena (Dr. L. Gary Leal) 408 


IX 


MSAD Program Tasks & 


— FY1994 


Table of Contents 

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Oscillatory Cross-Flow Electrophoresis: 

Application to Production Scale Separations (Dr. Davis T. Leighton) 

Low Dimensional Models for Thermocapillary Convective 

Flows in Crystal Groivth Processes (Prof. A. Liakopoulos) 

Absolute and Convective Instability of a Liquid let at Microgravity (Prof. Sung P. Lin) 

Magnetorheological Fluids in Micrgravity (Prof. Jing Liu) 

Cross Effects in Microgravity Flows (Prof. Sudarshan K. Loyalka) 

Controlling the Mobility of a Fluid Particle in Space 

by Using Remobilizing Surfactants (Prof. Charles Maldarelli) 

Stabilization and Low Frequency Oscillations of Capillary Bridges 

with Modulated Acoustic Radiation Pressure (Prof. Philip L. Marston) 

Study of Disturbances in Fluid-Fluid Flows in 

Open and Closed Systems (Prof. Mark J. McCready) 

Study of Forced Convection Nucleate Boiling in Microgravity ( Prof. Herman Merte, jr.) 

Control of Oscillatory Thermocapillary Convection in Microgravity (Prof. G. Paul Neitzel) 

Industrial Processes (Prof. Simon Ostrach) 

Marangoni Effects on the Bubble Dynamics 

in a Pressure Driven Flow (Prof. Chang-Won Park) 

Two-Phase Interfaces in Weak External Fields (Prof. Jerome K. Percus) 

Containerless Capillary Wave Turbulence (Dr. Seth J. Putterman) 

Studies of Radiation-Driven and Buoyancy-Driven 

Fluid Floivs and Transport (Prof. Paul D. Ronney) 

Fluid Creep Effects on Near -Wall Solute Transport for Non-lsothermal 

Ampoules and Suspended Particle Transport Coefficients (Prof. Daniel E. Rosner) 

Dynamics of Superfluid Helium in Low Gravity (Dr. Graham Ross) 

Microscale Modeling of Microgravity Multiphase Flow (Dr. Paul H. Rothe) 

Gas Flow from Porous Media and Microgravity Battery Spills (Dr. Robert T. Ruggeri) 

Ground-Based Studies of Thermocapillary Flows in Levitated Drop (Dr. Satwindar S. Sadhal) .. 
Effects of Gravity and Shear on the Dynamics and 

Stability of Particulate and Multiphase Flows (Prof. Ashok S. Sangani) 

Dielectric and Electrohydrodynamic Properties of Suspensions (Dr. Dudley A. Saville) 

Electrohydrodynamic Pool Boing in reduced Gravity (Prof. Banjamin D. Shaw) 

Transport Processes Research (Dr. Bhim S. Singh) 

Solute Nucleation and Growth in Supercritical Fluid Mixtures (Dr. Gregory T. Smedley) 

Behavior of Unsteady Thennocapillary Flows (Prof. Marc K. Smith) 

Flow- Influenced Shape Stability : Breakup in Low Gravity (Prof. Paul H. Steen) 

Interactions of Bubbles and Drops in a Temperature Gradient (Prof. R. Shankar Subramanian) 

Instability in Surface-Tension-Driven Benard Convection (Prof. Harry L. Swinney) 

Crystal Growth and Fluid Mechanics Problems in 

Directional Solidification (Prof. Saleh Tanveer) 

Oscillatory/Chaotic Thermocapillary Flow Induced by 

Radiant Heating (Dr. Robert L. Thompson) 


411 

412 

413 
415 
417 

419 

421 

423 

424 
426 
428 

430 

431 
. 433 

. 435 

. 437 
. 438 
. 440 
. 441 
. 443 

. 446 
. 448 
. 450 
.. 451 
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.. 457 
.. 459 
.. 461 

.. 463 

.. 465 



MSAD Program Tasks & Bibliography 


_ FY1994 Table of Contents 

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Light Scattering Studies of Relative Motions of 

Solid Particles in Turbulent Flows (Prof. Penger Tong) 467 

Computational Studies of Drop Collision and Coalescence (Prof. Gretar Tryggvason) 468 

Nonlinear Bubble Interactions in Acoustic Pressure Fields (Prof. John Tsamopoulos) 470 

Residual Accelerations in a Microgravity Environment (Prof. Jorge Vinals) 472 

Studies of the Dynamics of Charged Free Drops (Dr. Taylor G. Wang) 474 

Experimental Study of the Vapor Bubble Thermosyphon (Prof. Peter C. Wayner, Jr.) 476 

Interactions Between Solidification and Compositional 

Convection in Alloys (Prof. M. Grae Worster) 478 

Nucleation and Chiral Symmetry Breaking under Hydrodynamic Flows (Dr. Xiao-lun Wu) 479 

Oscillatory Thermocapillary Convection (Prof. Abdelfattah Zebib) 481 


Ground: Materials Science 

Synthesis and Characterization of Single Macromolecules: Mechanistic 

Studies of Crystallization and Aggregation (Prof. Spiro D. Alexandratos) 483 

A Novel Electrochemical Method of Flow Visualization (Dr. T.J. Anderson) 485 

Foam Metallic Glasses (Prof. Robert E. Apfel) 487 

Nucleation and Cluster Formation in Levitated Drops (Prof. Stephen Arnold) 489 

Microwave Materials Processing in Microgravity (Dr. Martin B. Barmatz) 491 

Studies of Containerless Processing of Selected Alloys (Prof. Robert J. Bayuzick) 493 

Studies of Nucleation and Growth of Intermetallic Compounds (Dr. Robert J. Bayuzick) 495 

Transport Phenomena During Equiaxed Solidification of Alloys (Prof. Christoph Beckermann) 497 

Gravitational Effects on the Development of Weld-Pool and 

Solidification Microstructures in Metal Alloy Single Crystals (Dr. Lynn A. Boatner) 500 

Modeling of Convection and Crystal Growth in Directional 

Solidification of Semiconductor and Oxide Materials (Prof. Robert A. Brown) 502 

Microstructure Formation During Directional Solidification of 

Binary Alloys without Convection: Experiment and Computation (Prof. Robert A. Brown) 505 

Evolution of Crystals and Amorphous Phase Structure 

During Processing of Thermoplastic Polymers (Dr. Peggy Cebe) 508 

Optical Properties for High Temperature Materials Research (Dr. Ared Cezairliyan) 510 

Fluid Mechanics of Directional Solidification 

at Reduced Gravity (Prof. Chuan F. Chen) 512 

Microgravity Chemical Vapor Deposition (Dr. Ivan O. Clark) 513 

Glass Formation and Nucleation in Microgravity: Containerless- Processed, 

Inviscid Silicate/Oxide Melts [ Ground-Based Studiesl (Dr. Reid F. Cooper) 515 

Directional Solidification in 3 He- 4 He Alloys (Prof. Arnold Dahm) 518 

Advanced Photonic Materials Produced by Containerless Processing (Dr. Delbert E. Day) 520 

The Effect of Gravity on Natural Convection and 

Crystal Growth (Prof. Graham D. deVahl Davis) 524 

Use of Synchrotron White Beam X-Ray Topography for the Characterization of the Microstructural 
Development of Crystal- Normal Gravity Versus Microgravity (Dr. Michael Dudley) 526 


xi 



MSAD Program Tasks & Bibliography 


FY1994 Table of Contents 

HI.. Mil HI. 


Reverse Micelle Based Synthesis of Microporous Materials in Microgravity (Prof. P.K. Dutta) ... 

Growth of Nonlinear Optical Thin Films/Vapor Processes (Dr. Donald O. Frazier) 

Growth of Nonlinear Optical Crystals by Melt and Solution Processes (Dr. Donald O. Frazier) 

Investigation of Local Effects on Microstructure Evolution (Dr. Donald O. Frazier) 

Electronic Materials (Dr. Thomas K. Glasgow) 

Combustion Synthesis of Materials in Microgravity (Prof. Dr. Irvin Glassman) 

Evolution of Microstructural Distance Distributions 

in Normal Gravity and Microgravity (Dr. Arun M. Gokhale) 

Influence of Free Convection in Dissolution (Prof. Prabhat K. Gupta) 

Noncontact Thermal, Physical Property Measurement of 

Multiphase Systems (Dr. Robert H. Hauge) 

Microgravity Processing of Oxide Superconductors (Dr. William Hoffmeister) 

Non-Equilibrium Phase Transformat ions (Dr. Kenneth A. Jackson) 

Combined Heat Transfer Analysis of Crystal Growth (Dr. Mohammad Kassemi) 

Fundamentals of Thermomigration of Liquid Zones through Solids (Prof. Michael J. Kaufman) 

Kinetics of Phase Transformations in Glass Forming (Prof. Kenneth F. Kelton) 

Compositional Dependence of Phase Formation and Stability (Prof. Kenneth F. Kelton) 


530 

531 
533 
535 

537 

538 

540 

541 

542 
544 
546 
548 
550 
552 
554 


Solutocapillary Convection Effects on 

Polymeric Membrane Morphology (Prof. William B. Krantz) 

Containerless Property Measurement of High-Temperature Liquids (Dr. Shankar Krishnan) 

Noise and Dynamical Pattern Selection in Solidification (Prof. Douglas A. Kurtze) 

Chemical Vapor Deposition of High-t c Superconducting Films in a 

Microgravity Environment ( I ) (Prof. Moises Levy) 

Microstructural Development during Directional Solidification of 

Peritectic Alloys (Dr. Thomas A. Lograsso) 

Numerical Investigation of Thermal Creep and Thermal Stress Effects in 

Microgravity Physical Vapor Transport (Dr. Daniel W. Mackowski) ■ 

Polymerizations in Microgravity: Traveling Fronts, Dispersions, 

Diffusion and Copolymerizations (Prof. Lon J. Mathias) 

Quantitative Analysis of Crystal Defects by 

Triple Crystal X-Ray Diffraction (Dr. Richard J. Matyi) 

The Interactive Dynamics of Convection, Flow and 

Directional Solidification (Prof. T. Maxworthy, Ph.D.) 

Y 2 BaCu 05 Segregation in YBajCu^Oy.x During Melt Texturing (Dr. Paul J. McGinn) 

Interaction ofHele-Shaw Floivs with Directional Solidification: Numerical Investigation of the 
Nonlinear Dynamical Interplay and Control Strategies (Prof. Eckart H. Meiburg) 

The Synergistic Effect of Ceramic Materials Synthesis Using 

Vapor- Enhanced Reactive Sintering Under Microgravity Conditions (Prof. John J. Moore) 

Diffusion, Viscosity, and Crystal Groivth in Microgravity (Prof. Allan S. Myerson) 

An Electrochemical Method to Measure Diffusivity in Liquid Metals (Prof. Ranga Narayanan) 


555 

557 

560 

561 

563 

565 

568 

571 

573 

.574 

576 

578 

580 

582 


Crystal Growth and Segregation Using the Submerged Heater Method (Prof. A.G. Ostrogorsky) .... 584 


xii 


MSAD Program Tasks & Bibliography — FY1994 Table of Contents 

mu mi mu mum mm 

Investigation of " Contactless " Crystal Groivth 

by Physical Vapor Transport (Dr. Witold Palosz) 586 

Containerless Processing for Controlled 

Solidification Microstructures (Prof. John H. Perepezko) 587 

Containerless Processing fof Composite Materials (Prof. John H. Perepezko) 589 

Comparison of the Structure and Segregation in Dendritic Alloys Solidified in 

Terrestrial and Low Gravity Environments (Prof. David R. Poirier) 591 

Kinetics of Phase Transformation in Glass Forming Systems (Dr. Chandra S. Ray) 593 

The Effects of Microgravity on Vapor Phase Sintering (Prof. Dennis W. Readey) 595 

Modeling of Detached Solidification (Dr. Liya L. Regel) 599 

Electrostatic Containerless Processing (Dr. Won-Kyu Rhim) 601 

Drop Tube Operation (Dr. Michael B. Robinson) 604 

Measurement of the Optical and radiative Properties of High-Temperature 

Liquid Materials by FTIR Spectroscopy (Dr. Michael B. Robinson) 606 

Undercooling Behaving of Immiscible Metal Alloys in the 

Absence of Crucible Induced Nucleation (Dr. Michael B. Robinson) 607 

Undercooling Limits in Molten Semiconductors and Metals: 

Structure and Superheating Dependencies (Dr. Frank G. Shi) 608 

Crystal Nucleation , Hydrostatic Tension , and Diffusion in 

Metal and Semiconductor Melts (Prof. Frans Spaepen) 609 

Micro- and Macro-Segregation in Alloys Solidifying 

with Equiaxed Morphology (Prof. Doru M. Stefanescu) 611 

The Impaction , Spreading , and Solidification of Partially 

Solidified Udercooled Droplets (Dr. Julian Szekely) 613 

Microporous Membrane and Foam Production by Solution Phase Separation: Effects of 

Microgravity and Normal Gravity Environments on Evolution of Phase Separated 

Structures (Dr. John M. Torkeison) 615 

Fundamentals of Mold-Free Casting Experimental 

and Computational Studies (Prof. Gretar Trvggvason) 617 

Electromagnetic Field Effects in Semiconductor Crystal Growth (Dr. Martin P. Volz) 618 

Coarsening in Solid-Liquid Mixtures (Prof. Peter W. Voorhees) 620 

Containerless Liquid Phase Processing of Ceramic Materials (Dr. J. K. Richard Weber) 622 

BSO/BTO Identification of Gravity Related Effects on Crystal Growth , 

Segregation , and Defect Formation (Prof. A.F. Witt) 624 

ATD 

Microwave Furnace Development (Dr. Martin B. Barmatz) 626 

Stereo Imaging Velocimetry (Dr. Mark Bethea) 628 

Real-Time X-Ray Microscopy for Solidification Processing (Dr. Peter Curreri) 630 

Microgravity Combustion Diagnostics (Paul S. Greenberg) 632 

Small Stable , Rugged Microgravity (Frank T. Hartley) 636 


xiii 



MSAD Program Tasks & Bibliography — FY1994 


r id 


Table of Contents 


High Resolution Pressure Transducer and Controller (Dr. (Jlf E. Israelsson) 

Surface Light Scattering Instruments (William V. Meyer) 

Crystal Growth Instrumentation Development: 

A Protein Crystal growth Studies Cell (Dr. Marc L. Pusey) 

Multizone Furnace Control Algorithm Development (Bruce N. Rosenthal) 

High Resolution Termometry and Improved SQUID Readout (Dr. Peter Shirron) 

Determination of Soot Volume Fraction 

Using Laser-Induced Incandescence (Dr. Karen J. Weiland) 

Multi-Color Holography (Mr. William K. Witherow) 

Ceramic Cartridges via Sintering and Vacuum Plasma Spray (Dr. Frank R. Zimmerman) 


637 

639 

641 

643 

.645 

647 

650 

651 


III. BIBLIOGRAPHY 


653 


APPENDIX 


Appendix A: 
Appendix B: 
Appendix C: 


Table of Acronyms 

Guest Investigator Index .... 
Principal Investigator Index 


A-l 

B-l 

C-l 


xiv 



I. MSAD Program Tasks & Bibliography — FY1994 Objectives & Metrics 

I. 

Introduction 

• Objectives and Focus for FY1994 1-1 

• Program Task Summary Data 1-5 


I-l 



I. MSAD Program Tasks & Bibliography — FY1994 

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Objectives & Metrics 

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I. MSAD Program Tasks & Bibliography — FY1994 

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Objectives & Metrics 

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OBJECTIVES AND FOCUS FOR FY1994 


S Microgravity Science and Applications Division (MSAD) sponsors a program that seeks to 
focus on the use of space as a laboratory by undertaking the study of important physical, chemical, and 
biochemical processes on orbit that cannot easily be studied in the terrestrial gravity environment. 
However, since flight opportunities are rare and flight hardware is very expensive, a strong ground- 
based research program from which only the best experiments evolve is the keystone of the program. 


The microgravity environment affords unique characteristics that allow the investigation of phenomena 
and processes that are difficult or impossible to study on Earth. Significant reductions in critical 
characteristics, such as buoyancy driven forces, convection, sedimentation, and hydrostatic pressures, 
make it possible to isolate and control gravity-related phenomena and make measurements that have 
significantly greater accuracy than can be achieved in normal gravity. Space flight gives scientists the 
opportunity to study the fundamental states of physical matter— solids, liquids and gasses— and the 
forces that affect those states. Because microgravity tends to allow the treatment of gravity as a variable, 
research in microgravity leads to a greater fundamental understanding of the influence of gravity on the 
world around us. With appropriate emphasis, the results of space experiments lead to both knowledge 
and technological advances that have direct applications on Earth. Microgravity research also provides 
the practical knowledge essential to the development of future space systems. 


The Office of Life and Microgravity Sciences and Applications (OLMSA) is responsible for planning and 
executing research stimulated by the Agency's broad scientific goals. OLMSA’s Microgravity Science and 
Applications Division (MSAD) is responsible for guiding and focusing a comprehensive program, and 
currently manages its research and development tasks by dividing them into five major scientific 
disciplines: benchmark science, biotechnology, combustion science, fluid physics, and materials science. 

Fiscal year 1994 was an important year for microgravity science in general and for MSAD in particular. 
Not only was the ground research program enhanced, several new investigators and research areas were 
added to the program through maturation of experiments in a flight development phase. The on-orbit 
research carried out in FY 1994 with two microgravity Space Shuttle missions is currently coming to 
fruition as the results from these missions are gathered and evaluated. Scientific data from the second 
United States Microgravity Payload (USMP-2), March 1994, and the second International Microgravity 
Laboratory (IML-2), July 1994, provided valuable insight into each of the five discipline fields in FY 1994. 
The processing and evaluation of these results have provided a solid basis for the planning of future 
microgravity missions, such as USML-2 scheduled in September 1995, thus beginning the research cycle 
anew. 


This document, NASA Technical Memorandum 4677 [1995], The Microgravity Science and Applications 
Program Tasks and Bibliography for Fiscal Year 1994 (October 1993 - September 1994), includes research 
projects funded by the Office of Life and Microgravity Sciences and Applications, Microgravity Science 
and Applications Division, during that year. This document is published annually and is sent to 
scientists in the microgravity field, both foreign and domestic. The information provided in the Task 
Book is used in reports to the NASA Associate Administrator, the Office of Management and Budget, and 
to the United States Congress. 

The Microgravity Science and Applications Division wishes to thank The Bionetics Corporation, and in 
particular recognizing Mr. Bill Wilcox (task review process and publications manager) and Mr. Duke 
Reiber (data system development) for their lead efforts in the development, compilation and publishing 
of this report. Gratitude is also expressed for significant data processing support at the responsible 
Centers for MSAD task management, recognizing: Dr. Mark Lysek and Angela Belcastro, JPL; Phyllis 
Golden, JSC; Mary Malone, LeRC; and Richard McConnell, MSFC. 


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1-3 


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> v FY1994 Objectives & Metrics 

TASK SUMMARY: 

Overview Information and Statistics 

Total Number of Principal Investigators: 

Total Number of Co-Investigators: 254 


I. MSAD Program Tasks & Bibliograpl 
FY1994 PROGRAM RESEARCH 


Total Number of Bibliographic Listings: 

• Proceedings Papers: 

♦ Journal Articles: 

♦ NASA Tech Brief Articles: 

• Science/Technical Presentations: 

* Books /Chapters: 


942 
146 
370 
. 13 
389 
. 24 


Total Number of Patents Applied for or Awarded: 


Number of Graduate Students Funded: 

Number of Graduate Degrees Granted 
Based on MSAD-funded Research: 


Number of States with Funded Research (including District of Columbia): 


FY1993 Microgravity Science & Applications Budget: 


$188.0 Million 


Microgravity Science & Applications Research Tasks and Types 
— Responsibilities by Center — 

Centers, Types of Research 

Ground 

Flight 

ATD 

Center Totals 

Jet Propulsion Laboratory 

29 

7 

3 

39 

Johnson Space Flight Center 

10 

0 

0 

10 

Langley Research Center 

3 

2 

0 

5 

Lewis Research Center 

129 

35 

5 

169 

Marshall Space Flight Center 

62 

25 

4 

91 

Goddard Space Right Center 

0 

0 

1 

1 

Research Task Totals 

233 

69 

13 

315 







II. MSAD Program Tasks — FY1994 

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Research Disciplines 

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II. 

Microgravity Science & Applications 
Program Tasks for FY 1994 


• Flight Research Tasks 

Benchmark Science II-7 

Biotechnology 11-23 

Combustion Science 11-36 

Fluid Physics 11-72 

Materials Science 11-112 

• Ground Research Tasks 

Benchmark Science 11-159 

Biotechnology 11-198 

Combustion Science 11-250 

Fluid Physics 11-337 

Materials Science 11-483 

• ATD 

Advanced Technology Development 11-626 


1 1-5 


PRECEDING PAGE BUN1CMOT FILMED 



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Research Disciplines 




II. MSAD Program Tasks — FY1994 


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II. MSAD Program Tasks — Flight Research 

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Critical Dynamics in Microgravity 

Discipline: Benchmark Science 

iiiHiiiiMHiiiimmiiMi'iiiHiiiiiiiiiiiMHmHMmimiiMHtiiiHiMmiMiimiiiimiiHtiiimHMiiimmiiiiiiimitiiH 

Principal Investigator: Dr. Robert v. Duncan 

Sandia National Labs, and University of New Mexico 

Co-Investigators: 

Talso C.P. Chui 

Jet Propulsion Laboratory (JPL) 

U.E. Israelsson 

Jet Propulsion Laboratory (JPL) 


Task Objective: 

The objective of the Critical Dynamics in Microgravity Experiment are as follows: 

1. Measure the dependence of the normal state thermal conductivity (K) on the heat flux Q, and on the proximity 
of the cell endplate: 

- Nonlinear transport very close to T*. 

- Q sets distance from criticality, as predicted by DRGT; 

- Explore boundary suppression of fluctuations near criticality; 

- 0.3 nW/cnr < Q < 10 |iw/cm 2 with no convection in a 2 cm cell. 

2. Measure the temperature profile very near, and through, the Hel-Hell interface: 

- Measure AT X (Q) and explore "supercooled" Hel region as a function of small temperature and pressure changes 

- Determine the boundary conditions on j s and possibly cp; 

- Determine if the interfacial width (w) scales as predicted by DRGT and DS: w = w^V Q; 

- Measure the supertluid AT, hence Hell vorticity. 

3. Search for hysteresis in the supertluid transition under heat flux: 

- Up/down reproducibility; 

- Latent heat. 

Task Description: 

A high-resolution, all-aluminum thermal conductivity cell containing a sample of ultra-high purity helium will be 
employed for these measurements. The high resolution thermometers (HRT) developed for and used successfully on 
the Lambda Point Experiment will also be used on DYNAMX to measure temperature gradients when a small heat 
current is applied. 

Task Significance: 

The improvements to the HRTs developed for the CHeX mission will also be applied to the DYNAMX HRT’s. 

The all-aluminum construction will reduce the mass of the sample cell to reduce the degradation of the measurement 
resolution caused by ionizing radiation in orbit. 

Progress During FY 1 994: 

The DYNAMX project has worked to set up a cryoprobe for measuring the thermal conductivity of liquid helium 
very near the lambda transition. This cryoprobe will be used to demonstrate the feasibility of the measurements that 
were proposed for flight. Setting up the cryoprobe has involved: design and fabrication of a flight-like all-aluminum 
experimental cell; fabrication and assembly of the parts of the cryoprobe; installation of major components like the 
high resolution thermometers and the SQUIDs; and installation of the experimental cell with its heat flow paths 
tailored to the requirements of a thermal model. Some details of the progress made on each of these tasks will be 
provided below. 






II. MSAD Program Tasks — 

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Flight Research Discipline: Benchmark Science 

I HIM * "»"* * 


In addition to preparation of the hardware lor the feasibility demonstrations, the DYNAMX team has also taken 
pains to communicate the aims of the experiment to the science community, and to establish channels ot 
communication to the nonscience community. The educational and outreach actions taken by DYNAMX team 
members will also be delineated below. 

Hardware Development 

Two considerations have led to an all-aluminum experimental cell for DYNAMX: Aluminum has a smaller 
cross-section for interaction with ionizing radiation than has copper, so the added thermometer noise experienced on 
the Lambda Point Experiment will be reduced significantly by using aluminum; and, the existence of both 
high-conductivity and low-conductivity forms of aluminum permits an all-welded construction with rings ol 
high-conductivity A1 spaced by the low-conductivity alloy. Attaching HRTs to the high-conductivity rings then 
allows the thermal profile to be measured along the walls with a negligible fraction ot the heat flow through the 
metal, while nearly all the heat flows through the near-critical helium; high-conductivity aluminum is used tor 
making these attachments, also. A rather detailed thermal model ot the aluminum cell filled with helium near the 
lambda transition has directed the placement of the high-conductivity rings at three points along the cell sidewall. 
Two versions of the aluminum cell were built as the model was refined and as the range of parameters tor testing 
became better defined. A two-dimensional thermal model ot the cell has been developed which takes into account 
the radial heat flux created by the sidewall thermometer rings. 

The cryoprobe for the ground-based measurements must provide the very stable thermal environment that allows 
high-resolution measurements to be performed as the lambda point is approached. Three temperature-controlled 
stages are placed between the cell and the 4 K liquid helium bath. To maintain a stable temperature at the cell, the 
heat leak between stages must be small and predictable. Thus, a very low pressure must be established around the 
platform to eliminate the vagaries of gaseous heat conduction between stages. With 42 vacuum seals and 65 
electrical penetrations of the cold flange for passing signals, pump lines, and fill lines into the experiment space, 
preserving the vacuum integrity of this large volume presents a challenge. Each component of the DYNAMX 
cryoprobe has been successfully operated at low temperature during the past year. 


The instrumentation for DYNAMX has progressed well. The screened room in which the ground-based experiments 
will be performed has been completed, and provides excellent protection from unwanted signals. Three high 
resolution thermometers (HRTs) have been assembled and installed in the cryoprobe, and a fourth HRT is ready for 
installation in the next phase of the experiment. Four SQUIDs are installed and operating well, so the HRTs can be 
monitored with high resolution. A fifth SQUID feedthrough is also installed on the cold flange should monitoring 
of a superconducting pressure transducer be required in the tuture. The lock-in amplifier, ratio transformer, and 
temperature controller chain of instruments for controlling the temperature of the stages has been shown to provide 
noise levels equivalent to less than 10' 6 K control uncertainty. The first implementation of the superconducting 
pressure transducer was found in testing to have shorts in the pick-up coil, so a rebuild is under way. An innovative 
DYNAMX-designed hydraulically -actuated valve for the sample cell has been fabricated and tested at liquid nitrogen 
temperatures, and will be ready for installation when required for filling the cell. This valve features a modular seat 
which may be detached from the valve stem assembly without hot work. This ease ot removal permits the valve tip 
and the valve seat to be independendy maintained and replaced. 

Education and Outreach 

The DYNAMX team members have been proactive in relating he objectives and potential benefits ot the mission 
to the public. By participating in open houses, fairs, university classes and competitions, the story ot DYNAMX 
has been delivered to thousands of citizens. 

DYNAMX has been directly involved in several educational endeavors. One graduate student and a postdoctoral 
fellow are continuing *• ± education with DYNAMX support. The Principal Investigator taught a Physics 
Department graduate seminar at the University of New Mexico that was attended for 10 weeks by 15-25 graduate 
students and faculty members; the seminar described the basic principles ot superfluidity and of the lambda 


IHIIIIIIIIII 


1 1-8 



II. MSAD Program Tasks — Flight Research 
MiiiiMiiiiitoiiiiiiiimimiHitiiiimiiiiitiiimiiMimHimitiitittiitiitiiiiiiiiiiimiaiiHiHin 


Discipline: Benchmark Science 




transition, and demonstrated die uniqueness of the DYNAMX investigation of the transition under nonequilibriuin 
conditions. The PI has aJso delivered two seminars and one invited guest lecture at UNM to convey die intellectual 
excitement ot DYNAMX. 

Anodier direct outreach involvement by DYNAMX was the sponsorship ot a competition to design a DYNAMX 
patch at a community college in St. Petersburg. Florida. The competition was advertised in the school newspaper to 
the 25.()()0-student community of St. Petersburg Junior College, with descriptions of the experiment and its 
objectives being part ol the ad. 45 entries were received by the Art Department, and the five that they judged 
superior were forwarded to the DYNAMX team. The final selection was made at a meeting of die DYNAMX team 
at JPL in July. Award ot a plaque will be made in November when die student designer visits die DYNAMX 
facility at die University of New Mexico, and again in December when die plaque will be presented at the Junior 
College in a public ceremony. 

The DYNAMX team has also participated in presentations to the public at a JPL open house, and at two county 
lairs in the Los Angeles area. These presentations generally include a DYNAMX story board explaining the 
objectives and techniques of the DYNAMX experiment. Demonstrations of phase transitions and of superfluid and 
superconducting phenomena relate the experiment to everyday phenomena of phase changes out of equilibrium. 
Thousands of brochures describing DYNAMX as part of the program of low temperature microgravity 
experimentation were provided to interested persons attending these events. Well over l(UXK) citizens attended diese 
presentations according to estimates by the JPL Public Affairs Office. 

Outreach to the scientific community has included several more actions by the DYNAMX team. All members 
participated in die pre-SCR review held in Washington in January. There the DYNAMX objectives and experiment 
plans were presented to a distinguished group of low' temperature experimentalists and tiieorists comprising the JPL 
Low Temperature Science Steering Group. The resulting enthusiastic endorsement of the mission by die review 
panel reinvigorated die DYNAMX team; the panel’s recommendations for actions to test the design of die 
DYNAMX experiment cell will be followed in detail. The DYNAMX experiment was also described to the wider 
audience of 75 low temperature scientists attending the 1994 JPL Workshop on Low Temperature Research in 
Microgravity. DYNAMX team members reached out to a very different group of scientists at the Twelfth 
Symposium on Therm ophysical Properties at Boulder in June. The PI presented a paper describing die DYNAMX 
experiment, and team members heard of many other studies of phase transitions, both Earth-bound and in orbit. The 
PI also attended a meeting of scientists studying order-disorder transitions, held at the University of California at 
Santa Barbara in August, again describing the DY ANMX experiment in a presentation. At both of diese meetings 
die team members profited from private discussions with many scientists, both for relating die nonequilibrium 
experiment to others, and learning of diverse studies diat could be relevant to die performance of the DYNAMX 
experiment and to die interpretation of the results. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 1/93 Expiration: 12/95 

Project Identification: 963-24-04-04 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals 

Duncan, R.V , Boyd, S.. Moeur. W.. Robinson. S.. Akau. R.. and Gianoulakis. S. Critical dynamics in microgravity 
International Journal on Thermophysical Properties, in press. (1994). 

Proceedings 

Duncan, R.V., Boyd, S., Moeur, W., Robinson, S., Akau, R., and Gianoulakis, S. "Critical dynamics in microgravity.’’ 
Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 


tlllllMIIIIMIIIMIMIMIMIIMIIIItllMIIIKItMIIIIIIIIIIIMMHIliliiiii I III Ml IH MHI lltl III IIIIIMIMIIMIIf IMIllltlltMtllHHHIH III I HHHill 


1 1-9 



II. MSAD Program Tasks — 

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Flight Research 

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Discipline: Benchmark Science 

iiimiiiitiinmtiiri»inHnmimimiiiMiMHmiMMiM»iiMMiiMMMiMi*»«MH»M»n»H*i*»*<**iiiiMiiMimitiiiitii*»iinn 


Presentations 

Duncan, R.V. Progress and review nt DYNAMX," Pre-SCR Review. Washington D.C.. January 1994. 

Duncan. R.V.. Boyd. S.. and Moeur. R. "Critical dynamics in microgravitv." International Symposium on Order and 
Disorder. Santa Barbara CA. 1994. 


• •* 


11-10 



II. MSAD Program Tasks — Flight Research 




Discipline: Benchmark Science 

"• iiiiiiiiiimiiiiiii 


Satellite Test of the Equivalence Principle (STEP) 

Principal Investigator: Prot. c. f. Everitt 

Stanford University 

Co-Investigators: 


P. Worden 

Stanford University 


Task Objective: 

The objective oi the Satellite Test ol the Equivalence Principle (STEP) experiment is to investigate the foundation 
ot gravitational theory, the equivalence ot inertial and gravitational mass. 

Task Description: 

The mission, now called Quick STEP, is a NASA led experiment with possible colloboration with the French 
space agency. The Quick STEP mission is a descope M2 mission with the essential Equivalence Principle and 
geodesy science intact. The overall cost has been reduced from approximately S600 m to SI 50 m. 

Task Significance: 

The STEP experiment may be thought ot as a modem version of die experiment attributed to Galileo of dropping 
two weights Irom the Leaning Tower of Pisa. Any difference in die ratio of gravitational to inerual mass causes a 
corresponding difference in the rate ot tall. The detection of a difference would substantially alter present theories of 
relativity and gravitation. 

Progress During FY 1 994 : 

Following the unsuccessful M2 study, the Satellite Test of the Equivalence Principle (STEP) proposal team 
splintered into two independent efforts: an M3 proposal headed by the European elements of the original STEP 
Study Team; and Quick STEP -- a JPL/Stanford effort emphasizing low cost and fast turn-around. This section 
oudines activities and achievements ot the Quick STEP proposal team during fiscal year 1994. 

In brief, the Quick STEP experiment is attempting to improve the current verification of die Equivalence Principle 
(a postulate ot general relauvity) by six orders ot magnitude. This is accomplished by measuring die differential 
displacement of mass pairs as they travel around the Earth on a drag compensating satellite. The masses are coaxial 
cylindrical tubes suspended on superconducting magnetic bearings. Violations of the Equivalence Principle will 
manifest as a differential displacement between the masses. 

A complete Satellite redesign (except Payload), uulizing oft-the-shelt technology wherever possible, was needed to 
reduce the complexity and cost ot the M2 approach. The Payload returned to its pre M2 six accelerometer 
configuration. This redesign started with the definition of a new’ Satellite configuration capable of being launched on 
an Orbital Science Taurus launch vehicle. The Taurus was selected for the strawman configuration because it 
presented the most constraining yet still possible scenario. The strawman configuration was finalized in November. 
Once established, the redesign turned toward three parallel activities: soliciting information about available 
spacecraft buses; analyzing the Satellite thermal/mechanical design; and defining the Payload/Spacecraft electrical 
interfaces. JPL lead the search tor an acceptable oft-the- shelf spacecraf t bus. A Request for Information (RFI) went 
out in early December to a number ot commercial aerospace companies soliciting input on a low' cost, earth 
orbiting bus meeting Quick STEPs power management, data handling, and communications needs. Several 
responses came in below the allotted 25M cost. JPL also lead the work on thermal and mechanical design analyses. 
The mechanical analysis indicated a tairlv conservative design with no major worries however, the thermal design 
pointed to heat transfer into the dewar through the warm electronics interface as an area needing further study. 

Finally, the definition of electrical interfaces and the overall system block diagram was a joint JPL/Stanford effort. 
These activities culminated in the baseline Quick STEP design furnished at the JPL/OSSI Cost Review in May and, 
in abridged format, at subsequent presentations to JPL senior management and to NASA Headquarters in June, Final 
result: excluding reserves, Quick STEPs overall mission cost, including launch, was less than MOM - a fraction of 


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II-l 1 


IL MSAD Program Tasks 

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Flight ReS ^rCh ||i(ij(i|i()tH ..........Ml... 


Discipline: Benchmark Science 


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ijie original M2 cost without compromising the primary scientific objective. 

Kev technology development underway in FY94 include drag-free control studies, trapped flux work, helium motion 
analysis and initial development of accelerometer fabrication facilities. With the exception ot the analysis and 
design of an electrostatic helium confinement system done by Peter Mason at JPL. all technology development 
activities were undertaken by Stanford team members. Drag- free control studies were the basis lor HaiPing Jms 
doctoral thesis. These analyses formed a comprehensive examination of the Quick STEP proportional thrust attitude 
control scheme leading to die definition of subsystem performance requirements, baseline thruster configuration, and 
the proposed Pavload feedback control methodology. Rodney Torii, and Paul Worden began the tabncauon and test 
of a flux microscope and niobium test samples needed to characterize how environmental effects correlate to trapped 
flux in superconductors. This work is essential to idenufy and understand factors pertinent to the superconducung 
bearing design. Computer analyses of the liquid helium surface shape under the tidal effects ot Earths gravity were 
performed by John McCuan largely for the GPB experiment but also with some relevance to Quick STEP. Helium 
motion has been identified as a potential noise source for the EP measurement. Lastly, the design and assembly ot 
fabrication facilities needed for three dimensional photolithography used m the creation ot the superconducting 
bearings, began. Matthew Bye is overseeing the development of these tools; work will conUnue well into fiscal 

1995. 


Other items of note for fiscal 1994; Stanfords new labs; the Science Review; CNES activities; and the new direcuon 
for fiscal 1995. Stanford allocated some much needed lab space to the Quick STEP team at the start ot the fisc a l 
year. This action represents a growing commitment on the part of the university toward making the Quick STC 
proposal a reality. Some of the space requires substantial redesign and reconstrucuon to house the Quick STE 
fabrication labs (and much of FY94 was spent on exactly that); this reconstruction etfort is expected to extend into 
the middle of FY95. In the interim, the design, assembly and utilization of fabrication equipment will be 
accommodated in the existing (though somewhat crowded) Quick STEP lab. A Quick STEP science review was held 
in Washington in late February. The review board concluded that Quick STEP will; strengthen die foundation ot 
general relativity; provide drastic improvement on the bounds of new interactions between light elementary 
particles; give substantial improvement in understanding the Earths gravity field. The board also agreed that Quick 
STEP is the only realistic means to achieve such a large improvement in the accuracy ot the verification ot the 
Equivalence Principle, and dial Quick STEP is feasible with only minor improvement in the current technology. 
Participation of the French Space Agency CNES has been (and still is) under consideration as a possible 
risk/cost/technology sharing partner with NASA in a version of Quick STEP dubbed GeoSTEP. DeUu s o sue a 
scenario have remained fairlv fluid. In closing. Quick STEP suffered a bit of a set back at the end ot fiscal 19 94 
when its sponsor. Microgravitv (Code U), elected to delay startup due to 1995 funding realities. While this delay is 
disappointing, it has allowed Quick STEP time to focus on technology development and pursue a CNES and/or 
other outside partnership. 


Students Funded Under Research; 

BS Students: 1 BS Degrees: 0 

MS Students: 0 MS Degrees: 0 

PhD Students: 3 PhD Degrees: 1 


Task Initiation; io /84 Expiration: 9/94 

Project Identification: 962-24-07-10 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Proceedings 

Mason P.V., Strayer. D.. Petrac. D.. Gutt. G.. Warfield. K., Worden, P., and Torii, R. "The control of liquid Helium in 
space by electrostatics for the satellite test of the equivalence principle experiment." Proceedings of the 39th Cryogenics 
Engineering Conference. Advances in Cryogenic Engineering, vol 39. 

Swartwout. M.A., and Worden. P.W. "Error analysis for the QuickSTEP." Proc. Seventh Marcel Grossman Meeting on 
General Relativity, Stanford University. 1994. 

Worden, P. "The Quick STEP instrument and science." Proceedings of the Seventh Marcel Grossman Meeting on General 
Relativity, Stanford University, 1994. 


Illl 


II— 1 2 


II. MSAD Program Tasks Flight Research Discipline: Benchmark Science 

I II I II I III It I III 1 1 1 1 1 1 1 It 1 1 1 II 


Critical Dynamics of Fluids 

Principal Investigator: Prof. Richard a. Fen-eii 

University of Maryland 

Co-Investigators: 


Dr. M. Moldover 
Dr. R.A. Wilkinson 

National Institute of Standards and Technology (NIST) 
NASA Lewis Research Center (LeRC) 


Task Objective: 

This work has a three-part objective all relating to critical phase transitions in fluids. Part one confirms the 
untested asymptotic limiting acoustic attenuation in simple liquid-vapor systems. The second part seeks to confirm 
the last dynamics ot adiabatic heat transfer in compressible liquid- vapor critical systems using a near-term space 
experiment. The third objective is to accelerate the theory of second sound attenuation at the lambda transition of 
liquid 4He. The theory would allow tor comparison to data from currently planned space experiments. 

Task Description: 

The work involves three critical fluid investigations: 1) ground-based definition of an acoustic attenuation in a pure 
liquid- vapor system space experiment, 2) Principal Investigator activities for a fast adiabatic thermal/density 
relaxation space experiment to fly on 1ML-2 in 1994, and 3) theoretical work on second sound attenuation near the 
lambda transition ot 4 He. Item 1 involves repeating the Garland &: Thoen experiment to establish technique and 
demonstrate that adiabatic heat transler losses are detectable and predictable. That knowledge wall be useful in 
defining a space experiment that wall not be hampered by the effect. It is the space experiment that would fulfill the 
first objective. 

Item 2 employs ESA's Critical Point Facility (CPF) wath visual and interferometric data. A heat pulsed wire and a 
500v charged wire are used to stimulate fast transients. This activity also allows reflight of an IML-1 experiment 
to study slow density relaxation with better geometric and thermal boundary conditions. 

Task Significance: 

Significance is based on the fundamental character of this w ? ork, all of which is driven by experiments only 
possible in low-gravity. The 4He w'ork is to bring current theory with experiments in process. The liquid- vapor 
acoustics work is to probe one ot the unverified predictions of older theory while properly accounting for adiabatic 
heat transfer loss mechanisms. The experiment on IML-2 also works toward the confirmation of the theory 
describing adiabatic heat transfer in highly compressible, strongly property varying, critical fluids. One and two 
dimensional models are still qualitative in their description of experiments. 

Progress During FY 1 994 : 

I. Ambient Temperature 
A. IML-2 

1. TEQB: A method tor projecting out the individual thermally relaxing modes of the fluid and thereby extract 
their specific relaxation rates, has been developed by Dr. Hong, and is currently being applied to the flight data. 

2. AFEQ - heat pulse: By means of a more complete theoretical treatment, an error in the formula that has been 
provided by the French group has been corrected. A comparison of the corrected formula with the flight data is 
being carried out by Dr. Greg Znnmerli. 

3. AFEQ - Voltage step: We have been able to derive an analytic expression for the electrostnctive effect as seen 
in the interterograms. The latter, by virtue of the microgravity environment, provide the first experimental evidence 
tor this effect. The post-flight delivery of photographic images wall soon make possible their comparison w ith the 
theoretically predicted fringe shifts. 




11-13 



II. MSAD Program Tasks — Flight Research Discipline: Benchmark Science 

«» 


B. Critical Ultrasonic Attenuation 

\ Theory: An analytic treatment of the corrections to dynamic scaling has been reported at the NASA workshop 
on low temperature physics (January 1994. Washington) and published in the proceedings. This theoretical work is 
also applicable to the ambient temperature phase transitions of a one component fluid. 

2. Experiment: The ongoing collaboration with Dr. Bob Kusner is starting to yield data on the damping ot sound 
waves by the effect of fast adiabatic equilibration. Visiting Professor Jayanta Bhattacharjee has determined the 
theoretical crossover temperature at which the bulk contribution to the attenuation becomes equal to the adiabatic 
surface contribution. He is in continuous contact during the course ot this experiment, providing information on 
the method of ploting the data so as to reveal and separate these two contributions, which have a quite different 
physical origin. 

C. Critical Viscosity 

We have reported on extended investigation into the feasibility of carrying out earth based measurements ot the 
viscosity of a thin fluid layer closer to the critical point than has heretofore been possible. 

D. Corrections to Dynamic Scaling 

An analytic treatment of this problem, as a contribution to the "Festschrift" for K. Kawasaki has been reported. 

II. Low Temperature 

The method of images, combined with light scattering data, makes possible an experimental prediction tor the 

Che experiment of Lipa et al. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 12/92 Expiration: 12/95 
Project Identification: 963-24-0C-25 
NASA Contract No.:nag3-1395 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Ferrell, R.A. Singular correction to dynamic scaling for a fluid. Physica A, (1994). 

Ferrell R.A. and Moldover, M R. On the limitations imposed by the Earth’s gravity on measurements of the critical 
viscosity of a one-component fluid. Ann. der Phys., (1994). 


Proceedings 

Bhattacharjee, J.K. and Ferrell. R.A. 'Corrections to dynamic scaling for the critical ultrasonic attenuation in a 
one-component fluid.” Proceedings of the NASA Workshop on Low-Temperature Physics. Washington, DC, January, 
1994. 

Ferrell R.A. and Bhattacharjee, J.K. "An experimental prediction for CHeX." Proceedings of the NASA Workshop on 
Low-Temperature Physics, Washington, DC, January. 1994. 





IMMItlllllllimiMItllllltllMIIIIMHIMIMIMIIIIIHIIIMIItlltlMIMHMUIMMIII 


11-14 


II. MSAD Program Tasks — Flight Research Discipline: Benchmark Science 




Critical Fluid Light Scattering Experiment - ZENO 


Principal Investigator: Prof. Robert w. Gammon 

University of Maryland 

Co-Investigators: 

No Co-I’s Assigned to this Task 



Task Objective: 

The objective of this project is to measure the decay rates of critical density fluctuations in a simple fluid (xenon) 
very near its liquid-vapor critical point using laser light scattering and photon correlation spectroscopy. Such 
experiments are severely limited on Earth by the presence of gravity which causes large density gradients in the 
sample. The goal is to measure fluctuation decay rates with Ipercent precision two decades closer to the critical 
point than is possible on Earth, with a temperature resolution of +/- 3 microKelvin. This will require loading the 
sample to 0.1 percent of the critical density and taking data as close as 100 microKelvin to the critical temperature 
(Tc = 289.72 K). The minimum mission time of 100 hours will allow a complete range of temperature points to 
be covered, limited by the thermal response of the thermostat and correlation averaging times. Other technical 
problems have been addressed such as multiple scattering and the effect of wetting layers. 

Task Description: 

We have demonstrated the ability to avoid multiple scattering by using a thin sample (100 microns), and a 
temperature history which can avoid wetting layers, a fast optical thermostat with microcomputer temperature 
control and measurement, and accurate sample loading. Further, the important engineering tasks of mounting the 
experiment to maintain alignment during flight have been confirmed. 

The experiment entails measurement of the scattering intensity fluctuation decay rate at two angles for each 
temperature and simultaneously recording the scattering intensities and sample turbidity (from the transmission). 
The analyzed intensity and turbidity data gives the correlation length at each temperature and locates the critical 
temperature. 

The fluctuation decay rate data set from these measurements will provide a severe test of the generalized 
hydrodynamics theories of transport coefficients in the critical region. When compared to equivalent data from 
binary liquid critical mixtures they will test the universality of critical dynamics. 

Task Significance: 

Such experiments are severely limited on Earth because gravity causes a large density gradient in the fluid due to the 
divergence of the fluid compressibility as the critical temperature is approached. The data from this experiment will 
provide a test of critical phenomena theories in a temperature realm that has not been adequately tested to date, due 
to the limitations imposed by gravity. The data tests the current theory of crossover from assymptatic behavior 
near Tc to pure background behavior far from Tc. Such a crossover theory is useful for predicting thermophysical 
properties in supercritical fluid solvents 

Progress During FY 1 994: 

Zeno apparatus and POCC team enjoyed a long and exciting flight on Columbia (STS-62), USMP-2 payload, in 
March 1994. The experiment ran for 13 days and 17 hours continuously, a probable record. The critical 
temperature of our xenon sample was located in orbit on a homogenous sample to 50 microK. During its run we 
collected 520 valid correlograms of the critical fluctuations at 35 temperatures spanning 600 mK to -100 microK 
from Tc. This covered the primary data range of 100 mK to 100 microK with three points per decade and added 
points above 100 mK in a linear steps through Tc. The average decay rate was determined from fitting all the 
correlograms at each temperature and gave the planned precision of Ipercent. 




II— 1 5 



II. MSAD Program Tasks — Flight Research Discipline: Benchmark Science 

HiiiiiiiimiimiHiiimmi * * 


The performance of the radiation control of the Optics Module temperature was excellent and we were able to 
optimize it because of the long period of holding a single Shuttle attitude. The temperature control ot the sample 
met our stringent requirements with margin: we routinely had a less than 3 microK rms noise in three hours on our 
temperature readings. 

We have been working toward understanding of our experiment in two ways since the mission. One has been 
carefully organizing the 200 Mbytes of data with some structure and indexes. Improvements were made in the speed 
and buffering of our ground software so that we could look at large blocks ot the archival data. We have corrected an 
error in our analysis of the back scattering correlograms and are now approaching critical comparisons with available 
data such as the Berg/Moldover viscosity data set. The second major activity was to do the Tc search of our sample 
in extremely stable, </+ 10 microK/month and to confirm that the sample had survived shipping, storage, and 
orbital flight, without losing more tl an O.lpercent of its gas. The laser beam alignment was maintained through 
and after the flight 


Students Funded Under Research: 


Task Initiation: 12/88 Expiration: 2/95 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-5O-0C-25 

MS Students: 

0 

MS Degrees: 

0 

NASA Contract No.nas3-25370 

PhD Students: 

5 

PhD Degrees: 

-j 

Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Li. W.B., Serge, P.N., Gammon, R.W., and Sengers, J.V. Small-angle Rayleigh scattering from nonequilibrium 
fluctuations in liquids and liquid mixtures. Physica A, Vol. 204, 399 (1994). 

Li, W.B., Sergwe, P.N., Gammon, R.W., and Sengers, J.V. Determination of the temperature and concentration 
dependence of the refractive index of a liquid mixture. J. Chem. Phys., Vol. 101, 5058 (1994). 

Presentations 

Briggs M.E., and Gammon R.W, "Photothermal deflection in a supercritical fluid.” Paper at the Conference on Optical 
Characterization of Coatings and Substrates, Symposium on Optical Interface Coatings, Grenoble, France. June 6-10, 
1994. 

Gammon, R.W.. Shaumeyer. J.N., Boulari, H., Briggs, M.E.. and Gent, D.A. ’Zeno: Critical fluid light scattering from 
xenon in microgravity. ” Invited talk at the 12th Symposium on Thermophysical Properties, Boulder, CO. June 19-24. 
1994. 




1 1— 1 6 



II. MSAD Program Tasks — Flight Research Discipline: Benchmark Science 

HHIllllHIMIItlllllllHIIIHIMIMIIIIIHIIIIHIIIIIIIHIIIMMIIIIIIMIMIMIItIMIMIIHItllllMIIIIIIIIIIIIIIMIIMIIHIMIIHIHIMIIIIIItlllllllllllltllllMllllllllllllllltlllllllllllllllllltlllllllHIlHtMIIIIHIIIIIIIIIilllllllllllll 


Heat Capacity Measurements Near the Lambda Point of Helium 


Principal Investigator: Prof. John a. Lipa 

Stanford University 

Co- Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

Central to condensed-matter physics is the phenomenon of second-order phase transitions. These come about when 
a wide class of interactive terms is added to the simple ideal gas picture of matter. To understand condensed matter 
in general, it is necessary to address the phase transition issue, since phase transitions are involved in nearly all 
interesting effects observed. Our goal is to perform the most stringent test currently feasible of the present theory 
of second- order phase transitions in the asymptotic limit as the transition is approached. To do this we will 
measure the heat capacity of helium very close to its lambda transition at 2.177 K. 

Task Description: 

To perform the heat-capacity measurements, two main requirements must be met: first we must have sufficient 
temperature resolution to establish the temperature scale, and second, we need to control the energy input to the 
sample to determine its heat capacity. 

To these ends we have been developing a new high -resolution thermometer and an advanced, multilayer thermal 
control system. The thermometer makes use of superconducting technology to achieve a resolution of about 
3x10 10 K in a 1-Hz bandwidth, and die thermal control system can achieve a power resolution approaching 10' 12 W. 

Task Significance: 

These two systems give us the capability to make measurements to the limits imposed by the Space Shutde 
environment. A third requirement is to achieve an operating temperature near the lambda point. To do this we 
make use of the superfluid helium research facility previously down on Spacelab-2 by JPL. 

Progress During FY 1 994: 

For the past 50 years scientists have been developing theories of condensed materials, the form of matter w^e are 
most familiar wadi in everyday life. These theories have had great difficulty predicting phase transiuons, especially 
a type called co-operative transiuons. Since these transitions occur in practically all forms of matter, it was a major 
challenge for the theories to predict them accurately. In the early 70s K. Wilson developed a new theory, based on 
ideas from high energy physics. This appeared to wwk very well and he was awarded the Nobel Prize for the work. 
The Lambda Point Experiment is the latest and by far the most precise test of this theory. By making 
measurements in microgravity it probes a transition 100 times more closely than is possible on the ground 
allowing substantially improved tests of the theory. The main test derived from the experiment is to compare the 
predicted and observed values of the exponent characterizing the divergence of the heat capacity at the transition. A 
second, somewhat less direct test of the theory can be made. The advantage of this test, however, is that the 
theoretical prediction is exact. To perform the test we must combine the heat capacity result with that from another 
experiment, a measurement of the behavior of the superfluid density near the transition. Theory states that the 
exponents from the two experiments must obey an exact relationship, called a scaling law. Fortunately, new high 
accuracy results have recently been obtained in this area at Stanford. Additional results from the experiment are in 
the area of the thermal response of the helium just above the transition. Here, measurements can be compared with 
the expected behavior of the thermal conductivity, based on predictions of dynamic theories of phase transitions. 

This year marked the successful completion of the LPE program. All effort during the year was directed to data 
analysis. Numerous small effects that perturb the results were characterized and corrections applied. Unfortunately, 


HI I III III 1111111111101111111111111 III III IIIttMIIMIIIIIIIIIIHIHIIMI 111 I II lllltllllllllltlflllllllllllilHIIIIIHIIHIIIIIIIIIIIIIIMlIttlllttlillllllltltllHIIMIIIHHIIIIHtlllllMIIMIHItllllMIIIIIIIMIIIItlllHIIIIHIIIIIIIIIHMIM 


11-17 


II. MSAD Program Tasks — Flight Research 


Discipline: Benchmark Science 

1111 


this process has yet to be completed in a Hilly satisfactory manner. The analysis is continuing on a time available 
basis and is expected to be complete by die end of 94. Preliminary results have been obtained in all areas. The 
value found for the exponent -.0128 ±.0004, is within die current theoretical range, and five tunes more accurate 
than before. The test of die theory is weakened by the much larger uncertainties now existing in die theoretical 
estimates. Their uncertainties are now about 15 times greater dian diat in the experiment. Thus, our result will 
stand for some time as a benchmark for comparison with new theoredcal calculations in this area. Using the 
scaling law and the latest Stanford superfluid density exponent theory predicts that the heat capacity exponent 
should be: -.01 05 ±.00024. Tins is off die observed value by about five standard deviations. The probability of this 
being a statistical accident is less than 0.1%. However, we cannot take the discrepancy too seriously just yet, 
because of the potential for systematic errors in the results. This is part ot the reason w ? e are proceeding very 
cautiously in the analysis of the flight data. The tentative result of the analysis is therefore that the theory 
continues to work even in the extreme conditions of the flight experiment. This gives us a great deal ot contidence 
that Wilson’s theory completely solves the phase transition problem. Other aspects of the theory, predicting the 
properties of condensed matter in general, need to be examined on their merits, but it is clear that the underlying 
principles are capable of explaining a very wide range of properues of ordinary matter. 


The thermal conductivity of helium was also measured in the region just above the lambda point, where it varies 
very rapidly w-ith temperature. These measurements extend the testing of phase transition dynamics by about an 
order of magnitude in temperature resolution. Reasonable agreement w'as also obtained in this area. 


Students Funded Under Research: 


Task Initiation: 10/86 Expiration: 12/93 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-24-04-05 

MS Students: 

2 

MS Degrees: 

0 

Responsible Center: jpl 

PhD Students: 

3 

PhD Degrees: 

1 



Bibliographic Citations for FY 1994: 

Journals 

Adriaans, M.J., Swanson. D.R.. and Lipa. J.A. The velocity of 2nd sound near the lambda-transition in superfluid He-4. 
Physica B, vol 194. 733-734 (1994). 

Chui. TCP.. Swanson. D.R.. Adriaans. M.J.. Nissen. J.A.. and Lipa. J.A. Temperature noise measurements in the 
cannonical ensomble. Physica B. vol 194. 23-24 (1994). 

Lipa. J.A.. Swanson. D R.. Nissen. J.A.. and Chui, T C P. Heat capacity and thermal relaxation of hulk helium very near 
the lambda point. Physica B. vol 197. 239-248 (1994). 

Lipa. J.A.. Swanson. DR.. Nissen, J.A.. and Chui. T.C.P. Lambda-point experiment in microgravity. Cyrogenics. vol 
34. no 5. 341-347 (1994). 

Proceedings 

Lipa, J.A., Adriaans. M.J., and DiPirro. M.J. "Mission concept for a new test of the universality hypothesis using order 
parameter measurements below the lambda transition of helium." Proceedings of the NASA/JPL 1994 Microgravily Low 
Temperature Physics Workshop. 

Lipa, J.A., Swanson, D.R., and Nissen, J.A. "Heat capacity and thermal relaxation of bulk helium very near the lambda 
point." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 





11-18 


II. MSAD Program Tasks — Flight Research Discipline: Benchmark Science 

* ' „„„ 


Confined Helium Experiment (CHeX) 
Principal Investigator: Pmi. John a. Lipu 


Co-Investigators: 

T. C.P. Chui 

U. E. Israelsson 
F.M. Gasparini 


Stanford University 


Jet Propulsion Laboratory (JPL) 
Jet Propulsion Laboratory (JPL) 
State University of New York, Buffalo 


Task Objective: 

Ot significant current interest in the field of condensed matter is the study of crossover behavior as a bulk system if 
confined more and more tightly in one or more dimensions. Crossover occurs when the effect of the boundaries is 
significant but not dominant. An ideal way to explore this effect is to perform measurements on films of ever 
decreasing thickness until the lower dimensional behavior is dominant. Unfortunately, it is not possible to vary the 
him thickness in most cases without totally changing the sample, making it difficult to keep track of intrinsic 
changes in the parameters. Near the lambda transition of helium die correlation length diverges, magnifying the 
ehects ot the confinement while simultaneously decreasing the importance of substrates. This situation gives us a 
unique tool to look at a diverse set ot conditions in a controlled way, opening a new window on the general 
question ot finite size phenomena in condensed matter systems. For example, at 0. 1C below the transition, the 
correlation length is on the order of a few Angstroms, whereas 10' 9 C below the transition the correlation length is 
about 0.1 mm. If we can access the temperature region very close to the transition, we will have — for die first 
time — a finite size system with a truly macroscopic length scale, allowing exceptional control of the effects of 
boundaries. This situation appears to be absolutely unique in condensed matter systems. The Confined Helium 
Experiment should lead to dramatically improved tests of the theory of finite size effects. 

Task Description: 

We plan to measure the heat capacity of helium confined between closely spaced parallel plates and compare die 
results with the bulk heat capacity data obtained on the Lambda Point Experiment (LPE). The relationship between 
the two data sets is predicted by theories of confinement. Most of the LPE flight hardware will be reused to 
perform the required measurements. 

Task Significance: 

The Confined Helium Experiment should provide a much improved test of the theory of confinement and may 
provide a firm basis tor its extension to other properties of confined materials. 


Progress During FY 1 994 : 

In the past year most of the effort has been centered on developing the confinement stack for the helium, fabricating 
and testing ot tlight prototype thermometers, and setting up the environment for flight code development. Also, at 
JPL, the tlight cryostat performance has been enhanced to better match the needs of the mission. 

The spacing in the confinement stack was changed from 100 to 50 microns on recommendation of the science 
review panel, to allow improved measurement of any potential deviations from theoretical predictions. This 
precipitated a significant ettort to fabricate the new geometry using silicon water etching technology. This has been 
successful on a sample basis, and testing for flight production is currendy in progress. In parallel, a 100 micron 
stack was subjected to a qualification shake at low temperatures with poor results. This led us to perform a major 
redesign of the stack to calorimeter fixturing, to minimize the streses on the silicon. A model of the new design was 
recendy shaken sucessfully. 





11-19 



II. MS AD Program Tasks — Flight Research 

HI HMHMHII *' 


Discipline: Benchmark Science 

mu. in II I 


Prototype thermometers were developed to give improved performance over the LPE devices. The bandwidth ot the 
devices was increased to 10 Hz to minimize the effect of charged particle radiation. This change also had the effect 
of reducing die random noise of the devices in a 1 Hz bandwidth. Their resolution was found to be about JO 
pico-Kelvins with 1 second of integration, a factor of 3 improvement over LPE. For CHEX, Uiese devices will 
probably become limited by acceleration noise on the Shuttle. Since the CHEX equirement was set close to the 
LPE observed noise, we should have margin in this area. 

For flight code development, we have set up a clone ot the flight electronics and connected it to a prototype 
instrument, and an engineering model computer. This system is now operational and code work has started. Most 
of the high level code will be ported from LPE, but the lower levels will be built from scratch. Two of the major 
changes from LPE are 100 Hz sampling capability and 1000 byte telemetry packages. Both these features have been 
demonstrated. 

The flight cryostat was modified to reduce the heat leak into the helium tank, extending its lifetime. Also the 
transfer procedure was upgraded to reduce the thermal transients on the refills, allowing a lower level to be reached 
without impacting the experiment. This latter improvement alleviates problems with cryostat mamenance on die 
pad. A 12 day hold time in orbit has been achieved, comfortably accommodating the science objectives. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 12/92 Expiration: 12/97 
Project Identification: 963-24-04-02 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals 

Coleman. M. and Lipa. J.A. Heat capacity of helium confined to 8 micron cylinders near the lambda point. Phys. Rev. 
Lett,, m press, (December 1994). 

Nissen, J.A., Chui. T.C.P., and Lipa. J.A. The specific-heat of confined helium near the lambda-point. Physics B. vol 
194, 615-616 (1994). 

Nissen. J.A.. Chui. TCP.. and Lipa. J.A. The specific-heat of confined helium near the lambda point. J. Low Temp. 

Phys.. vol 92. 353-366 (1993). 

Swanson. D.R.. Nissan, J.A.. Chui. T.C.P.. Williamson. P.R.. and Lipa. J.A. Optimization and performance of 
high-resolution thermometers in low-earth orbit. Physica B, vol 194, 25-26 (1994). 

Proceedings 

Nissen J.A., Swanson, D.R.. Qin, X. Salvino. D.. Lipa, J.A., Chui, T.C.P.. Israelsson, U., and Gaspanm. F.ML Hie 
confined helium experiment in microgravity." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics 
Workshop. 


itmiiMiimii 


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11-20 


II. MSAD Program Tasks — Flight Research 

1 - - 


Critical Fluid Thermal Equilibrium Dynamics 


Principal Investigator: Dr. r. a. Wilkinson 

NASA Lewis Research Center (LeRC) 

Co-Investigators: 


Dr. R. Berg 
Dr. M. Moldover 

National Institute of Standards and Technology (NIST) 

Prof. R. Gammon 

National Institute ol Standards and Technology (NIST) 

Prof. ]. Straub 

T t m/ 

University of Maryland 
Technical University of Munich, DE 


Task Description: 

Facility oTlMI ^ “ bsen ^ usln S interferometry, visualization, and transmission using ESA's Critical Point 

Task Significance: 

Progress During FY 1994: 

r z r r e 7 w,rt — a «* 

time constants of the slowest relaxarinn mn^ f - ' V °^ servatIon indicated that the observed 

amount scaller in ^ 1 mm„ T' I™ T "* *■*“ “>» I"*** *«■ an unusual 

misleading. d,e pal has urn ton kT S * **** “ d «” » ** “* «l*nmem was 

msulis w,ih more ,L, ttellt^SS * rC ' ,,ghl ” '" 4 ° n ,ML ' 2 sto ’ ra be “ n 

s,T„ h „Ta:,r" y ™ c ”'™ * ne * — “ - sc sr£ lcccc*. 

This work has merged into the Ferrell Adiabatic Fast Equilibration experiment activity on IML-2. 


* 





tut 


11-21 



. Discipline: Benchmark Science 

II. MSAD P,o 8 .am Task,- High. K = h 


Task Initiation: i/89 Expiration: 9/93 

Students Funded Under Research: Project Identification: 963-24-05-06 

Responsible Center: LeRC 


»«••••*•"• I,,MM MIMWPIMtWMHH 







11-22 



II. MSAD Program Tasks — Flight Research Discipline: Biotechnology 

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Protein Crystal Growth Vapor-Diffusion Flight Hardware and Facility 


Principal Investigator: Dr. Daniel c. Carter 

NASA Marshall Space Flight Center (MSFC) 

Co-Investigators: 


j. Ho (X. He) 
T. Miller 

NASA Marshall Space Flight Center (MSFC) 
NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

The major objectives ot this research are to provide a user-friendly interface between ground-based and flight protein 
crystal growth hardware, increased (common) availability of flight hardware, elimination of late access requirement, 
and individual loading by the principal investigator. 

Task Description: 

Initially, these experiments will be conducted with a small hand-held unit using human serum albumin. 

Subsequent tests will involve the growth ot Fab 3D6, a human anti-HIV antibody. When the necessary tests and 
procedures have been completed with the hand-held unit, facility flight hardware will be constructed. The 
inicrogravity experiments will be conducted in two stages. In the first stage, the hand-held unit will be flown to 
test the overall concept, refine the hardware if necessary, and establish protocols for later scale-ups with multi-user 
hardware. The design would then be configured to accomodate several trays and interface directly with the existing 
refrigerator/incubator module (R/EM) and thermal environment system (TES) temperature control hardwares without 
modification. In addition, a new plastic tray will be developed to provide additional advantages in optical, storage, 
and hardware interfaces with a potential increase in the number of experiments in each tray assembly (VDT). In the 
early periods ot the second stage, the facility hardware will utilize cryogenics only for improvements in experiment 
pre-loading efficiency. In order to proceed with the cryogenic aspects of the second stage, a sub-zero freezer will 
have to be developed. When flight freezers are utilized, the hardware is left in the activation configuration, and 
protein crystallization proceeds alter the experiments are withdrawn from the freezer and placed in the temperature 
control units. 

Task Significance: 

This research is concerned with the development of a protein crystal growth system for microgravity which provides 
for rapid, convenient access to the microgravity environment and a greater number of samples, and eliminates 
numerous problems associated with logistics and handling of the current flight hardware. 

Progress During FY 1 994 : 

1. Over the course of the past year the Hand-Held Protein Crystallization Apparatus for Microgravity (HH-PCAM) 
hardware was constructed, flight approved, and tested as a mid-deck hand-held experiment during STS-62. The flight 
contained tour HH-PCAMs with a total capacity of 96 individual vapor diffusion protein crystallization chambers. 
The operation and crystallization experiments performed flawlessly. Some of the crystals grown were of the highest 
quality. 

2. Based on the success ot HH-PCAM as the proof of concept, facility hardware has been designed, and a prototype 
contructed and tested. Complete flight drawings have been approved and 18 flight units of the facility hardware 
constructed. The hardware, with a total of 378 individual experimetns, has unprecedented capacity within the STES. 
Additionally, it has been designed to function in a cryogenic capacity within JSC flight dewars, as well as provide a 
flexible glove box interface. The cylindrical PCAMs are manifested on three upcoming flights in 1995. 

3. Procedures have been established to solicit and review crystallization experiments proposed for the facility. A 
co-investigator group has been established. 


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11-23 



II. MSAD Program Tasks — Flight Research 

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Discipline: Biotechnology 

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4 Another area of the flight experiment series was initiated as a request for flight experiments which could take 
advantage of the longer duration, early MIR flights. The Dialysis Crystallization Apparatus tor Microgravity was 
proposed and developed. The hardware is specifically designed to take advantage of the diffusive properties of liquids 
at zero-g to control inexpensively and effectively the critical approach to supersaturation. The new hardware has 
numerous advantages such as not requiring activation or deactivation by the crew. Current design allows 81 large 
volume diffusion cells shich can accommodate a variety of crystallization techniques and works equally well tor 
small molecule and protein crystallization. The hardware has great potential fora variety ot ground-based 
applications as well. 


Students Funded Under Research: Task Initiation: 5/93 Expiration, n/97 

Project Identification: 963-23-08-08 
NASA Contract No.: in-house 

Responsible Center: msfc 


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11-24 


II. MSAD Program Tasks — Flight Research Discipline: Biotechnology 

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Advanced High Brilliance X-Ray Source 


PRINCIPAL INVESTIGATOR: Dr. Daniel C. Carter NASA Marshall Space Flight Center (MSFC) 


CO-INVESTIGATORS! 

W. Gibson State University of New York, Albany 

M. Kumakhov I V. Kurchatov Institute of Atomic Energy 

J. Ho (X. He) NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

The primary objective ot this research is to produce the first x-ray generator and Kumakhov lens system optimized 
in design for 8.0 KeV x-rays. 

Task Description: 

The x-ray unit will be integrated with existing x-ray diffraction equipment at Marshall Space Flight Center to 
produce a diffraction facility with the most advanced laboratory x-ray source for application in crystallography in the 
world. The approach to complete the task will be to produce intense small cross section parallel x-ray beams for 
structural analysis using third-generation Kumakhov optics. 

Task Significance: 

Protein crystallography is currently the most powerful method for the determination of the three-dimensional 
structure ot proteins and other macromolecules. This method usually requires crystals which are relatively large in 
size and which possess a reasonably high degree of internal order. This research is concerned with the development 
ot an extremely bright x-ray source for application in the evaluation and determination of the atomic structure of 
crystalline matter from both ground-based and current flight experiment activities. 

Progress During FY 1 994: 

The prototype x-ray lenses in this study are close packed capillary tubes with changing cross section along their 
entire length from input to output. An armagement of tubes with the appropriate shape can collect and guide x-rays 
from a point source to produce an intense parallel beam. 

1 . Stage I optic completed: The first in a senes of three x-ray concentrators has been completed and tested. 

Although not optimum in terms ot transmission efficiency and focal length, this prototype optic already shows an 
excellent intensity increase of a factor of 34. 

2. High flux microtocus source acquired and tested: A unique microfocus x-ray source was obtained from the 
Russian collaborators and was tested at the Center for X-ray Optics at SUNY, Albany. The measured source 
intensity was 30 watts at Cu Ka (8.04 KeV) in a 5 pin spot which is at least six times greater than is available in 
standard commercial sources. 

3. Manufacturing capability upgraded: A computerized capillary drawing fixture has been installed, replacing 
manual operation, and modelling has progressed to the point that actual x-ray performance can be accurately 
predicted. Simulation shows that an optimum shape would give enhancement of about 650 over circular 
collimation. 




11-2 5 


II. MSAD Program Tasks — Flight Research 

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Discipline: Biotechnology 

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Students Funded Under Research: Task Initiation: 4/93 Expiration: 3/96 

Project Identification: 963-40-20-30 
NASA Contract No.: in-house 

Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Ullrich. J.B.. Gibson. W.M.. Gubarev. M.V.. and MacDonald. C.A. Potential for concentration ot synchrotron beams 
with capillary optics. Nuclear Instruments and Methods, vol. A347. 401-406 (1994). 

Ullrich, J.B.. Kovanstev. V.. and MacDonald. C.A. Measurements of polycapillary X-ray optics. J. Appl. Phys., vol. 74. 
5933-5939 (1993). 

Proceedings 

Gibson. W.M., and MacDonald. C.A. "Polycapillary Kumakhov optics: a status report.” X-Ray and UV Detectors, SPIfc 
Proc., 2278. 156-167 (1994). 

MacDonald. C.A.. Abreu. C.C.. Budkov. S.. Chen. H . Fu. X.. Gibson. W.M.. Kardiawarman. Karnaukhov. A.. Ponomarev. 
I.Y.. Rath, B.K.. Ullrich. J.B.. Vartanian. M.. and Xiao. Q.F. "Quantitative measurements ot the pertormance of capillary 
X-ray optics." Multilayer and Grazing Incidence X-ray/KUV Optics II. SPIE Proc.. 2011 (1993). 

Ullrich. J.B.. Ponomarev. I.Y.. Gubarev. M.V.. Gao. N.. Xiao. Q.F., and Gibson. W.M. "Development of monolithic 
capillary optics for X-ray diffraction applications." X-Ray and UV Detectors. SPIE Proc.. 2278, 148-155 (1994). 

Wentink. R.. Carbone. J., Aloise. D.. Gibson. W.M.. MacDonald. C.A.. Hanley. Q.E.. Fields. R.E.. and Denton. M B. 
"Charge injection device (CID) technology: an imaging solution for photon and particle imaging applications." SPIE 
Proc.. 2279 (1994). 


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II. MSAD Program Tasks — Flight Research Discipline: Biotechnology 

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Protein Crystal Growth in Microgravity 

Principal Investigator: Dr. Lawrence j. DeLucas 

University of Alabama. Birmingham 

Co-Investigators: 


Noted Guest Investigators 

See List, Appendix B 


Task Objective: 

The objectives of this research are: to develop improved protein crystal growth flight hardware to produce larger, 
high quality protein crystals in microgravity lor use in the determination of protein molecular structures for 
applications in medicine, drug design, agriculture, and the biological sciences; and to understand the 
dynamics/process of protein crystal growth. 

Task Description: 

A breadboard system will be developed that utilizes light scattering to detect the onset of crystal nucleation. This 
optical monitonng system will be developed for both vapor diffusion and temperature-induced crystallization 
techniques. This hardware will be used to grow crystals with dynamic control of the appropriate crystallization 
parameter (i.e., temperature or vapor diffusion). The crystals will be evaluated microscopically and, from this 
evaluation, the best crystals will be used for x-ray data collection using the facilities available within the CMC. 
The data will then be compared with the best data obtained from ground-based crystals, and an evaluation of the 
usefulness of these dynamically-controlled systems will be made. 


Task Significance: 

Larger, high quality protein crystals may be used in molecular structure determinations for applications in medicine, 
drug design, agriculture, and the biological sciences. 


Progress During FY 1 994: 

• DCPCG-Vapor Diffusion 

Automated dynamic control of protein crystal growth using controlled vapor diffusion has been achieved. Two 
primary devices have been constructed to prove the feasibility and utility of this approach. The main features of the 
first device include the ability to: evaporate water from a growth solution at virtually any rate, quantitatively 
monitor the water evaporated over time, perform up to 40 different evaporation profiles simultaneously, and use 
feedback from sensors to maintain or modify a given evaporation profile. This device uses a microcomputer, 
humidity sensors and various analog and digital interfaces under the control of custom software to effect the desired 
evaporation profiles. The first device has been used to show the dependence of the evaporation profile on the size 
and number of crystals obtained for a given solution condition. This device has proved extremely useful in showing 
that the crystals obtained for a given condition greatly depend upon the rate at which water is evaporated from a 
growth solution. The main features of the second device includes the ability to: evaporate water from a growth 
solution at virtually any rate, quantitatively monitor the water evaporated over time, detect and respond to nucleation 
events sensed by laser scattering, and perform six replicates of one user defined evaporation profile utilizing a 
Master/Slave configuration. This device also includes a microcomputer, a humidity sensor, various analog and 
digital interfaces, and custom software for controlling the system. Additionally, a laser scattering subsystem 
consisting of a laser, photodetector and fiber optics is used to detect nucleation events. This recently constructed 
device is currently being used to show the improvement that detection of nucleation and modification of the 
evaporation profile while the experiment is in progress can have on the crystal growth results. 


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11-2 7 


II. MSAD Program Tasks — Flight Research Discipline: Biotechnology 

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• DCPCG-Temperature 

Automated dynamic control of protein crystal growth using temperature as a control parameter has been achieved. 
Results were presented at the 46th Annual Southeastern Regional Meeting ot the American Chemical Society held 
in Birmingham, AL dunng October 16*19, 1994. The main features of the device include thermoelectric heating and 
cooling between about 5-50°C ± 0.1 °C, laser scattenng detection of nucleation, and user programmable temperature 
profiles for automated response to nucleation and subsequent growth conditions. The device has been used to prove 
the detection and reversibility of nucleation and the dependence ot nucleation on various solution conditions such as 
protein concentration, pH and crystallizing agent concentration. The initial version ot the device provided unitorm 
temperature control of the entire protein solution volume. That feature proved to be usetul tor studying nucleation 
response to solution conditions, but was unsatisfactory tor producing crystals with size suitable for x-ray analysis. 
Uniform temperature simply produces too many growth sites and a resultant shower ot crystals. Second and third 
versions of the device are presently under study in which a localized temperature gradient (or sting) has been 
incorporated in an attempt to minimize the number of growth sites, thereby producing larger crystals. These 
systems are currently being tested; preliminary results are encouraging in that fewer but larger crystals have been 
grown. 


Students Funded Under Research: 

Task Initiation: 4/93 Expiration: 3/98 

BS Students: 

0 

BS Degrees: 0 

Project Identification: 963-23-08-06 

MS Students: 

1 

MS Degrees: 1 

NASA Contract No.nass-39762 

PhD Students: 

3 

PhD Degrees: 0 

Responsible Center: msfc 


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11-28 


II. MSAD Program Tasks — Flight Research Discipline: Biotechnology 


Electrophoretic Separation of Cells and Particles from Rat Pituitary 

PRINCIPAL Investigator; Dr. Wesley C. Hymer Pennsylvania State University 


Co-Investigators: 

A. Mastro Pennsylvania State University 

R. Grindeland NASA Ames Research Center (ARC) 

R. Snyder NASA Marshall Space Right Center (MSFC) 


Task Objective: 

The objectives are to separate (1) pituitary cells and (2) hormone containing granules by tree flow electrophoresis 
using the Japanese Free-tlow Electrophoresis Unit (FFEU) on Earth and in space. 

Task Description: 

To accomplish these objectives it is necessary to: (1) optimize conditions for maintaining live pituitary cells in 
Japanese cell culture kits (CCK) for 21 days; (2) remove cells fron the CCK in space and fractionate them by 
electrophoresis; and (3) break open the cells in space and fractionate the lysate by electrophoresis to obtain 
hormone-containing granules. These procedures must be done in such a way as to be executable in flight. It is also 
necessary to modify existing technologies in order to analyze different hormone forms of growth hormone and 
prolactin in these fractions. Both hormones will be assayed by both immune and biological assays. 

Because FY94 was the flight year for this experiment, the logistics associated with conducting pre-flight, flight and 
postflight operations was also required. 

Task Significance: 

(1) Pituitary growth hormone and prolactin are required for proper function of the bone, muscle and immune 
systems. Because these systems are modified by spaceflight, and because the results from 4 previous space 
experiments show that the biological activities of growth hormone and prolactin are diminished during and after 
spaceflight, this experiment is intended to probe the mechanism(s) by which these changes occur. 

(2) Biotechnology research on earth routinely utilizes coupled technologies to meet focused objectives. Coupled 
technologies are difficult to accomplish in a low gravity environment; yet these will be routine on Space Station 
Alpha. This experiment serves as a prototype for such activities. 

Progress During FY1994: 

(1) The flight experiment was carried out during the IML-2 mission (July, 1994). 

(2) Preliminary data document microgravity-induced changes in growth hormone cell structure and function. 

(3) Coupled technology procedures were successfully carried out in flight. 

(4) Preliminary data regarding growth hormone are to be presented at the Darmstadt, Germany meeting in 
November, 1994. 

(5) Active postflight analysis continues. 

(6) A repetition of the entire flight experiment on both the ground and flight FFEU hardware in Japan is being 
planned. 


11-29 



II. MSAD Program Tasks — Flight Research 

Mill Ill IIIIIHItlll 


Discipline: Biotechnology 

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Students Funded Under Research: Task Initiation: 12/89 Expiration. 6/95 

Project Identification: 963-23-oi-oi 
NASA Contract No.: nags-953 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Hymer. W.C., Shellenberger, K„ and Grindeland. R. Pituitary cells in space. Adv. Space Res., vol. 14. 61-70 (1994). 

Books . w . 

Perez. F.M.. Deaver. D.R., and Hymer, W.C. “Why use a flow cytometer for cell analysts? in Endocrine Research 

Techniques." Edited by: F. de Pablo, C.G. Scanes, and B.D. Weintraub Academic Press. Inc., pp 157-179, 1993. 

Presentations 

Gudi, T., and Hymer, W.C. "GRP94: A molecular chaperone in rat pituitary tissue." Thirteenth Summer Symposium in 
Molecular Biology, The Pennsylvania State University, University Park. PA. August, 1994. 


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11-30 



IL MSAD Program Tasks — Flight Research Discipline: Biotechnology 


An Observable Protein Crystal Growth Flight Apparatus 


Principal Investigator: Dr. Alexander McPherson, Jr. 

University of California, Riverside 

Co-Investigators: 


S. Koszelak 

University of California, Riverside 

A. Malkin 

University of California, Riverside 

Y. Kuznetsov 

University of California, Riverside 

A. Kathman 

Teledyne Brown Engineering 

A. Dodds 

University of California, Riverside 

M. Garavito 

University of Chicago 


Task Objective: 

The task objective is to initiate research and development efforts in the area of macromolecular crystal growth, and 
specifically focused on the direct observation of the relevant phenomena as they pertain to the design and ultimate 
flight of an observable protein crystal growth apparatus (OPCGA). 

Task Description: 

The experiment objective included the identification and characterization of candidate biochemical systems that 
included proteins, nucleic acids, and viruses. It further included the construction of an optical platform that would 
be suitable for detailed interferometric analysis of protein crystal growth experiments and the visualization of 
concentration fields, the time lapse microphotography of macromolecular crystals, and the further characterization of 
the mechanisms and fundamental parameters that determine the features of macromolecular crystal growth. 

Task Significance: 

The need for structural information on biological macromolecules is of paramount importance to the emerging field 
of biotechnology. Such information provides the basis for the rational design of pharmaceuticals, the determination 
of enzymatic mechanisms and the engineering of proteins to enhance or modify their function. The value of X-ray 
crystallography to provide structural information at atomic resolution is unsurpassed. This technique does, 
however, depend on the availability of crystals for the macromolecule under study, and furthermore, which possess a 
high degree of internal order and suitable size and shape to allow the accurate collection of X-ray diffraction data. 

Typically, crystals grown in the earth's gravitational field suffer from one or more types of flaws which decrease the 
structural information that can be derived from them. These imperfections include the relatively simple, but 
nonetheless adverse, problem of intergrowth. In a 1-g field several crystals which nucleate independently, sediment 
to the bottom of the growth chamber where they inter grow into a mass not suitable for X-ray diffraction analysis. 
Such intergrowth or the appearance of satellite crystals, which were earlier thought to occur by nucleation at the 
sides of defects in pre -exiting crystals, have been shown to be almost exclusively due to the effects of sedimentation 
and inter growth. The value of a microgravity environment for the elimination of sedimentation in the preparation 
of these crystals is obvious. Early experiments conducted on board the space shuttle clearly indicated such benefits. 
They also provided the impetus for other researchers to design experiments and procedures for mimicking the effect 
of microgravity in ground based experiments. The development of methods for successfully growing protein 
crystals in gels is an example of such activities. 

Progress During FY 1 994: 

Research continued with the objective of defining the critical science requirements for design and construction of an 
advanced protein crystallization facility for space station, and other carriers likely to be available in the interim. 

This research has included time lapse video microscopy of protein crystal growth, the application of quasi elastic 
light scattering to prenucleation events, and more recently the introduction of both Mach-Zehnder and Michelson 


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II— 3 1 




II. MSAD Program Tasks — Flight Research 

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Discipline: Biotechnology 


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interferometry. Substantial progress has been made in advancing these techniques tor macromolecular 
crystallization. The size of the critical nucleus, surface tree energy, and activation energy have been estimated tor 
several systems that include both viruses and proteins. Interferometry has been used to visualize growth sources on 
growing crystal surfaces, to measure tangential and normal growth rates, and to measure the heights and slopes ot 
growth hillocks arising from dislocations. 


The International Microgravity Laboratory (IML-2) mission was successfully completed in July and the results have 
been analyzed by a number of techniques including X-ray diffraction. Some substantial successes in growing 
protein and virus crystals were achieved and a report ot these results lor publication is now being assembled. Most 
important among these were (1) the demonstration that cubic crystals of satellite tobacco mosaic virus, and both 
rhombohedral and hexagonal crystals of the plant seed protein canavalin, diffracted to significantly higher resolution 
than ground grown controls. (2) The largest particle that has been attempted was successlully crystallized tor the 
first time. This was the plant virus Turnip Yellow Mosaic Virus (TYMV). Importantly, some distinctive 
alterations in the morphology of the space grown crystals were clearly evident, (3) Unique morphological changes 
were seen for microgavity grown crystals ot hexagonal canavalin and tuna cytochrome c. 


Students Funded Under Research: Task Initiation: 5/93 Expiration: 5/98 

Project Identification: 963-23-08-07 
NASA Contract No.:nas8-3963 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Cudney. R., and McPherson, A. Screening and optimization strategies for macrmolecular crystal growth. Acta Cryst.. vol. 
D50. 414-423 (1994). 

Day, J., Ban, N., Patel, S., Larson. S.B., and McPherson, A. Characterization of crystals of satellite panicum mosaic 
virus. J. Mol. Biol., vol. 238, 849-851 (1994). 

DeLucas, L.J., Long, M.M., Moore, K.M., Rosenblum, W.M., Bray, T.L., Smith C., Carson, M., Narayana. S.V.L., Carter. 
D., Clark, D., Clark, Jr., A.D.. Nanni. R.G.. Ding J., Jacobo-Molina, A., Kamer. G.. Hughes, S.H., Arnold, E.. Einspahr, 
HM., Clancy, L.L.. Rao, G.S.J.. Cook, P.F., Harris. B.G., Munson, S.H., Finzel. B.C., McPherson, A., Weber. P.C., 
Lewandowski. F., Nagabhushan, T.L., Trotta, P.P., Reichert, P., Navia, M.A., Wilson, K.P., Thomson, J.A.. Richards, 
R.R., Bowersox, K.D., Meade, C.J.. Baker, E.S., Bishop, S.P., Dunbar, B .J., Trinh, E., Prahl, J., Sacco, Jr.. A., and Bugg, 
C.E. Recent results and new hardware developments for protein crystal growth in microgravity. J. Cryst. Growth, vol. 

135, 183-195 (1994). 

Felden, B., Florentz, C., Giege, R.. and McPherson. A. A histidinylatable tRNA-like fold at the 3’ -end ot satellite tobacco 
mosaic virus RNA. Nucleic Acids Res., vol. 22. 2882-2886 (1994). 

Larson, S.B., Greenwood, A., Cascio, D., Day, J., and McPherson, A. The refined molecular structure of pig pancreatic 
a-amylase at 2.1 A resolution. J. Mol. Biol., vol. 235, 1560-1584 (1994). 

Malkin, A., and McPherson, A. Light scattering investigations of nucleation processes and kinetics of crystallization in 
macromolecular systems. Acta Cryst., vol. D50, 385-395 (1994) 

Patel, S., Cudney, and McPherson, A. Crystallographic characterization and molecular symmetry ol edestin. a legumm 
from hemp. J. Mol. Biol., vol. 235, 361-363 (1994). 

Patel, S., Cudney, R., and McPherson, A. Using a silica hydrogel for macromolecular crystallization. Acta Cryst., vol. 
D50, 479-483 (1994). 

II 


11-32 



II. MSAD Program Tasks — Flight Research 


Discipline: Biotechnology 

Flllllt 


Weis era her. K.H.. Newhouse. Y.M.. and McPherson. A. Crystallization and preliminary X-ray analysis of human plasma 
apolipoprolein C-l J. Mol. Biol., vol. 236, 382-384 (1994). 

Proceedings 

Ban. N.H., Escobar, C.. Gaarcia. R.. Hasel. K., Day. J.. Greenwood. A., and McPherson, A. "Crystal structures of an 
anti-idiotypic fab and of the idiotype-anti-idiotype complex." Proc. Natl. Acad. Sci. USA. 91. 1604-1609 (1994). 

B o o k s 

McPherson, A. "Crystallization ot Biological Macromolecules'’ in "Handbook of Crystal Growth." Edited by: T. J. Hurle 
vol. 2 A, pp 419-463. 1994. 

McPherson. A "The Role ol X-ray Crystallography in Structure Based Rational Drue Design" in "Rational Drug Design.” 
CRC Press. 1994 


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11-33 



II. MSAD Program Tasks — Flight Research 


Discipline: Biotechnology 

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Electrophoresis Technology 

PRINCIPAL Investigator: Dr. Robert S. Snyder NASA Marshall Space Flight Center (MSFC) 


Co-Investigators: 

P. Rhodes 
T. Miller 
G. Roberts 


NASA Marshall Space Flight Center (MSFC) 
NASA Marshall Space Flight Center (MSFC) 
Roberts Associates, Inc. 


Task Objective: 

The task objectives are to study the effects of sample concentration and dielectric constant on sample stream 
distortion and the limits of the electrohydrodynamic stability of the sample stream in the absence ol shear flow. 

Task Description: 

The electrophoresis separation process can be considered to be simple in concept, but flows local to the sample 
filament produced by applied electric field have not been considered. These electrohydrodynamical flows, formulated 
by G.I. Taylor in 1965 for drops suspended in various liquids, distort the sample stream and limit the separation. In 
addition, electroosmosis and viscous flow, which are inherent in the continuous-flow electrophoresis device, 
combine to disturb further the process. Electroosmosis causes a flow in the chamber cross section which directly 
distorts the sample stream, which viscous flow causes a parabolic profile to develop in the flow plane. These flows 
distort the electrophoretic migration of samples by causing a varying residence time across the thickness ot the 
chamber. Thus, sample constituents at the center plan will be in the electric field a different length of time and 
hence move more or less than comparable constituents closer to the chamber wall. 

Both horizontal and vertical laboratory electrophoresis test chambers have been built to test the basic premise of 
continuous-flow electrophoresis that removal of buoyancy-induced thermal convection caused by axial and lateral 
temperature gradients will result in improved performance of these instruments in space. These gravity-dependent 
phenomena disturb the rectilinear flow in the separation chamber when high-voltage gradients and/or thick chambers 
are sued, but distortion of the injected sample stream due to electrohydrodynamic effects causes major broadening ot 
the separated bands observed in these chambers. 

The initial part of the proposed space experiment was planned to be done in the French electrophoresis hardware 
(RAMSES) on the second International Microgravity Laboratory (IML-2). This hardware has the capability ot 
applying the required voltage at 1,000 Hz which can permit the dielectric dependence to be determined. Two 
different frequencies were planned to vary the dielectric constant of the samples and the cross-section illuminator 
used to show the sample filament cross section, and recorded photographically. This experiment was not done on 
IML-2 because of a hardware failure on orbit. 

The experiment can be accommodated on a later RAMSES flight, or available TEXUS electrophoresis hardware, 
with its cross-section illuminator, can be supplied with the required high-frequency power supply. These 
measurements can then be completed during a short-duration rocket flight. Additional opportunities are being 
evaluated. 

Task Significance: 

Since the Continuous Flow Electrophoresis System (CFES) built by the McDonnell Douglas Astronautics 
Company achieved results in space on seven shuttle missions that were influenced by electrohydrodynamics, these 
scientific phenomena are a critical part of electrophoresis in space. The severity of sample distortion due to 
dielectric constant variations is poorly known in the laboratory because of the concurrent sample concentration 

effect 


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11-34 



II. MSAD Program Tasks — Flight Research 

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Discipline: Biotechnology 

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Progress During FY 1 994 : 

Most activities during FY94 were directed toward adapting our requirements to the RAMSES design tor LML-2 
which flew in July. The borate buffer preferred by the European Principal Investigators (Pis) was optimized for our 
polystyrene latex samples. A prototype RAMSES chamber was built in which we tested our latex sample stream 
distortions and also performed a separation of two different latex particle sizes. This chamber was also used in crew 
training for our portion of the RAMSES experiment. 

We have completed expenments using our miniature electrohydrodvnamic test chamber w'here we observed a 
conclusive dielectric etlect on the sample studied. We have taken these results and compared them to the dielectric 
constant ettect observed in drop determination of immiscible fluids. We will now' quantify a selection of 
polystyrene latex particles with respect to Debye length, zeta potential, and particle radius. The dielectric constant 
ol this selection can then be determined as a function of frequency by observation of sample stream distortion in our 
chamber. 


Students Funded Under Research: Task Initiation: 9/89 Expiration: 9/95 

Project Identification: 963-23-08-04 
NASA Contract No.: in-house 

Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Books 

Rhodes, P.H., and Snyder. R.S. “Chapter 3, Theoretical and Experimental Studies on the Stabilization of Hydrodynamic 
Flow in Free Fluid Electrophoresis” in ' Cell Electrophoresis." Edited by: J. Bauer CRC Press. Inc.. 1994. 

Presentations 

Rhodes, P.H., Snyder. R.S.. and Roberts, G O. "Role of dielectric constant in electrohydrodynamics of conducting fluids.” 
2nd Microgravity Fluid Physics Conference, Cleveland. OH, June 21-23, 1994. 

Snyder, R.S., and Rhodes, P.H. "The NASA electrophoresis program/' The International Aerospace Congress, IAC ‘94. 
Moscow, Russia. August 15-19, 1994. 


miimiiiMii 


11-3 5 



II. MSAD Program Tasks — 

III! 


Flight Research Discipline: Combustion Science 

in him mi. ..mum.. 


Scientific Support for an Orbiter Middeck Experiment on Solid Surface Combustion 
PRINCIPAL Investigator: Prof. Robert A. Altenkirch Mississippi State University 

CO-INVESTIGATORS! 

No Co-fs Assigned to this Task 


Task Objective: 

The objective of this flight experiment is to determine the controlling mechanisms ol flames spreading over solid 
fuels in the absence of buoyant or externally imposed, gas-phase flows. Ground-based testing ot flame spreading in 
quiescent microgravity environments has identified the qualitative importance ot radiative heat losses in determining 
flame spread rates, but these tests are too short in duration to establish spreading flames without residual eflects ot 
the ignition process. 

Task Description: 

The Solid Surface Combustion Experiment (SSCE) is to be built and flown to pertorm a minimum ol eight 
experiments. The experiments are to consist of five flame spreading tests using a thin fuel, varying the 
atmospheric composition and pressure, then three additional tests using a thick fuel with tewer variations ol the 
same parameters. In these tests, measurements of the fuel and flame temperature are to be made and recorded, and 
the flames are to be photographed, using motion picture film. A parallel elfort is to be made to develop a complex 
numerical model of the opposed-flow flame spread problem, including the important effects ol surface and gas-phase 
radiative losses. Finally, a detailed, quantitative comparison ol experimental and computed results lor flame 
spreading over thin and thick fuels in various oxidizer and pressure environments is to be perf ormed including 
comparisons of spread rate, temperature and heat transler he Ids and the structure ot the flame. 

Task Significance: 

The spreading of flames over solid fuels is a fundamental combustion problem that has practical significance in the 
prevention and control of fires. Flame spreading in normal gravity is usually dominated by buoyant air flow that 
introduces a significant complexity into the fundamental models ot the phenomena. Experiments conducted in the 
microgravity environment nearly eliminate this complexity, providing a more tundamental scenario lor the 
development of flame spreading theory. 

Progress During FY 1994: 

During the year, the seventh flight of the Solid Surface Combustion Experiment (SSCE) was completed aboard the 
Shuttle Discovery during the STS-64 Mission. This flight was the second for the PMMA (polymethyl 
methacrylate) thick fuel phase of the flight program in which the fuel was ignited and burned in an atmosphere of 
50% Oxygen/ 50% Nitrogen at a pressure of 2.0 times normal atmospheric pressure. 

Other major accomplishments of the year include: 

1. The results of the sixth flight of the SSCE, the first to use PMMA, included the observation that the 
thermocouples, near and imbedded in the fuel samples to measure temperatures, may have influenced the spreading 
flame by absorbing or conducting heat. A series of ground based tests was conducted to evaluate this influence, 
which has not been previously observed. Based on these tests the flight configuration ol the thermocouples lor this 
year's flight was changed from the original design to use much smaller thermocouple wire (l/5th the size ol the 
original) for the gas-phase measurements. Preliminary studies ol the most recent flight results show no indication 
of interference from the gas-phase thermocouples. 


mu mini min him. mil iiiMmiiiMmmmiMmiiiim 


11-36 


II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

tiiiiiiiiniit mini hiii * imimiiii mimmiiiiiiiiiiiiiiiii min 


2. The two samples burned on the sixth flight of the SSCE, the First to use PMMA, showed a high degree of 
repeatability in the flame spreading measurement. The Principal Investigator recommended reconfiguring the 
sottware in the seventh flight so that the first sample would be quenched to obtain surface regression measurements, 
and the second sample would not be quenched to obtain observations of non-spreading burning alter the flame 
reaches the end ot the sample specimen. The preliminary results of the seventh flight indicate that this objective 
was achieved. 

3. The results ot the sixth flight of the SSCE indicated surface temperatures of the PMMA samples higher than are 
normally observed in Earth gravity experiments. The results of the recent seventh flight show more conventional 
temperatures and indicate the probability that the surface thermocouples in the sixth flight were uncovered by fuel 
pyrolysis, and hence surface regression, during the retarded flame spreading caused by the gas-phase thermocouples. 

4. The results ot the seventh flight of the SSCE indicate that repeatability of the experiment, from the perspective 
ot the flame spread velocity, is again quite good. The temperature data from the two tests are of high quality and 
can be assembled into an integrated temperature field. These temperature data can be compared directly to 
temperatures computed by the numerical models developed by the Principal Investigator and can be further used to 
calculate heat transfer rates between the flame the fuel and the surroundings. 


Students Funded Under Research: 


Task Initiation: 12/84 Expiration: 12/96 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-22-05-cn 

MS Students: 

8 

MS Degrees: 

8 

Responsible Center: LeRC 

PhD Students: 

2 

PhD Degrees: 

1 


Bibliographic Citations for FY 1994: 

Journals 

Bhattacharjee, S., Altenkirch, R.A., and Sacksteder. K.R. The effect of ambient pressure on flame spread over thin 
celluosic fuel in a quiescent, microgravity experiment. To appear in J. of Heat Transfer. (1994). 

Bhattacharjee, S., Bhaskaran, K.K., and Altenkirch, R.A. Effects of pyrolosis kinetics on opposed-flow flame spread 
modeling. Combustion Science and Technology, Vol. 100. 163 (1994). 

Bullard, D.B., Tang, L., Altenkirch, R.A., and Bhattacharjee, S. Unsteady flame spread over solid fuels in mtcrogravity. 
Adv. Space Res., vol. 13, no. 7, 171-184 (1993). 

West, J., Bhattacharjee, S., and Altenkirch, R.A. Surface radiation effects on flame spread over thermally thick fuels in an 
opposing flow. J. of Heat Transfer, vol. 116. 646-651 (1994). 

Presentations 

Ramachandra, P.A., Altenkirch. R.A., Tang, L. Wolverton, J.K., Bhattacharjee, S. and Sacksteder, K.R. "The behavior of 
flames spreading over thin solids in microgravity/' Twenty-Fifth Symposium (International) on Combustion, to appear in 
Combustion and Flame, 1994. 


m* 


11-37 



II. MSAD Program Tasks — Flight Research 

. * 


Discipline: Combustion Science 


Low-Velocity, Opposed-Flow Flame Spread in a Transport-Controlled, Microgravity Environment 


Principal Investigator: Prof. Robert a. Aitenkirch 

Mississippi State University 

Co-Investigators: 


S. Bhattachanjee 
S.L. Olson 

San Diego State University 
NASA Lewis Research Center (LeRC) 


Task Objective: 

The overall objectives of the proposed work are to uncover the underlying physics and increase the fundamental 
understanding of the mechanisms that cause flames to propagate over solid fuels against a low velocity flow of 
oxidizer in the low-gravity environment. Although the work is fundamental in nature, it has clear applications to 
tire safety in space and on Earth. Specific objectives are: 

1 . To analyze experimentally observed flame shapes, measured gas-phase field variables, spread rates, radiative 
characteristics, and solid-phase regression rates for comparison with theoretical prediction capability previously 
developed that will be continually extended. 

2. To investigate the transition from ignition to either flame propagation or extinction in order to determine the 
characteristics of those environments that lead to flame evolution. 

Task Description: 

To meet the objectives of the research program, a series of experiments has been developed to exercise several of the 
dimensional, controllable variables that affect the flame spread process in microgravity. Those variables that will 
be changed from experiment to experiment are the opposing flow velocity (l-20cm/s), the external radiant flux 
directed to the fuel surface (0-2) W/m : , and the oxygen concentration of the environment (35-70%). An experiment 
matrix is used that minimizes the number of experiments to be conducted in order to obtain the information needed 
to meet the scientific objectives of the effort. 

Because the amount of data to be collected is limited, modelling is necessary to interpret the results and to sort out 
the important physics of the phenomenon. The modelling effort that will support the experimental program is 
numerical in nature and includes the capability to solve model flame spread problems over both thermally thin and 
thick fuels posed as steady-state, eigenvalue problems tor spread rate or as unsteady problems from ignition through 
flame spread. In each approach, the two-dimensional continuity, momentum, species, and energy equations in the 
gas and the continuity and energy equations in the solid are solved using the SIMPLER algorithm. Gas radiation 
is included in the model to assist in the interpretation of species-specific emission data obtained with band 
pass-filtered video cameras in the experiments. 

Task Significance: 

Radiative heat transfer is critical to these and many other microgravity flame spread experiments, and so radiant 
heating will be imposed, and radiant heat loss will be measured. These are the first attempts at such experimental 
control and measurement in microgravity, and the experimental results and numerical modelling will allow the role 
of radiation, as well as diffusive transport, in these flames to be delineated. 

Progress During FY 1994: 

In October 1993, Learjet-based, reduced gravity tests of the effect of the laser diode on flame spread were successfully 
conducted. In November 1993, the Science Requirements Document was upgraded to reflect the improved 
understanding of the diagnostics requirements for the experiment. Unsteady 2D flame spread computations were ran 
with a variable low gravity level, to simulate the Learjet test conditions. 


min Minim 


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11-38 



II. MSAD Program Tasks — Flight Research 

mi ihiiiiiihihmi MIHIMmi 


Discipline: Combustion Science 

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In December 1993 the Science Rec|uireinents Document was finalized. In January, DARTFire held a very successful 
RDR. 

In February, another Learjet senes was flown which revealed a problem with the laser diode system. Excellent data 
were obtained, however, with the intensified array camera used lor flame imaging. Non-unity Lewis number 
capability was added to the unsteady numerical code, and work to incorporate a two-flux radiation model to the code 
began. The steady code was used to determine the sensitivity of the flame spread to g level. Computations showed 
that tor g levels below 10“\ the effect is pretty small. 

In March, the effect of variable Lewis number was examined for the base case of the DARTFire test matrix. While 
the unity Lewis number case extinguishes, the non-unity Lewis number propagates with significant differences in 
tuel vapor, water vapor, and carbon dioxide distributions. The fuel surface concentration of fuel vapor is three times 
that ot the unity Lewis number case. Doug Seaton defended his thesis “A Complete Parametric Study of Flame 
Spread Over Thin Fuel in Forced-Convective and Microgravity Environment" at San Diego State University. 

In April, Dr. Lin Tang visited Prof. Subrata Bhattacharjee to compare the steady and unsteady codes. 

Thermocouple vacuum tests were conducted to determine the effect of the laser on the thermocouple readings. 

In June and July, work on reconciliation ol the steady and unsteady codes was completed. 'Validation 1 of the 
unsteady thick tuel model continued. The problem of a flame spreading over a thermally thick solid is an 
inherently unsteady problem because ol the changes ot boundary layer thickness and the length of pyrolysis zone as 
the flame spreads. It is assumed that at any given instant, the problem can be treated as a steady problem which is 
the hypothesis used by Tien tor a thin fuel ( 1979). Based on this hypothesis, a series of steady-state results was 
compared with the unsteady results. Good agreement was obtained for cases where the variable fields for the steady 
case are used as initial conditions for the unsteady case. However, for cases with an ignition transient, the flame 
spread rates are lower by about 30%. This is attributed to the low thermal diffusivity of the condensed phase such 
that the solid temperatures downstream ol the flame are much lower than predicted from steady-state theory. Thus 
heat losses in depth are larger for die unsteady computations, and the flame propagates more slowly. 

In August, DARTFire held a CDR. Computationally, the influence of gas-phase kinetic properties on ignition, 
flame structure and solid vaporization temperature were studied in hopes of reproducing PMMA Learjet experimental 
results. The predicted flame appearance agrees with the experimental one: the flame is thin, close to the fuel 
surface, and somewhat curved. The predicted flame moves closer to the surface when the activation energy is 
assumed smaller than the base case. The computational results show that the influence of gas-phase kinetic 
properties on surface evaporation temperature is small. The dependence of the flame spread velocity, V f , on 
opposed-flow gas velocity, V g , tor thick fuels was investigated for a fully developed flow in a channel geometry. A 
simple formula for the spread rate was constructed as an extension of the de Ris formula and works well not only 
tor the correct dependence ot V f on V g , but also for predicting the flame structure. Work is now in progress on using 
band radiation to assist in the selection ot the transmittance of the optical filters to be used in the experiments. 

In September, the steady model was successfully applied to the case of "excited" flames, i.e., those that are 
irradiated. With an external flux ot 1 W/cnr, the spread rate increases by almost five times. Additionally, because 
the DARTFire geometry is, strictly speaking, a channel flow, differences between the open boundary layer flow that 
we have been assuming and the channel flow have been investigated. Three flames have been compared: 1) flame in 
an externally imposed flow, 2) flame on one side of a channel wall, and 3) flame on two walls of a channel 
(equivalent to solving a half-channel problem using a symmetry condition at half the channel height). Results 
indicate that 1) and 3) are similar in spread rate (less that 1% difference), but the velocity fields are dissimilar near 
the center of the channel. 


The open flow produces a significantly different spread rate though because of the acceleration of the flow in the 
channel. Unsteady computations ot channel flow have also been earned out from ignition through spread to the end 
of the sample. The spread rate tails from ignition and eventually approaches a relatively constant value, i.e., die 
same as the steady predictions. At present we are working on including soot radiation in the radiation model and 
code and are checking previous work on variable properties. 


II— 3 9 


II. MSAD Program Tasks — Flight Research 




Discipline: Combustion Science 
„„ 1 


Students Funded Under Research: 

BS Students: 1 BS Degrees: 0 

MS Students: 10 MS Degrees: 3 

PhD Students: 1 PhD Degrees: 0 


Task Initiation: 6/91 Expiration: n/98 

Project Identification: 963-22-05-02 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

BullarcL D.B.. Tang. L„ Altenkirch. R.A.. and Bhattacharjee. S. Unsteady flame spread over solid fuels in microgravity. 
Adv. Space Res., vol.13. no. 7, 171-184 (1993). 

West. J. Bhattacharjee, S. and Altenkirch. R.A. Surface radiation effects on flame spread over thermally thick fuels in an 
opposing How. J. Heat Trans.. 116. 646-651 (1994). 


BhlttLMee 0 ”*. Charles. T.L.. and Altenkirch. R.A. Modelling gas-phase radiation from laminar flame spreading over 
solids." ASME Winter Annual Meeting. New Orleans. November 1993. 


Olson. S.L., Hegde. U. "Imposed radiation effects on flame spread over black PMMA in low gravity. 
Meeting of the Eastern States Section of the Combustion Institute, December 5-7, Clearwater Florida. 


Fall Technical 
1994. 


West. J., Bhattacharjee, S„ Ranter, ez. B and Altenkirch. R.A. "Low Reynolds number flow near the leading edge of a 
burning and non-burning plate in a mocrogravity environment." AIAA/ASME Thermophysics and Heat Transfer 
Conference, Colorado Springs, CO June 20-23. 1994. 


.mil.' 


DM III... ...H»H. II. It. 


11-40 



II. MS AD Program Tasks — Flight Research Discipline: Combustion Science 

MM""" "Ill"" "lilt" """Ill" 


Reflight of the Solid Surface Combustion Experiment with Emphasis 
Extinction 

on Flame Radiation Near 

Principal Investigator: Prof. Robert a. Aitcnkirch 

Mississippi State University 

Co-Investigators: 


Prof. S. Bhattacharjee 

San Diego State University 

K.R. Sacksteder 

NASA Lewis Research Center (LeRC) 

Dr. M. Delichatsios 

Factory Mutual Research 


Task Objective: 

The objective ot this flight experiment is to determine the mechanisms of flame spreading over solid fuels in the 
absence ot buoyant or externally imposed, gas-phase flows. This experiment is an extension of the Solid Surface 
Combustion Experiment with the purpose of observing flame spread with radiative losses near the flammability 
limit. 

Task Description: 

The Solid Surface Combustion Experiment (SSCE) is to be reflown to perform additional tests and to obtain 
quiescent flame spread data lor cylindrical, thermally thick fuels. In these tests, measurements of the fuel and flame 
temperature are to be made and recorded, and the flames will be photographed using motion picture film. The 
numerical model, developed as part of the SSCE project, is to be further extended to predict flame spread behavior 
over cylindrical samples in which the geometry of the gas-phase radiative interactions are simplified 
computationally. A detailed quantitative comparison of the experimental and computational results is to be 
performed, including comparisons of spread rate, temperature field, heat transfer rates, and flame structure. 

Task Significance: 

The spreading ot flames over solid fuels is a fundamental combustion problem that has practical significance in the 
prevention and control ot tires. Flame spreading in normal gravity is usually dominated by buoyant air flow that 
introduces a significant complexity into fundamental theoretical models. Experiments conducted in the 
microgravitv environment nearly eliminate this complexity, providing a more fundamental scenario for the 
development of flame spreading theory. 

Progress During FY 1 994: 

This is a new task in Fiscal Year 1994 beginning with die award of a new flight experiment project entided, 
Reflight ot the Solid Surface Combustion Experiment with Emphasis on Flame Radiation Near Extinction,” under 
NRA-93-OLMSA-1, "Microgravity Combustion Science: Research and Flight Experiment Opportunities." 

Since the award ot the new flight experiments the following accomplishments have been achieved: 

1. Formulation began on the analytical treatment of flame spreading on a cylindar in a quiescent environment; this 
is distinct trom the existing numerical modeling efforts. This treatment will include provisions for radiative losses 
from the flame/luel system, leading to a model suitable for predicting flame spreading in the microgravity 
environment. 

2. From the experimental point of view, the reflight project has been separated into two distinct parts: the fust 
erfort will be to choose an additional test condition, compatible with the existing SSCE-PMMA test matrix, but 
attempting to observe a flame very near the flammability limit. The second effort will be to develop a cylindrical 
sample to simplify the modeling effort required to simulate the gas-phase radiative losses dominating the flame 
spreading phenomenon in microgravity. 


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11-41 


II. MSAD Program Tasks — 


Flight Research 

iiiii.ii*i..i.i..ih... i.h... ...... miiHi.i.iiit.i.. 


Discipline: Combustion Science 
... 


Students Funded Under Research: Task Initiation: 5/94 Expiration: 11/97 

Project Identification: 963-15-oe 

Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

West. J.. Bhattachaijee, S., and Altenkirch. R.A. Surface radiation effects on flame spread over thermally thick fuels in an 
opposing flow. J. heat Trans., vol. 116. 646-651 (1994). 


II .III.... Ill Ml.... ......Ml........ .MM 


II — 4 2 


II. MSAD Program Tasks — Flight Research r,. 

- 

£//tC ' S °" trans itional, and Turbulent Gas-let Diffusion Flames 

Principal Investigator: Dr. m. y. Bahadon " ~ " ~ " - 

— Science Applications International Corporation (S AIC) 

Co-Investigators: 

Dr. Uday G. Hegde 


NYMA, Inc. 


Task Objective: 

tlames in the entire landnar tr^Mtion'Il ^L'ld mrhulem 1UndamentaJ understand >ng of microgravity gas jet diffusion 
microgravity with the nuroo'sc ^ SpecU.cally, tests are to be conducted in 

relative importance of buoyancy- induced turbulencp 6 C 01 huoyailcy on these flames, (ii) determining die 

may be masked by buoyant convection. 0I ' 411116 ° aractensUcs ’ 311(1 (lli) revealing phenomena which 

Task Description: 

tn order to achieve these objectives, the program pursues two distinct but complementary paths, as follows: 

ssssesz* -zzzzr* n t “=■ - *«% - «, 

turbulent flame features, and (iv) stand-off characterisri an < ^ ^ eXlm 01 ^ lrans,t,on re £mie, ( iii) 

normal-gravity and in the NASA LeRC around h h ^ ° W '° conci * tions - ^ ese tesLs will be conducted in 

and/or aLalt The <* »°P Tow* Zer„.Gm»i.y Facility, 

The d* will be used lo valrdate delarled analyiicd ; ^ ™ a8me ' 

r “ which 

phase of the program, aIla ' V tKa ' alU * numer ical modeling effort will be an integral component of this 

Task Significance: 

S3“s*^“-=2=5r 


Progress During FY 1994: 


ttTuTenVgSetdiffu^ lam,nar - ^ans.tionaJ, and 

microgravity flames compared to those in n i ? stances and higher blow-off Reynolds numbers for 

microgravity. whe« *f “““ ■*«“ * <*"*« 




11-4 3 



Discipline: Combustion Science 

Ji!22E2ffi=2S^aKS==i — 

smaller than in normal gravity for the transitional and turbulent flames. 

The science tequnements to, an experiment 

October 1903 in a Science Concept Review a « NASA L Levm I ^ nKd for mic togravi.y 

the proposed experiments have scienutic war . ® experiment that provides an extended durauon ot 

experiments, and that the objectives can on y following- (a) Focus on axisymmetric 

radiometer location. The following is the progress m addressing these 

A senes of approximately 15 tests ,n for 

recommendations and to check out e lg mpndations has a major impact on the design ot the flight 

e^^r^^Tdesign h^continu^^n^^^lcl^iA the ground-based tests. It is anticipated that the Investigators and 
the Engineering team will be ready for RDR in early 1995. 

The design of the ajtisymmelric -perturbation ^^^j^^^^^l^^j^j^jfe^u^izationtestswere 
properly to ptoyitle the requited trequenctes eharactensauon for night 

satisfactorily conducted at LeRC in support o 6 ^ convection, and interaction with the jet were made, 

experiment. Observations ot the impose vor ^ x 8 dvnamics 0 f the imposed vortex and subsequent entrainment 
The tests did not indicate any influence ot s nonuniformities. In addition, LDV measurements 

into the jet, and led to a change in hardware design to redu tl results for 3 . D velocity field of 

currently in progress at Georgia Tech (through a ^bconhB ) ^ ‘ ^ components of velocity are 

(i e< ’ SW,I1) COmP< " ent °‘ Vd0CUy ^ 

not show this correlation. 

ssksssi 

performed as part of the LeRC Zero-G Facility tests in FY95. 

Measurements of dte thennocouple time constat,, and — 

tests. The circuits for these measurements ate hong BBh.1 in l ZooO Facility whh the 
analysis techniques, the tesls show i* „eed for the high sampling rate, provisions will be 

mTfm^'r Sh2"rp.,ug dK temperature dam a, d.se rates. 

Numerical calculations were petfotmed hi 

for die normal-gravity flames are in good a ^ e " respect to the flame height) of 
optimum location ot the radiometer is at a mon optimum location is at a non-dimensional 

0 5-0.7. For microgravity flames, the on flame radiative characteristics) 

“omp^wi^ Facility ms^ for futthe, model validadon and confumahon o, the 
optimum radiometer locadon for the flight experiment. 

The modeling effort consists of analytical mtp^mran hm^ teen*Mnducted. U M* 

of imposed disturbances. To date, lam,n ^ a denendent flame behavior predictions are 

Navier - stokes modd ^ in pro8ress - Disturbed 







11-44 



II. MSAD Program Tasks — Flight Research 

* ••• 


Discipline: Combustion Science 

....him. ..... in . hi 


cold jets and hot jets are currently under investigation. Numerical simulation of the jet transient development under 
the experiment condition is obtained. Jets with both axial and radial pulsations (initial test of the model) have been 
studied. Detailed modeling ot iris-induced flowfield in jets is in progress, and the results will be compared with the 
LDV measurements. Also, dtis comprehensive transient model is currently being extended to include the laminar 
ilame in the presence ot the iris-generated disturbances. 


Students Funded Under Research: Task Initiation: 11/91 Expiration: 11/96 

Project Identification: 963-22-05-03 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Hegc, U.G. Heat release effects on the instability of parallel shear layers. AIAA journal, vol. 32, no. 1, 206-207 (1994). 
Books 

Bahadori. M.Y., Stocker. D.P.. Vaughan. D.F. Zhou. L.. and Edelman. R.B. "Effects of buoyancy on laminar, transitional, 
and turbulent gas jet diffusion dames." in "Modern Developments in Energy, Combustion, and Spectroscopy." Edited by 
eddited by F A. Williams. A.K. Oppenheim. D.B. Olfe. and M. Lapp. Pergamon Press. Oxford, pp 49-66. 1993. 

Presentations 

Hege, U.G., Zhou, L., and Bahadori, M.Y. "Transitional and turbulent gas-jet diffusion flames in microgravity." Paper 
AIAA -94-0432, AIAA 32nd Aerospace Sciences Meeting, Reno. NY, January, 1994. 


mi 


ii.iiii 


11-45 



II. MS AD Program Tasks — Flight Research 

mu 


Discipline: Combustion Science 

•mu ..mm. ilium* •» * 


Sooting Effects in Reduced Gravity Droplet Combustion (SEDC) 


Principal Investigator: Prof. Mun y. Choi 

University of Illinois, Chicago 

Co-Investigators: 

No Co-I’s Assigned to this Task 



Task Objective: 

To determine the effects of sooting on droplet combustion characteristics using optical and intrusive techniques. 
The parameters to be studied include burning rate, flame dynamics, extinction, disruption and soot parUcle 

dynamics. 


Task Description: 

The sootine behavior will be studied using expanded beam line-of sight extinction and subsequent 3-poinl Abel 
deconvolution to determine the soot volume fraction distribution; two-wavelength optical pyrometry to determine 
the soot temperature within the region between the flame and the droplet; and thermophoreuc 
samplinu/transmission electron microscopy to determine the soot morphology (radius ot gyration, primary parucle 
size, fractal geometry, etc). Feasibility studies will also be performed using Laser-Induced-Incandescence techniques 
lo determine droplet soot volume traction. 

These experiments will be performed for a wide range of conditions to vary the sooting propensity ot the droplet 
using various fuels, pressure, oxygen indices, droplet dimension and inerts as parameters. In addition, 
computational modeling of the soot parucle dynamics using the balance between thermophoresis and Stetan drag 
will be compared with the experimental measurements. The modeling efforts will be advanced interactively wi 
the experimental measurements of the soot volume fractions and the soot particle dimensions. 


Task Significance: 

The combustion of a pure, single-component liquid droplet provides an ideal problem from which to obtain valuable 
information for both basic and applied scientific purposes. The importance ot the isolated droplet burning process 
has promoted extensive experimental and theoreUcal investigations for more than 40 years. In terms ot the pracucal 
relevance the knowledge of individual droplet burning characteristics provides insights into some ot the more 
complex mechanisms involved in spray combustion. Since esumated energy production through spray combustion 
processes accounts for more than 25% of the world's output, droplet combusuon remains a viable held lor conunued 

research. 

Since the pioneering microgravity droplet combustion experiments of Kumagai and coworkers back in 1957, there 
have been numerous theoretical, computational and experimental studies analyzing the burning characteristics ot 
isolated droplets. However, sooting effects have typically been neglected due to the complexiues involved (both 
experimental and computational/theoretical). However, recent microgravity experiments indicate that soot/sootshell 
formation affects all four of the important measurable parameters involved in droplet combustion: burning rate, 
flame diameter, extinction and disruption. Thus, our understanding of the burning charactensucs of droplets can 
only be complete by considering a detailed study of the sooting behavior for a wide range ot characteristic times and 

dimensions. 


In all previous microgravity studies, the degree of sooting was estimated by visual observations ot the sootshell. 
This study will focus on the effects of sooting on the droplet burning rate, flame dimensions, extinction and 
disruption by accurately measuring the soot volume traction, temperature and soot morphology and dynamics. 
These measurement of the temperature and soot volume fractions will also prove beneficial in assessing the 
importance of radiative heat transfer. 





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11—46 



II. MSAD Program Tasks — Flight Research 

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Discipline: Combustion Science 

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Progress During FY 1994 : 

1 . Motivations and concepts tor space experiments were presented to the engineering team prior to the start of the 
QFD (Quality Function Deployment) process. The PI participated in initial QFD sessions at LeRC to provide 
input regarding the Science Requirements. The meetings yielded an initial cut at the science and engineering 
requirements tor the flight experiments. The product ot the QFD process is to identity potential high-risk features 
ot the experiment to guide the choice ot which experimental elements will be breadboarded first. The subsystems of 
the experiment which will be breadboarded are the data storage system, droplet deployment system, droplet size 
measurement system, soot volume fraction measurement system, soot temperature measurement system and 
thermophoretic soot sampling system. 

2. The PI was at Lewis during the summer months working with Dr. Randall Vander Wal and Dr. Karen Weiland on 
implementing Laser-Induced Incandescence tor pertorming soot volume fraction measurements in droplet 
combustion. Dr. Randall Vander Wal and the PI are considering performing LII experiments in reduced-gravity 
droplet combustion (on DC-9) during the summer of 1995. 

3. The PI has acquired a combustion chamber from LeRC for use in normal -gravity feasibility studies to be 
performed at UIC. For reduced-gravity testing in the ground-based facilities, discussions were held with the DCE 
(Droplet Combustion Experiment) project scientist to use the DCE drop rig for some preliminary tests with the Pfs 
proposed fuels. A droplet combustion chamber which utilizes several features of the DCE drop tower hardware is 
being fabricated to take advantage ol the design solutions. It is anticipated that an operational rig to be used in the 
DC-9/2.2 sec drop tower will be ready by early summer of 1995. 

4. A full-field normal-gravity experimental apparatus to perform soot volume fraction and temperature 
measurements was designed and implemented at UIC. Performed normal gravity soot volume fraction experiments 
using toluene, benzene, decane and heptane at 1 atm, 0.5 atm and 0.25 atm. 

5. Developed an interactive Abel-deconvolution algorithm to determine soot temperature using two- wave length 
pyrometry tor full-field data (512 by 512 pixel locations). Developed image processing program (using Data 
Translation frame grabber boards) that can produce the extinction and emission output tiles for direct use in the Abel 
deconvolution program. Tested the Abel deconvolution program using known distributions which produced very' 
good comparisons between actual and predicted soot volume fractions. Developed similar programs to determine 
temperatures from 900 nm and 1000 mn emission data. Tested various wavelength combinations (700nm/800nm, 

800nm/900nm, 900nm/1000nm) to determine best combination that will produce accurate results and low detection 
temperatures. 

6. Developed a digital image processing program to determine the radius of gyration from transmission electron 
micrographs that are obtained using thermophoretic sampling techniques. The students are fully trained in TEM and 
Selected Area Electron Diffraction Analyses. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 6/94 Expiration: 5/98 
Project Identification: 963-15-ob 

Responsible Center: LeRC 


Bibliographic Citations for FY 1994 : 

Presentations 

Vander Wal. R., Dietrich. D.. and Choi, M.Y. Relative soot volume fractions in droplet combustion via laser-induced 
incandescence. Presented at the Eastern States Section of the Combustion Institute. Clearwater, FL. December 5-7. 1994. 


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11-4 7 


II. MSAD Program Tasks 

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Flight Research 

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Discipline: Combustion Science 




Candle Flames in Microgravity 


Principal Investigator: Dr. Daniel l. Dietrich 

NYMA. Inc. 

CO-INVESTIGATORS! 


Dr. Howard Ross 
Prof, james S. Tien 

NASA Lewis Research Center (LeRC) 
Case Western Reserve Univerity 


Task Objective: 

The coal of this work is to further investigate some of the features of candle flame combustion observed during a 
recent small scale candle flame expenment conducted on board the space shuttle. These are specifically as follows. 


1 . To observe whether a steady flame can exist in a purely diffusive environment; 

2. To understand from a fundamental aspect the observed near-extinction flame oscillations, 

3. To examine the nature of the interactions between two candle flames. 

As a secondary objective, we will use the candle as a model system (non-propagating, steady-state diffusion 
(non-convective) flame) to investigate buoyant scaling arguments for diffusion flames. Testing and scaling analysis 
to date shows that utilizing reduced presure, enhanced oxygen environments do not produce a buoyancy-tree 
environment, as currently published scaling arguments suggest. 

Task Description: 

These objectives will be accomplished by a program consisting of the development of a comprehensive numerical 
model of the candle flame, ground-based testing in normal-gravity laboratories and drop towers, and another 
small-scale glovebox experiment 

The development of a comprehensive numerical model represents the most significant addition to the proposed 
program. The eas-phase model will be a modification of an existing two-dimensional code developed tor flame 
spread over solid fuels under the guidance of one of the investigators. The initial model tor the wick/liquid phase 
has already been developed by the principal investigator. 

The ground based testing will utilize existing drop rigs and other existing experimental equipment to tully 
characterize the candle flame in a range of ambient conditions (i.e., atmospheric to sub-atmospheric pressures, 
nitrogen-oxygen, helium-oxygen ambients). The data will be imaging of the flame, thermocouple measurements, 
LDV and possibly PIV, all of which the investigators have experience using. The use ot more advanced diagnostics 
will also be explored during the later phases of the program. 

The space experiment will be a glovebox experiment that is similar to the existing Candle Flame in Microgravity 

glovebox experiment (same investigators). The minor proposed changes will be; a larger tree volume, the 

performance of the thermocouple measurements (a capability that existed but was not used on the last expenment 
because scheduling conflicts), the ability to maintain a large candle spearation distance and to simultaneously ignite 

the two candles. 

Task Significance: 

The candle flame in microgravity is a unique/model system (non-propagating, steady-state dittusion 
(non-convective) flame). The data from this work is expected to improve our understanding of diffusion flames on a 

fundamental level. 




■ III 


11-48 


II. MSAD Program Tasks — Flight Research 




Discipline: Combustion Science 

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Progress During FY 1 994 : 

A Case Western Reserve University graduate student, J. Konecny, began working the modeling aspect of the 
problem in June. The initial formulation of the computational model is complete and implementation of the 
computer code is nearly complete. The candle will be treated as a saturated porous material at a constant temperature 
which greatly simplifies the wick and coupling of the wick and gas phase. The gas phase will solve the full 
Navier-Stokes equations with a simplified radiation model and one step chemistry. 


Drop tower tests in the 5.2 second drop tower of two candles on axis candles with simultaneous ignition were 
conducted. Oxygen ambients of 19, 18, 17, and 16 percent with different inter-candle separation distances were 
tested. The results showed no ignition ot either candle at 16 percent 02, and successful ignition and burning at both 
19 and 18 percent. The results are currently being analyzed. 

A prototype design for a liquid candle (porous metal wick with a pure liquid fuel) was completed. This is being 
considered as an alternative to solid candles to simplify comparisons with the theoretical predictions. The Candle 
Flames project was also selected as a glovebox experiment aboard the MIR glovebox. This purpose of this project 

is to complete some ot the work not done on the USML-1 candle flames experiment and serve as a precursor to the 
current experiment. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 5/94 Expiration: 4/98 
Project Identification: 963 - 15 -ob 

Responsible Center: LeRC 


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11-49 



II. MSAD Program Tasks — Flight Research 

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Investigation of Laminar let Diffusion Flames in Microgravity : A Paradigm for Soot Processes in 
Turbulent Flames 


Principal Investigator: Prof. Gerard m. Faeth 

University of Michigan 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The flight project is an experimental and theoretical investigation of the mechanisms of soot tormauon in laminar 
jet diffusion flames under conditions ot low buoyancy. 

Task Description: 

Several types of experiments have been conducted. The majority have been in normal gravity studying die 
influence of gravity by varving the ambient pressure. In addition, experiments have been conducted on NASA To 
gravity aircraft, (the KC-135 at JSC). The work has focussed on mapping soot volume traction, temperature, soot 
particle size and gas species in a variety of hydrocarbon flames. The flight experiment wil unite to 
measurement of soot volume fraction, soot particle size and some temperatures. 

Task Significance: 

In most flames of practical interest, soot radiation is the dominant mode of heat transport to combustor components 
and a dominant mechanism for flame spread and growth. The experimental results, combined with theoreuod 
modelling will confirm or deny the applicability of the conserved scalar formalism to soot properties in diffus 
flames. These results, when combined with those of ground-based low- and normal gravity experiments wi 
increase the current fundamental understanding of soot formation processes in both laminar and turbulent flames and 
increase our ability to model them. Consequently this will have a significant impact on our understanding o 
systems such as the spread of unwanted fires, design of jet engines and large scale boilers, among others. 

Progress During FY 1994: 

October- Additional property measurements have been conducted along the axis of the weakly buoyant flames, 
concentrating on samples for soot structure and TEM analysis of the samples. Measurements ot the acetylene 
flames were reduced in order to study mechanisms of soot nucleation, growth and oxidation: the results indicated 
gross soot nucleation rates that were first-order in acetylene and gross soot growth rates that were roug y 
second-border in acetylene. Other data is being accumulated for various fuels. Finally, the LSP experiment had a 

successful RDR. 

November: Measurements and data analysis continued in the weakly-buoyant flames considering results tor 
acetylene as well as other fuels. Results for acetylene were completed and a paper describing the findings was 
prepared for the 25th International Symposium on Combustion; these results continued findings that soot 
nucleation was roughly first-order in acetylene with a modest temperature dependence (an activation i energy ot 
roughly 23 kcal/gmol) while growth is roughly second-order in acetylene concentration with a negligible activation 
energy Additionally, our findings concerning soot growth in diffusion flames are similar to existing findings in 
premixed flames, although our nucleation rates are smaller than results of earlier studies (but the earlier work has 
considerable uncertainties about soot reactive surface areas). 

December: Measurements and analysis of weakly -buoyant acetylene flames continued, emphasizing soot nucleation 
and growth. In addition, concerns about effects of acetone contamination of acetylene were addressed (acetylene is 
stored in contact with acetone), finding negligible effects of acetone on our results. Our newest findings about soot 
nucleation support first-order behavior in acetylene but growth rates appear to be somewhat lower than e 
second-order behavior found last month. Developmental test results concerning laser exunction measurements by 
imaging at LeRC were reviewed. 





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11-50 



II. MSAD Program Tasks — Flight Research 

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Discipline: Combustion Science 

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January. Study ot soot growth in weakly-buoyant acetylene tlames continued, with additional measurements added 
to the data base. This growth data are being reduced considering (1 ) raw data with growth due to acetylene only, (2) 
raw data assuming a tirst-order acetylene reaction (which is conventional wisdom in the literature) and an effect of 
age, and (3) as a net reaction rate allowing tor oxidation by the low levels of oxygen present in the soot growth 
region (roughly 1% by volume) using the Nagle/Strickland-Constable soot oxidation results. The last appears to be 
most reasonable and yields a collision efficiency for acetylene of roughly 0.4%. In addition, a test campaign on the 
KC-135 lor LSP was attempted when the KC-135 was at NASA LeRC. The campaign was largely unsuccessful 
because a nearby experiment on the aircraft developed a leak and sprayed the Gas Jet rig’s electronic systems with a 
conductive water solution. 

February: Study ot soot nucleation and grow th continued, w ith some anomalous data remeasured and all data 
reanalyzed. The soot growth results continue to hold up and still are similar to results in premixed flames, although 
we do not detect an effect ot soot age on growth that generally is observed in premixed flames. Soot nucleation has 
remained first order in acetylene, with a low' activation energy ot 33 kcal/gmol. Measurements of flame and soot 
structure for fuels other than acetylene were initiated. 

March: Study ot soot nucleation and growth continued in order to resolve effects of soot oxidation by oxygen, 
carbon dioxide and water vapor. The Nagle/Strickland-Constable expression was evaluated based on our 
measurements of soot oxidation rates: the expression w as at least order of magnitude correct. It also was found that 
water vapor and carbon dioxide are important for soot oxidation in the growth region, which affects the apparent 
order ot soot growth with respect to acetylene (tending to make it larger than the actual order with respect to 
acetylene). The revised results, allowing lor effects of oxidation by oxygen, carbon dioxide and water vapor, 
indicated soot growth via acetylene collisions with a collision efficiency of roughly 0.5%. Measurements continued 
tor a variety of fuels in diffusion flames, considering both weakly-buoyant low pressure flames and buoyant flames 
at atmospheric pressure. In view of the relationship between present measurements and those in premixed flames, 
we began assembly ot a premixed flame apparatus in order to carry out new measurements in premixed tlames with 
better definition of soot surface areas than past w ork. A revised SRD was prepared and sent to LeRC for review. 

April: Measurements continued in both weakly-buoyant and buoyant flames for a variety of fuels (ethylene, ethane, 
propane, propylene, butadiene and butane). In view of die number of flames to be considered (six) and the number 
of variables to be measured (soot volume fractions, soot temperature, soot structure, gas temperature, gas velocities 
and species concentrations) these measurements will require several report periods to complete and analyze. Work 
also continued on the development ot the premixed flame apparatus. Round V ot the KC-135 test was undertaken 
yielding new results tor ethylene tlames that currently are being analyzed. 

May: Data from the KC-135 test was analyzed to find the correlation between burner mass flow rates and luminous 
flame lengths at low gravity; it w r as found that the length is independent of burner diameter and pressure for a given 
fuel flow rate but required fuel flow' rates are larger then earlier estimates for a given flame length. These results 
were checked using weakly-buoyant diffusion tlames, indicating little effect of burner diameter and pressure on the 
luminous flame length, similar to the KC-135 results. Tests also were undertaken to establish imaging techniques 
for multiline temperature measurements; this w r ork w ill continue for the next few report periods. The P.I. attended 
the PDR and was generally satisfied w'lth the design. 

June: Measurements continued in order to resolve flame and soot structure for the various flames. A portion of 
these results involved measurements of species concentrations for an ethane flame; these measurements were in 
excellent agreement with estimates based on die universal state relationships developed earlier in this laboratory. 
Analysis of soot growth and nucleation tor w'eakly-buoyant acetylene and butadiene tlames was completed; these 
results are in lair agreement with our earlier acetylene mechanism but more measurements are needed before firm 
conclusions can be made. Test flames similar to those ot Hams and Weiner have been set up on the premixed 
burner and we currently are working to resolve problems ot flame disturbances. Measurements of flame lengths as a 
function ot fuel flow rate tor low gravity and weakly-buoyant conditions were completed; these results confirm that 
larger fuel flow rates are needed tor a given flame length than thought previously. Tests to evaluate multiline 
temperature measurements by imaging continued, emphasizing effects ot improved spatial resolution (or collection f 
number); evaluation ot the results based on extrapolation of radiation -corrected thermocouple measurements from 


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11-51 



II. MSAD Program Tasks — Flight Research 

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Discipline: Combustion Science 


soot free regions was satisfactory. A more definitive evaluation will require alternative temperature measurements 
in the soot-containing region: such measurements based on the emission and absorption properties of carbon dioxide 
in the infrared are being considered. 

July: Measurements to resolve flame and soot structure properties for various fuels (ethylene, ethane, propane, 
propylene, butadiene and butane) burning in air were completed; these results currently are being analyzed to tin 
soot nucleation and growth rates as well as continued evaluation of universal state relationships for hydrocarbon 
diffusion flames. Measurements of premixed ethylene/air flames were initiated finding soot volume fractions in 
reasonably good agreement with earlier measurements of Harris and Wiener; these measurements will continue 
throughout the next report period. Direct evaluation of the multiline temperature measuring system, based on 
imaging, will require an instrument system capable of measuring temperatures in the infrared based on the carbon 
dioxide bands; this arrangement currently is being designed. 

August: Data from various fuel/air diffusion flames were analyzed to find soot nucleation and growth rates; results 
indicate an ethylene growth channel having a collision efficiency of 1.8% which is parallel to the acetylene growth 
channel while nucleation rates were correlated by acetylene similar to acetylene/air flames; a paper describing these 
results is being prepared while analysis ot state relationships continues. 

September: Some gaps in data relevant to fuel/air diffusion flames were found during preparation of a paper 
describing these results; thus measurements were completed to rectify this problem while preparation ot the paper is 
nearing completion. Measurements of soot volume fraction distributions in the premixed ethylene/air flames were 
completed; work on soot temperatures began. Analysis of soot nucleation and growth was completed in three 
acetylene/air flames in order to check earlier results for different soot paths and flame conditions; results did confirm 
our earlier results and a Brief Communication is being prepared to describe the findings. Analysis ol imaging 
measurements of soot volume fractions obtained at NAS A-LeRC was undertaken. All these activities required that 
work on state relationships and on the evaluation of the multiline soot temperature measuring system had to be 
deferred; we hope to make more progress in these areas during the next year. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 2 

PhD Students: 1 


Task Initiation: 2/92 Expiration: 2/98 
Project Identification: 963-22-05-04 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Farias T.L.. Carvalho, M.G.. Koylu. U.O. and Faeth. G.M. Computational evaluation ot 

Rayleigh-Debye-Gans/fractal-aggregate theory of the absorption and scattering properties of soot. J. Heat Trans, (in 
press). 

Koylu. U.O. and Faeth G.M. Optical properties of overfire soot in buoyant turbulent diffusion flames at long residiner 
times. J. Heat Trans., vol. 116, 152-153 (1994). 

Koylu, U.O. and Faeth, G.M. Optical properties of soot in buoyant laminar diffusion flames. J. Heat Trans, (in press). 

Law, C.K. and Faeth, G.M. Opportunities and challenges of combustion in microgravity. Prog. Energy Combust. Sci., 
vol. 20. 65-113 (1994). 

Sunderland, P.B.. Mortazavi. S.. Faeth. G.M. and Urban. D.L. Laminar smoke points of nonbuovant jet diffusion flames. 
Combustion and Flame, vol. 96. 97-103 (1994). 

Presentations , , _ • 

Faeth, G.M. "Soot morphology and optical properties in nonpremixed flame environments. Proceedings ot the Spring 

Technical Meeting, Canadian Section of the Combustion Institute, Kingston. ON, Canada. 2-1 to 2-5. 1994. 





11-52 



II. MSAD Program Tasks — Flight Research 

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Discipline: Combustion Science 

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Faeth. G.M. ‘"Issues in premixed and nonpremixed combustion.” DOE Workshop on Fundamental Research in Support of 
Industrial Combustion Needs. Irvine. C A. 1994. 

Faeth. G.M., Sunderland, P.B.. Koylu. U.O. and Urban. D.L. ‘Laminar jet diffusion flames in microgravity: A paradigm 
tor soot processes in turbulent tlames. Proceedings of International Symposium on Aerospace and Fluid Sciences, 
Tohoku University, Sendai, Japan. 185-198. 1993. 

Farias, T.L.. Carvalho. M.G.. Koylu. U.O. and Faeth, G.M. "A computational study of the absorption and scattering 
properties ot soot. Proceedings ot the Fall Technical Meeting, Eastern Section of the Combustion Institute Pittsburgh 
PA, 394-397, 1993. ’ ’ 


Farias. T.L., Carvalho, M.G., Koylu. U.O. and Faeth. G.M. "Scattering properties of polydisperse soot aggregates.” 
Eurothem Seminar No. 37: Heat Transfer Radiating and Combusting Systems -2, Saluggia, Italy, in press. October 1994. 


Koylu, U.O., Faeth, G.M.. Farias, T.L., and Carvalho, M.G. "Fractal and projected structure properties of soot 
aggregates." Combust. Flame, in press. 


Koylu, U.O., Sunderland, P.B.. Mortazavi. S. and Faeth. G.M. "Soot nucleation and growth in weakly-buoyant laminar jet 
diffusion flames.’' 32nd AIAA Aerospace Sciences Meeting, Reno, NV, AIAA Paper No. 94-0561. 1994. 

Sunderland. P.B. and Faeth. G.M. "Soot formation in hydrocarbon/air laminar jet diffusion flames." Proceedings of the 
Fall Technical Meeting, Eastern Section of the Combustion Institute, Pittsburgh. PA. in press. December 1994. 

Presentation Sunderland, P.B.. Koylu, U.O. and Faeth, G.M. "Soot formation in weakly buoyant acetylene-fueled laminar 
jet diffusion flames burning in air.” 25th Symposium (International) on Combustion. Irvine. CA, August 1994. 

Presentation Sunderland, P.B., Koylu, U.O. and Faeth, G.M. "Soot formation in hydrocarbon -fueld jet diffusion flames 
burning in air. 25th Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, poster paper, 
abstract only. 1994. 


Presentation Sunderland, P.B,, Koylu. U.O.. Faeth. G.M. "Soot formation in acetylene-fueled laminar jet diffusion flames 
burning in air. Proceedings ot Spring Technical Meeting, Central States Section, The Combustion Institute Pittsburgh 
275-280. 1994. 


Presentation Sunderlasnd. P.B., Koylu, U.O. and Faeth, G.M. "Soot formation in weakly buoyant acet yl erne- fu led laminar 
jet diffusion flames burning in air.” 25th Symposium (International) on Combustion. Irvine. CA, Combust. Flame, in 
press, August 1994. 


„„ 


11-5 3 



.SSmS—”™ ~ """ — " 


Unsteady Diffusion Flames: Ignition, Travel , and Burnout 


Principal Investigator: Dr. Frank Fendeii 

TRW 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objective is to investigate the adequacy of frequently adopted, simplified mathematical models to describe the 
behavior of laminar flames, primarily diffusion flames, by comparison with definitive experimental data, made 
available by burning in a microgravity environment. 

Task Description: 

The experiment investigates the adequacy of frequency adopted, simplified mathematical models to describe the 
behavior of laminar flames, primarily diffusion flames, by comparison with definative experimental data, 
conveniently available from burning in a microgravity environment. 


Task Significance: 

To study parametric variation of stoichiometric proportion and reactant dilution at ignition to provide sufficient data 
to test the adequacy of simplified analyses frequently used to predict diffusion-flame behavior in different practical 
applications. The work is parucularly pertinent for flames (and near-cold-wall quench layers) involving natural gas, 
hydrogen, butane, propane, or other fuels that are in the gas phase at atmospheric temperature and pressure. 

Progress During FY1994: 

Experimentally, the layout of the apparatus is close to final. Parts' lists have been generated, and are ready to be 
placed with TRW purchasing agents, alter a final critique of the design. Conceptual design of the lest chamber is 
completed. The design will be finalized alter discussions with the parylene-film manufacturer in Goleta, CA. 

LeRC provided information about H : 0 spectral emission characteristics, spark and hot-wire ignition electrical 
circuitry and power requirements on the space shuttle and station to TRW. LeRC also sent TRW the results ot 
adiabatic flame temperature calculations, done by the Project Scientist, Dr. Suleyman Gokoglu, tor different mitral 
stoichiometric proportions and reactant dilutions to help the decisions regarding experimental design and operaung 

conditions. 

The plan is to initiallv segregate hydrogen diluted with argon, and oxygen diluted with helium, into two equal 
half-volumes within a squat rectangular-solid-configured container with isothermal, noncatalyuc, impervious walls. 
The contents of the two half volumes are each to be at atmospheric pressure and temperature, and to have equal 
density, so that the "average molecular weight" for each half volume is the same. The overall contents are to be 
sufficiently fuel-deficient such that, if (conceptually) the initial, segregated contents of the container were mixed to 
form a perfectly homogeneous gaseous mixture, the adiabatic flame temperature (equilibrium burned-gas 
temperature) would be consistent with a vigorous diffusion flame, but not so hot that either dissociation oi product 
species (mainly water vapor) or gaseous radiative heat transfer or the physical integrity ot the container is ot 
concern. 


In practice, a thin parylene film seems a candidate material to serve as the impervious initial interface, to be 
perforated on command at multiple sites by the movement of an intrusive "array" of pointed prongs, at least some 
of the tips of which are to serve as spark electrodes. Ignition is to occur after a short interval to enable some 
reactant interdiffusion. The diffusion flame is to propagate into that half volume which is free of the intrusive 
device. The key objective is to measure the flame temperature and flame position as a function ot time until 
depletion of the deficient reactant (hydrogen) results in extinction of the planar diffusion flame. 


Hill • "»»" 


* * 


11-54 



II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

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A manuscript entitled "Unsteady Planar Diffusion Flames: Ignition. Travel. Burnout" is to he presented in die 
Microgravity Combustion Session at the A1AA 33rd Aerospace Sciences Meeting in Reno, NV. in January 1995. 
Issues to be discussed include: (1) Lhin-llame modeling for cquidiffusion and differing diffusivitics (including 
peripheral calculation of when the sufficiency condition for extinction, derived from a global second-order 
irreversible Arrhemus-type model of the finite-rate chemical kinetics, is met); (2) results for finite-rate global 
chemical kinetics; (3) flame quenching and possible water- vapor condensation, in proximity to the cold lateral walls 
of the container; and (4) assignment of values to the dimensionless parameters arising in the parabolic 
boundary/initial-value problem describing the travel of a planar diffusion flame. These parameters include the 
Lewis-Semenov numbers for fuel vapor (hydrogen) and gaseous oxidizer (oxygen), the first and second Damkohler 
numbers, the isentropic coefficient, the dimensionless Arrhenius activation temperature, and the stoichiometricallv 
adjusted mass fractions for fuel vapor and gaseous oxidizer. 


Students Funded Under Research: Task Initiation: 7/94 Expiration: 7/98 

Project Identification: 963-is-oo 

Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Fendell, F.E., Bush, W.B., Mitchell, J.A., and Fink IV, S.F. Diffusion-flame burning of fuel-vapor pockets in air. 
Combustion and Flame, vol. 98, 180-196 (1994). 


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11-5 5 





II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

• * ” 


Fundamental Study of Smoldering Combustion in Microgravity 


Principal Investigator: Prof. a. c. Femandez-Peiio 

University of California, Berkeley 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

The overall project objective is to increase the fundamental understanding and the prediction ol smoldering 
combustion under normal and microgravity conditions. This in turn will help the prevention and control ot smolder 
originated tires both, in normal gravity and in space-based environments. The specific objectives are to determine 
the smolder characteristics ot a polymeric porous combustible material (polyurethane loam), in a quiescent or 
convective oxidizing environment, both at normal and micro-gravity. The final objective is a set ot flight 
experiments in a GAS Can facility in the Orbiter's cargo bay. 

Task Description: 

The project objectives are accomplished by conducting experiments on ground-based and space-based tacilities, and 
by developing theoretical models of the process. The experiments are conducted with polyurethane loam as tuel 
with mixtures of oxygen/nitrogen as oxidizer. Temperature at several locations ot the sample are measured with 
thermocouples; and the resulting temperature histories are used to obtain the smolder propagation velocity and 
smolder reaction temperature, as a function ot the oxidizer flow velocity and oxygen concentration. The 
experimental results are used to verify and improve the theoretical models ot smolder combustion. Experiments are 
also conducted to observe the potential transition trom smoldering to flaming combustion, and to determine the 
conditions and mechanisms leading to this transition. 

Task Significance: 

Smolder is important as both a fundamental combustion problem, i.e., the propagation of a heterogeneous, 
non-flaming, surface combustion reaction through a porous combustible material, and as a lire safety problem, i.e., 
the production of toxic compounds and the potential initiation of a lire through the transition to flaming. There is a 
need for further understanding of the problem for better prediction and control of smolder in both normal gravity and 
microgravity. Furthermore, microgravity introduces additional questions about the transport ol mass to and trom 
the reaction, and the transfer of heat from the reaction, that must be resolved in order to predict smolder behavior in 
a space-based environment. 

Progress During FY 1994: 

Task 1: Ignition Study of Opposed Smoldering 

The main objective of the current research is to gain an understanding, and eventually a concrete theory, ol the 
ignition process in the smoldering of polyurethane. The immediate information we seek trom the experiments are 
two types of plots. The first of these is the Power vs. Time plot and the second is Minimum Energy vs Power. 
Comparison of these curves with similar ones produced by Kitano in Japan show a number ol differences. There is 
an apparently strange behavior of our curves at the 1 15W power. Further testing must be done at this power level 
to ensure our results are not due to experimental error. The same is true of the 100 W power level. We are also 
planning to do some testing at 160W and 40W. In addition, several experiments were run with no air or keeping 
the air flow rate constant at 0.1 mm/s rather than increasing it at a given time. No conclusions are yet available 
from these experiments but further testing of this nature could prove very interesting. Finally, a Power vs. Time 
curve was produced using a theoretical approach. The problem was modelled assuming one-dimensional heat 
conduction in a semi-infinite medium with prescribed heat flux boundary condition. 

Char is also being manufactured to be used in the next space shuttle mission. Larger char samples were sent to 
NASA Lewis. Experiments are being run comparing the feasibility of replacing the char insulation behind the 
heater with shredded FiberFrax insulation. 


Mill 





II— 5 6 


II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

MiMMtMmMiiHMiitiMimiiMiMHiMiiiMHiHMHiHmmiMiaitMiHHiiiiiiiiHMiHHHiitHmHiMiii mini him 


Task 2: Forward Smoldering 

The building of the experimental apparatus has been completed. Experiments have been started to determine the 
ignition characteristics. Currently, the configuration of the apparatus is as follows: the test section is of a 
cylindrical geometry, 12cm in diameter and 30cm in length. The quality of the samples using this method is good 
enough such that the use of liquid nitrogen to freeze the foam is not necessary. Attachments of Hanged sections of 
20cm in length have been constructed (allowing for a total length of 50cm) for use in later phases of the project. 
Species histories for HC, C02, CO, and 02 are obtained by gas sampling. Temperature histories are gathered using 
special prefabricated, fast response, probe thermocouples inserted into the centerline of the section every 2cm along 
its length. A nichrome wire sandwiched in-between ceramic honeycomb plates ignites the foam. The bottom of 
the igniter is insulated with shredded Fiberfrax. Insulation below, which is a 2 micron pore size, pours metal plate 
acting as a flow diffuser. Bottled, compressed air serves as oxidizer for the determination of the ignition 
characteristics. Later phases will involve varying the oxygen concentration. The test samples are cut from a block 
of foam using a core drill constructed from rolled sheet metal. 

Tests have been run using varying igniter powers and air flow rates to determine their effect on smolder ignition. 
Initial thermocouple data has indicated the possibility of two or three separate reaction fronts. We think these are 
the pyrolysis front and a char oxidation front in addition to the smolder front. Experiments with lmm/s flow 
velocity are almost finished. We are now moving onto running experiments at 2mm /s flow velocity. Data for the 
lmm/s flow velocity is being analyzed. W r e are looking to distinguish the pyrolysis, smolder propagation, and char 
oxidation fronts. 

Task 3: 2-D Smoldering with Transition to Flaming 

Work has involved the modification of a wind tunnel such that a longer mixing chamber is incorporated for better 
mixing of aggregate exhaust gases. Data for HC, CO, C02, and 02 species histories are still being taken. An 
array of 10 thermocouples have also been added at the gas/solid interlace in order to confirm and investigate the 
possibility of transition to flaming at the fuel surface exposed to the ambient. Ever since the inclusion of a 2-D 
matrix of 32 thermocouples embedded within the foam, experiments seem to indicate that dramatic increases in 
temperature within the foam (which were previously believed to reflect actual transition to flaming) well precede 
visual observations of flaming phenomena. The data acquisition system and software were modified to allow for 
recorded temperature measurements at the solid/gas interface. 

Experiments for flow velocity conditions ranging from Om/s (natural convection) to 2.5m/s have been run 
incorporating shear interferometry to investigate flaming phenomena at the solid/gas interface. Analysis of the 
additional data will hopefully verify the validity of the two flaming regimes proposed in the Fall 1993 Western 
States paper. 

Visual observations and thermocouple histories seem to indicate that transition to flaming occurs in the char and not 
at the interface. Extremely localized temperature peaks (-1200C) occur in the char, well preceding flaming at the 
interface. It is unclear as to whether these high temperatures peaks are the result of gas phase reactions, or very 
exothermic, heterogeneous surface reactions. Other avenues of experimental investigation to better analyze this 
phenomenon are being looked into such as, x-ray tomography, ultrasonic holography, and laser absorption imaging. 

Data is still being analyzed and we are submitting an abstract to the 8th International Symposium on Transport 
Phenomena in Combustion, S.F., U.S.A., July, 16-20, 1995. We have explored the use of ultrasonic imaging, and 
the results are not too promising. The foam is opaque to sound frequencies on the order of 100kHz. Lower 
frequencies on the order of 20kHz are being looked into. However, lower frequencies correspond to lower spacial 
resolution. We are still collaborating with Prof. Miyasaka at Fukui University on this technique. 


11-5 7 


II. MSAD Program Tasks — Flight Research 

iiimmiitmmmi hi 


Discipline: Combustion Science 

HUH 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 1 MS Degrees: 1 

PhD Students: 2 PhD Degrees: 0 


Task Initiation: 3/94 Expiration: 3/97 

Project Identification: 963-22-05-05 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Shultz. D.A., Matkowsky, B.J.. Volpert. V.A. and Fernandez-Pello. A.C. Propagation and extinction ot forced opposed 
flow smolder waves. Combustion and Flame (in press), (1994). 

Stocker. D.P., Olson, S„ Torero, J.L. and Fernandez-Pello. A.C. Microgravity smoldering combustion on the USML-1 
shuttle mission. ASME 1993 Winter Ann Meeting. New Orleans. LA. vol. 269. 99-110 (1993). 

Torero, J.L.. and Fernandez-Pello, A.C. Natural convection smolder of polyurethane foam, upward propagation. Fire 
Safety Journal, (in press), (1994). 

Torero, J.L., Fernandez-Pello, A.C. and Urban. D. Experimental observations of the effect of gravity changes on 
smoldering combustion. AIAA Journal, vol. 35, 5. 991-996 (1994). 

Presentations 

Fernandez-Pello, A.C. "Smoldering combustion in microgravity: from ground to space shuttle experiments, . 

Proceedings of the International Symposium on Aerospace and Fluid Sciences, Sendai, Japan, 243-273, 1993. 

Fernandez-Pello, A.C. "Smoldering combustion in microgravity: from ground to space shuttle experiments." Lecture, 
COSPAR '94 Conference, G1 -Symposium on Microgravity Sciences: Results and Analysis of Recent Space Flights. 
Hamburg, Germany, July 1994. 

Torero, J.L. and Fernandez-Pello. A.C. "Downward smoldering of polyurethane foam ." Proceedings ot the Fourth 
International Symposium on Fire Safety (in press) 1994. 

Tse, S.O.. Sanchez, C. and Fernandez-Pello, A.C. "Smoldering in the presence of a gas/solid interface and its transition to 
tlaming." 1993 Fall Meeting, Western States Section/The Combustion Institute. October 1993. 

Tse, S.O., Sanchez, C.G.. Fujita. O. and Fernandez-Pello, A.C. "Smoldering in the presence ot a gas/solid interface and its 
transition to flaming." Work-in-Progress Poster. Twenty-Fifth International Symposium on Combustion. Irvine. CA. 
August 1994. 


inmmttT timmiiiimH ••••• 


11-5 8 


II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

iiiMiiiiiiiiiiiiMiiiiiimmiiiHimniiMHiiiiiiiiiiiiiiiMiiiiiiiiiiiitiHiiiiHiiitimiiiiiHiHiiiMHiiiiniiitiiiiHiiiiiiiiiiiiiiiatitMiiii 


Ignition and the Subsequent Transition to Flame Spread in Microgravity 


PRINCIPAL Investigator: Dr. Takashi Kashiwagi National Institute of Standards and Technology (NIST) 


Co-Investigators: 

Dr. Howard Baum National Institute of Standards and Technology (NIST) 

Dr. Kevin MacGrattan National Institute of Standards and Technology (NIST) 


Task Objective: 

The objective is to conduct radiative ignition followed by transition to flame spread over various, different 
combustible solid surfaces in microgravity in order to understand the transition mechanisms from the ignition to 
subsequent flame spread, and to determine the effects of preheating, oxygen concentration, external flow velocity, 
geometrical configuration, and sample materials on the transition and flame spread characteristics. 

These results are needed for comparison with the numerically calculated data taking advantage of microgravity to 
determine their accuracy and to examine the validity of the chemical and physical processes used in the calculations. 

Task Description: 

The proposed space experiments will examine the effects on ignition and transition to flame spread of physical 
parameters which include oxygen concentration (21-50% 02), preheated fuel temperature (ambient -100 C), fuel 
thickness (thin/thick), fuel type (paper/pmma), geometrical configuration (including complex three-dimensional 
geometry such as edges, open and closed comers), external flow velocity (0-5 cm/s), and flame conditions 
(flaming/smoldering) . 

Proposed diagnostics includes a laser diode external radiant source, a digital data acquisition system, improved color 
flame and char front imaging, infrared imaging of the fuel surface for a time-dependent surface temperature 
distribution, and color shadowgraphy for flow+flame visualization. Gas species concentration measurements of 02 
and CO, "Desirements" include PIV, FTIR, and 2-Color Pyrometry. Standard diagnostics include thermocouples 
and experiment control verifications (flow, g level, radiant flux, etc.). 

Task Significance: 

For the first time, it is possible to study the transition from a radiative ignition to flame spread in the absence of 
overwhelming buoyant convection. The elimination of natural convective flow in the microgravitv experiment 
simplifies both the formulation and subsequent computation of these time-dependent, three-dimensional problems 
that include other complexities such as finite rate chemical kinetics in both the gas and solid. 

Progress During FY 1994: 

There is no progress to report at this time as the project has not started yet. 


Students Funded Under Research: Task Initiation: 11/94 Expiration: 11/98 

Project Identification: 963-15 -ob 

Responsible Center: LeRC 


(HIM HIIIIIIIIIIMIttllMHIl Ill 


11-59 


II MSAD Program Tasks — Flight Research Discipline: Combustion Science 




Studies of Premixed Laminar and Turbulent Flames at Microgravity 


Principal Investigator: Prof. Paul d. Ronney 

University of Southern California 

Co-Investigators: 

No Co-I’s Assigned to this Task 



Task Objective: 

The objective of this work is to study the effects of gravity-induced buoyancy on the combustion limits ot premixed 
gas tlames. The following four subtasks have been pursued: 

1. Radiation effects on premixed gas tlames. 

2. Flame structure and stability at low Lewis number. 

3. Flame propagation and extinction in cylindrical tubes. 

4. Experimental simulation of combustion processes using autocatalytic chemical reactions. 

Task Description: 

For task 1, we are studying the effects of the addition of inert, radiant particles to gas mixtures to increase the 
absorption coefficient of the gas. This enables us to study both the optically thin and optically thick radiation 
regimes in a single experiment. 

For task 2, we are studying flames in a variety of gas mixtures having low Lewis number (Le) in aircraft tests. The 
goal of these studies is to determine under what conditions, if any, the instabilities which occur in low-Le mixtures 
may lead to the development of stable, stationary spherical flames called "flame balls.” 

For task 3, we have conducted experiments at Earth gravity on flame propagation in vertical tubes of varying 
diameter, at varying pressures and with mixtures having varying fuels, inerts, and Le, and have measured the flame 
propagation rates just inside the extinction limit. Since this quantity is predicted by most relevant theoretical 
models, the relative importance of buoyancy, flame stretch, heat loss to the tube wall, radiation loss, etc., may be 
assessed. 

For task 4, we have introduced the use of aqueous autocatalytic propagating chemical fronts (in particular, the 
arsenous acid-iodate system) for the experimental simulation of premixed combustion in nonunilorm and unsteady 
flows. These fronts more nearly match the assumptions made by most relevant theoretical models that do gaseous 
flames; for example, constant density, constant thermodynamic and transport processes, and no heat losses. We 
have studied propagation in a Taylor-Couette (TC) flow, in the annulus between two rotating concentric cylinders, 
and in capillary-wave (CW) flow in a thin layer ot fluid in a vibrating dish. 

Task Significance: 

It is anticipated that the results of these studies will lead to an improved understanding ot the tire hazards that may 
exist in orbiting spacecraft and of ways to minimize these hazards. Furthermore, such studies may lead to an 
improved understanding of the mechanisms of combustion limits in Earth-based combustion devices, which in turn 
could lead to the development of cleaner and more efficient engines through the use of lean premixed combustors. 

Progress During FY 1 994: 

For task (1), a radiometer preamplifier circuit was designed, built, and evaluated on real gaseous flames. It was used 
on several KC- 1 35 flights in order to measure flame radiation from flame-balls. These tests were parucularly 
important for the hydrogen-air flames which emit only weak, but fundamentally important, thermal radiation that is 
difficult to detect without preamplification of the radiometer signal. 




11-60 



II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

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For task (2), six weeks of low-gravity flight tests were performed on NASA's KC-135 research aircraft. A large 
amount oi engineering data was obtained; no new scientific phenomena wax seen, nor were any expected because ;ill 
test mixtures had been studied in previous flight experiments. Several excellent examples of" the "sudden 
propagation" phenomena, seen in methane-oxygen-sulfur hexafluoride mixtures and thought to be caused by gas 
radiation, were observed. The most important lessons learned which will affect the spaceflight experiment are 1) die 
possibility ol etching of fused silica windows during spaceflight experiments due to corrosive combustion 
by-products, 2) the difficulties in obtaining accurate gas mixtures based on partial pressures and measured by gas 
chromatography, 3) the radiometers worked as expected but for hydrogen-air mixtures preamplification is required, 4) 
operational confidence in the spaceflight hardware can be enhanced by checking their operation of them during 
evacuation, chamber filling, and chamber lighting, and 5) the Xybion cameras are able to detect the combustion 
phenomena, however, they can be damaged by intense chamber lighting. 

In addition to the buildup of the radiometer preamplifier circuit, several other hardware improvements were made. A 
new partial pressure gas mixing system and algorithm was built and tested in the laboratory. An improved spark 
energy measurement system built around a digital oscilloscope and data processing system was developed. A 
computerized PC-based image processing system wave was implemented. One preliminary finding is that many of 
the tests run in the KC-135 have resulted in overexposed images. A workstation for conducting flame-ball 
modeling calculations was delivered, and a one-dimensional, unsteady flame code employing detailed chemical and 
transport sub-models, developed by B. Rogg at Cambridge University, wits obtained. This system will form die 
basis of the flame-ball modeling calculations to be used for comparison with the spaceflight experimental results. 

The PI participated in the first meeting of the joint US/Japan Microgravity Combustion Coordinating Group. The 
PI proposed to perform a set of flame-ball experiments in the Hokkaido 10 second drop facility to supplement the 
spaceflight test matrix. 

The PI also collaborated in a study with the Aerospace Corporation regarding the use of lasers for ignition. 

Minimum ignition energies of methane-air mixtures at 1 atm initial pressure as a function of fuel-air ratio were 
measured and compared to prior spark ignition and numerical modeling. The results suggest a critical role of the 
size of the energy deposition region, and the potential for significantly reduced minimum ignition energies compared 
to classical experiments if the size of the deposition region is made sufficiently small. 

For task (3), to complement his current study of combustible mixtures with low Lewis number, the PI participated 
in a study of flame propagation at high Lewis number in tubes with Dr. Howard Pearlman, a NRC postdoctoral 
research associate at NASA Lewis. Theory predicts at high Lewis number, pulsating and traveling- wave 
instabilities should occur. The experiments have shown spiral-wave flame fronts in addition to the predicted modes. 
None of these modes have been conclusively observed experimentally in previous works, probably because these 
experiments employed more advanced diagnostics and mixtures with higher Lewis numbers than any previous work 
of its type. 

For task (4), plans were made for the study of chemically reacting fronts responding to hydrodynamic strain. A 
Taylor tour-roll mill, where the strain rate is determined by the rate of rotation of the rollers has been constructed. 


Students Funded Under Research: 


Task Initiation: 3/91 Expiration: 12/94 

BS Students: 

9 

BS Degrees: 

9 

Project Identification: 962-22-05-06 

MS Students: 

2 

MS Degrees: 

2 

Responsible Center: LeRC 

PhD Students: 

2 

PhD Degrees: 

1 


1 1-6 1 



II. MSAD Program Tasks — Flight Research 

° 


Discipline: Combustion Science 





imm 


Bibliographic Citations for FY 1994: 

Journals 

Haslam. B.D. and Ronney. P.D. Fractal properties of propagating fronts in a strongly stirred fluid. Submitted to Physics 
of Fluids. (1995). 

Lozinski. D.. Buckmaster. J.D. and Ronney. P.D. Absolute flammability limits and (lame balls in optically thick 
mixtures. Combustion and Flame, vol. 97, 301-316 (1994). 

Pearlman. H.G. and Ronney. P.D. Self-organized spiral and circular waves in premixed gas flames. Journal of Chemical 
Physics, vol. 101, 2632-2633 (1994). 

Pearlman, H.G. and Ronney. P.D. Near-limit behavior of high Lewis-number premixed flames in tubes at normal and low 
gravity. Physics of Fluids, vol. 6. 4009-4018 (1994). 

Ronney, P.D. Laser versus conventional ignition ol flames. Optical Engineering, vol. 33, 510-521 (1994). 

Ronney. P.D.. Whaling, K.N.. Abbud-Madrid. A.. Gatto. J.L.. and Pisowicz. V.L. Stationary premixed flames in spherical 
and cylindrical geometries. AIAA Journal, vol. 32. 569-577 (1994), 

Zhu, J.Y. and Ronney, P.D. Simulation of front propagation at large non-dimensional flow disturbance intensities. 
Combustion Science and Technology (in press), vol. 100. 183-201 (1994). 

Books . . , 

Ronney, P.D. "Some open issues in premixed turbulent combustion." in “Mathematical Modeling in Combustion and its 

Interaction with Numerical Computation." Edited by: J.D. Buckmaster and T. Takeno Springer-Verlag, in press, 1995. 

Presentations 

Pearlman. H.G. and Ronney, P.D. "Near-limit behavior of high Lewis-number premixed flames in tubes at normal and low 
gravity." Spring Technical Meeting, Combustion Institute, Central States Section. Madison. WI, June 6-7. 1994. 

Ronney. P.D. "Requirements design review: structure of flame balls at low Lewis-number (SOFBALL). NASA Lewis 
Research Center. Cleveland, OH, Oct. 14, 1993. 

Ronney, P.D., "Combustion at zero-gravity," Dept, of Mechanical Engineering." University of Southern California, Los 
Angeles. CA, November 1993. 

Ronney, P.D. "Preliminary design review: structure of flame balls at low Lewis-number (SOFBALL).’ NASA Lewis 
Research Center, Cleveland. OH. May 17. 1994. 

Ronney. P.D. "Propagation and extinction mechanisms of premixed turbulent flames." Joint U.S. /Japan Workshop on 
Mathematical Modeling in Combustion and its Interaction with Numerical Computation. Kaapa, HI, July 25-29. 1994. 




11-62 



II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

1 1 II I HI II llttlll lit IIIH tllltllltl 11111111111111 MM Illlll II III I III llllllllllll 111(1 II I II I II 1 1 1 1 1 II I II I II I III I III 1 1 1 1 It 1 1 II I II III 1 1 II I III II I It 1 1 II llll II I II 1 1 II 1 1 1 1 1 1 1 1 1 1 II I II I II I II I II 1 1 II I II 1 1 II I II 1 1 II I H 1 1 HIIMIIIIH 


Ignition and Flame Spread of Liquid Fuel Pools 


Principal Investigator: Dr. Howard d. Ross 

NASA Lewis Research Center (LeRC) 

Co-Investigators: 


Prof. W.A. Sirignano 

University of California, Irvine 

Dr. F.J. Miller 

Case Western Reserve University 


Task Objective: 

For flame spread over liquid fuel pools, the existing literature suggests three gravitational influences: (a) 
liquid-phase buoyant convection, delaying ignition and assisting flame spread; (b) hydrostatic pressure variation, due 
to variation in the liquid pool height caused by thermocapillary-induced convection; and (c) gas-phase buoyant 
convection in the opposite direction to the liquid-phase motion. No current model accounts for all three influences. 
In face prior to this work, there was no ability to determine whether ignition delay times and flame spread rates 
would be greater or lesser in low gravity. 

Flame spread over liquid fuel pools is most commonly characterized by the relationship of the initial pool 
temperature to the fuel’s idealized flash point temperature, with four or five separate characteristic regimes having 
been identified. In the uniform spread regime, control has been attributed to (a) gas-phase conduction and radiation, 
(b) gas-phase conduction only, (c) gas-phase convection and liquid conduction, and most recently (d) liquid 
convection ahead of the flame. Suggestions were made that the liquid convection was owed to both buoyancy and 
thermocapillarity. In the pulsating regime, complicated flow structures have been observed in both the gas and 
liquid phases, with circulation around several centers; these flows were attributed to combined thermocapillary and 
buoyant effects. 

Task Description: 

The approach we have taken to resolving the importance of buoyancy for these flames is (a) normal gravity 
experiments with advanced diagnostics, (b) microgravity experiments, and (c) numerical modeling at arbitrary 
gravitational levels. 

Task Significance: 

Of special interest to this work is the determination of whether, and under what conditions, pulsating spread can and 
will occur in microgravity in the absence of buoyant flows in both phases. One possible mechanism for pulsating 
spread in microgravity is if the “premixed gas diffusive burning'’ pulsations are due to periodicity between gas-phase 
conductive and liquid-phase convective control. A second possibility, which will be determined by these 
investigations, is whether pulsations may be induced in low gravity by the presence of slow, forced, gas-phase 
flow. 

Progress During FY 1 994: 

During FY1994 the foremost accomplishment was the completion of the flight hardware for the first sounding 
rocket flight. Early in FY1994 the final fabrication of parts was completed and assembly continued throughout the 
spring. Component and assembly vibration tests were successfully completed at Lewis and two full normal-gravity 
combustion tests were carried out in the flight hardware. In both tests the hardware performed well, though an 
initial switch setting prevented good science data from being obtained in the first test, and a misconnected cable and 
poorly focused camera plagued the second test. All of these problems were traced to lapses in procedures, and steps 
were taken to improve the assembly and test practices. The hardware underwent another round of vibration testing at 
Wallops Island, and sequence testing and spin balancing were performed. The hardware is currently underway to 
White Sands Missile range for a scheduled November 22nd launch, the first Lewis sounding rocket experiment in 
nearly 30 years. 


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11-63 


II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 

mu •» »»«.» 


In order to obtain 1-g data tor comparison purposes, and to spare the flight hardware having to undergo multiple 
combustion tests, a full breadboard version of SAL was designed and constructed out ot (mostly) spare parts. Using 
this apparatus the following tests were performed. 

• Using a beam splitter, video mixer, and long local length lenses we captured some simultaneous close-up gas and 
liquid phase schlieren views and visible flame views ot flame spread in the unilorm regime. A slight preheating ot 
the gas was visible in the schlieren view (about 1 mm), but any liquid-phase view was generally swamped by 
temperature gradients caused by surface evaporation. Thus, it appears tor this case that the preheating occurs 
extremely close to the surface and the flame leading edge (on the order ot 1mm), which agrees well with theoretical 
modelling but not with the previous interferometry work by others. 

• We conducted several tests using a Kodak Ektapro High Speed video camera to capture PIV images at 500 
frames/sec. Floating particles were used to record the surface movement. The video clearly indicates liquid-phase 
movement ahead of the flame (several mm) even in the highly uniform spread region (1 -propanol, 22-23 C). 
However, no evidence has been found that the liquid phase accelerates to a speed taster than the flame front. 

• We successfully used the Object Tracking Workstation system to track surface particles ahead of a 1 -propanol 
flame in the uniform regime. The analysis, which involved data taken with the high speed video camera, 
corroborates and significantly strengthens preliminary data taken last summer which indicate surface flow ahead ot 
the flame. The data is presented in graphs which show flame and particle location vs. time, and the particles are 
clearly seen to move 3-4 mm ahead of the flame, though the flame normally does overtake them. 

• For pulsating spread, the high-speed video showed that the flame never caught the flow head. We also obtained 
good views of the vortex forming in the bulk liquid. 

We continued working on improvements to the rainbow schlieren deflectometry (RSD) technique which will benefit 
all projects employing this diagnostic. We completed programs to make arbitrary cartesian, symmetric, gray scale, 
and single color filters, as well improved the optimization program to handle filters of any size and type. A NASA 
TM is planned to describe the new filter generation process and programs. We also performed the first quantitative 
comparison of RSD derived temperatures with temperatures measured independently. This was done lor a stably 
stratified liquid layer and showed a disagreement of 0.4 °C when the schlieren data was integrated over a distance of 
10 mm. Work continues to improve this. 

Development of a code used to animate our numerical results was largely completed. Using these animations we 
were able to uncover some errors in the flame spread code, notably a nonconservation ot mass whenever the grid 
shifted. Finding such an error would have been nearly impossible using only still images, but the animations 
showed it clearly in the flame motion. This error and some others have now been corrected. However, a large 
gas-phase recirculation cell that we also discovered, and has been traced to numerical problems at the top boundary 
of the domain, still remains. Fortunately, it does not seem to affect the calculated flame spread rate. Particle 
tracking was added to the animation code, to mimic the experimental PIV data, and mock RSD and interferometry 
was also performed. Excellent agreement between the calculated and measured RSD views was obtained regarding 
vortex size and location, while differences in the calculated and measured (by others) interferometry views remain. 
Some differences in the surface particle trajectories still exist between the code and the experiments as well. 

The Zero Gravity Facility returned to operation in FY94 and many experiments were conducted using the old 
hardware with some improvements such as better flow control, and a top view video camera. The drops showed 
successful ignition and initial spread over 1 -butanol at opposed flow rates between 10 and 20 cm/s, which is the 
range chosen for the sounding rocket flights. We also did a few experiments with propanol which showed flame 

spread with opposed flow. 

A low-speed wind tunnel that allows operation between 5 and 200 cm/s was set up and flow profiles were measured 
for several speeds and locations. Flow visualization was also conducted with dummy fuel trays in place. This 
tunnel will allow testing of flame spread over liquid and solid s in the presence of opposed or co-current flow at 
normal gravity. 


mum 




11-64 


II.MSAD 


Program Tasks — Flight Research Discipline: Combustion Science 

IIIMMtlMlltllllllllllillMtllllMIIIIMtllMIIHIMIMMIIKtlMIHIMIIIIIIIIIIIIIIIIIIIIIIIIMIItMtllllltlllllllllllllllllltllllimillMIIIIIIMIIIIItlHIMIIinmilllllllMHIIIIIIIIIIIIIIIIIImitllllllMtlll 


Students Funded Under Research: 


Task Initiation: 2/91 Expiration: 2/97 

BS Students: 

2 

BS Degrees: 

0 

Project Identification: 962-22-05-07 

MS Students: 

0 

MS Degrees: 

0 

Responsible Center: LeRC 

PhD Students: 

1 

PhD Degrees: 

1 



Bibliographic Citations for FY 1994: 

Presentations 

Miller, F.J., Ross, H.D., and Schiller, D.N. 'Temperature field during flame spread over alcohol pools: Measurements and 
modelling." Accepted at the Eastern States Section of the Combustion Institute Fail Technical Meeting, Clearwater Beach, 
FL, 1994. 

Miller, F.J., Ross. H.D . and Schiller. D.N. "Rainbow schlieren deflectometry of flame spread over liquid pools: A 
comparison of experimental and numerical results." Poster at the Twenty-Fifth International Symposium on Combustion, 
Irvine. CA, 1994. 


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11-6 5 



II. MSAD Program Tasks — Flight Research 

Discipline: Combustion Science 

Combustion of Solid Fuel in Very Low Speed Oxygen Streams 

Principal Investigator: Prof. James s. Tien 

Case Western Reserve University 

Co-Investigators: 


K.R. Sacksteder 
P.V. Ferkul 

NASA Lewis Research Center (LeRC) 
National Research Council 


Task Objective: 

The objectives are to: 


1. Enhance the understanding of flame spreading above solid-fuel surfaces through a systematic investigation in the 
low-speed, forced and buoyant flow regimes. 

2. Determine the mechanisms that induce flammability limits ot flames over solid surfaces in low-speed flows. 

3. Resolve the structure of flames spreading in low-speed flows through a characterization ot the velocity, 
temperature and selected- species fields in their vicinity. 

Task Description: 

This task consists of the development and flight ot a space-based experiment, the continued pursuit ot ground-based 
results in drop towers and aircraft experiments, and the continued development ot a comprehensive predictive model 
of concurrent-flow flame spreading. 

The flight experiment is to be accomplished in three phases. An experiment to be conducted in a Glovebox Facility 
is to provide insight into global flame characteristics of thin and thick fuels. In the second phase, thin tuels are to 
be burned as they are dispensed from a continuous supply in such a way that the flame is fixed in space relative to 
the test apparatus. In this way, detailed diagnostic measurements are greatly simplified and transient flame behavior 
can be observed as the test conditions are slowly varied. In the third phase thick fuels will be burned to address the 
effect of transverse heat conduction into the fuel, yet with flames spreading slowly enough that the same diagnostic 
measurements can be made. 


The ground-based experimental program consists of observations of flame spreading in partial gravity environments 
(first attempted as part of this program), the ignition behavior of flames over thin and thick solid fuels in 
microgravity forced flows, and the implementation of temperature, velocity and species concentration measurement 
systems. 

The model development consists of integrating a fully elliptical fluid mechanics formulation with surface and gas 
phase radiative interactions in a transient model that attempts to predict the behavior ot the selected experimental 
test fuels in concurrent-flow burning. 

Task Significance: 

In normal gravity, buoyant air motion in flames is at least 20 to 30 cm/sec. Flame spreading mechanisms that are 
present only in lower flow velocities, such as spacecraft air-ventilation currents, cannot, therefore, be studied in 
normal gravity. This research seeks to contribute to fundamental combustion science, and to improve the basis for 
engineering improved spacecraft tire safety. 


IIIMIIIIIIIIIMMIIMIIIHIIMIMMIIimiltllimillMMMIM Him IIIIHItlltlMIIIIIttl 1*01 





n-66 


II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 


Progress During FY 1 994 : 

This is a new task in Fiscal Year 1994 beginning with the award of a new flight experiment project entitled, 
“Combustion ot Solid Fuel in Very Low Speed Oxygen Streams,' 1 under NRA-93-OLMSA-1, "Microgravity 
Combustion Science: Research and Right Experiment Opportunities.” 

Since the transition to the flight program, this task has achieved the following major accomplishments: 

1. The numerical formulation of the theoretical model of concurrent flow flame spreading has been modified to 
permit the simulation of purely buoyant flows. This model has been used to predict flammability limits and flame 
spreading behavior over a range of oxygen concentrations and gravitational acceleration levels, predicting a 
flammability limit in air (21% oxygen) of 0.0003g. 

2. The numerical formulation of the theoretical model of concurrent flow flame spreading has been modified to 
simulate the gas phase radiation from flames in low speed flows. 

3. The Forced Row Ramespread Test glovebox experiment (FFFT) was successfully reviewed in a peer-reviewed 
Science competition, and has been manifested aboard the USMP-3 mission, and is a candidate for flight aboard the 
MIR Space Station. An aircraft glovebox facility was prepared for testing of the FFFT in a free-tloat mode, unique 
among glovebox experiments, in which observations were made of the ignition of both thin and thick fuel sample 
candidates. The final design of the FFFT was completed, including the addition of a novel imaging system for 
in-situ, real-time velocity measurements incorporated into the video data from the experiment. 

4. Experiment technology for the newly awarded flight experiment has been developed to permit the continuous 
dispensing of thin fuel into an established flame in low-speed forced flows in microgravity. The device consists of 
rolls of 7 cm wide, thin-fuel strips edged with a conductive foil to quench the fuel edge and a small combustion 
tunnel through which the fuel strip is pulled. An optical device detects the burnout front of the fuel where the flame 
is stabilized and controls the fuel feed rate. The gas flow is based upon the successful design of the Forced Row 
Ramespread Test glovebox experiment technology. This device is designed to be integrated into the existing 
aircraft facility which was designed originally for used in purely buoyant flow flame spread studies, providing quick, 
low-cost access to reduced gravity testing of this new technology, and providing quick, low-cost access to rainbow 
schlieren measurements of forced-flow flame spreading experiments. 

5. A series of experiments were completed in the NASA KC-135 aircraft providing the first stereo (3 -dimensional) 
photographs of microgravity combustion flames; specifically downward flame spreading experiments in partial 
gravity environments. This imaging technology is a candidate for the newly awarded flight experiment. 

6. A new set of experiments were completed in the 5 second drop tower providing observations of concurrent flow 
flame spread ignition processes using the flammable sample translation device developed in this program. These 
tests provided a direct comparison of hot-wire ignition techniques with and without a chemical promoter, and some 
improved observations of the beginnings of transitions toward spreading. 

7. A new formulation of traditional methods for correlating opposed flow flame spreading experimental results was 
derived using the results of the partial gravity flame spreading tests. This new formulation for the first time 
correlates reduced and mircrogravity results with normal gravity results, accounting for radiative losses from 
low-speed flames. 

8. A new concept for the research of partial gravity flame spreading was identified: using the Canadian Large Motion 
Isolation Machine (LMIM) reprogrammed to a set point of, for example, 0.001 g instead of the conventional set 
point of O.Og. This device may permit observations of flame spreading in steady, milli-g environments, which may 
be the transition region between high-speed and low-speed buoyant flow regimes. 


IIMMIIM IM Ml lit I 


min inn 


11-67 



II. MSAD Program Tasks 

1 1 It I 


Flight Research Discipline: Combustion Science 

...MM. ...MM 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 

MS Students: 1 MS Degrees: 

PhD Students: 1 PhD Degrees: 


Task Initiation: 2/94 Expiration: 2/99 
0 Project Identification: 962-22-05-40 

3 NASA Contract No.:nag3-io46 

2 Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals . 

Ferkul. P.V. and Tien, J.S. A model of low-speed concurrent flow flame spread over a thin fuel. Combustion Science and 

Technology, vol. 99, 345-370. (1994). 

Presentations ... 

Ching-Biau. Jiang and Tien. James S. ’’Numerical computation of flame spread over a thin solid in forced concurrent flow 
with gas-phase radiation." accepted for presentation at the Eastern States Section Meeting of the Combustion Institute 
(December 1994). 

Jiang, C., Tien, J.S. and Ferkul. P.V. "Numerical computation of buoyant upward flame spread and extinction over a thin 
solid in reduced gravity." presented to the Central States Section Meeting ol the Combustion Institute. Madison 
Wisconsin, June 5-7, 1994. 

Sacksteder, K.R. and Tien, J.S. "Buoyant downward diffusion flame spread and extinction in partial gravity 
accelerations.” Presented at the Twenty-Fifth Symposium (International) on Combustion, The Combustion Institute. 
1994. 

Sacksteder, K.R. and Tien J.S. "Buoyant downward diffusion flame spread and extinction in partial gravity accelerations, 
presented to the Micro -Gravity Measurements Group Meeting #13. Montreal Quebec Canada, September 1994. 


Mill I Mill MIMIHIIMIMHIII.il, II Ml MIMHMIII I 


11-68 



II. MSAD Program Tasks — Flight Research Discipline: Combustion Science 




Droplet Combustion Experiment 

Principal Investigator: Prof. Forman a. Williams 

University of California, San Diego 

Co-Investigators: 


Prof. F.L. Dryer 

Princeton University 


Task Objective: 

The objective ot this research is to provide scientific support (in collaboration with Professor F. Dryer of Princeton 
University) tor a droplet burning experiment to be performed on-board a space platform. This support will include 
pertormance ot theoretical analyses relevant to the experiments, execution of drop-tower experiments to acquire 
additional data, analysis of experimental data obtained in ground-based experiments, and identification of test 
conditions for experiments in space. 

Task Description: 

The objectives stated above will be pursued through the use of the NASA LeRC 2.2-Second Drop Tower with 
measurements made on heptane and methanol burning in atmospheres of normal air and in diluted atmospheres and 
through the analysis ot data from this tower, and also the 5-Second Drop Tower with these fuels as well as decane. 
The data will be analyzed for droplet diameter and extinction diameter by use of high-precision analysis systems. 
Rame diameters also will be obtained by suitable digital image analysis procedures. 

The theoretical approach will employ asymptotic methods to relate observed extinction conditions to elementary 
rate parameters. Treatment of the data by use of theory will help identify experiments that need to be done in space. 
Additional experiments will also be performed to address the effects of relative droplet-gas convection on burning 
rates. In the theoretical part of the project, a spherosymmetnc, time -dependent finite element-based numerical 
model with detailed gas phase kinetics, and variable property effects will be extended to study the effects of soot 
formation in droplet burning. Extension of the existing one-dimensional code to two-dimensional axisymmetric 
geometry will be evaluated. 

Task Significance: 

The overall purpose of the research is to achieve fundamental advances in the science of droplet combustion. In 
particular, unsteady liquid and gas phenomenon, and extinction chemistry of normal alkanes and alcohols are 
investigated. 


Progress During FY 1994: 

Theoretical Studies at UC-San Diego 

Analytical modeling on the structure and extinction of quasi- steady, spherically symmetric diffusion flames around 
methanol droplet corresponding to two, three, and four-step reduced mechanisms have been already completed. For 
methanol droplets, the equilibrium of water-gas shift is very good so that extinction diameters obtained from the 
two and three-step analysis are almost the same. The asymptotic analysis corresponding to the four-step 
mechanism, obtained by relaxing the H atom steady-state assumption, gives extinction diameters 50% smaller than 
those of the two and three-step analyses. Comparison between UCSD asymptotic results and the numerical 
calculations performed at Princeton show significant disagreement with the asymptotics predicting extinction 
diameters roughly one order magnitude smaller. When water absorption is included and an assumption of 40% water 
at extinction is included, the asymptotic results agree well with the numerics for methanol burned in air at 1 atm. 
However, at this stage the amount of water absorption at extinction must be guessed so asymptotic analysis of 
time-dependent water absorption problem has been started. Also, pool burning experiments to gain better 
understanding of the water absorption is underway. 


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11-6 9 


II. MSAD Program Tasks — Flight Research 



Discipline: Combustion Science 

tintiiiiitiiiiiiiimti immiitii 


Numerical and Experimental Studies at Princeton 

Methanol and N-Hentane Dronlet Vaporization and Combustion Modeling 

A report describing in detail the numerical modeling which was pertormed to develop the test envelopes tor the 
second flight test matrix entitled. Theoretical Basis tor Estimating Test Times and Conditions tor Drop Tower and 
Space-Based Droplet Burning Experiments with Methanol and N-Heptane" was issued as Princeton University 
MAE Report No. 1999. 

Numerical Modeling of the Combustion of Methanol/Water Mixture Droplets 

Extensive numerical calculations tor methanol/water mixture droplets of 1-5 mm diameter in air were pertormed. 
These results will be compared with those obtained using die FSDC glove box experiments (USML-2) as well as 
drop tower testing which will be conducted this fall. 

Development of 2-D Droplet Combustion Model 

Progress has been made in developing a droplet combustion/vaporization hnite-element model. As a test case, 
boundary conditions for the case ot pure vaporization involving two species (methanol/water) with tixed surface 
temperature has been implemented into the FORTRAN program. This program is currently being debugged and is 
expected to run shortly. 

Other 

Extensive tests were carried out tor n-heptane burning in 02/He environments at the NASA Lewis 5 -second drop 
tower. These tests cover the proposed DCE first flight test matrix. New and important results on OH-imaging ot 
the droplet flames were accomplished using UV cameras. The test results are being analyzed and the results will be 
presented at the 3rd microgravity combustion workshop. 

During this reporting period a successful RDR/PDR for the Droplet Combustion Experiment (DCE) was completed 
in collaboration with the NASA personnel. 


Students Funded Under Research: 


Task Initiation: 3/9 i Expiration: 3/95 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-22-05-08 

MS Students: 

0 

MS Degrees: 

0 

Responsible Center: LeRC 

PhD Students: 

3 

PhD Degrees: 

3 



Bibliographic Citations for FY 1994; 

Journals 

Card, J.M. Asymptotic analysis for the burning of n-heptane droplets using a four-step reduced mechanism. Combustion 
and Flame. (1993). 

NASA Tech Briefs 

Dryer, F.L. Computational/experimental studies of isolated, single component droplet combustion. Second International 
Microgravity Combustion Workshop, NASA Conference Publication 10113. NASA Tech Brief, 291-196 (1993). 

Williams, F.A. Studies of droplet burning and extinction, Second International Microgravity Combustion Workshop, 
NASA Conference Publication 10113. NASA Tech Brief, 283-290 (1993). 

Presentations 

Choi, M.Y., Dryer, F.L., Green. G.J. and Sangiovanni. J.J. "Soot agglomeration in isolated, free droplet combustion. 
AIAA Paper No. 93-0823, January 1993. 

Marchese, A.J. and Dryer, F.L. "Computational modeling of transient methanol droplet vaporization.' presented at the 
Easter States Section of the Combustion Institute Meeting, October 1993. 



II* MSAD Program Tasks — Flight Research Discipline: Combustion Science 

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Marchese. A.J. and Dryer. F.L. Transient modeling of the combustion of bi-component liquid droplets: methanol/water 
mixtures, presented at the Faster States Section of the Combustion Institure Meeting. 1994. 

Marchese. A.J.. Dryer. F.L. and Choi. M.Y. "Theoretical basis for estimated test times and conditions for drop tower and 
space-based droplet burning experiments with methanol and n-heptane." MAE Report No. 1999. Princeton University. 
August 1994. 

Zhang. B.L.. Card, J.M. and Williams. F.A. Application ol rate ratio asymptotics to the prediction of extinction for 
methanol droplet combustion." Western States Section of the Combustion Institute. March 1994. 


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11-71 


II. MSAD Program Tasks — Flight Research 

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Discipline: Fluid Physics 


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Surface Controlled Phenomena 


Principal Investigator: Prof. Robert e. Apfei 

Yale University 

Co-Investigators: 


R.G. Holt 

Jet Propulsion Laboratory 

Yuren Tian 

Yale University 


Task Objective: 

The goals of this research are to investigate the rheological properties of surtactant-bearing liquid drops. By 
comparing experimental results in the ideal environment of the Spacelab to our theory for spherical equilibrium 
drops, we can validate the model. We can then synthesize a generic theory which can handle arbitrary acoustic fields 
and static deformations, in order to have a technique for studying static and dynamic surface properties tor 
surtactant-bearing drops which can be successfully applied in 1-g experiments. 

Task Description: 

Single liquid drops are introduced into the center node of an acoustic standing wave in DPM's Near- Ambient 
Chamber. They are allowed to reach quiescent equilibrium. Then, shape oscillations about either a spherical or a 
spheroidal equilibrium shape are excited - either by a momentary increase and release of the z-axis acoustic pressure 
or by a periodic modulation of that pressure. The resulting oscillations are recorded on video tape and cine film tor 
later analysis. 

Three sample materials will be investigated on USML-2: triply distilled water, water with small amounts of Triton 
X-100 or bovine serum albumin at five different concentrations. The additives provide contrasting time scales: 
Triton X-100 is a nonionic fast-sorbing surfactant while BSA is sorption-inhibited. A range of drop sizes from 4 to 
12 cc will be investigated for each of concentration. 


Task Significance: 

The flight experimental data will be used to validate the theory which describes drop shape-oscillations as a function 
of various surface parameters. These parameters will be obtained in microgravity from drops oscillating about a 
spherical equilibrium shape as well as about an acoustically induced oblate shape. By comparing the differences in 
the natural frequency and damping constant tor these oscillations, the theory and experimental techniques can be 
used to perform measurements of the surface properties on the ground. Theoretical development and ground-based 
experiments to support the microgravity work are also performed. 


Progress During FY 1 994: 

Ground-based work, primarily in preparation for the USML-2 mission has focused on assuring ourselves that a) the 
improved DPM will work up to expectations, b) the crew will be well trained for the mission, and c) the quality of 
the science and the ultimate science return will be maximized. 

In preparation for USML-2, tests have been performed to determine an optimal tip configuration for drop 
deployment; the best of the ground based designs were tested in KC-135 flights as well. Tests have been performed 
on whether the flexible tubing used to transport fluids for forming drops can produce bubbles. Both levitated and 
suspended samples are being used to study spurious sample rotation of the type observed on USML- 1 , from our 
understanding techniques for compensation are being developed. 

We have designed a computer simulation of drop dynamics that can be used in training the USML-2 crew. It has 
been delivered to the Payload Crew Training Complex at MSFC. 


IIMIII I HUM 


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11-72 


II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

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Ten papers covering the experimental, analytical, and computational studies into the rheology of surfaces covering 
the work done in this fiscal year will be submitted within the calendar year. Experimental measurements of surface 
tension trom the static shape of a very small levitated drop compare well with theoretical predictions. Oscillating 
drop experiments analogous to those of USML-1 and USML-2 have been carried out on the ground. An automated 
system tor reducing the video image of a drop to half a dozen parameters is now processing three frames a minute. 
The detormation on both static and oscillating drops due to the levitating and oscillation-driving acoustic field has 
been studied using a boundary-integral technique. The interaction of speakers in various configurations and the 
resulting torques have been studied with levitated and suspended samples. 


Students Funded Under Research: 


Task Initiation: 2/90 Expiration: 6/96 

BS Students: 

3 

BS Degrees: 

3 

Project Identification: 963-24-04-03 

MS Students: 

2 

MS Degrees: 

0 

Responsible Center: jpl 

PhD Students: 

3 

PhD Degrees: 

1 


limilllllllllllMIIIIIIIIIIIIIIIMIIIIMIIIIIIIIIIIIIMIMIIIIIIKMItimiMHIIIIMIII* 


11-7 3 



II. MS AD Program Tasks — Flight Research Discipline: Fluid Physics 

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Critical Viscosity of Xenon 

Principal Investigator: Dr. Robert f. Berg 

National Institute of Standards and Technology (NIST) 

Co-Investigators: 

Dr. Michael R. Moldover 

National Institute of Standards and Technology (NIST) 


Task Objective: 

The objective of the experiment is to produce archival viscosity data on xenon that is closer to its liquid-vapor fluid 
critical point than is possible in 1-g. 

Task Description: 

1. Develop a low frequency, low shear rate viscometer with |iK temperature control near room temperature. It will 
be of an electrostatically driven micro-flexure design; 

2. Characterize vibration isolation sufficient to approach the critical temperature to within 300 pK while measuring 
viscosities to 0.5% precision; 

3. Load xenon sample to within 0.3% of the critical density; 

4. Choose sample geometry and do heat transfer analysis to establish expected thermal gradients and thermal 
equilibration times realistic for a Space Shuttle flight timeline; 

5. Involve critical point dynamics theorists in data analysis before and after flight. 

Task Significance: 

The data will provide complementary results with Critical Fluid Light Scattering Experiment (CFLSE) to test the 
mode-coupling theory of critical phenomena and provide guidance to renormalization group theory development on 
dynamic critical-point fluid behavior. 

Progress During FY 1 994: 

Oscillator calibration: 

We developed a novel, accurate calibration procedure for the oscillating screen viscometer. This procedure, which 
makes use of the viscometer s wide bandwidth and hydrodynamic similarity, allows the viscometer to be 
self-calibrating. To demonstrate the validity of this procedure we measured the oscillator s transfer function under a 
wide variety of conditions. We obtained data using CO, at temperatures spanning a temperature range of 35 K and 
densities varying by a factor of 165, thereby encountering viscosity variations as great as 50%. In contrast the 
flight experiment will be performed over a temperature range of 29K and at only a single density, and the viscosity 
is expected to change by less than 40%. The measurements showed that the viscometer's behavior is fully 
consistent with the use of hydrodynamic similarity for calibration. 

Cell loading and viscometer testing near Tc: 

The same cell used for the CO, tests was later filled with xenon to within 0.2% of its critical density by use of a 
carefully characterized filling procedure. This is better than the required accuracy of 0.3%. The critical temperature 
T c was then located to a precision of better than 1 mK by observing the appearance and disappearance of the 
liquid-vapor meniscus. This is better than the 10 mK precision required to choose the value of the reference resistor 
of the cell's temperature bridge. 

Viscosity measurements taken up to 40 C with the xenon-filled cell were consistent with the measurements made 
with the older, high-Q oscillator. However, within 0.3 K of Tc the observed transfer function deviated from the 


Illlllllll 


11-74 


II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 




expected response by as much as 3 %. The behavior was consistent with a ’'sloshing” mode of the stratified of the 
sample, an effect which will not be present in low gravity. 

Improvements of the cell: 

We implemented several improvements to the construction of the first flight cell, delivered in September 1994. The 
metal gaskets were made more secure by increasing the torque on the gasket's bolts to 17 inch-pounds, by using 
stronger bolts with a thread lubricant, and by retightening the bolts following the thermal cycles due to vacuum 
bakeout and sample loading. The mechanical stress on the electrical feedthrus was reduced by use of a pliable jig to 
increase the precision of electrode attachment and by casting epoxy around the external pins. The stainless steel fill 
line was replaced by a copper till line which could be crimped reliably. 

Motivated by the observation of undesired sloshing modes between 0.5 and 2.5 Hz, we added an anti-sloshing baffle 
to the cell. Although these modes will not exist in low gravity, they complicate the analysis of the 1-g data. The 
new baffle eliminated modes above 1 . 1 Hz, and it reduced the amplitude of the lower-frequency modes by a factor of 
more than two. Its design was guided by measurements on water troughs of variable geometry as well as by 
extensive tests in xenon cells with and without a baffle. 

Supplemental technical support: 

We collaborated with Nile Oldham of NIST’s Electricity Division to develop a prototype single-board, 
programmable, voltage divider which met CVX's requirements for precision and stability in balancing the 
capacitance bridge. Although the first concept of a multiplying DAC circuit exhibited an unacceptable temperature 
coefficient in prototype, the second concept of a 9-bit ratio transformer was successful. The prototype's transfer 
function matched that of the large commercial ratio transformer presently used in the laboratory, and it contributed 
negligibly to the noise of the viscosity measurement. 

To clarify the design of the viscometry electronics, we obtained assistance from J. Cies of Hewlett-Packard in the 
form of a technical report. 

Miscellaneous: 

The magnitudes of the drive and detection voltages were refined to reduce nonlinear behavior of the oscillator’s 
transfer function to 0.3%. The expected effect of a possible divergence of the dielectric constant near the critical 
point was shown by calculation to be negligible. The effect of residual gas during the oscillator's vacuum 
characterization was shown to be negligible. 


Students Funded Under Research: 

Task Initiation: i/m Expiration: 1/97 
Project Identification: 963-03-0A-19 
Responsible Center: LeRC 

Bibliographic Citations for FY 1994: 


Journals 

Berg, F.F. and Gruner, K. Remarkably small critical exponent for the viscosity of a polymer solution. J. Chem. Phys., 
vol. 101, 1513 (1994). 

Presentations 

Berg, R.F. 'Hydrodynamic similarity in an oscillating body viscometer." 
Properties, Boulder. CO, June 19-24. 1994. 

12th Symposium on Thermophysical 


II— 7 5 




Discipline: Fluid Physics 


II. MSAD Program Tasks — Flight Research 


The Dynamics of Disorder-Order Transitions in Hard Sphere Colloidal Dispersions 


Principal Investigator: Prof. Paul m. Chaikin 

Princeton University 

Co-Investigators: 

Prof. W.B. Russell 

Princeton University 


Task Objective: 

To study the disorder-order transition in a hard sphere colloidal particle system, utilizing laser light scattering to 
delect (1) viscosity changes as the transition from fluid to crystal to glass occurs, (2) diffusion of particles, (3) 
nucleation and growth of the crystals and (4) rigidity after the transition to a glass is complete. 

Task Description: 

The approach has focused on simulating low-gravity by fluidizing a bed of specially prepared hard spheres (silica 
particles with coatings of short-chain polymers) with a counterflow of solvent. This counterflow allows an 
approximation of microgravity. 

Task Significance: 

Materials Research - the study of crystal formation in the microgravity environment can lead to a greater 
understanding of how gravity af fects the formation of many kinds of materials. The focus of this experiment is to 
use a material which can exist in multiple phases depending on its concentration in a colloidal suspension. Laser 
light scattering images will provide structural information about the material as it goes through liquid, ordered 
crystal, and disordered glass phases. 

Progress During FY 1994: 

Light scattering has been used in the lab to verify material structure in 1-g. Sample preparation techniques are 
being refined which include procedures for index matching the sample and the sample container. Various volume 
fractions of solvent mixture have been tested to assess which combinations will be used for flight. The main focus 
in 1995 will be the determination and minimization of particle polydispersity of the samples. 

A preliminary Science Requirement Document (SRD) was prepared and Science Concept Review (SCR) was held in 
January, 1994. The investigators presented the science status and plans for the flight experiment to an independent 
peer review panel. The review panel reccomended approval of SCR based on outstanding scientific merit of the 
proposed experiment. NASA HQ approved the SCR. 

The SRD was updated to its near-final form based on results of the ground-based testing and recommendations of the 
SCR peer review panel. Requirements Definition Review was held in September, 1994. The investigators made 
the science presentation. The RDR was also successful and the experiment has now been selected for flight. 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 2 MS Degrees: 0 

PhD Students: 0 PhD Degrees: 1 


Task Initiation: 4/90 Expiration: 7/95 
Project Identification: 963-24-0A-29 
NASA Contract No.:nag3-H58 
Responsible Center: LeRC 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 


Bibliographic Citations for FY 1994 : 

Journals 

Russel. W.B.. and Sperry. P.R. Effect of microstructures on the viscosity of hard sphere colloids and modulus of 
composites. Progress in Organic Coatings, vol. 23. 305 0994). 

Rutgers. M.A.. Dunsmuir, J.. Russel, W.B.. and Chaikin, P.M. Crystalline fluidized beds. Physical Review E, (to appear). 
Rutgers, M.A.. Dunsmuir. J.. Russel. W.B., and Chaikin, P.M. Hard sphere equation of state. Science, (submitted). 


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11-7 7 



II. MSAD Program Tasks — 

him 


Flight Research 

IIMIHIIMIMIH.H..MII.IMMIIIIIIM 


Discipline: Fluid Physics 

IMIMIIMIMIMIM.IMM.IIMIHHMIMIIIII.IMItll M I II Ml I II I II I M I HI HIM I 


Kinetics of Diffusional Droplet Groioth 

PRINCIPAL Investigator: Dr. Donald O. Frazier NASA Marshall space Flight Center (MSFC) 


CO-INVESTIGATORS! 

M. Glicksman 
J. Rogers 
J. Downey 


Task Objective: 

To determine droplet growth rate constants and changes in size distributions using optical techniques tor recording 
droplet data with time. 

Task Description: 

A transparent model binary liquid/liquid miscibility-gap type solution was the system ot choice. The experimental 
approach was to deploy a fixed array ot droplets ot one liquid phase into a cell tilled with the conjugate phase. This 
approach was to greatly reduce any residual gravity effects and eliminate the possibility ot coalescence. 
Ground-based studies were to determine the experimental parameters required to maximize the amount ot data on 
“pure" Ostwald ripening obtainable during the flight experiment. For tethered droplets, it was considered important 
to determine such parameters as volume fraction ot droplet phase, initial droplet number, droplet spacing and sizes, 
the time required for the experiment, and ideal concentrations tor supersaturation and growth. 


Rensselaer Polytechnic Institute 
NASA Marshall Space Flight Center (MSFC) 
NASA Marshall Space Flight Center (MSFC) 


Task Significance: 

To a large extent, particle growth and distribution determine the mechanical properties of an alloy. Capabilities 
provided by holographic techniques enabling observations ot ditfusional growth ot a second phase in a model, 
transparent two-phase system, allow detailed analyses ot particle size and number distribution. Direct observation 
of these phenomena allow experimental determination ot the scaling laws which detine the time evolution ot 
discrete phase droplets in the asymptotic limit. To our knowledge, this technique is unique tor providing real-time 
optical observation of these processes. 

Progress During FY 1 994: 

Our work has resulted in determination of the best methods tor pertorming ground-based testing. Ground work 
requires a transparent isopycnic system. Sensitivity to gravitational fields should be tested, in the laboratory, by 
tethering two droplets in a test cell and comparing growth kinetics at varying temperatures. Convective flows 
increase with increasing conjugate phase density differences which are relatively strong functions ot temperature. 
Quench experiments in narrow path-length cells should allow observation of coarsening, possibly on the cell walls, 
in an ensemble of droplets. Narrow path-length is a prerequisite tor establishing transparency quickly in high 
droplet density media. 


These experiments began while submitting a new proposal to continue ground-based testing. Postponment ot flight 
preparation is a consequence of the inadequacy ot hardware suggested tor flight. The Bubble Drop and Particle Unit 
was not appropriate because of its inefficiencies regarding thermal fluctuations. Unless approximately one 
millikelvin thermal control is available, spurious nucleation and droplet dissolution will disrupt distribution 
self-similarity, critical to late-stage coarsening theory. 


Ml..,,..,.,,. 


11-7 8 



II. MSAD Program Tasks — Flight Research 


Discipline: Fluid Physics 

M ! MMUlll Mill M#| lltl Hill | IHI III IIIIIIMIIHII 


Students Funded Under Research: Task Initiation: nm Expiration: 12/93 

Project Identification: 963-24-os-oi 
NASA Contract No.: in-house 

Responsible Center: msfc 


|, mm|M , 


11-7 9 



II. MS AD Program Tasks 

» 


— Flight Research 


Discipline: Fluid Physics 


Microscale Hydrodynamics Near Moving Contact Lines 


Principal Investigator: Prof. Stephen Garoff 

Carnegie Mellon University 

Co-Investigators: 


M. Weislogel 

NASA Lewis Research Center (LeRC) 

Task Objective: 


The objective of this study is to characterize the relationship between macroscopically observed dynamic contact 
angles and the microscopic fluid physics occurring near the contact line. 

Task Description: 

This task consists primarily of low-gravity experimental studies on moving contact lines. The experiments will 
simultaneously measure tlow fields and the fluid/fluid interface very near the moving contact line using video 
microscopy and particle unage velocimetry. The experiments will be conducted in low gravity since it is in low 
eravity that interfacial phenomena dictate the fluid/fluid interface shape and location. 

Task Significance: 

The essentia] points of the investigation are: 

1 . Are the viscous stresses near a moving contact line appropriately described by present phenomenological 
models? 

2. Can predictive models for spreading be developed for complex systems (rough surfaces, non-Newtonian fluids, 
etc.) if the flow fields and interface shapes near a contact line are known? 

3. What is the nature of the unique fluid dynamical processes near amoving contact line? How do these processes 
depend on the properties of the fluids and the solid surface involved? How do these processes determine the true 

dynamic contact angle? 

Progress During FY 1 994: 

Our efforts tins year focused on two areas: (1) working with the engineering team to refine science requirements for 
the flight experiment, consult on hardware design, prepare the Science Requirement Document, and present the 
Science Concept Review and (2) ground-based research on the moving contact line problem. 

Definition of science requirements and discussions on hardware design for the abbreviated ("fasttrack") flight 
experiment were a major fraction of the total effort during the past contract year. Cell dimensions were set by 
calculations of static interface shapes, critical bond numbers, and recirculation flows. The requirement on thermal 
gradients in the experiment was chosen through a comparison of residual Marangom flow and the driven flow under 
investigation. New UV cleaning chambers were built and tests were run on the effectiveness and resiliency of the 
UV cleaning process. In several meetings and correspondence, details of the cleaning techniques were transmitted 
from the science team at CMU to the engineering team at NASA Lewis Research Center. The science objectives o 
the flight experiment were refined and a minimal flight test matrix was established. Requirements were established 
for optical design, materials selection and characterization, data acquisition, temperature and pressure control, as well 
as acceleration levels and measurement. All requirements were recorded in drafts of the Science Requirement 
Document. The Science Concept Review occurred on May 4, 1994. This review presented the scientific 
motivation and experimental plans only for the "fasttrack flight experiment. 

Our ground-based research on moving contact lines produced important results both on the hydrodynamics in the 
intermediate region and on the inner scale physics: 


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II-80 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

tlMMIMMlIttllltlltlltllllMIMIMMM MM lllltlMIMIIMHMMMMtMliMIMIMMMMMMIMMIIIIIMIIMIIIHIIIIHIIt MMIIMMIIMI 


We have measured the dynamic interface shape over long distances (*2mm). We found that the parameter wO 
determined by fitting the dynamic data near the contact line to the composite model is the contact angle for the 
interface shape tar trom the contact line fit to a static interface shape. This result confirms a fundamental 
hypothesis of the model of the microscale hydrodynamics near a moving contact line. However, within the accuracy 
ot our experiments, the interface shape at Ca’s as low as 0.01 is measurably different from the static shape even at 
distances ot 1 .2mm trom the contact line. This result raises questions about the accuracy of measurements of 
dynamic interfaces made by other techniques and reported in the literature. 

By measuring the interface shape at increasing Ca, we have determined the limits of the presently available models 
tor the hydrodynamics near moving contact lines. We have made the first measurements of dynamic interface shapes 
in depression. We find that the present models are adequate for CacO.l. Above this Ca, the model predicts too 
large a curvature at small distances from the contact line. The region where the model is inadequate expands as CA 
increases. The breakdown is either due to an insufficient number of terms in the Ca expansion describing the 
intermediate region or to the inner scale hydrodynamics affecting the interface shape at unexpectedly large distances. 
The model of the intermediate region can be extended to higher Ca. It then provides an additional parameter 
describing the inner scale physics. However, our measurements show that this expansion cannot be used in 
terrestrial measurements because ot contamination from geometry dependent terms which cannot be expressed 
analytically. This result proves that microgravity measurements, which increase the outer length scale, will provide 
a unique opportunity to measure an additional parameter with which to characterize inner scale physics. 

Our materials studies show that the inner scale hydrodynamics of polymer melts is sensitive to local 
polymer/surface interactions. In a low Ca regime, the spreading of polydimethylsiloxanes (PDMS) across a 7740 
Pyrex surface is strongly affected by the end termination chemistry of the polymer hydroxyl terminated PDMS 
exhibiting a strong velocity dependence and methyl terminated PDMS exhibiting a weak dependence. Further, the 
hydroxyl terminated spreading vanes with polymer viscosity in this regime. At higher Ca, the behavior of PDMS 
with either termination is similar. We are presently investigating scaling relations in this high Ca regime. W r e 
have also lound that the spreading behavior of the hydroxyl terminated PDMS is strongly dependent on the level of 
absorbed water on the Pyrex surface. 

Initial measurements of the velocity field near the moving contact line have been made. The PDMS is seeded with 
particles of Al 2 (OH), coated with oleic acid. 

The particles are in 1- 1 0|im in diameter. Particle trajectories and velocity fields are measured and compared to the 
fields which are predicted by the modulated wedge approximation central to the model of the intermediate region 
which we use to fit the interface shape. At low Ca, the model correctly predicts the flow field down to distances on 
the order ot 50|im trom the contact line. These studies will continue probing closer to the contact line and higher 
Ca flows. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 3 


Task Initiation: 12/92 Expiration: 12/95 
Project Identification: 963-25-0 a-81 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Willson, K.R. and Garoff, S. Effect of chain termination chemistry and molecular weight on dynamic wetting of polymer 
liquids, to be published in Colloids and Polymers, (August 1994). 


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Ill 


11-81 



II. MSAD Program Tasks — Flight Research 

unit mm 


Discipline: Fluid Physics 

»•'» * 


oSJ.V Chen. Q., Rame. E., and Willson, K.R. "Microscale hydrodynamics near moving contact lines." Proceedings 
of the 2nd NASA Microgravity Fluids Conference, Cleveland, OH, June. 1994. 


Chen, Q., and Garoff, S. "Dynamic contact angles and interface shapes at high capillary number. American Physical 
Society Meeting, Pittsburgh, PA, March, 1994. 

Chen. Q., Rame. E„ and Garoff, S. "Measuring dynamic contact angles: an experimental study of the breakdown of present 
theory.” AIChE Annual Meeting, San Francisco. CA, November 1994. 

Garoff. S.. Chen. Q„ Rame. E„ and Willson, K.R. "Microscale hydrodynamics near moving contact lines." Second NASA 
Microgravity Fluids Conference, Cleveland, OH, June 1994. 

Rame, E. "The boundary condition at a moving contact line: an experimental study of the interpretation of the dynamic 
contact angle." American Physical Society/Division of Fluid Dynamics. Atlanta, GA, November 1994. 

Willson, K.R., and Garoff, S. "Dominant factors controlling dynamic wetting of PDMS fluids." American Physical 
Society Meeting, Pittsburgh, PA, March, 1994. 

Willson. K.R. and Garoff, S. "Dominant factors controlling dynamic wetting of PDMS fluids." 68th ACS Colloid and 
Surface Science Symposium, Stanford. CA. June 1994. 


him mm 


11-82 



II. MSAD Program Tasks — Flight Research 

mmumii it ■ inn, •■■Hunt minimum 

Plasma Dust Crystallization 

Discipline: Fluid Physics 

Principal Investigator: Prof. John a. Goree 

University of Iowa 

Co-Investigators: 


No Co-I's Assigned to this Task 



Task Objective: 

The objective ot this research is to demonstrate that charged particulates in a plasma environment form an ordered 
structure. 

Task Description: 

The investigator will design and test apparatus for radio-frequency (R F) plasma generation / particulate 
confinement, and analyze the structure ot suspended particulates. This will include working with German scientists 
in designing microgravity experiments. 

Task Significance: 

This investigation begins a new genre of microgravity research. It will provide: (1) a macroscopic model of how 
atoms arrange themselves in a crystal or liquid, (2) a much-needed test of dusty plasma theories used in space 
physics and astronomy, and (3) an understanding of particulate contamination during plasma processing steps of 
microchip manufacturing. 


Progress During FY 1 994 : 

This project represents an entirely new area of scientific research. When micron-size particulates are inserted into a 
plasma, they become charged and can arrange themselves in an ordered structure, ranging from a liquid to a 
crystalline lattice. This structure is suspended in the vacuum, and it is visible to the unaided eye. This is of interest 
tor basic science, since it serves as a model system tor studying crystalline structures and phase transitions to more 
disordered states. It is also of interest for industry, since we use apparatus identical to the tools used to etch silicon 
wafers in semiconductor manufacturing; particulates are of great importance because they can contaminate the 
silicon wafer. Gravity is a significant force acting on these particulates. 

Experimental progress : 

1. We have submitted and published in Physical Review Letters a paper describing for the first time an observation 
of a crystalline lattice of charged grains suspended in a plasma. This paper has generated considerable interest, and 
news articles about it have been written in Nature , Physics World , and Science News. 

2. A new laboratory test stand has been assembled, and we have now used it to prepare more extensive data. We 
now have images of our particulate cloud made by video cameras pointing at sheets of laser light that cut through 
the cloud in vertical and horizontal cross sections. These experiments are yielding very clear images of ordered 
states ranging from liquid to hexatu: regimes. We have analyzed these data using pair and bond-angle correlation 
methods developed originally by experimenters in colloidal suspensions. These experiments serve the dual role of 
providing exciting experimental results in their own right, helping to define this new area of research, while also 
serving as an early model tor developing flight hardware. It is increasingly clear from the data that gravity crushes 
our particulate cloud into an essentially 2-D ordered structure, and that microgravity conditions will be required to 
achieve a fully 3-D ordered state. 

3. In cooperation with our DARA-tunded German collaborators, we are now discussing apparatus configurations for 


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n-83 


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tlHMIMIHIItlllMMimillltlltMIHtll 



II. MSAD Program Tasks — 




Flight Research 

Ml III III I II III HIM III 


Discipline: Fluid Physics 




a future Get Away Special flight experiment. In this international scientific collaboration, the PI is the senior 
experimenter. 


Theory progress : 

We have begun a second theoretical effort, having already completed a first during FY93 . We will model the 
dynamics of the particulates in our plasma. This effort will continue over the next year, with a visiting scientist 
from Norway doing much of the work. It will help in understanding our experiments and in quantifying the role ot 

gravity in them. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 2 

PhD Students: 0 


Task Initiation: 4/93 Expiration: 4/96 
Project Identification: 963-24-08-02 
NASA Contract No.: nags-292 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

CurC^md Goree. J. Fluctuations of the charge on a dust grain in a plasma. IEEE Transactions on Plasma Science, vol. 
22. 151-158 (1994). 

Goree. J. Charging of particulates in a plasma. Plasma Sources Science and Technology, vol. 3. 400-406 (1994). 

Goree. J., and Chiu, Y.T. Dust contamination of the spacecraft environment by exposure to plasma. J. of Spacecraft and 
Rockets, vol. 30, 765-767 (1993). 

Thomas. H., Morfill. G.. Demmel. V.. Goree, J.. Feuerbacher, B.. and Mohlmann. D. Plasma crystal: coulomb 
crystallization in a dusty plasma. Physical Review Letters, vol. 72, 652-656 (1994). 

Presentations _ . „ KTX , 

Goree. J. "Plasma crystals." AIAA 32nd Aerospace Sciences Meeting, Symposium on Micrograv.ty Science, Reno. NV. 

Janaury 10-13, 1994. 

Goree. J. "Plasma crystals." NASA Microgravity Fluid Physics Conference. Cleveland. OH. June 12-13. 1994. 

Goree. J. "Dusty plasma exoenments and theory." UCSD Plasma Physics Seminar. June. 1994. 

Goree, J. "Dusty plasma experiments and theory." Invited talk at the Workshop on Non-Neutral Plasma. July, 1994. 

Praburam. G., and Goree. J. "Observations of particle layers levitated in an rf sputtering plasma." Gaseous Electronics 
Conference, Montreal, Canada, October. 1993. 

Praburma, G., and Goree, J. ’’Observations of particle layers levitated in an rf sputtering plasma.’’ American Physical 
Society Meeting, Division of Plasma Physics, November, 1993. 


<•<« 


IHIMIIIIM.ItmmMli.mMMIMIMMiMinilMimMmillHmlM.M 


11-84 



II. MSAD Program Tasks — Flight Research 

M III III Ilium Ml III 


Discipline: Fluid Physics 




Evaporation from a Meniscus within a Capillary Tube in Microgravity 


Principal Investigator: Prof. Kevin p. Haiiinan 

University of Dayton 

Co- Investigators: 


Dr. J. Ervin 

University of Dayton 


Task Objective: 

The primary objective of this project is to investigate the thermocapillary effect on the interfacial instability of an 
evaporating extended meniscus and to corroborate the disjoining pressure gradient theory for describing the thin film 
tluid flow. 

Task Description: 

In order to eltectively study the thin film region of a capillary interface, experiments will be conducted in a large 
evaporation/condensation loop in a low-gravity environment. The experiments will include simultaneous particle 
image velocimetry (PI V), interferometry, and wall temperature measurement in order to obtain the fluid velocities, 
the interlace shape, and the wall temperature in the thin film region. Thennocapillary effects will be quantified by 
the measured wall temperature and the fluid velocity profile in the thin film region. 

Task Significance: 

1. The study ot the thermocapillary effect on the interfacial instability of an evaporating extended meniscus may 
help explain the tailure of Capillaiy Pump Loops in a microgravity environment. The knowledge obtained from 
this study could result in radical new heat exchanger technologies that will benefit both space exploration and 
terrestrial applications. 

2. This study can help strengthen support for the use of disjoining pressure gradient theory to describe fluid flow in 
thin films. Such an understanding can complete the theory of thin-film physics which is relevant to many 
important technologies from the thin-film coating to materials processings. 

Progress During FY 1 994 : 

In FY94, numerical simulation of die thermo-fluid physics in the near contact line region was conducted to better 
understand the competing effects of thermocapillary stresses which oppose the liquid motion into this region and the 
disjoining pressure gradient which acts as the driver for the flow in this region. It was shown that a temperature 
difference of as little as 0.001 K between the wall and the vapor could significandy affect the thin film flow field and 
marginally affect the total thin film heat transport and shape. The macroscopic influences of the thermocapillary 
stresses at near contact line were also observed experimentally by applying heat input to an evaporadng liquid in a 
small-diameter, verucal capillary tubes. As the heat input to the meniscus was increased, the meniscus receded from 
the static equilibrium position which, by scaling arguments, is attributable to near contact line diermocapillaiy 
stresses. In addidon, progress has been made in the continuing development of the Coherent Forward Scattering 
Particle Velocimetry technique which ultimately will be used to measure die velocity field in the evaporating thin 
liquid film near the contact line. An analytical analysis has idendfied the lengthscales near the contact line where 
the thermocapillary stresses can be most severe. Knowledge ot the salient lengthscales has provided the guidance for 
selecting the optics and light source to be employed to extract information near the contact line. Polystyrene 
spherical seeding particles, 0.1 microns in diameter, will be the fluid tracers used to measure the near contact line 
velocity field. A Nikon Labophot microscope with Koehnler illumination and having a 60X, 0.85 N.A. 
microscopic objective lens has been proven capable of providing reasonable diffraction images of particles in and out 
of focus inside of an evaporating liquid film. 




11-8 5 



II. MSAD Program Tasks 

(Ml III 


Flight Research 

I IHIIIIMIMIHMII1MIIIIII 


Discipline: Fluid Physics 




Students Funded Under Research: 

BS Students: 3 

MS Students: 0 

PhD Students: 3 


Task Initiation: 12/92 Expiration: 12/95 
Project Identification: 963-25-OA-21 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994 : 


HaMnan' K P Chebaro. H.C.. Kim. S.J. and Chang, W.S. Evaporation from a capillarity-resupplied extend meniscus 
within a cylindrical pore for non-isothermal interfacial conditions, accepted for publication to J. of Thermophysics and 
Heat Transfer, (1994). 


Presentations 

He, Q. and Hallinan, K.P. ’Thermocapillary effects on the evaporating extended meniscus, 
the ASME-WAM, Chicago. IL. November 5-8. 1994. 


accepted for presentation at 


Pratt. D M. and Hallinan. K.P. "An investigation of thermocapillary effects on a heated capillary re-supplied meniscus tor 
low bond numbers." accepted for presentation at the 3rd Latin American Symposium on Fluid Mechanics. Caracas. 
Venezuala. February 5-8. 1994. 


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11-86 



II. MSAD Program Tasks — Flight Research 



Discipline: Fluid Physics 


Geophysical Fluid Flow Cell 


Principal Investigator: Dr. John e. Hart 

University of Colorado, Boulder 

Co-Investigators: 


F. Leslie 

NASA Marshall Space Flight Center (MSFC) 

T. Miller 

NASA Marshall Space Flight Center (MSFC) 

j. Toomre 

University of Colorado, Boulder 

D. Ohlsen 

University of Colorado, Boulder 


Task Objective: 

The Geophysical Fluid Flow Cell experiment (GFFC) takes advantage of the unique environment of the 
microgravity laboratory, which permits forces that would otherwise be swamped by normal terrestrial gravity to 
become dominant. The GFFC uses electrostatic forces to warp gravity into a radial vector field, centrally directed 
towards the center of the cell. This allows us to perform visualiztions of thermal convection in a spherical shell of 
liquid subject to imposed differential heating and basic rotation, where the active buoyancy forces are radially 
directed, as in planetary atmospheres and stars. The objective of the experiments is to categorize the types of 
convective patterns that can occur in highly nonlinear and turbulent tlows with varying amounts of basic rotation 
and thermal stress. 

Task Description: 

1. A significant modification to the original GFFC experiment that flew previously on Spacelab-III is the addition 
of real-time video visualizations of the fluid turbulence that can be downlinked from the shuttle to scientists on the 
ground. This permits interactive experiments that can identify and focus on important flow regimes. Design, 
construction and verification of space qualified hardware to effect this video downlink is a major hardware task. 

2. In preparation for flight, theoretical, computational, and terrestrial laboratory simulations of rotating convection 
are required in order to suggest particular experiments that can critically advance our basic understanding of such 
phenomena, as well as make contributions to the science of geophysical and astrophysical fluid dynamics. 
Theoretical and computational models typically involve assumptions that will be checked in the spacelab flights, 
and terrestrial experiments are planar in geometry, allowing comparison of fundamental differences between 'flat" 
and "spherical” convection . 

Task Significance: 

The spherical configuration and radial gravity of the Geophysical Fluid Flow Cell is significant because large-scale 
motions of the atmospheres of planets and stars are constrained by the inherent spherical geometry of these bodies. 
Furthermore the flows on them are constrained by rotation, under the action of same Coriolis forces that shape 
Earth's weather, and by buoyancy forces which result in hot fluid rising in a radial direction. It is impossible to 
study such motions in the terrestrial laboratory because gravity is uniformly directed. The GFFC experiments will 
provide basic laboratory data that can be applied to problems of cloud patterns on the giant planets, differential 
rotation on the Sun, and motions in Earth's core, mantle and atmosphere. 

Progress During FY 1 994: 

1. The GFFC Video Acquisition Module (VAM) and associated documentation were completed and shipped to 
MSFC for integration with the GFFC. Tests there indicate the VAM is functioning properly. 

2. The computational code of Gary Glatzmaier, previously used with the SL3 GFFC results, was upgraded. Now 
more resolution can be used, and it will be possible to computationally simulate most of the anticipated GFFC 
USML-2 runs. Research Associate Dr. Dan Ohlsen will begin running cases to be studied on USML-2 in early 
FY95. 


I limilMIIIIIIIIIMIIIIIIIIIIIIHnilllllllllllllllimillllltlllllllllllllllllllllHIimilllllllllllllllllllllllllllllllMIHI 


11-8 7 





II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

mint .<•'•• * * 


3. A major laboratory experiment on turbulent rotating convection was constructed. It permits in situ thermal 
measurements and remote measurment of velocity tields ot rotating convection using particle image velocimetry 
(PIV). Initial results show strong cyclonic vortices (tornado turbulence) which are associated with a strong unstalbe 
interior stratification (compare with non-rotating convection where the interior stratification in neutral). 

4. Experiments and computational simulation ot b-convection (rotating convection constrained to lie near the 
equator where gravity is perpendicular to rotation) were completed. The computational simulations show strong jets 
(like Jupiter), but the experiment, which run at higher Prandtl number, do not. We intend to look more closely at 
this problem in FY95. 


Students Funded Under Research: Task Initiation: 12/88 Expiration: 3/94 

Project Identification: 963-24-08-04 
NASA Contract No.nas6-31958 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Hart, J.E.. Albaiz, A., and Leben. R Flow separation and chaos in a rotating annulus. Computational Fluid Dynamics, 
vol. 2, 59-72 (1993). 


Hart, J.E.. and Brummell, N. High Rayleigh number b-conveclion. Geophys. and Astrophys. Fluid Dyn., vol. 68. 85-1 14 
(1993). 


him iii mi if ml iii • it mini 


11-88 


II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

llllll III I It 1 1 II lllllltllllllllMIIIIIIHIIIIIHtll II I II 1 1 1 1 1 1 1 II, II I III llllllll IM I tllllllllltllll IIIIIIIM I1 1 1I I It 1 1 III II I tl I II Mill II llttll 1 1 II I II III I III I II I II I II IIIIIH II IIIIIIIIIMIIHH tllllHIIIIIIMIIIIIIIIMIIIIIHimillllllHIIIIII II 


Interfacial Phenomena in Multilayered Fluid Systems 


Principal Investigator; Prof. Jean n. Koster 


University of Colorado, Boulder 


CO-INVESTIGATORS! 

Prof. S. Biringen University of Colorado, Boulder 


Task Objective: 

The main objective of the research is to design a three-liquid-layer flight experiment that will study the interaction 
of two interfacia] tension forces of different magnitude, and their effects on thermocapillary fluid flow induced in 
adjacent liquid layers. The thermocapillarv flow results from temperature gradients parallel to the fluid interfaces. 

In addition, the mechanical coupling between the immiscible layers and the suppression of convective flow wall be 
investigated. The conditions for the existence for oscillatory flow, and the effects of g-jitter may also be studied. 

Task Description: 

The general approach is to conduct ground-based normal -gravity testing and develop theoretical models of the 
combined buoyant and thermocapillary convection phenomena. The instrumentation and diagnostics are centered 
around the physics of interest; namely, flow fields, temperature fields, and interfacial shapes. The theories and 
numerical models developed and verified with the 1-g data was used to predict the results of the flight experiment on 
the IML-2 mission. 

Task Significance: 

The results are expected to significantly advance our knowledge in the area of surface-tension-driven convection in 
multilayered fluid systems. The scientific results will find applications related to encapsulated float zone 
processing. Float zone processes are a technique in which space processing of crystals can be done while 
minimizing imperfections. 

Progress During FY1994: 

There were many activities on the flight project side. Activities were concentrated on preparing for and in support 
of the flight experiment in July 1994. These activities included participating in ground testing of the 
engineering/flight models in Europe; familiarizing the crew with science background of the experiment; and 
attending various mission simulations at MSFC. During the course of the year, the PI expressed concerns about 
maintaining liquid-liquid interfaces during curtain retraction, having sufficiently small particles in the liquids to 
achieve the required velocity field resolution, and having equal pressures in each of the three fluid layers so that the 
interfaces remained flat. During the actual mission in July, flat interfaces were, unfortunately, lost w'hen the first 
curtain withdrawal was nearly half completed. The final fluid configuration (when both curtains were retracted) was 
the undesirable shape of a fluorinert ball surrounded by silicone oil. Although some tests were subsequendv done 
with this configuration, it is felt that little scientific data resulted from the experiment. 

Ground-based research continued in the PFs labs in Boulder during the year. Research was conducted in the 
following areas: natural convection in multilayer systems; combined thermocapillary and natural convection in 
multilayer systems; Rayleigh Benard convection in multilayer systems; and assessing the effect of g-jitter on fluid 
interfaces. The work for the next year is currently being replanned in light of the flight experiment resuits. One of 
the priorities of the work to be done will be to better understand how to establish such interfaces in microgravity. 


1 1 linn i 


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11-89 






Bibliographic Citations for FY 1 994: 

Journals 

Burkersroda, C.V., Prakash. A. and Koster. J.N. Interfacial tension between fluorinerts and silicone oils, accepted by 

Micro gravity Quarterly , (1994). 

Prakash, A. and Koster, J.N. Penetrative Convection in sublayer ot water including density inversion. Warme-und 
Stoffubertragung, 29, 37-49 (1993). 

Prakash, A. and Koster, J.N. Convection in multiple layers of immiscible liquids in a shallow cavity - Part II: steady 
thermocapillary convection. International Journal of Multiphase Flow. 20, 397-414 (1994). 

Prakash. A. and Koster, J.N. Thermo capillary convection in three immiscible liquid layers, accepted by Microgravity 
Quarterly, (1994). 

Prakash, A. and Koster, N.N. Natural and thermo capillary convection in three layers. European Journal of Mechanics 
B /Fluids, 12, 635-655 (1993). 

Schmitt, T., Koster, J.N., and Hamacher, H. Particle design for displacement tracking velocimetry. accepted by 

Measurement Science and Technology, (1994). 

Journal Tong, W. and Koster, J.N. Penetrative convection in sublayer of water including density inversion. Warme-und 
Stoffubertragung, 29, 37-49 (1993). 


IIHIHIMMIIIMIIIIIIIIItllllltllHIHIMIMIKIMIIIIMIIIimMIMIHMIMIIIIIIIIIIIIIIMHIIMIMMIMIIIIHIIHIM 


11-90 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

IIIHMIlllllllllllltlllMMMIMIIIIIIIIIIIIIIIIIIIMIItll Ml I II I II t III tl I II 1 1 III II I III II 1 11(111 III III III III HI 1 1 1 i 1 1 tlltlHIIIIIHIt IMIIMIHIHIII IIIIIHIIHIHIIHIHiHIHIIHIMIHIIHIHIHIHIHIHttllllf IMIII tllllllllll • I HIIIIIIMII 


Extensional Rheology of Non-Newtonian Materials 


Principal Investigator: Prof. Gareth h. McKinley 

Harvard University 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objective of this work is to determine the extensional viscosity in uniaxial stretching flow of fluid systems 
such as dilute polymer solutions, emulsions, and suspensions. Also, to generate a simple homogeneous shear free 
flow in the material, and to measure the stress response of the material from an imposed rate of deformation 
(constant deformation rate expenmen ts). 

Task Description: 

This effort will require an initial ground-based experimental design, and ultimate payload implementation, of a 
novel experimental apparatus to measure accurately the rheological response of non-Newtonian fluids under 
shear-free conditions that are characteristic of those expenenced in the containerless processing of materials. 

The proposed instrument generates a homogeneous uniaxial elongation through an exponential stretching of the test 
sample, and the spatial uniformity of the deformation rate experienced by the fluid is verified by digital particle 
image velocimetry. Direct measurements of the tensile force exerted by the material then allow calculation of the 
extensional viscosity of the fluid. 

The design of the apparatus utilizes several of the exisung or planned fluid diagnostic modules being considered by 
NASA, and in addition, provides a completely new fluid-science flight capability, which can be used repeatedly to 
support multi-user rheological measurements for a wide range of non-Newtonian fluids. 

Task Significance: 

The extensional viscosity is a fundamental physical property of all non-Newtonian materials, and cannot be 
determined from simple viscometric shear flow experiments. Constitutive equations for viscoelastic fluids such as 
dilute polymer solutions predict large changes in the extensional viscosity as the elongation rate is increased; 
however, the validity of these theories cannot be confirmed due to the lack of experimental data obtained in 
extensional flows. To date, quantitative rheological measurements in shear-free flows have only been possible for 
highly elastic or '’stiff' materials such as polymer melts which can easily be elongated without sagging under a 
gravitational body force. By performing similar experiments in an extended microgravity environment it will be 
possible for the first time to obtain accurate measurements of the extensional viscosity for more ’mobile' fluids 
such as polymer solutions, suspensions and liquid crystalline materials. This rheological data will allow designers 
of both space- and ground-based material processes to use improved constitutive models in numerical simulations of 
complex two- and three-dimensional fluid flows. 

In a simple stretching flow, fluids such as water or syrup exhibit a resistance to stretching that is exactly three 
times the value of their Newtonian viscosity. This resistance is usually termed the "extensional viscosity of the 
material." However, for fluids containing long macromolecules (e.g., synthetic polymers, liquid crystals, or DNA) 
is predicted that the extensional viscosity can be anywhere from 100 to 10000 times greater than the viscosity of 
the fluid. In the near future, NASA plans to develop "containerless processing" operations under microgravity and a 
detailed understanding of extensional properties in fluids will be absolutely critical — since, in the absence of 
container walls, the only way to mix, pour, and shape fluids will be through pure stretching motions. Knowledge 
of such nonlinear material functions is fundamental to the development and verification of relatively cheap 
ground-based computational modeling techniques which can be used effectively in the "a priori" design of advanced 


II-9 1 





II. MSAD Program Tasks — Flight Research Discipline: 


Fluid Physics 

iiiiiitiiiiiiiiiiiiiimiimiiti 


inicrogravity material processes thereby alleviating the need tor costly in-flight pilot experiments. Finally, in 
addition to their significance in many industrial processes such as tiber-spinning and him coating operations, 
stretching flows of non-Newtonian fluids are of fundamental scientific importance to a number ot complex fluid 
dynamics phenomena, including the stability and breakup ot jets, enhanced oil recovery and turbulent drag reduction 
for advanced aircraft boats, and submarines. 


Progress During FY 1994: 

The second draft of the Science Requirements Document has been submitted and the Science Concept Review was 
successfully completed on May 6, 1994. A Boger (polymer solution) Fluid Column deployment breadboard and an 
expotentially grooved wheel breadboard tor the neutral density tank were completed. A dry wheel breadboard has also 
been constructed, and tests are being planned. The particle image velocimetry apparatus has been built and is being 
tested at LeRC. 

Future plans include further development and construction ot the following: 

1. The drive mechanism breadboard testing - Inertial motion of neutral density fluid: viscous diffusion ot Boger 
fluid 

2. Birefringence tests 

3. Optical testing: DPIV software integration, particle and laser selection and radial measurement 

4. Reducing diameter device (RDD) breadboard testing 

5. Load cell and microbalance testing (.01 to 30 grams range required) 

6. Sridhar Apparatus testing - Fixed plates then RDD with electronic balance 

7. Adiabatic heating - Theoretical estimation 

8. Fluid choice - rheological analysis of varying concentrations ot polyiobutylene (monodisperse) 

9. Lubrication - Analysis of slip on wheels in plateau tank 

10. Surface tension - Determine correlation of dynamic surface tension to extensional rheology experiment. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 1 

PhD Students: 1 


Task Initiation: 12/92 Expiration: 12/95 
Project Identification: 963-25-0A-36 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Presentations 

Gaudet, S„ McKinley, G.H.. Stone, H.A. in AIAA, 32nd Aerospace Sciences, Reno NV. p.l, 1994. 

Spiegelberg, S.H., Gaudet. S.. McKinley. G.H. Second Microgravity Fluid Dynamics Conference, Cleveland. OH, 1994. 


nun mm 





11-92 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 




Pool Boiling Experiment 


Principal Investigator: Prof. Herman Merte, Jr. 


University of Michigan 


Co-Investigators: 

No Co-I’s Assigned to this Task 


Task Objective: 

The program described here seeks to improve the understanding of the fundamental mechanisms that constitute 
nucleate pool boiling. The vehicle for accomplishing this is an investigation, including experiments to be 
conducted in microgravity and coupled with appropriate analyses, of the heat transfer and vapor bubble dynamics 
associated with nucleation, bubble growth or collapse, and subsequent motion. Certain effects that can be neglected 
at normal Earth gravity, such as surface tension and vapor momentum, can become quite significant in 
inicrogravity. Momentum imparted to the liquid by the vapor bubble during growth tends to draw the vapor bubble 
away from the surface, depending on the rate of growth, which in turn is governed by the temperature distribution in 
the liquid. Thermophoretic forces, arising from the variation of the liquid-vapor surface tension with temperature, 
on the other hand, tend to move the vapor bubble toward the region of higher temperature. The bubble motion will 
be governed by which of these two effects prevail. 

The elements of nucleate boiling, for which research conducted under microgravity would advance the basic 
understanding, are: 

1. Nucleation or onset of boiling. Indications are that both heater surface temperature and temperature distribution 
in the liquid are necessary to describe nucleation. 

2. The dynamic growth of a vapor bubble in the vicinity of the heater surface. This includes die shape as well as 
motion of the liquid-vapor interface as growth is taking place. These are influenced by the liquid temperature 
distribution at the initiation of growth. 

3. The subsequent behavior of the vapor bubble. This includes the motion, whether departure takes place or not, 
and the associated heat transfer. 

Task Description: 

In the proposed experiment, a pool of liquid — initially at a precisely defined pressure and temperature — will be 
subjected to a step-imposed heat flux from a semitransparent thin-fllm heater forming part of one wall of the 
container, such that boiling is initiated and maintained for a defined period of time at a constant pressure level. 
Transient measurements of the heater surface and fluids temperatures near the surface will be made, noting especially 
the conditions of the boiling process in two simultaneous views, from beneath the heating surface and from the 
side. The conduct of the experiment and the data acquisition will be completely automated and self-contained. For 
the initial flight, a total of nine tests are proposed, with three levels of heat flux and three levels of subcooling. 

Task Significance: 

The outcome of the experiment is expected to include the following: 

1. Observation of the liquid-vapor behavior, including bubble growth and motion as functions of heat flux, initial 
subcooling and time, and correlation with observed heater surface temperature variation. 

2. Use of initial liquid temperature distribution at nucleation to compute vapor bubble growth rate for comparison 
with observation. 

3. Measurement of delay time to nucleation for correlation with nucleation theory. 


mi 


11-9 3 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 




Anyone who has ever boiled water on a stove is familiar with nucleate pool boiling. Even though it is an everyday 
event, scientists do not understand precisely how it works, because Earth's gravity influences how bubbles form and 
grow in boiling liquids. 


NASA is interested in results from this experiment, because boiling liquids generates bubbles which tire very 
efficient at transferring large amounts of heat. Finding new ways to dissipate heat from the space shuttle or future 
manned space platforms will be vital to the success of long term missions. 

There are potential benefits closer to home as well, including more effective air conditioning and refrigeration 
systems and improvements in power plants that could reduce the cost of generating electricity. 

Progress During FY1994: 

The prototype hardware for the Pool Boiling Experiment was flown aboard the SL-J mission on September 12-20, 
1992. Performance of the hardware was "near perfect.” The data clearly reveal that pool boiling in reduced gravity 
(10 ' 3 g) is a transient process and not a steady periodic one. At the higher-heat flux tests (8 W/cnr), the 
temperature, as well as the vapor content continued to increase. Tests conducted at the lower-heat flux levels 
resulted in a rapid spreading of the vapor across the heater as compared to the high-heat flux levels. In low gravity, 
the vapor bubbles adhered to the heater surface and were 1 cm to 5 cm in diameter. In normal gravity, the vapor 
bubbles lift off the heater surface due to buoyancy and are approximately 1.5 mm in diameter. 

The flight hardware was flown on STS-57 mission in June 1993. Eight of nine test points were successful. The 
Pool Boiling Experiment was flown again on the STS-60 mission, in February 1994. All nine test points were 
successful. 

The principal investigator submitted the final report on the results of the STS-47 mission to NASA-Lewis in July 
1994. A combined final report of the STS-57 and STS-60 missions should be completed by January 1995. 

The results from these three flights can be summarized as follows: 

In microgravity the absence of buoyancy causes large bubbles to form and often remain on the heater surface as 
surface tension plays a dominant role. Some dryout and rewetting was observed. In normal gravity (lg) convection 
causes the bubbles to depart from the heater surface while they are quite small. 

Correlation of dry out area to mean, h„ and boiling, h B , (wetted) heat transfer coefficients and mean heater surface 
temperature, T w , for microgravity pool boiling tests is first of its kind. 

Professor Merte successfully passed a Microgravity Hardware Reflight Reviews held on June 24, 1994 on his 
proposed related experiment, "Study of Pool Boiling in Microgravity-Rewetting Following Dryout," was approved 
by NASA based on favorable evaluations from peer review panel. Two flights are planned using the same pool 
boiling hardware with a few modest changes. The first mission should occur in the spring or summer ot 1995. 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 1 MS Degrees: 1 

PhD Students: 1 PhD Degrees: 1 


Task Initiation: 2/90 Expiration: 9/95 
Project Identification: 963-24 -ob-io 
Responsible Center: LeRC 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 




Bibliographic Citations for FY 1994: 

Journals 

Merte. H. Jr. and Lee. H.S., Keller. R.B. “Pool boiling experiment prototype model flown on STS-47 (PBE-IA),’' report 
NASA contract NAS 3-25812. Report No. UM-MEAM-93-10. The University of Michigan, Department of Mechanical 
Engineering and Applied Mechanics. (December. 1993). 

NASA Tech Briefs 

Lee, H.S. and Merte. H. Jr. Vapor bubble dynamics in microgravity, report NASA Contract NAS-3-25812. Report No. 
UM-MEAM-93-10. The University of Michigan, Department of Mechanical Engineering and Applied Mechanics. NASA 
Tech Brief, (December, 1993). 

Presentations 

Merte. H. Jr. ’'Nucleate pool boiling in microgravity and variable gravity.” Department of Chemical Engineering, 
Clarkson University, Potsdam. New York. December 7. 1993. 

Merte, H. Jr. "Nucleate pool boiling in microgravity - results from STS-47.” NASA SSSAAS meeting (Space Station 
Science and Applications Advisory Subcommitte) Houston. Texas, Feb. 16. 1994. 

Merte, H. Jr. "Gravity effects on liquid/vapor phase change." Two Seminar Series presented in the Department of 
Mechanical Engineering at McMaster University, seminar entitled: “Condensation Heat Transfer under High Gravity, and 
Pool Boiling in Microgravity and Variable Gravity. Hamilton. Ontario. May 11. 1994. 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

mi .mm.... it •• 


Surface Tension-Driven Convection Experiment (STDCE-1, STDCE-2) 

PRINCIPAL INVESTIGATOR: Prof. Simon Ostrach Case Western Reserve University 


Co-Investigators: 

Prof. Y. Kamotani Case Western Reserve University 


Task Objective: 

The objective of this research is to further the understanding of the physical mechanisms associated with 
non-oscillatory (STDCE-1) and oscillatory (STDCE-2) thermocapillary flow by (a) developing an accurate 
description of the physical mechanisms, (b) developing an accurate numerical model, and (c) obtaining ground-based 
and flight experimental data to verify the physical mechanisms and the numerical model. The thermocapillary flows 
result from the fluid motions generated by the surface-tractive force that is caused by surface-tension variation due to 
the temperature gradient along the free surface. 

Task Description: 

STDCE-1: The basis of Surface-Tension-Driven Convection Experiment 1 (STDCE-1) flight experiment is a 
copper test cell 10 cm in diameter and 5 cm deep, filled with silicone oil, able to provide both flat and curved free 
surfaces in a microgravity environment. The outer wall ot the test cell is water cooled. The silicone oil can be 
centrally heated either externally by a carbon dioxide laser (constant heat flux, CF) or internally by an immersion 
heater (constant temperature, CT). The cross section is illuminated by a 1-mm-thick sheet of light, which scatters 
from small aluminum oxide particles mixed into the oil, allowing observation and measurement, using a 
particle-tracking technique, of the axisymmetric flow velocity. An infrared imager is used to measure surface 
temperature, and thermistors are used to measure fluid and wall temperature. The velocity and temperature 
measurements are compared with the numerical predictions. 

STDCE-2: The center of Surface-Tension-Driven Convection Experiment 2 (STDCE-2) is an interchangeable 
module containing a test cell and fluid reservoir. Six modules containing copper test cells of 1 .2, 2.0 and 3.0 cm 
diameter, each with the depth equal to the radius, will be filled with 2 centistoke silicone oil, to provide both flat 
and curved free surfaces in a microgravity environment. In three of the modules, one of each size, the fluid will be 
heated by a carbon dioxide laser, imposing a Gaussian heat flux on the free surface, and in the remaining three the 
fluid will be heated internally by an axially located heater which is ten percent of the chamber diameter. The outer 
walls of the test chambers will be cooled. This modular approach was taken to accommodate the large test matrix. 

During the experiment, the surface temperature— which is the driving force in the flow— is measured 
non-intrusively by an infrared imager. The free-surface deformation, felt to play a critical role in the oscillation 
phenomenon, is measured quantitatively using a Ronchi deflectometer. The flow field is observed by illuminating 
the entire test chamber volume with laser light which is scattered from 20 micron aluminum oxide particles mixed 
in the fluid, allowing for three-dimensional qualitative visualization. Thermistors are used to measure bulk fluid, 
wall and heater temperatures. 

At the start of each test the heater power will be slowly increased until the flow transitions from steady and 
axisymmetric to periodic and three dimensional. This will be performed for 43 combinations of test chamber size, 
heating mode and free surface shape. The temperature difference at the transition point will be used to calculate 
non-dimensional parameters which are used to characterize the onset of oscillations. The flow field, surface and 
bulk temperature distributions, and the free surface deformations will be correlated to support the proposed physical 
mechanism for the oscillatory phenomenon. 


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11-96 


II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

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Task Significance: 

The Surface Tension Driven Convection Expenment is designed to study the nature and extent of steady and 
oscillatory thermocapillary tlows using state of the art diagnostics to measure and characterize these flows over a 
wide range of parameters. Valuable data, which can only be gained from low gravity-based experimentation, will be 
obtained resulting in an understanding of the fundamental physical mechanisms and improved implementation of 
related industrial processes such as life support systems, containerless processing of materials, crystal growth, 
propellant storage management, and bio-tluids engineering both in space and on earth. 


Progress During FY 1 994 : 

STDCE-l 

STDCE-1 was flown on USML-1 in June, 1992. 38 tests were completed returning over 12 1/2 hours of data. To 
date approximately 75% of the data has been analyzed and compared to the numerical model. The comparisons show 
good agreement. The analysis of the data has been broken into sections and numerous presentations of those 
sections of the reduced night data have been made. These include tlow data from the 1 hr CT and CF tests, 
temperature data from the 1 hr tests, tlow data from the shorter CT flat surface tests, and flow' data from the shorter 
CF curved surface tests. All of the data is presently being compiled by a graduate student for die final contract 
report. In addition, no flow oscillations were observed in any of the tests corroborating the Principal Investigator’s 
theory that the Marangoni number alone is not sufficient to indicate the onset of oscillatory flow. 

STDCE-2 

Right Experiment: 

STDCE-2 is scheduled to fly on USML-2 in September of 1995. In preparation, the PI and Co-I participated in two 
USML-2 Investigator Working Group meetings at the Marshall Space Right Center in addition to numerous 
meetings and reviews at the Lewis Research Center. 

Ground-based work: 

1 . Analysis 

A scaling analysis of axisymmetric thermocapillary flows was conducted. Various important velocity and length 
scales were determined. The scaling laws were shown to agree well with the results of a numerical analysis. Based 
on the scaling analysis a surface deformation parameter (S-parameter) was derived for each CT and CF heating mode. 
Both Marangoni number and the S-parameter must be larger than certain values in order to obtain oscillatory 
thermocapillary flow. The work has been written up as a Ph.D. thesis. 

2. Experimental Work 

The deformation of the free surface has been measured in oscillatory thermocapillary flow. The free surface motion 
was measured by observing the surface in one radial cross-section through a micro- video system. An organized free 
surface motion was found. The frequency of the free surface oscillations was the same as that of the temperature 
oscillations detected by a thermocouple probe in the fluid. Both oscillation patterns were closely related. 

An optical system is being set up to measure the free surface motion over the entire free surface instead of on 
section. This optical measurement will provide us with information regarding a wave-like motion of the Tree 
surface. The information is important in establishing a coupling among the surface motion and the rotating 
temperature oscillation pattern. 

An experiment on oscillatory thermocapillary flow in cylindrical containers is being performed. The objective is to 
confirm the S-parameters obtained by analysis. In order to do so the effect of buoyancy on oscillatory 
thermocapillary flow must be understood. The buoyancy effect is being investigated numerically and 
experimentally. 


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11-9 7 


II. MSAD Program Tasks — Flight Research 

I 


Discipline: Fluid Physics 

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Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 1 MS Degrees: 3 

PhD Students: 3 PhD Degrees: 1 


Task Initiation: 4/91 Expiration: 3/96 
Project Identification: 963-25-0D-09 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals , . . . 

Kamotani. Y., Ostrach, S and Pline. A. Analysis of velocity data taken in surface tension driven convection experiment in 

microgravity. Physics of Fluids A, vol. 6, no. 11, 3601-3609 (1994). 


Chang, A. "Scaling analysis of thermocapillary flows in cylindrical containers,” Ph.D. thesis, August, 1994. 

Kamotani, Y., Ostrach, S. and Pline. A. "Some results from surface tension driven convection experiment aboard USML-1 
spacelab." Paper AIAA-94-0238, 32nd AIAA Aerospace Sciences Meeting, Reno, NV, January 10-13, 1994. 

Kamotani. Y.. Ostrach. S. and Pline. A. "Some Velocity Results from the thermocapillary flow experiment aboard USML-1 
Spacelab." COSPAR Meeting, Hamburg, German. 1994. 

Kamotano, Y., Ostrach, S. and Pline, A "A thermocapillary convection experiment in microgravity. 1 1993 ASME Winter 
Annual Meeting, New Orleans. LA, Nov. -Dec. 1993. 





11-98 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

Illlll 


Modeling and New Experiment Definition for the VIBES 


Principal Investigator: Prof. Robert l. Sani 


Co-Investigators: 

Dr. H. Azuma 
Dr. T. Doi 
Dr. S. Kamei 
Dr. M. Ohnish 
Dr. T. Kida 
Dr. K. Yamamoto 


University of Colorado, Boulder 


Japanese National Aerospace Laboratory (NAL) 
NSDA — Japanese Space Agency 
Mitsubishi Research Institute 
Japanese National Aerospace Laboratory (NAL) 
Japanese National Aerospace Laboratory (NAL) 
Japanese National Aerospace Laboratory (NAL) 


Task Objective: 

The Vibration Isolation Box Experiment System (VIBES) is an IML-2 flight experiment being designed by the 
Japanese National Aerospace Laboratory. Its primary goal is to evaluate the performance of a vibration isolation 
device in conjunction with typical fluids experiments. The IML-2 flight experiment will contain two experimental 
units: the Convection Diffusion Unit (CDU) and the Thermal-Driven Flow Unit. The purposes of the CDU 
experiment (the one of interest herein) are to observe natural convection and diffusive transport in a micro-g 
environment and to observe the effect of g-jitter with and without the vibration isolation due to the vibration 
isolation box. The objective of this project is to provide numerical modeling for the CDU experiment for aiding in 
design refinements and evaluation of terrestrial benchmark experiments as well as post-flight evaluation of the 
experimental data. 

Task Description: 

The numerical modeling will utilize a Galerkin finite element algorithm for the linear momentum, energy and 
species balance equations using the Boussinesq approximation. This project will make comparisons of two codes 
(Pi's research code and a commercial code, FIDAP) in a transient, 3-D calculation to determine their efficiency and 
accuracy. Timing comparisons will also be made between FIDAP and the research code. The numerical 
experiments will include example cases with and without the test cell being subjected to g variation; both single 
and multiple frequency variations will be considered. The numerical experiment will also consist of simulating the 
g-environment (to be provided by the Japanese research team) both inside and outside the isolation box. 

Comparison of these results should allow a quantitative assessment of the isolation capability of the apparatus. 

Task Significance: 

The microgravity environment available for space experiments is not quiescent but is subjected to significant 
background vibrations generated by aerodynamic and machinery vibrations, crew motion, etc. Such g-jitter can be 
relatively random in orientation and can attain significant magnitudes. There is a growing list of observations and 
data analyses that demonstrate the existence of significant g-jitter episodes and their potential for having very 
deleterious effects on many proposed flight experiments. A potential solution to this problem in the micro-g 
environment is the use of vibration isolation for the experiments which require it. The assessment of such an 
apparatus is one of the main thrusts of the research proposed in this project. 

Progress During FY 1 994: 

During this reporting period, the following have been accomplished: 

1. The development, testing and benchmarking of the semi-consistent mass finite element projection algorithm for 
2D and 3D transient Boussinesq flow has continued. 

a. The algorithm has been modified in order to include the option of utilizing as skew-symmetric form of the 
advection operator as a prelude to the implementation of a variable time step capability. This option required the 





11-99 


II. MSAD Program Tasks 


— Flight Research Discipline: Fluid Physics 

miimmimhimmiihihimiih 


implementation of an iterative solution technique, bi-conjugate gradient stabilized, appropriate tor unsymmetric 
algebraic systems. This has been done and the algorithm has been tested and benchmarked against known solutions 
existing in the literature as well as solutions generated via the commercial code FIDAP tor a spin-up ot a lid driven 
cavity. 

b. The development ot a variable time step algorithm with local time truncation error control is currendv being 
pursued. 

c. The inclusion of the capability to model additional fields, for example, concentration, is being addressed. Its 
eventual complementation will be an essential tool in the definition ot potential new flight expernnents tocused on 
the behavior of coupled tluids in a g-jitter environment. 

2. Optimization and parallelization studies are underway. 

a. Since the last progress report Prof. Sam has further unproved the optimization ot the algorithm as well as 
initialized an investigation of the potential parallelization of the algorithm via domain decomposition. 

3. Initial time- varying gravity Boussinesq flow simulation has been done. 

a. The simulation reported in the previous progress report has been completed and the results are being compared 
with experimental observations made by a Japanese research team. 

4. Ongoing communication with the Japanese research team for VIBES has been maintained. 

a. The data from the VIBES flight (IML2) experiment i.e.. video, accelerometer data, etc., should be available in 
the next few months and post-flight analysis of the data will be initiated. 


Students Funded Under Research: Task Initiation: i/93 Expiration: i/% 

Project Identification: 963-24-05-14 
Responsible Center: LeRC 




11-100 


II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 


Studies in Electrohydrodynamics 


Principal Investigator: Dr. Dudley a. Saviiie 

Princeton University 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

This research is designed to strengthen and test the experimental foundations of the theory of electrohydrodynamics. 
Electrohydrodynamic forces can be used to manipulate fluids, especially fluid interlaces. As such, they offer a 
means of controlling fluid motion on very small length scales. 

Task Description: 

Theoretical studies will center on adapting the existing leaky dielectric theory for the stability of a fluid cylinder to 
account for pinning the contact line at the upper and lower boundaries in a liquid bridge configuration. 

Experimental studies will be carried out to (1) evaluate the influence of ionic surfactants on conductivity so as to 
enable us to control the time scale of the electrohvdrodynamic fluid motion and (2) test the existing 
electrohydrodynamic theory for the stability of a cylinder subject to an axial field with isopycnic systems. 

Task Significance: 

Despite substantial efforts over the past two decades, the foundation of electrohydrodynamics is weak. Relatively 
few experiments have been done to test the leaky dielectric theory, the most promising model of behavior, ar id 
much of the work has been of limited scope because of the need to use isopycnic systems to avoid sedimentation 
and hydrostatic pressure effects. This restricts the range of fluid properties that can be studied and as a result there 
are many gaps in our knowledge. In addition to its scientific importance, there are a wide range of applications 
where electrohydrodynamic phenomena play important roles. 

Progress During FY 1 994: 

Experimental work: 

1. We were able to identify an ionic compound with which enables us to control the conductivity of low dielectric 
constant liquids. We studied the conductivity of castor oil containing various amounts of the solute and showed that 
the solution behaved as an ohmic conductor. The use of this system will enable use to control the time scale of the 
electrohydrodynamic motion. 

2. The initial stages of the collapse of fluid cylinders was studied and we showed that the linearized theory was 
capable of representing the experimental results over the initial period. Unfortunately, the need to use very viscous 
fluids to control sedimentation limited the range of our results. 

Theoretical work: 

We tested the existing theory for infinite cylinders against all the known asymptotic results and found that it was 
internally consistent. The next task is to adapt it to liquid bridges (pinned cylinders). 


11-101 


II. MSAD Program Tasks — Flight Research 


Discipline: Fluid Physics 

iiimh 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 4/93 Expiration: 4/96 
Project Identification: 963-24-08-03 
NASA Contract No.: nags-969 
Responsible Center: msfc 


mini mi 


11-102 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 




Mechanics of Granular Materials 


Principal Investigator: Dr. Stein Sture 


University of Colorado, Boulder 


Co-Investigators: 

N. Costes NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

The objective of this research is to examine the use of microgravitv to gain a quantitative understanding of the 
mechanical behavior of cohesionless granular materials under very low confining pressures. 

Task Description: 

Ground-based displacement-controlled triaxial experiments are conducted on a cohensionless granular material at the 
lowest effective confining pressures possible, that do not result in material instability, to assess constitutive 
properties, stability phenomena, and control parameters that will be applied to in-space experiments on 75 mm 
(diameter) and 150 mm (length) right cylindrical specimens. The ground-based tests on similar-sized specimens are 
conducted in the range 3.5-69 kPa, while the microgravitv tests will be conducted at effective confinement levels in 
the range 0.05-1.30 kPa. 

The displacement-controlled mode of loading confined specimens was chosen mainly to maintain overall 
specimen-apparatus stability while strain-softening resulting from continuous or discontinuous bifurcation and 
discontinuous deformation fields are allowed to take place. Optical and other noncontacting displacement-sensing 
techniques are used to measure specimen response during experimentation. Prescribed displacements are transmitted 
in terms of loading, unloading, and reloading histories, while volume change is measured in "drained" tests, and 
pore fluid pressure is measured in "undrained M isochoric tests. Confinement pressure is transmitted to the granular 
material assembly through a thin flexible latex membrane surrounding the specimen. A subangular and uniform 
Ottawa quartz sand constitutes the specimen. 

Specimens tested both in space and on ground will be subjected to nondestructive and destructive (thin-slicing) 
testing to assess degrees of material uniformity and isotropy before and after experimentation. It appears that 
instability phenomenon associated with specimens of certain configurator s result in curved internal surfaces of 
localized deformation and high rates of dilatancy, whose structure depends on bifurcation mode. 

Task Significance: 

Specifically, the purpose is to study the influence of particle interlocking and other fabric properties on the strength 
criterion near the effective stress space origin, i.e., can it be represented by a straight-line envelope passing through 
the origin or does it have a curved shape with shear (cohesion or interlocking) or tensile strength intercepts. The 
experiment will determine whether conhesionless granular materials under very low effective confining 
pressures/effective stresses tend to dilate or contract regardless of their initial state of compaction, and whether their 
mechanical behavior under relatively large displacement or quasi-static cyclic loading is according to conventional 
constitutive theory. In addition, bifurcation and material instability phenomena resulting in formation of shear 
bands, before and after peak strengths have been reached, will be studied. Based on terrestrial experiments and 
theory, it has been found that critical hardening, strain- softening behavior, and shear band orientation are dependent 
on confining stress. 


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11-103 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

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Progress During FY1994: 

The progress in the MGM project during FY94 includes the following: 

1 . Design of the MGM apparatus; 

2. Improved specimen preparation technique; 

3. Improved optical-unaging system and measurement of specimen motion; 

4. Improved analysis of specimen bifurcation instability conditions; 

5. Improved constitutive analysis methods. 


Students Funded Under Research: 


Task Initiation: 12/92 Expiration: 9/97 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-24-08-05 

MS Students: 

1 

MS Degrees: 

1 

NASA Contract No.nass-38779 

PhD Students: 

2 

PhD Degrees: 

0 

Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Macari, E.J.P., Sture, S., and Runesson, K. Prediction of response of granular materials at low effective stress levels. J. 
Geotechnical Engineering, vol. 120, no. 7. 1252-1268 (1994). 

Peric, D., Sture, S., and Runesson. K. Effect of pore fluid compressibility on localization in elastic-plastic solids. Int. J 
Solids and Stuctures, vol. 32, no. 4, (1994). 

Proceedings 

Peric, D.. Runesson, K., and Sture. S. "Effect of pore fluid compressibility on localization of elastic-plastic solids under 
undrained conditions." Proceedings of the US National Congress for Applied Mechanics, Seattle, WA (1994). 


llll.Mllllim.il Ill mill MM* I mi IMiMIMMIIIMI I 


11-104 



II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

I II lit IIIIMIIIIIIIIIIIIMIIII 1(11111 IIIIIIIIIIIIMtlllllMIIII III ItllMMMIIMII.IIIIIIII.IIIIMIIIIIIMIIIIIIMINIIIMIIIIIItlllllllMllltlllllllllllltlltl lit llllllllllltllllllllllilllMIIIIMIIIIIKIIIIIIIIIIIIMIIMIIMIIIMIMIIIIIIItlll 

Thermocapillary Migration and Interactions of Bubbles and Drops 

Principal Investigator: Prof. R. S. Subramanian Clarkson University 

Co-Investigators: 

Dr. R. Balasubramaniam NASA Lewis Research Center (LeRC) 


Task Objective: 

The objectives of the research are to experimentally measure the thermocapillary migration velocities and the shapes 
of single and interacting gas bubbles, and liquid drops in a continuous phase under the action of an applied 
temperature gradient. Comparisons between the observed velocities and shapes with those that are predicted from 
theory will be made. 

Task Description: 

The general approach has been to conduct ground-based normal -gravity testing and to develop theoretical models of 
the thermocapillary migration phenomena. The instrumentation and diagnostics are centered on the physics of 
interest, namely, tlow fields, temperature fields, and bubble/droplet velocities and shapes. The theories and 
numerical models developed and verified with the 1-g data will be used to design and predict the results of the tlight 
experiment. Preliminary assessment of night data will also begin within FY94. 

Task Significance: 

The results from these bubble migration experiments are not only expected to advance our knowledge in the area of 
surface tension driven motion, but are, in addition, relevant to several applications with respect to space processing 
of materials. Some examples of the latter include solidification, glass processing, and composite preparation. The 
physics studied in the experiments offer a method by which undesirable void formation in metals and composites 
can be avoided. 

Progress During FY 1 994: 

There were a lot of activities on the flight project side. Activities were concentrated on preparing for and in support 
of the tlight experiment in July 1994. These activities included participating in ground testing of the 
engineering/tlight models in Europe; in mission sequence testing of engineering models at KSC; providing test 
plans for the low-g aircraft flights that took place in July; familiarizing the crew as to the science background of the 
experiment; and attending various mission simulations at MSFC. During the course of the year, the PI expressed 
concerns about being able to inject single bubbles; about being able to extract bubbles; and about getting reliable 
PDI data. During the actual mission in July, the injection and extraction systems performed well, but little useful 
PDI data was obtained. The PI and his team are currently analyzing flight data results which will be reported on in 
the next period. 

Ground based research continued in the Pi’s labs at Clarkson. Research was conducted in the following areas: 
migration of a pair of bubbles in a vertical temperature gradient; the study of drops held fixed under the 
simultaneous action of thermocapillary and gravitational effects; and the development of predictions of free 
convection due to transient gravitational fields. 


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11-105 






IL MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

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Students Funded Under Research: 


Task Initiation: i/90 Expiration: 12/95 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-25-0C-61 

MS Students: 

1 

MS Degrees: 

0 

Responsible Center: LeRC 

PhD Students: 

2 

PhD Degrees: 

1 



Bibliographic Citations for FY 1994: 

Journals 

Wei. H. and Subramanian. R.S. Interactions between two bubbles under isothermal conditions and in a downward 
temperature gradient. Physics of Fluids A. A6. 9, 1971-78 (1994). 

Presentations 

Forbes, Rashidnia. N. and Balasubramaniam. R. "Abel inversion of irregularly spaced discrete interferometric fringe data: 
A geometrical approach." Division ot Fluids Dynamics Meeting, American Physical Society, Albuquerque, New Mexico, 
November, 1993. 

Rondos. P.A. and Subramanian, R.S. ’Buoyant flow driven by a time-dependent gravitational field in a two-dimensional 
cavity." AiChE Annual Meeting, San Francisco, November 1994. 

Subramanian, R.S., and Rondos. P.A. "Gas bubble dissolution and growth in glass melts." invited review. American 
Ceramic Society Meeting, Indianapolis. Indiana. April 1994. 


MM, Ml* limit,, Ml, 

II— 1 0 6 


II. MSAD Program Tasks — Flight Research 


Discipline: Fluid Physics 


Drop Dynamics Investigation 


Principal Investigator: Prof. Taylor g. Wang 

Vanderbilt University 

Co-Investigators: 


C.P. Lee 

Vanderbilt University 

A.V. Anilkumar 

Vanderbilt University 

A.B. Hmelo 

Vanderbilt University 

H.J. Hussein 

Vanderbilt University 


Task Objective: 

The objective of this program is to understand the behavior of free drops, primarily by studying them in a 
microgravity environment. The Drop Physics Module (DPM) operated in the Space Shuttle provides an 
opportunity to address outstanding fluid-dynamics issues of rotating and oscillating simple and compound drops. 

To maximize the return from this short on-orbit opportunity, ground-based experiments will be performed to verify 
concepts and experimental techniques, and modeling will be done to select the parameters for the DPM experiments. 

This investigation will use a triple-axis acoustic positioning chamber to study the static behavior and dynamics of 
simple and compound drops as well as of liquid shells. Equilibrium shapes and the stability of rotating and 
nonrotating drops, their associated internal flow patterns, and the centering force associated with shape oscillatory 
dynamics of rotating compound drops — will be the principal scientific areas of interest. 

Task Description: 

A variety of experiments will be performed in space. Compound drops and liquid shells will be formed to study 
their oscillation modes and the effectiveness of those modes in centering the core. The interaction between the 
acoustic field and the drops will be studied: the drops' static shape, the stability of distorted shapes, and the 
generation of any flows in the liquid. The dynamics and stability of rotating drops near the point of fission will be 
explored. 

Task Significance: 

This investigation uses the low gravity provided by the Space Transportation System, the working laboratory of 
Spacelab, and the Drop Physics Module hardware to study large drops. Studying drops from 1-3 cm. in diameter 
shows dynamic phenomena to time scales which can be observed by the experiment operator as well as captured on 
high-speed film. 

Progress During FY 1 994: 

Due to the late arrival of the DPM video data, the reduction and analysis of most of the USML-1 data was performed 
in FY 94; three papers have been prepared using this data and have been submitted for publication. Support to the 
DPM Project in the area of understanding tumble rotation progressed from flow visualization experiments at 
Vanderbilt to preparations for torque measurements on the flight system at KSC. 

One of the primary objectives of USML-1 was to perform careful experiments on rotating drops. The DDM results 
from Spacelab-3 deviated from analytical and numerical predictions. The USML-1 results showed that flattening due 
to acoustic forces would cause experimental measurements to deviate from theoretical predictions that assume a 
spherical geometry; when the drops are spherical, there is no discrepancy. The results will be published in the 
Journal of Fluid Mechanics (Oct. 94). 

Another set of USML-1 experiments studied the tendency of compound drops to become concentric under the 
influence of capillary oscillations. A compound drops is composed of two relatively immiscible fluids one totally 


II— 1 07 





II. MSAD Program Tasks — Flight Research Discipline: Fluid Physics 

Minimi it imi tint mm tun 


contained within the second fluid drop. Studies of both bubbles and liquid-liquid compound drops showed that the 
core slowly oscillated about the center and after several periods remained concentric. These results which can not be 
explained by existing inviscid models were published in the Journal ot Colloid and Interlace Science. 

A third paper has been generated from USML-1 sequences of oscillation and natural decay. The experimental results 
were obtained using rotating and non-rotating drops with small but finite viscosities. The latter data agree with 
current theory while the flattening inherent in a rotating drop caused deviation Irom the simple models. This work 
has been submitted to the Journal of Fluid Mechanics. 


A major reason that the science return from USML-1 was less than expected was the appearance ot an uncontrollable 
rotation. In support of the DPM Project a team at Vanderbilt has been studying how the air moves inside the DPM 
chamber under various combinations of acoustic signals. Flows were observed to be due to both to the quartz wind 
from the individuals drivers as well as to the interaction of DPM's unique signals. The strength ot the former is 
larger and correlates with the weak DPM driver on USML-1. Characterization measurements ot the torque on a 
suspended ball in DPM-like chambers at Vanderbilt, the trainer at Marshall SFC, and the flight system at KSC are 
being carried out. 


Students Funded Under Research: 


Task Initiation: 8/92 Expiration: 7/96 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-24-04-01 

MS Students: 

3 

MS Degrees: 

2 

Responsible Center: jpl 

PhD Students: 

1 

PhD Degrees: 

0 



Bibliographic Citations for FY 1994: 

Journals 

Lee, C.P. and Wang, T.G. Acoustic radiation pressure. J. Acoust. Soc. Am., vol. 94. 1099-1109 (1993). 

Wang, T.G., Amikumar. A.V.. Lee, C.P. and Lin. K.C. Core-centering of compound drops in capillary oscillations: 
Observations on USML-1 experiments in space. Journal of Collois and Interface Science, vol. 165, 19-30 (1994). 

Proceedings 

Wang. T.G.. Amikumar. A.V.. Lee. C.p. and Lin, K.C. "AIAA Paper No. 93-0252, (1993).” A preliminary analysis of the 
USML-1 drop dynamics experiment results. 


IIIMIIIIHMHMI 


11-108 



II. MS AD Program Tasks — Flight Research Discipline: Fluid Physics 

i mi hi Mini 


Colloid Physics in Microgravity 

Principal Investigator: Dr. David a. weitz 

EXXON Research and Engineering Co. 

Co-Investigators: 


Prof. P.N. Pusey 

The University of Edinburgh 


Task Objective: 

This experiment entails the study of the physics of colloidal particles in microgravity. It consists of two distinct 
parts. The first deals with ordered structures while the second deals with highly disordered structures. The study of 
ordered structures entails the growth of colloidal superlattices formed with mixtures of different-sized particles. The 
goal is to develop useful periodic structures using colloidal particles as precursors, through "colloid engineering." 
The study of the highly disordered structures entails the formation of fractal colloidal aggregates of much greater 
extent than has ever been done, and the formation of very weak structures that would collapse under their own 
weight in normal gravity. 

Task Description: 

The work within this effort will be ground-based research to study the formation of novel materials from colloidal 
dispersions, and to study the physical properties of such materials. As part of the effort, space experiments to be 
carried out in a space shuttle middeck earner, will be defined. These experiments will utilize the laser light 
scattering apparatus currently being developed at NASA LeRC. 

The focuses of the ground-based experiments will be the study of colloidal superlattices formed from mixtures of 
different-sized colloidal particles, the in-depth study of the formation of fractal colloidal aggregates, and the study of 
granular particles tluidized in a gas. While considerable knowledge exists about the formation or growth of fractal 
colloidal aggregates, much less is known about the unique properties of these objects and the consequences of their 
scale invariance. A major reason for this is the relatively small scale over which the aggregates exhibit scale 
invariant behavior. By growing structures that are scale invariant over a much greater range of length scales, the 
properties of these objects can be studied much more directly. This will provide the first detailed information about 
the consequences of scale invariant structure on the properties of these materials. 

Task Significance: 

Very little is currently known about the structures of binary colloidal crystals, and these experiments will initially 
be directed at determining the phase diagrams of the superlattices for mixtures of different sizes of particles. In 
addition, virtually nothing is currently known about the kinetics of the formation of these superlattices, and about 
their dynamics once they are formed. This will also be studied by these experiments. This will represent the first 
in-depth study of the growth and properties of colloidal superlattices. 

Progress During FY1994: 

The necessary arrangements for the grant were put in place in June 1994. The SCR will take place on October 28, 
1994. The investigators have developed plans for the experiments to be conducted in space. This plan will be 
presented at the SCR. The ground-based research to support the flight experiment has just been initiated. 


Students Funded Under Research: Task Initiation: 3/94 Expiration: 3/97 

Project Identification: 963-24-05-13 
Responsible Center: LeRC 


11-109 



II. MSAD Program Tasks — Flight Research 

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Discipline: Fluid Physics 

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Study of Two Phase Flow Dynamics and Heat Transfer at Reduced Gravity 


Principal Investigator: Prof. Larry Witte 

University of Houston 

Co-Investigators: 


J.B. McQuillen 

NASA Lewis Research Center (LeRC) 

Task Objective: 

The objective of this study is to develop and experimentally verify theoretical models that predict gas-liquid flow 
regimes and their characteristics in reduced gravity. 

Task Description: 



Reduced-gravity experiments will be conducted in NASA aircraft to measure the previously listed two-phase flow 
parameters for a range of tube diameters, gas and liquid flow rates, and fluid properties. The gas phase for the 
experiments will be air; the liquids to be employed are water, water-glycerin mixtures, and water-zonyl mixtures. A 
theoretical modeling effort will be integrated with the experimental efforts. 

Task Significance: 

The purpose of this study is to achieve a better understanding — better predictability — ot two-phase (gas-liquid) flow 
in pipes to assist in the design of space-based power and thermal management systems and ot the terrestrial -based 
nuclear power plants and oil and natural gas pipelines. 

Progress During FY 1 994: 

A series of low gravity tests were conducted aboard the NASA LeRC Leaijet in November and December 1994 
using a 1 .27 cm. inner diameter test section. The focus of these tests was to obtain additional data concerning the 
characteristics of slug and annular flow. A new technique using a hot film anemometer to measure wall shear stress 
was incorporated. 

In February, the original PI for this effort. Dr. Abe Dukler passed away. The University of Houston, with the 
concurrence of the NASA technical grant monitor, named Dr. Larry Witte to succeed Dr. Dukler. NASA 
Headquarters decided to descope the original plans for a space flight experiment into a ground-based activity. 

In April 1994, several tests were performed aboard the NASA JSC KC-135 yielding flow regime maps tor air and 
three fluids — water, water-glycerin, and Zonyl-FSP/water in a 2.54 cm. inner diameter tube. Additional 
measurements were made, both near the gas-liquid mixer and near the exit, ot the liquid film thickness, void 
fraction, pressure drop and wall shear stress. 

A 2.54 cm. inner diameter heated test section was designed and fabricated to extend the flow dynamics research into 
microgravity two-phase heat transfer. The section is designed to obtain local, time-averaged heat transter 
coefficients along the heated length as well as instantaneous coefficients that can be correlated with the motion oi 
liquid waves or slugs. Resistance temperature elements (RTD's) are positioned between the heaters and the external 
tube to estimate the internal wall temperature. A thin-film thermocouple, capable ot response times as short as 103 
milliseconds, is mounted inside the tube near the exit. A film thickness probe just after the exit is used to correlate 
the temperature fluctuations with waves or slugs. A special mixer section is used after the heated test section to 
obtain the mixing-cup temperature. 


* 




11-110 



II. MSAD Program Tasks — Flight Research 

it mu 


Discipline: Fluid Physics 

lit! Ml) ....Mill 


Students Funded Under Research: 
BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 12/92 Expiration: 11/94 
Project Identification: 963-24-0A-35 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994 : 

Presentations 

Bousman, W.S. and Dukler. A. ’’Studies of gas-liquid flow in microgravity: Void fraction, pressure drop, and flow 
patterns.” Presented at the 1993 WA ASME Meeting, New Orleans. November 1993. 

Bousman, W.S. and Dukler, A. ’’Ground based studies of gas-liquid flows in microgravity using learjet trajectories.” AIAA 
paper 94-0829, presented at AIAA Aerospae Sciences Meeting, Reno. January 1994. 

Bousman. W.S. and McQuillen. J.B. ’’Characterization of annualar two-phase gas-liquid flows in microgravity. ” presented 
at the Second Microgravitv Fluid Physics Conference, Cleveland. OH. January 1994. 


II-l 1 1 



II. MSAD Program Tasks — Flight Research 




Discipline: Materials Science 

IIIIIM Hlllllllll 


In Situ Monitoring of Crystal Growth Using MEPHISTO 

PRINCIPAL INVESTIGATOR*. Prof. Reza Abbaschian, Ph.D. University ot Florida 


Co-Investigators: 

A.B. Gokhale 
S.R. Coriell 
JJ. Favier 


University of Florida 

National Institute of Standards and Technology (NIST) 

CENG (France) 


Task Objective: 

The objective is to determine the morphological stability of solid/liquid interfaces and resulting macro and micro 
segregation patterns, and to determine the attachment kinetics at the freezing interlace deduced via measurements ot 
the growth-rate/interface-supercooling relationship. 

Task Description: 

To investigate the solidification behavior and stability of solid/liquid interfaces during the growth ot pure Bi (a tacet 
lonnine material), and Bi alloyed with small amounts ot Sn, in 1-g and fig. The experiments were designed to 
make use of die second flight of MEPHISTO on USMP-2 (3/94). 

The experiments make use of the Seebeck technique to measure the interface temperature m-situ and non-mvasively 
during crystal growth in both the ground-based and tlight experiments. Both 1-g and pg experiments make use ot 
the measured resistance change across the sample to determine interlacial velocity and Peltier pulsing tor 
demarcation of the interface shape. 

Task Significance: 

The first tlight studied morphological stability in Sn alloyed with Bi (non-tacet forming material), conducted by 
French scientists as part of this collaborative study. The results of the second tlight experiment will therefore 
complement the results and findings of the first tlight. 

Progress During FY 1994: 

A comprehensive directional solidification experiment was recently carried out successfully on the USMP-2 mission 
(STS-62) utilizing the MEPHISTO directional solidification facility. The 14 day shuttle flight was launched on 
Friday, Minch 4, 1994. Using three samples processed in parallel, a total of 45 cm ot dilute Bi-Sn alloys were 
solidified directionally in microgravity under well controlled and well characterized conditions. Prior to the final 
directional solidification, extensive measurements were performed on the samples, consisting ot Seebeck 
measurements to measure the solid/liquid (s/1) interface temperature, resistance measurements to track the position 
of the s/1 interface and thermal gradient measurements in the solid and liquid during freezing and melting. The final 
solidification also included a procedure for marking the shape of the s/1 interface via mechanical perturbations, as 
well as rapid quenching of a 2 cm section of one of the samples. 

The experiments were performed to gain a detailed understanding of the role ot gravity driven convection during the 
solidification of faceted materials. Two fundamental and interrelated aspects of the liquid to solid transformation 
have been investigated: (a) Morphological stability of the solid/liquid (s/1) interlaces and the resulting macro- and 
micro-segregation patterns and (b) atomic attachment kinetics at the freezing interface, deduced via measurement ot 
die growth rate -interface supercooling relationship(s) 

To achieve the goals of the project in a relatively short period, a three-pronged strategy for achieving the stated goals 
was used: (a) Development of experimental apparatus for ground based kinetics and morphological stability studies 
at University of Florida (UF), (b) Scientific and technical collaboration with the MEPHISTO teams at CENG and 




II— 1 1 2 


II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

NIimillllMIMIIIIIMIMIMItMIIIIMIHIIIIIIItlllllMIIIIIIIIMnilllMIIMtlMIIIIMIIMIIIIIIINMIllMItllNIIIIIIMIMIMIIIIIMMIIMIMIIIIMtMItMMIMIIMIIUtMIIIIIMMIMIIIMIIIIIMIIIIIItlllllllllllMNIIIIMMIlit 


CNES and (c) Analytical modeling of morphological stability and interface kinetics in collaboration with Sam 
Coriell (NIST). Particular reference is also made to an extensive collaboration between the various scientific and 
technical personnel from NASA-Lewis for developing a comprehensive flight program. 


The research team at UF developed the facilities necessary for ground based experiments to ensure maximum 
conformity with the MEPHISTO space hardware. In addition, four ’campaigns" were conducted ppor to the 
USMP-2 mission (three on the MEPHISTO engineering model at CENG and one on the MEPHIS TO flight model 
at CNES). Each campaign required three samples approximately 1 meter in length, which were prepared at UF 
according to MEPHISTO specifications. The campaigns not only proved the integrity of the samples produced, but 
also provided valuable ground based data, which is currently being compared with the flight experiments. 
Concurrently, NIST has carried out analytical modeling of the morphological stability of faceted solid/liquid (s/1) 
interfaces for the alloy system under investigation. 

These flight experiments utilized a novel technique (termed the Seebeck technique) to measure the interface 
supercooling directly, non-invasiveiy and in-situ (i.e. in real time during growth). The interface velocity was 
measured by monitoring the resistance change across the sample, while the interface shape was delineated by 
subjecting the sample to electrical current pulses (lor ground based studies) and mechanical perturbations (for (i-g 
studies) to cause a momentary demarcation of the interfaces. 


Initial ground-based experiments were carried out using high purity Bi and dilute Bi-Sn alloys. Bi-Sn alloys were 
chosen to complement the experiments conducted by CENG/CNES on the first flight of MEPHISTO 
(MEPHISTO- 1): on this flight, dilute, non-taceted Sn-Bi alloys were used, while this research program (the second 
flight of MEPHISTO, or MEPHISTO-2) used strongly faceted Bi- 0.1 at % Sn alloys. In this manner, the results 
of the two flights are being used to compare and contrast various fundamental aspects of solidification without and 
with a strong influence of atomic attachment kinetics, respectively, in the presence (ground-based studies) and 
near-absence (fi-g studies) ot gravity induced convection. It is expected that this comprehensive investigation 
approach will significantly further our understanding of key crystal growth parameters. 

We further expect to use these data to test and improve many of the current solidification theories. In particular, the 
interplay between morphological stability and interface kinetics is not well understood at the present time. The 
microgravity experiments will yield an integrated database involving interface velocity/interlace shape/interface 
supercooling. Such data are important from both practical and theoretical standpoints. For example, a knowledge 
ot the transition from a faceted to a rough interface (from the Seebeck data) and the interface shape (f rom 
solute -dump-demarcated interfaces) under identical growth conditions has important applications in pracdcal crystal 
growth situations: the information can be used to understand the correlation between defect generation and solute 
banding. In addition, because the information has been obtained in diffusion dominated conditions without the 
overriding effects of gravity-induced thermo-solutal convection, meaningful tests (and appropriate refinements) of the 
current crystal growth theories can be made. 


Two other spin-offs of the proposed program are worthy of note here: we will be able to obtain values of key 
parameters, such as liquid ditfusivities, via this investigation. In addition, the novel and non-intrusive technique 
used to measure the interface temperature can potentially be utilized for monitoring and controlling the space-based 
single crystal growth of technologically important semiconductors. 

We are currently analyzing the approximately 6 gigabytes of USMP-2 MEPHISTO data. During the mission, 
extensive use was made ot the telemetry commanding capability to modify and refine experimental procedures for 
better scientific yield. Preliminary analysis ot the data acquired during the first 28 hours of mission shows excellent 
correlation of the Seebeck signal with melting/freezing as well as solute build-up/decay. Numerical calculations are 
being earned out concurrently to correlate the Seebeck signal with thermal/solutai decay and hence to back calculate 
an accurate value of the diffusion coefficient of tin in liquid bismuth. 


tint it iMitmitim Mit 


11-113 



II. MSAD Program Tasks — Flight Research 

...............mi* 


Discipline: Materials Science 

,,,,,11111. II. .1... 


Students Funded Under Research: 

BS Students: 1 

MS Students: 4 

PhD Students: 0 


Task Initiation: 1/90 Expiration: 9/95 

Project Identification: 963-25-05-04 
Responsible Center: urc 


Bibliographic Citations for FY 1994: 

Proceedings 

Abbaschian. R.. Gokhale. A.B.. DeWitt. R.. Cambon. G.. Favier. J.J.. Coriell. S.R.. and deGroth. 01, H.C. "In situ 
monitoring of crystal growth using MEPHISTO." Proceeding of the Microgravity Materials Science Conference. 
Huntsville, Alabama, May. 1994. 

Gadonniex. D„ Gokhale, A., amd Abbaschian. R. "Morphological stability of faceted solid/liquid interfaces in dilute 
Bi-Sn alloys." Proceedings ot the 32nd Aerospace Science Meeting, AIAA 94-0791. January, 1994. 


iMM.iimHmmiiiiiiiMHiiiiiiiimiiiMttHMtHtmMMm 11 ' 1 ** 1 * 


11-114 



II. MSAD Program Tasks — Flight Research 

i • ii iiiiii iiitiiivii ii mi iimii im mu ii 1,, mi ii, in H I, I,, m I,, I,, ••m, mi 1 1,, in in in ■^1111111111 

Discipline: Materials Science 

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Coupled Growth in Hypermonotectics 


Principal Investigator: Dr. j. b. Andrews 

University of Alabama, Birmingham 

Co-Investigators: 


A. Sandlin 
S. Coriell 

National Research Council (NRC) 
National Institute of Standards and Technology (NIST) 


Task Objective: 

The objective ot this investigation is to gain a further understanding of solidification processes in immiscible alloy 
systems. A portion ot the study involves the development of a model for die coupled growth process in monotectic 
systems. This analysis starts with the basic equations for diffusion controlled grow'th and avoids many of the 
simplifying assumptions otten utilized in similar analyses. A parallel effort is underway to develop and refine 
experimental techniques which will permit steady-state coupled growth of hypermonotectic composition samples to 
produce aligned microstructures. The results from these experiments will then be compared to predictions from the 
model and utilized to improve the model. In order to permit steady-state coupled grow'tJh in hypermonotectic 
composition samples experimentation must be carried out under low-gravity conditions. 

Task Description: 

This project includes the major research tasks of theoretical modeling, selection of sample materials, selection of 
ampoule materials, experimentation, data analysis, and development of ampoules for processing. In addition, the 
project is concerned with the evaluation of current flight hardware for use in experimentation and with input into the 
development of new hardware. Experimentation requires directional solidification of immiscible aluminum-indium 
alloys under low-gravity conditions in order to avoid convective instability and promote steady-state coupled 
growth. 

Task Significance: 

The significance ot this project lies primarily in die scientific gains to be made in truly understanding die coupled 
growth process in immiscible alloys. Many alloys in immiscible systems have great promise for potential 
applications in areas which include superconductors, magnetic materials, catalysts, and electrical contacts. However, 
there are many details of the solidification process that are poorly understood for these alloys because these details 
are masked by gravity driven phenomena. This project is aimed at using die unique environment available in space 
to improve this understanding in order to make possible the production of new materials using specialized 
processing techniques. 

Progress During FY1994: 

Major advances have been made in the development of a model for diffusion- controlled coupled growth in 
monotectic systems. Starting with the basic equations, the model has been developed w ithout many of the 
simplifying assumptions usually made in this area. We have found dial some of these presumably valid 
assumptions lead to a major restriction on die phase equilibria conditions for which the previous analyses are valid. 
These restrictions are avoided with die newly developed model. In addition, the new ; model determines die volume 
tractions ot the phases in a selt-consistent way. This factor may be quite significant at higher growth velocities. 

In the experimental area, contact angle and chemical compatibility tests have led to die selection of AIN and 
sintered Si 3 N 4 as viable ampoule materials for microgravity experimentation. Flight ampoule designs are nearing 
the testing stage. Work has been carried out which validates die current model for morphological stability 
conditions in hypermonotectic Al- In alloys. In addition, compositional analysis of ground processed 
hypermonotectic Al-In samples indicates convective instability is a major factor impeding die establishment of 
steady-state growth conditions. This ground based work has permitted the establishment of processing limits for 
microgravity expenmentadon on die Al-In alloy system. 




1 1-1 15 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

* »••«... «•••*» * 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 1/93 Expiration: 1 /% 

Project Identification: %3-25-08-09 
NASA Contract Nojnag8-39717 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Proceedings 

Arikawa. Y., Andrews. J.B.. Coriell. S.R.. and Mitchell. W.F. "Modeling and numerical simulation of processes at a 
hypermonotectic solidification front." Proceedings of the 6th International Conference on Experimental Methods for 
Microgravity Materials Science, TMS, R.S. Schiffman and J.B. Andrews, eds., 137-140 (1994). 

Cheney. A.B.. and Andrews. J.B. "The evaluation of ampule materials for low-g processing of immiscible alloys." 
Proceedings of the 6th International Conference on Experimental Methods tor Microgravity Materials Science. TMS, 

R.S. Schiffman and J.B. Andrews, eds. ,191-197 (1994). 

Hayes. L.J.. and Andrews. J.B. Proceedings of the 6th International Conference on Experimental Methods tor 
Microgravity Materials Science. TMS. R.S. Schiffman and J.B. Andrews, eds., 167-174 (1994). 

Books 

Andrews, J.B. "Solidification of Immiscible Alloys” in "Immiscible Liquid Metals and Organics. Edited by. L. Ratke 
DGM Informationsgesellschaft, Verlag Press, pp 199-222, 1993. 

Presentations 

Andrews. J.B. ' Coupled growth in hypermonotectics." NASA Microgravity Materials Science Conference, Huntsville. 
AL. May 24-25. 1994. 

Andrews. J.B., Hayes. L.J.. and Coriell. S.R. "Instabilities during coupled growth of hypermonotectics." COSPAR 30th 
Scientific Assembly. Hamburg, Germany, July 11-21. 1994. 

Andrews, J B . Hayes. L.J.. and Moss. C.B. "Factors influencing coupled growth in hypermonotectics." TMS Fall 
Meeting. San Francisco. CA. February 27-March 3. 1994. 

Arikawa. Y.. Andrews, J.B.. Coriell, S.R., and Mitchell. W.F. "Modeling and numerical simulation of processes at a 
hypermonotectic solidification front." TMS Annual Meeting, San Francisco. CA, February 27-March 3. 1994. 

Cheyney, A.B. and Andrews. J.B. "The evaluation of ampule materials for low-g processing of immiscible alloys." TMS 
Annual Meeting, San Francisco. CA. February 27-March 3. 1994. 

Hayes, L.J.. and Andrews, J.B. "The influence of convection on coupled growth in Al-In hypermonotectic alloys. TMS 
Annual Meeting, San Francisco, CA, February 27-March 3, 1994. 


iiimimiiiiiii iiimiMitinmii 


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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

mmmmilmMmimillMMIIIMNIimimiHMiminMmMlllimimmmilMIMIIIM|||||m»iminNMMIIIMIIimiHimMllllimilMmillNIII*ll#imi»MIMIIIMIMimillMMIIM*M*I.IIMIMIimillllllllllllllllll»miM 


Effects on Nucleation by Containerless Processing 

Principal Investigator: Prof. Robert j. Bayimck 

Vanderbilt University 

Co-Investigators: 


W. Hofmeister 
M. Robinson 

Vanderbilt University 
NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

Tlie primary scientific objective is to further the understanding of nucleation of solids from their melts. A 
secondary objective is to determine if ground based methods, such as drop tube processing, electromagnetic 
levitation, and electrostatic levitation, are equally useful for containerlessly processing bulk samples of pure metals 
as compared to electromagnetic heating and positioning in low Earth orbit. Within this secondary objective is a 
locus on identilying and quantifying any possible technique specific factors that influence nucleation behavior. 

Task Description: 

The presently existing containerless ground based methods are being used to study nucleation of solid from the 
liquid. This includes drop tube processing, electromagnetic levitation, and electrostatic levitation. Since nucleation 
is a statistical process, approximately 100 undercooling measurements are desired for each type of sample. This 
number of measurements facilitates the interpretation of results through the application of statistical techniques. 
Much care is taken in the measurement of temperature due to the sensitivity of the approach to the precision of the 
measurements. Increasing and investigating the absolute precision is an important part of the experiments. The 
precision aftects the width ot the distribution of undercoolings, which consequently determines die activation energy 
tor (lie phenomena. A large half-width of a distribution yields low values for the preexponential and exponential 
factors in the nucleation equation, thereby indicating heterogeneous nucleation by mechanisms other than contact 
with a container. Comparisons of the data from the ground based and night techniques give clues as to the nature of 
the nucleation of the solid from die liquid. Different processing methods have different environments and other 
factors that may affect the amount of undercooling in bulk samples. 

Task Significance: 

Solidification processing is one of the most prominent methods for die production of materials and most of these 
processes begin with a nucleadon step. The regime of nucleation known as deep undercooling, where liquids are 
cooled considerably below their equilibrium freezing temperatures prior to the formation of solids, has become 
particularly distincdve. With deep undercooling, a unique condition for microstructural development and control 
exists and, therefore, a unique condidon for improving and controlling die properties of materials exists. Hence, an 
understanding ot the rudiments of nucleation in the unique regime is most important. 


Progress During FY 1 994: 

Results indicate fundamental differences in the nucleadon behavior of the same sample types in the three ground 
based processing techniques, drop tube processing, electromagnedc levitauon, electrostadc levitadon. For 
zirconium, which has been processed by all three techniques, the distribudons of undercoolings are all non-Gaussian 
and clustered around the same undercooling but are wider for the electromagnedc levitator and the drop tube than for 
the electrostatic levitator. With all three techniques, the distributions retain the same general appearance but shift 
their centers to higher undercoolings (lower nucleadon temperatures) as the material purity is increased from 99.8% 
to 99.95%. This trend toward higher overall undercoolings but similar distribudons was also observed for 99.995% 
pure zirconium samples processed in the electromagnedc levitator. However, the 99.995% purity material did not 
undercool as well in the drop tube as it did in the electromagnedc levitator, although the shape of the distribudon 
was similar. For niobium, processing to date has been accomplished only in the drop tube. In this case 


I 


Min.... in 


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II. MSAD Program Tasks 

IIMIIIIII HIIIIIIMI1H 


Flight Research 




Discipline: Materials Science 


distributions were much narrower than tor zirconium although the percentage undercooling lor similar purity levels 
was approximately the same. 

Due to the presence of ultra high purity helium in the electromagnetic levitator. the cooling rate ot the samples can 
be changed by adjusting the flow of cooling gas. Two sets of undercoolings, one obtained at a cooling rate ot 100 
K/sec and the other at 20 K/sec. have been produced for the same sample type. The shape ot the distributions was 
the same, but the higher cooling rate set of undercoolings was clustered around an undercooling 10 K higher than 
tlie center of the lower cooling rate set. 

The values of the preexponential factors and the activation energies in the classical nucleation rate equation attect the 
distributions of undercooling data. A set of undercoolings distributed over a larger range has lower values, whereas a 
set of undercoolings distributed over a narrower range has higher values associated with it. Thus, tor zirconium, the 
drop tube and electromagnetic levitator had lower associated values than did the electrostatic levitator. The 
preexponential factors and activation energies tend to be higher as the undercoolings shift to higher over a| l 
With zirconium, values for the preexponential factors and activation energies ranged from 108 to 1013 and 13 kl to 
24 kT, respectively. For niobium, these values were 1034 and 72 kT. Overall, the values obtained tor niobium 
much more closely approach the values predicted for homogeneous nucleation as calculated by Turnbull and Fisher 
using classical nucleation theory. 

The thght experiment in low Earth orbit using TEMPUS. an electromagnetic heater and positioner, resulted in only 
one undercooling measurement for zirconium. This undercooling was 160 K. Due to sample instability in the 
facility, the experiments were prematurely terminated when the samples welded to the cage. However, even thoug 
no results on the nucleation behavior of zirconium were possible due to the lack ot data, thermophysical property 
measurements can be obtained. The latent heat of fusion of zirconium was determined to be 14.5 kJ/mol whereas 
values reported in the literature to date vary between 14.5 and 16 kJ/mol. In addition, the large surtace oscillations 
that occurred while the sample was molten should enable the determination of the surtace tension and viscosity o 
zirconium in the undercooled state . S urface analysis of the samples is being conducted using Auger Electron 
Spectroscopy (AES) and Electron Spectroscopy for Chemical Analysis (ESCA) in order to determine the chemic 
compositions of the surfaces of the samples. 

Preparations and additions were made in order to ready MEL, another electromagnetic heating and positioning 
facility, for flights in the NASA KC-135 aircraft. Nucleation frequency experiments using MEL, will be conducted 
in vacuum at a level of around 10* torr. The results will complement and allow comparisons between the ground 
based techniques. 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 0 MS Degrees: 0 

PhD Students: 1 PhD Degrees: 1 


Task Initiation: 4/90 Expiration: 6/95 
Project Identification: 963-25-08-06 
NASA Contract No.: nags-978 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Ntoto" 8 C.W., Hofmeister. W.H.. Bayuzick, R.J.. and Robinson, M.B. A statistical approach to understanding nucleation 
phenomena. Materials Science and Engineering, vol. A178, 209-215 (1994). 

Presentations , . . , 

Bayuzick. R.J., Hofmeister. W.H.. Morton. C.W.. and Robinson. M.B. "Effects ot nucleation by containerless 

processing." NASA Microgravity Matenals Science Conference, Huntsville. AL. May, 1994. 


* 


11-118 


II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

iiniiiiiiiiMiiMiiiiiiiiiiiiiiMiMtiiiiiiiiitiiiiiMiMiiMiiiiMiMiiMiiiiiMMiMiiiMtiitiitiiiMtMiiiiiinMiiiiMmiiiiiiiKniiiiiiiiMiiimiiiMiimimiitMMMiMmiiiiiiiiiiiiiitimmiiiiitiinitimitiinmitiiiiiiniiiii 

Alloy Undercooling Experiments in Microgravity Environment 

PRINCIPAL Investigator: Prof. Merton C. Flemings Massachusetts Institute of Technology (MIT) 

Co-Investigators: 

D.M. Matson Massachusetts Institute of Technology (MIT) 


Task Objective: 

The objectives of this task are to perform solidification experiments on undercooling binary alloys, to compare 
results of ground-based and microgravity experiments, and to examine effects of microgravity on solidification 
behavior and microstructure characteristics. 

Task Description: 

Through experiments applying direct high speed, high resolution pyrometric and cinematographic measurements 
during melting, undercooling and recalescence of nickel-tin binary alloys of different compositions, both on the 
ground and in microgravity, collect thermal history, nucleation and growth history, and resulting solidification 
microstructures. 

Task Significance: 

With experiments carried out in microgravity, it is expected to have improved specimen shape and stability and 
reduced convection during cooling, resulting in the possibility of higher undercooling, less microstructure 
alteration, reduced coarsening, and improved specimen observation in order to gain a complete understanding ot the 
solidification kinetics of undercooled melts, including: primary dendrite tip velocities; rapid thickening ot primary 
and secondary arms during recalescence; ripening, remelting, and solute redistribution; dendrite fragmentation and 
grain refinement; primary phase solidification and ripening; and eutectic solidification with concurrent primary 
phase ripening. 


Progress During FY 1 994: 

Work during the current grant period has resulted in the successful completion of the preliminary preparations tor 
the flight undercooling experiments and support of the 1ML-2 TEMPUS flight investigations. Samples have been 
prepared, analyzed, and submitted for installation in the flight module. Preliminary investigations to define optimal 
processing parameters were completed utilizing the NASA KC-135 experimental platform. All flight samples were 
subsequently processed by melting and observing the solidification behavior in microgravity during STS -65 and are 
presently under analysis following recovery from the orbiter payload compartment. Sample metallography and 
experiment documentation are also currently in progress. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 4/90 Expiration: 6/95 
Project Identification: 963-25-05-03 
NASA Contract No.: nags -971 
Responsible Center: msfc 





11-119 


II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

min it tittimt 


Compound Semiconductor Growth in Low-g Environment 


Principal Investigator: Dr. Archibald l. Fripp 


NASA Langley Research Center (LaRC) 


Co-Investigators: 

NASA Headquarters, Code UG (MSAD) 
NASA Langley Research Center (LaRC) 
NASA Langley Research Center (LaRC) 


R.K. Crouch 
W.J. Debnam 
l.O. Clark 


Task Objective: 

The objective of the Langley flight program is to determine the effects of gravity driven convection on the growth 
and crystal properties of the compound semiconductor alloy, lead tin telluride which is miscible over the entire 
compositional range. The electronic properties of this material are dependent on the ratio ot the two, psedobinary, 
components and consequently, the uniformity of an array of devices is dependent on good compositional control. 
Lead tin telluride is amenable to study for it is easily compounded; it has a relatively low vapor pressure; and there 
is existing, though limited, literature on its growth and properties. 

Task Description: 

This material was chosen for microgravity research for a number of reasons. Lead tin telluride is not only a useful 
semiconductor material which has been used for construction of infrared detectors and tunable diode lasers. It also 
has a phase diagram similar to other compound semiconductors of interest such as mercury cadmium telluride and 
mercury zinc telluride. 

Lead tin telluride is also interesting from a purely scientific point of view in that it is both solutially and thermally 
unstable. Both the temperature gradients and the compositional changes in the liquid near the melt/solid interface 
produce density gradients which, in turn, produce driving forces for convection when coupled with gravity. 

Task Significance: 

Earth based Bridgman growth of lead tin telluride has only produced inhomogeneous crystals that are a result of 
strong convective forces in the liquid during growth. The temperature gradients are required for growth and the 
solutal changes at the interface are a fundamental property of the material system. However, for convection to occur 
these gradients must be coupled to a gravational field. Growth in low Earth orbit offers an unique and fascinating 
opportunity to study the effect of convection on this class of materials. The resultant gravitational force is not zero 
in low Earth orbit hence convection is not completely eliminated but the fluid velocity, due to convection, will be 
greatly reduced. 

Two flights are planned in the Advanced Automated Directional Solidification Fumace (AADSF). The primary 
objective of both flights is to study the effect of gravity reduction, hence convection reduction, on the growth of 
lead tin telluride. In one experiment the growth rate of the crystal will be changed in steps to test the effect of 
varying the relative speed of the interface movement and the fluid velocity. In the other experiment the Space 
Shuttle will be rotated to vary the relative orientation of the gravity vector and the crystal growth axis. Both sets of 
experiments are expected to affect the compositional homogeneity of the crystal. 

Progress During FY 1 994: 

Tliis years effort has continued on finalizing the AADSF fumace configuration and calibration. Lead tin telluride 
has been grown in the flight prototype fumace. The newly designed calibration cartridge has been used for extensive 
characterization of the AADSF fumace. Doped germanium samples, with interface demarcation, have been grown in 
the prototype AADSF for comparison to the calibration data. Numerical modeling of the fumace and samples has 


IIMIIIIIIItlllllHIIIMMHItlllllltlltmilMIIIIIIIIHIIIIIIIIIIIIIimilmil 


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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 


shown remarkable correlation with experimental measurements on calibration samples and die marked germanium 
samples. 

A cartridge with a miniature, internal, pressure gauge was designed and tested in furnaces both at Langley and 
Marshall. These tests not only measured the pressure as a function of set point temperatures over the different 
thermal gradients but also measured the integrity of the cartridge seals and the rigidity of the cartridge as a function 
of temperature and differential pressure. Both the inconel aid WC-103 cartridges have been evaluated. 


Students Funded Under Research: 

Task Initiation: io/78 Expiration: 9m 

BS Students: 

0 

BS Degrees: 0 

Project Identification: 693-80-07-di 

MS Students: 

1 

MS Degrees: 0 

Responsible Center: LaRC 

PhD Students: 

3 

PhD Degrees: 1 



Bibliographic Citations for FY 1994: 

Journals 

Rosch. W., Fripp, A.. Debnam, W.. and Pendergrass. T.K. Heat transfer measurements in the Bridgman configuration. J. 
Crystal Growth, voi. 137, p. 54 (1994). 

Proceedings 

Fripp, A.L.. Debnam. W.J.. Crouch, R.K., and Clark. I.O. "Compound semiconductor growth in a low-g environment." 
Microgravity Materials Science Conference, Huntsville. AL, May 24-25. 1994. 

Books 

Sorokach. S.E.. Simchick. R.T.. Fripp, A.L., Debnam, W.J.. and Barber. P.G. "Characterization of Bridgman crystal 
growth using radiographic imaging,'' in "Grain Boundaries and Interface Phenomena in Electronic Ceramics." Edited by: 
L.M. Levinson and S-I. Hiiano The American Ceramic Society, Ohio, pp 379, 1994. 




11-121 



II. MSAD Program Tasks — Flight Research 

HU II III I II I II I MIIMI III I 


Discipline: Materials Science 

Hill Ill Illlllll 


Melt Stabilization of PbSnTe in a Magnetic Field 


PRINCIPAL Investigator: Dr. Archibald L. Fripp NASA Langley Research Center (LaRC) 


Co-Investigators: 

W.J. Debnam NASA Langley Research Center (LaRC) 

F.R. Szofran NASA Marshall Space Right Center (MSFC) 

A. Chait NASA Lewis Research Center (LeRC) 


Task Objective: 

The objective of this research is to further elucidate the gravity driven physical phenomena on the growth of the 
alloy compound semiconductor, PbSnTe. This work, coupled with the past microgravity experiment with the 
MEA and the existing flight program to grow PbSnTe in the AADSF, will form the most comprehensive set of 
space processing experiments performed todate. 

Task Description: 

The effect of the gravitational body force on the convective properties of the alloy compound semiconductor, 
PbSnTe, with that body force modified by both reduced gravity and by magnetohydrodynamic (mhd) damping is the 
subject under investigation. PbSnTe is an ideal material tor this study in that it was the material ot both a past 
flight experiment and a planned 1996 AADSF experiment. Both of these experiments are without magnetic fields. 
Subsequent experiments, both Earth based and in Space, using mhd damping will form a complete set ot 
experiments that will further elucidate the gravity dependent physical phenomena on the growth of this class of 
materials. 

The application of a magnetic field to PbSnTe growth will dampen convective flow. The anticipated results are that 
even in the MSFC superconductor magnetic furnace the growth will not become diffusion controlled but that the 
combination of magnetic field and low gravity environment will produce diffusion controlled growth. 

Task Significance: 

Numerical modeling is an integral part of this endeavor. Computer simulation can aid in the design of the space 
experiment by its predictive capacity to optimize conditions tor the growth. The key purposes ot this portion ot 
the study will be to optimize the growth for both the Earth and the space experiments and to obtain an estimate of 
the required magnetic field strength for low gravity growth. 

This proposed work will complete the set. It will compare the effects of convection, as modified by a magnetic 
field, on the growth of this material both on Earth and in the Microgravity environment found in low Earth orbit. 


Progress During FY 1 994: 

The progress within this first year of the research on the magnetic stabilization of PbSnTe consists primarily of 
preparations for future quantifiable, modelable experiments. 

Numerical modeling is an essential part of this program. The primary thrust for modeling is within the Materials 
Division at the Lewis Research Center. Modeling, both two and three dimensional, will evaluate both the 
sensitivity of the thermophysical parameters to determine if better measurements, in addition to electrical resistivity, 
are needed and attempt to determine the combination of low gravity and magnetic field strength required to attain 
diffusion controlled growth in PbSnTe. Preliminary modeling is complete. Diffusion controlled growth is 
predicted, with modest magnetic fields, in microgravity but heavy mixing is predicted on Earth even with a five 
Tesla field. 


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11-122 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 




The ampoule configuration ha ls been designed for ground based tests in the five Tesla magnetically stabilized furnace 
at the Marshall Space Flight Center. Seven crystals have been grown to date, six with full magnetic field and one 
with no field. The primary variable was ampoule pull rate. All crystals showed complete compositional mixing as 
was predicted by the numerical modeling. 

Additional modeling is underway to evaluate the ampoule diameter as it affects both viscous damping and extent of 
flux line intersection. The effect of thermal gradient, both magnitude and shape, will also be evaluated. 


Students Funded Under Research: Task Initiation: 10/93 Expiration: 9/95 

BS Students: 1 PROJECT IDENTIFICATION: 963-80-07-05 

MS Students: 0 RESPONSIBLE CENTER: LaRC 

PhD Students: 0 


Bibliographic Citations for FY 1994: 

Proceedings 

Fripp, A.L., Debnam, W.J.. Szofran. F.R.. amd Chait, A. 'Melt stabilization of PbSnTe in a magnetic field. " 
Microgravity Materials Science Conference, Huntsville. AL, May 24-25. 1994. 


II-123 


II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

Minim nun 


Gravitational Role in Liquid -Phase Sintering 


Principal Investigator: Prof. Rantiaii m. German 

Pennsylvania State University 

Co-Investigators: 

No Co-Ts Assigned to this Task 



Task Objective: 

The purpose of this research is to establish the gravitational role in liquid phase sintering with respect to both the 
macro-scale distortion and phase separation, and the micros true tural evolution over time at elevated temperatures. 


Task Description: 

The investigation has graduated to tlight status, with 21 samples (seven compositions ot tungsten-nickel-iron) 
subjected to liquid phase sintering treatments on STS-65 during July 1994. The experiments involved isothermal 
hold times of 1, 15, and 120 minutes at 1500°C in the Japanese-developed Large Isothermal Furnace on the IML-2 
mission. Identical ground- based experiments have been conducted to provide the baseline tor contrast with the 
microgravity samples, and post-flight analysis will focus on quantitative assessment ol distortion and 
microstructural evolution. 

Task Significance: 

The microgravity experiments will establish a modeling basis for the gravitational role in a viscous tlow distortion 
of sintered components. It will further assess the agglomeration of solid grains and possible coalescence 
contributions to grain growth for upgrading of current theories. These results will lead to the development ot 
manufacturing techniques which will permit formulation of new unique alloys. 

Progress During FY 1994: 

’'Sintering 11 means welding or fusing of metal or ceramic powders by heating them without melting. Frequently, it 
is aided by applying pressure in a special high- temperature press to squeeze the particles together. This experiment 
explores a different mechanism, by adding a portion of a powder that melts at a lower temperature and surrounds the 
powders that remain solid. This liquid then lets particles and materials move more easily, allowing the powders to 
more rapidly form a solid compact. Problems such as separation of the solid and liquid due to gravity (manifested 
by settling of the solid particles) still remain. Access to the low gravity environment ot Earth orbit provides a 
unique opportunity to study liquid-phase sintering without separation, settling, or other gravity -induced 
complications. The results will increase our understanding of the process, and the new knowledge will help 
introduce new industrial application of liquid-phase sintering, such as automotive components, resulting in new and 
improved products. 

In this investigation, mixed powders of tungsten, nickel, and iron are initially cold compacted under pressure in the 
shape desired for the final product. The compacts are then heated to just below the nickel-iron alloy melting 
temperature to provide handling strength, a process called "presintering." In the experiment, they are heated above 
1465°C to form a liquid-solid mixture. The tungsten, with its very high melting point (3370°C), remains a solid, 
while the nickel and iron, with much lower melting points, become liquid. The liquid permits more rapid transport 
of material for faster sintering than would be possible if all the material were solid. Alter sintering, the 
microstructure of the samples (i.e., the structure when viewed under very high magnification), consists of connected 
tungsten grains surrounded by the solidified liquid. 

This experiment flew as part of the second International Microgravity Laboratory (IML-2) mission in July 1994 
aboard the Space Shuttle Columbia. The experiment was conducted in an apparatus called the Large Isothermal 
Furnace (LIF), which could operate at the high temperatures required. The LIF was developed by 
Ishikawajima-Harima Heavy Industries Co., Ltd., for the National Space Development Agency of Japan (NASDA). 


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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

MMIMIIIIMIIIIinilllllliaMlllltMllllllltllllllllllMIIMHIIIIIItlllllllltllllllllllllllllltlllllllllllllimitlllllllllllllllillMMIIIIItlltlllMillllimiMIIIKIIIIIIIIHIIIIimiMKIIIimMlllllllllltlMmHIIIIIllllMIIIIIIIIMM 


This project was supported by the NASA Headquarters Microgravity Science and Applications Division, ;uid was 
managed by the NASA Lewis Research Center. 

The test specimens for the LIF consisted of three different cartridges, each containing seven samples 10 mm in 
diameter by 10 mm high. One cartridge was tested at each of the three critical sintering periods identified in earlier 
ground-based experiments ; 1,15, and 120 minutes. In one minute, liquid penetrates along existing solid-solid 
boundaries. Fifteen minutes is the time needed for full densifi cation. The 120-minute tune is needed to observe 
grain rotation and coalescence events. 

In summary, a nominal temperature of 1506°C was achieved for each of the desired test times. Free-drift of 
Columbia during the appropriate times was confirmed. All of the functional objectives were achieved. Analysis 
will begin upon return of the samples to the laboratories of the Pennsylvania State University. 


Students Funded Under Research: 

Task Initiation: 10/94 Expiration: 10/95 

BS Students: 

0 

BS Degrees: 0 

Project Identification: 963-25-05-05 

MS Students: 

0 

MS Degrees: 1 

Responsible Center: LeRC 

PhD Students: 

1 

PhD Degrees: 1 



Bibliographic Citations for FY 1994: 

Journals 

Belhadjhamida, A., Johnson. J. L., Tandon, R. and R. M. German, Advances in liquid phase sintering. Journal of 
Materials Synthesis and Processing, vol. 1, 275-285 (1993). 

Proceedings 

Heaney, D.F., R. M. German and I. S. Ahn. ’’The gravity effect on critical volume fraction in liquid phase sintering,” 
Advances in Powder Metallurgy and Particulate Materials, vol. 2." Metal Powder Industries Federation. Princeton. NJ. 
1993. 

Iacocca, R.G. and R. M. German. "Experimental design for liquid phase sintering in microgravity. " Advances in powder 
metallurgy and particulate materials, vol. 2." Metal Powder Industries Federation, Princeton. NJ. 1993. 

Books 

Heaney, D.F., German. R.M.. and Ahn. I.S. ’The gravity effect on critical volume fraction in liquid phase sintering,” in 
“Advances in Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation. Princeton, NJ. vol. 2. pp 
169-180, 1993. 

Iacocca, R.G. and German, R.M. "Experimental Design for liquid phase sintering in microgravity,” in “Advances in 
Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation. Princeton. NJ, vol. 2. pp 181-194. 

1993. 

Iacocca, R.G., German, R.M.. and Kidd, C. "Micro structural analysis of tungsten heavy alloy samples sintered in LG 
conditions: Preparation for shuttle flight,” in “Advances in Powder Metallurgy and Particulate Materials." Metal Powder 
Industries Federation, Princeton, NJ, vol. 5, pp 201-218, 1994. 

Heaney, D.F. and German, R.M. "New grain growth concepts in liquid phase sintering,” in “Advances in Powder 
Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton. NJ, vol. 3, pp 303-310, 1994. 

Raman, R., Heaney, D., and German, R.M. "Control of component distortion during liquid phase sintering,” in “Advances 
in Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton, NJ, vol. 3, pp 281-293, 

1994. 


mu 


11-125 



II. MSAD Program Tasks 


Flight Research Discipline: Materials Science 

mu mm mini mmimmmn 


Isothermal Dendritic Growth Experiment 


Principal Investigator: Prof. Martin e. Giicksman 

Rensselaer Polytechnic Institute 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

Successfully conduct the Isothermal Dendritic Growth Experiment (IDGE) on the STS-62 Space Shuttle mission. 
Analyze resulting space flight and terrestrial data to determine dendritic tip velocity and tip radius as functions ol 
supercooling (temperature). Use velocity and radius data to evaluate the validity of theoretical models, some ol 
which are nearly 50 years old, that purport to predict velocity and radius (these models are used to improve industrial 
metal production on Earth). Publish reports and give papers to inform the scientific community ol our findings. 

Task Description: 

The Isothermal Dendritic Growth Experiment (IDGE) is a fundamental Materials Science experiment performed on 
the Space Shuttle. The specific topic is dendritic solidification which is relevant to virtually all industrial 
manufacture of metals and alloys on Earth. 

IDGE will be performed in the cargo bay of the Space Shuttle using an apparatus designed, built, and tested at the 
NASA Lewis Research Center (LeRC) in Cleveland, Ohio, USA. Over 400 photographs of dendrites that solidified 
in space along with over 800 photographs of dendrites solidified on Earth will be produced on the first flight 
(STS-62). Each photograph will be accompanied by 8 (or more) scientifically important measurements of time, 
temperature, and local acceleration. While in space, EDGE will be operated by LeRC personnel located in the 
Payload Operations Control Center (POCC) at the George C. Marshall Space Flight Center (MSFC) in Huntsville, 
Alabama, USA, 

In the months prior to the flight, we will make several trips to LeRC and MSFC for mission operations planning 
and training. In addition, at RPI, we will analyze terrestrial data produced by the IDGE flight apparatus prior to its 
turn over to Kennedy Space Center (KSC) personnel on July 28, 1993. 

We will work with the LeRC personnel during the flight to assess the IDGE Slow Scan Television (SSTV) dendnte 
images in real time and replan subsequent experiments to take maximum advantage of circumstances. 

After the flight, we will analyze the resulting 35mm photographs and other data to determine the dendrite tip 
velocity and dendrite tip radius as functions of supercooling. These will be compared to predictions made by many 
theoreticians over the last 50 years (these theories have been used to try to improve industrial metal production on 
Earth). 

As soon as possible thereafter, we will publish reports and give papers at relevant conferences to disseminate the 
information to the scientific and industrial community. 

Task Significance: 

Ultimately, IDGE may result in improved industrial manufacturing of steel, aluminum, super alloys, and other 
metals that we use on Earth every day. Moreover, the data returned from space will remain relevant indefinitely. In 
fact, the Schriffer Committee report (1987) declared that IDGE was one of NASA’s tour "world class” microgravity 
science experiments due to the quality, scope, and long term relevance of its science. 

IDGE will study Dendrites. Dendrites are tiny crystalline structures that form inside molten metal alloys when they 
solidify during manufacture. 


IMI 


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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 


In summary IDGE is significant because: 

Dendritic growth is die ubiquitous form of crystal formation encountered when metal alloys and many odier 
materials solidify. Most industrially important metals (SBiliions) solidify dendritically from the molten state. 
Examples: Cast iron alloys and cast aluminum alloys used in automobile engine blocks. 

The dendrites formed inside alloys during manufacture result in microscopic zones of strength, weakness, ductility, 
and britdeness. Consequently, understanding precisely how dendrites form can lead to improvement of alloy strength 
and ductility by eliminating weak and brittle areas in the metal. Production costs can also be lowered. 

IDGE provides the only unambiguous set of scientific data diat can be used to test and correct the theoretical models 
of dendritic formation used to improve alloy production. Data gathered on Earth are confounded by gravitationally 
induced convective effects. 

During die past 50 years, numerous scientists have attempted to develop practical theoretical models to predict 
important dendritic growth parameters. However, years of experimentation on Earth has not produced a dataset 
capable of testing the models to find out which one is correct (if any). This is due to the influence of gravity. 

On Earth, dendritic solidification can be strongly affected by gravitationally driven convective currents in the molten 
metal. These currents exist during virtually all industrially important metal solidification processes. However, 
their effect on dendritic solidification cannot be accurately modeled without knowledge of dendritic solidification in 
the absence of such currents. 

The microgravity environment in space effectively turns off convection in the IDGE experiment. Extensive 
non-advocate peer review indicated that a comparison between space experiment data and Earth experiment data is the 
only practical way to separate the effects of convection from the underlying mechanisms of dendritic solidification. 

Progress During FY 1994: 

The Isothermal Dendritic Growth Experiment (IDGE) is a tele-operated microgravity science experiment payload that 
flew on the space shuttle Columbia STS-62 mission during March 1994. It was an outstanding success. 

All preflight activities were conducted as planned. These included evaluation of terrestrially acquired IDGE data and 
six trips to LeRC and MSFC for planning and training for flight operations. 

During flight, teleoperation allowed us (RPI and LeRC personnel) to modify the experiment protocol and, thereby, 
take advantage of unexpectedly fortuitous circumstances. Consequendy, by one measure, IDGE obtained nearly 300 
percent of the required data. Specifically: 58 dendrites were grown versus 20 required (290% success); the 
supercooling (independent variable) dynamic range spanned 37 to 1 versus 10 to 1 required (370% success); resulting 
measurement precision and accuracy w-as approximately twice as good as required for most measurements and met 
requirements on all others. 

Analysis of the flight data revealed that current theories need significant modification. Moreover, convection, both 
on Earth and in space, may have greater effect than previously believed. These findings are unexpected and 
immediately important to the science of Solidification and, longer term, to industrial alloy production (e.g., steel 
and aluminum). 

Our first Journal Article was received by Physical Review on March 23 (only 6 days after Columbia landed). 
Subsequently, we have presented at 10 prestigious seminars and conferences including the 26th COSPAR at the 
World Space Conference in Hamburg, FDR. Three proceedings publications are currently in press. Moreover, as data 
analysis proceeds to greater depth, we are in the process of writing further papers. 


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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

mm .mm. " 1 " m 


Students Funded 

BS Students: 0 

MS Students: 3 

PhD Students: 0 


Under Research: 

BS Degrees: 
MS Degrees: 
PhD Degrees: 


0 

1 

0 


Task Initiation: 12/88 Expiration: 12/98 
Project Identification: %3-25-05-oi 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Glicksman. M.E.. Koss. M B. and Winsa. E.A. Dendritic growth velocities in microgravity. Phys.Rev.Lett. 73(4), 573 
(1994). 

Proceedings 

Glicksman, M.E., Koss, M.B.. Busbnell. L.T.. LaCombe. J.C., and Winsa. E.A. "Space Bight data from the isothermal 
dendritic growth experiment." COSPAR ‘94 (in press) 1994. 

Glicksman, M.E.. Koss, M.B.. Bushneli. L.T., LaCombe. J.C.. Kobryn. P„ and Winsa. E.A. "The teile-operational 
capabilities of the IDGE." 6th International Symposium on Experimental Methods of Microgravity Science, edited by 
R.A. Schiffman and J.B. Andrews. The Minerals. Metals & Materials Society. 141. 1994. 

Smith. R.N., Glicksman. M E.. Koss. M B.. Bushneli. L.T.. and LaCombe. J.C. "Experimental study of dendrite growth in 
an undercooled melt under microgravity conditions." Heat Transfer session at the 1994 ASME Winter Annual Meeting in 
Chicago next November (in press) 1994. 

Presentations 

Glicksman. M.E. "Dendritic growth in microgravity: IDGE flight 1." Aachen Foundry Institute, Aachen, FRG, 1994. 

Glicksman, M.E. "Dendritic growth in microgravity: IDGE flight 1." DLR. Space Simulation Institute. Koln-Portz. FRG. 
1994. 

Glicksman. M.E. "The isothermal dendritic growth experiment: First results from USMP-2." Pittsburgh Chapter ot the 
ACCG, Pittsburgh, PA, 1994. 

Glicksman, M.E. "The isoothermal dendritic growth experiment: First results from USMP-2." Microgravity Materials 
Science Conference. Von Braun Civic Center. Huntsville. AL. 1994. 

Glicksman. M.E. "Space flight data from the isothermal dendritic growth experiment." At the 26th COSPAR. Hamburg. 
FDR. 1994. 

Glicksman, M.E. "Space flight data from the isothermal dendritic growth experiment." Giesserei Institut. RWTH Aachen. 
Aachen, FRG, 1994. 

Glicksman, M.E. "The isothermal dendritic growth experiment: Implications of Theory." NIST. Gaitherburg, MD. 1994. 

Glicksman, M.E. "Space flight data from the isothermal dendritic growth experiment: What have we learned? " Materials 
Engineering Department Seminar, Rennselaer Polytechnic Institute, Troy, NY, 1994. 

Koss, M.B. "Preliminary results from the isothermal dendritic growth experiment At the Space Experiments Division 
Awards Ceremony, NASA Lewis Research Center, Cleveland, OH, 1994. 

LaCombe, J.C. "Dendritic Solidification in a Microgravity Environment." Joint meeting of the Eastern New York Chapter 
of ASM International and the Hudson-Mohawk Section of TMS, Latham. NY, 1994. 




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II. MSAD Program Tasks — Flight Research 

■ i 


Discipline: Materials Science 

mi 


Evaluation of Microstructural Development in Undercooled Alloys 


Principal Investigator: Dr. Richard n. Grugei 

University Space Research Association 

Co-Investigators: 


W.F. Flanagan 

Vanderbilt University 


Task Objective: 

The objectives ol this study are to be conducted in view of experiment and pertinent theory, and will, upon 
completion, serve to enhance our scientific understanding of solidification processes. These include evaluating die 
microstructural morphology, external and internal to the sample, as functions of undercooling (AT), composition 
(C Q ), and volume (V 0 ). 

Task Description: 

A series ot cylindrical lead-tin alloy samples, some 16mm in length and 8inm in diameter, have been contained in 
quartz tubes and placed in a well controlled tumace. Nucleation of the solid is induced by one of the monitoring 
thermocouples when the desired undercooling, from 5 to 25K, is achieved. The sample is dien metal log raphically 
prepared and microstructural development from die point of nucleation is followed. Pmamctcrs which have been 
varied are sample composition, degree of undercooling, and, to some extent, sample size. This experimental 
procedure has been paralleled by a modelling effort which predicts die microstructural development of a single 
dendrite that is inidated at the upper surface and grows down into the undercooled melt. Model verification has been 
complemented by direct observation of the solidification process using samples based on the transparent, metal 
analogue, succinonitrile-water system. 

Task Significance: 

The microgravity environment of space is envisioned as a novel processing arena for the solidification of metals and 
alloys. Contamination of high temperature and/or reaedve materials is expected to be minimized as a container is 
not required to hold the melt and the samples are not limited in size. Greater undercoolings might also result due to 
elimination ot heterogeneous nucleation sites w ith the subsequent solidification microstructure expected to consist 
ot extremely tine constituents and/or novel phases, i.e. improved material properties. Unfortunately, processing in 
the microgravity environment is expensive and time consuming. Consequently, the intent of this work is to 
conduct a thorough, ground-based investigation which will evaluate microstructural development in bulk, 
undercooled alloys with the aim of ascertaining the advantage of processing in microgravity. 

Progress During FY 1994: 

Experimentally these include: 1) developing a technique to preferentially nucleate the undercooled liquid alloy. 2) 
developing a computer model to follow the thermal history and microstructural evolution after nucleation. 3) 
successfully utilizing transparent materials to complement the metal alloys. Based on the computational mid 
experimental results a number of conclusions can be drawn. These include: 1) Upon nucleation, the solidification 
velocity is initially very rapid, the dendritic mid eutectic microstructure becoming finer as the undercooling is 
increased. However, the undercooled sample heats up very quickly mid the majority of growth takes place at 
considerably less velocities. 2) Consequently, while the solidification microstructure is initially fine it coarsens 
rapidly as the velocity drops mid is generally non-uniform throughout the sample. 3) The best microstructural 
uniformity is achieved in the sample with the least initial undercooling, i.e., 5K. Unfortunately the slow, but 
relatively constant, growth was interrupted by formation of equiaxed grains which effectively served to destroy the 
desired directionality of the sample. Through use of the organic analogue, origin of the equiaxed region observed in 
Pb-Sn alloys likely occurs due to fragmentation (not heterogeneous nucleation) and settling of dendritic grains 
which evolve at the point ot nucleation. This detrimental quality would be minimized in a microgravity 
environment. 4) Care must be taken when measuring primary dendrite growth velocities in undercooled melts. 


11-129 


II. MSAD Program Tasks — Flight Research 


Discipline: Materials Science 

HimmiHIIIHIIHIIIIIIIIilMIHIIIMlIMMHMIMMlWIMIIHHIlHMMMIMIIM 


They do not grow at constant velocities, and what is measured may not be a primary dendrite at all but the 
continuation of secondary arms intersecting the visible surface. 5) While a microgravity environment may well suit 
to process high temperature and/or reactive ’bulk" materials, rapid heating ot the liquid is likely to preclude 
maintaining uniform, directionally fine, microstructures and /or significant amounts ot an undercooled, e.g., 
peritectic, phase. A list of relevant publications, presentations, and an award notitication follows. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 12/91 Expiration: 11/94 
Project Identification: 963-25-07-03 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals 

Grugel, R.N. Microstructural evolution of primary dendrite trunks in directionally solidified, hypoeutectic. 
aluminum -silicon alloys. Metallurgical Transactions A., (In press). 

Grugel, R.N., Fay Hua, and T.G. Wang. Evaluation of the NaNO, - Ba(NO ? ) 2 eutectic system for use in investigating 
solidification phenomena. Journal of Materials Science Letters.. (In press). 

Proceedings _ 

Hua, F. and R.N. Grugel. "Microstructural evolution in undercooled Pb - Sn alloys: Composition and sample size effects. 
Experimental Methods for Microgravity Materials Science: 6th International Symposium. 1994, TMS, eds.. R.A. 
Schiffman and J.B. Andrews, pp. 111-115. 

Presentations 

Grugel, R.N. "Appreciating gravity during directional solidification of metals and alloys." University of Missouri-Rolla, 
April 20, 1994. 

Grugel, R.N. and Fay Hua. "Using transparent materials to simulate soldification phenomena in metals - Microstructural 
development in undercooled alloys." 8th Annual Alabama Materials Research Conference, 26-27 September 1994, 
Tuscaloosa, AL. 

Grugel, R.N. and Fay Hua. "Evaluation of microstructural development in undercooled alloys." Microgravity Materials 
Science Conference, June 24-25, 1994, Huntsville, AL. 

Hua, F. and R.N. Grugel. "Microstructural evolution in undercooled Pb - Sn alloys: Composition and sample size effects. 
123rd TMS Annual Meeting, February 27 - March 3, 1994, San Francisco, CA. 

Hua, F. and R.N. Grugel. "Microstructural development in undercooled alloys." TMS Fall Meeting, October 17-21, 1993, 
Pittsburgh, PA. 

Hua, F., R.N. Grugel, and T.G. Wang. "Analysis of microstructural development during solidification in bulk, undercooled 
Pb - Sn alloys." ASM-TMS Fall Meeting, October 2-6, 1994, Rosemont, IL. 


IIIMHIlHMIllllllllMtimillllllllMlllllltmMimillMtMHHIMIHHIHMI 


11-130 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

III IMIlilMIIHIMIHIMIIIIIIIMIMIMIIHIIIIIIIMIIIIIII I IIMIIIII Mill lltlllll Mill llll IIMIIIIIIIII IIHIHIIIIHIIIItllilllllllllllMIIIIII Itllllllllll lltll II III I III HI llll I II III III I Itlllllllltlllllllllllllllltl Mlllllll III Ml II III • II I III 

Thermophysical Properties of Metallic Glasses and Undercooled Alloys 

Principal Investigator: Dr. William l. Johnson California Institute of Technology 

Co-Investigators: 

D. Lee California Institute of Technology (Caltech) 

Task Objective: 

The objective is to study thermophysical properties of undercooled alloy melts and how they relate to glass 
formation. Toward this end, we have developed non-contact calorimetric methods to investigate the specific heat and 
thermal conductivity of these melts, both in the liquid and undercooled region. These quantities are essential for the 
development of newer, more advanced processing technologies for both existing and future materials. 

Task Description: 

Non-contact AC calorimetry was successfully demonstrated on the IML-2 flight in July, 1994. We obtained 
information on the specific heat and thermal conductivity of liquid and undercooled Zr76Ni24 and Ni60Nb40 melts 
using TEMPUS. This data is currently being analyzed to calculate entropy and free energy functions for these melts. 
We will compare these quantities to their values for the corresponding equilibrium and metastable crystals to 
compare the relative stability of the phases. Also, we will determine the Kauzman isentropic temperature of the 
alloys and compare it to the observed glass transition temperature. 

In addition, the ground-based total radiance bolometer is currently being integrated onto a UHV levitation chamber 
for total hemispherical emissivity measurements. Measurement of temperature-dependent total hemispherical 
emissivity functions will allow us to unwind specific heat from undercooling data in an unambiguous manner. 

Task Significance: 

The non-contact AC calorimetry experiment is significant for many reasons. First the thermodynamic properties of 
these advanced materials are a prerequisite to the development of processing technologies for them. Without 
knowledge of heat capacities and thermal conductivities, it is not possible to define, for example, how much power 
is needed to melt and cast the materials. In addition, the specific materials chosen for our experiment are the parent 
compounds for a new class of bulk metallic glasses that have recently been discovered by our group here at Caltech. 
By studying the properties of these parent compounds, we hope to better understand the bulk metallic glasses and 
how they form. These materials will revolutionize metallic processing technologies with their novel, superior 
properties. These materials can be engineered to be more ductile, slipperier, harder, lighter and more corrosion 
resistant than the typical materials used today. It is essential that the processing technologies for these materials be 
developed as quickly as possible and that, therefore, the thermophysical properties be measured. 

Progress During FY 1 994: 

The AC non-contact calorimetry method was successfully demonstrated on IML-2 in July, 1994. We were 
successful in obtaining data for liquid and undercooled Zr76Ni24 and Ni60Nb40. This data is currently being 
analyzed and should provide thermodynamic data not previously measureable. Preliminary measurements indicate 
that the total hemispherical emissivity of an undercooled liquid changes by more than 20% between the melting 
temperature and the glass transition, making the standard assumption of constant total hemispherical emissivity 
through the undercooled region completely invalid. We will do these measurements for all samples flown on 
TEMPUS. 




11-131 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

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Students Funded Under Research: 


Task Initiation: 2/92 Expiration: 6/95 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 963-25-08-07 

MS Students: 

2 

MS Degrees: 

0 

NASA Contract No.: nags-954 

PhD Students: 

2 

PhD Degrees: 

1 

Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Proceedings 

Lee. D.. Uffelman. D.. and Johnson, W. 'Noncontact AC calorimetry of metals and alloys." Proceedings ol NATO 
Workshop on Science and Technology ot Rapid Solidification. West Point. NY (1994). 


MU III II Mil I III III III III I II IIIIIIIIIMI mill IMMII 


11-132 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 


Orbital Processing of High Quality Cadmium Telluride 


Principal Investigator: Dr. David j. Larson. Jr. 

Northrop- Grumman Corporation 

Co-Investigators: 


A. Levy 

Grumman Research & Development Center 

DiMarzio 

Grumman Research & Development Center 

F. Carlson 

Clarkson University 

J. Alexander 

University of Alabama, Huntsville 

D. Gillies 

NASA Marshall Space Flight Center (MSFC) 

J. Moosbrugger 

Clarkson University 


Task Objective: 

The objective of this research is to investigate the influence of gravitational ly-dependent phenomena (hydrostatic and 
buoyant) on the growth and quality of Cadmium-Zinc-Tellunde (CdZnTe). 

Task Description: 

Grow CdZnTe crystals in microgravity on USML-l/STS-50 using the seeded Bridgman-Stockbarger method of 
crystal growth. Bridgman-Stockbarger crystal growth is accomplished by establishing isothermal hot-zone and 
cold-zone temperatures with a uniform thermal gragient in between. The thermal gradient spans the melting point 
of the material (1095 °C). After sample insertion the furnace’s hot and cold zones are ramped to set-point 
temperatures establishing a thermal gradient of 35 °C/cm and melting the bulk of the sample. The furnace is then 
moved further back on the sample, causing the bulk melt to come in contact with the seed crystal, thus ’seeding' the 
melt. The seed crystal prescribes die growth orientation of the crystal grown. Having seeded the melt, the furnace 
is thermally equilibrated and then die furnace translation is reversed and die sample is solidified by passing die 
thermal gradient down the length of the stationary sample at a uniform velocity. 

Task Significance: 

The family of II- VI compound semiconductors, of which CdZnTe is a commercially significant member, is used in 
the fabrication of medium and long wavelength IR sensors and beta and gamma ray nuclear detectors. Orbital 
processing offers the unique opportunity to signilicandy advance toward the goal of increased structural perfection 
within bulk crystals of greater chemical homogeneity. The former results from solidification and post-solidification 
cooling with little or no wall contact. The latter from the damping of buoyancy driven convection and concomitant 
growth of a homogeneous crystal under diffusion controlled growth conditions. 

Progress During FY 1994 : 

Two CdZnTe crystals were grown in the Crystal Growth Furnace (CGF) during the First United States Microgravity 
Laboratory Mission (USML-1). These crystals were used for comparative analysis with terrestrial baselines (CGF 
and commercial). The microgravity (ff-g) and terrestrial (one-g) samples were quantitatively analyzed for chemical 
homogeneity, opto-electronic performance (infrared transmission), and structural perfection. 

Chemical homogeneity (macrosegregation) was predicted by the process model to be low for this alloy system, even 
in one-g. This was confirmed experimentally. Nearly diffusion-controlled growth was achieved in the CGF-size 
samples (15mm OD). The effective redistribution coefficient (kj of Zn in CdTe was reduced from k Q =l .25 to k^ 
=1.10 in commercial-size boules (>40mm OD), demonstrating that careful experiment control can significantly 
reduce macrosegregation terrestrially, even on a commercial scale. Longitudinal and radial segregation was 
monitored in the flight samples. It was found that the sohdification record was disturbed due to unanticipated 
asymmetric thermal fields experienced by the flight samples. This will be corrected on the flight experiment to be 
conducted on USML-2. 



II. MSAD Program Tasks — 

IIIMII lllll Ml HIM »••••■ »«' 


Flight Research Discipline: 

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Materials Science 

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FT1R transmission of both ground and flight materials was measured to be close to theoretical; 63% versus 66% 
t theoretical ). This suggested that both the ground and flight materials were close to the stoichiometric composition. 
Infrared microscopy and x-ray measurements confirmed that the principal precipitates were Te and their size (1-10 
(.tm) and density .suggested that both primary flight and ground base samples expenenced similar cooling rales and 
were close to stoichiometry. 

The flight samples, however, were tound to be much higher in structural perfection than the ground samples 
produced in the same furnace under identical growth conditions except for the gravitational level. Rocking curve 
widths were found to be substantially reduced, trom 20/35 arc-seconds (one-g) to 9/15 arc-seconds (|r-g) tor the best 
regions of the crystals. The value ot 9 arc seconds equals the best reported terrestrially tor this material. 
Morphologically, the ground samples were found to have a fully developed mosaic structure consisting ot subgrams 
and large regions of cross-slip, whereas the flight samples exhibited discrete dislocations and no mosaic 
substructure or cross-slip was evident. The defect density was reduced from 50,000 -100,000 (one-g) to 500 - 500 
(p-g sample 1) and 1200 - 3000 EPD (p-g sample 2). These, too, are the lowest reported. 

The thermo-mechanical model suggested that the low dislocation density was due to the near-absence ot hydrostatic 
pressure in p-g which allowed the melt to solidify with minimum wall content, reducing the stress transmitted to 
the crystal during growth and post-solidification cooling. Further, the highest quality material was predicted to be 
on the periphery of the boule, unlike the terrestrial samples where the best material is at the core, and this was 
confirmed microstructurally. 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 3 MS Degrees: 1 

PhD Students: 1 PhD Degrees: 1 


Task Initiation: 8/90 Expiration: io/96 

Project Identification: 963-21-08-02 
NASA Contract No.nass-38147 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Alexander, J.I.D. Residual gravity jitter effects on fluid processes. Microgravity Science and Technology, vol. 7, no. 2, 
131-136 (1994). 

Casagrande, L.G., Larson, Jr.. D.J.. DiMarzio, D„ Wu, J., and Dudley, M. The growth and comparison of large-diameter, 
vertical Bridgman CdZnTe and CdTe. J. Cryst. Growth, vol. 137, 195-200 (1994). 

Larroude, P., Ouazzam, J., and Alexander, J.I.D. Symmetry-breaking flow transitions and oscillatory flows in a 2D 
directional solidification model. European Journal of Mechanics B/Fluids, vol. 13, 353-381 (1994). 

Larson, Jr., D.J., DiMarzio. D., Casagrande. L.G., Carlson, F.M., Lee, T., Steiner, B.. Long, G., Seiler. D.G., Wu, J., and 
Dudley, M. Producibility improvemtns suggested by a validated process model of seeded CdZnTe vertical Bridgman 
growth. J. Cryst. Growth, vol. 137, 11-20 (1994). 

Larson, Jr.. D.J.. Silberstein, R.P., DiMarzio, D„ Carlson, F.M., Gillies, D.. Long, G.. Dudley, M„ and Wu. J. 
Compositional, strain contour, and property mapping on CdZnTe boules and wafers. Semiconductor Science and 
Technology, vol. 8, 911-915 (1993). 

Proceedings 

Alexander, J.I.D., and Rogers. M.J.B. "Passive accelerometer system: measurements on STS-50 (USML-l). Proceedings 
of the Joint Launch + One Year Science Review of USML-l and USMP-1 with the Microgravity Measurement Group, NASA 
Conference Publication 3272. vol. 2, 569-578. 1994. 

Casagrande, L.G., Larson. Jr.. D.J.. DiMarzio, D.. Wu, J„ and Dudley, M. "Growth of large-area, high quality, CdZnTe 
substrates by the computer controlled vertical Bridgman method." SPIE Proceedings 2228. Producibility ot II-VI 
Materials and Devices, H.K. Pollehn and R. Balcerak, eds., 21-32, 1994. 


......... ...» * ,,,,,# * 


II— 1 3 4 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 


DiMarzio. D.. Larson. Jr., D.J.. Casagrande. L.G., Silberstein. R.P.. Wu. J.. Dudley. M., and Liao. P.-K. ' Defect mapping 
ot CdZnTe substrates." IRIA-IRIS Proceedings: 1993 Meeting of the IRIS Specialty Group on Infrared Materials. 69-84, 
December. 1993. 

DiMarzio. D.. Larson. Jr.. D.J.. Casagrande. Wu. J.. Dudley, M . Tobin. S.. and Norton. P. "Large area X-ray topographic 
screening ot II -VI substrates and epilavers." SPIE Proceedings 2228: Producibility of II-VI Materials and Devices. H.K. 
Pollehn and R. Balcerak. eds., 5289-5300, 1994. 

Dudley, M.. Wu. J.. Larson, Jr., D.J.. and DiMarzio, D. "Use of synchrotron white beam topography to characterize IR 
detector manufacturing processing." Material Research Society Symposium Proceedings 324: Diagnostic Techniques for 
Semiconductor Materials Processing, O.J. Glembocki. F.H. Poliak, S.W. Pang, G. Larrabee. and G.M. Crean, eds., 
457-462, 1994. 

Larson. Jr., D.J., Alexander, J.I.D., Gillies. D., Carlson. F.M.. Wu. J.. and Black. D. "Orbital processing of high-quality 
CdTE compound semiconductors." Proceedings of the Joint Launch + One Year Science Review of USML-1 and USMP-1 
with the Microgravity Measurement Group, NASA Conference Publication 3272. vol. 1, 129-162. 1994. 

Rogers, M.J.B., Wolf, R.P.. and Alexander. J.I.D. "Correlation of accelerometer data on STS-50 (USML-l).” Proceedings 
ot the Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group, NASA 
Conference Publication 3272. vol. 2, 893-906. 1994. 

Presentations 

Alexander. J.I.D. 'What factors determine the influence of spacecraft attitude motions, vibration, and transient 
disturbances on convective transport in Bridgman systems?. ” COSPAR ‘94. Hamburg, Germany. July, 1994. 

Alexander, J.I.D. "Scaling and estimation of experiment response to g-jitter." FSA Physical Science Working Group 
Meeting, ESA HQ, Paris, FRance, September 9, 1994. 

Carlson, F.M., and Moosbrugger, J.C. "Hie role of thermal stress in vertical Bridgman growth of CdZnTe crystals." MAE 
Department Seminar Series, Clarkson University, Potsdam, NY. September. 1994. 

Carlson, F.M., Lee, T.. Larson, Jr., D.J.. Long, G.. and Dudley, M. "CdZnTe crystal growth predictive modeling and 
characterization." Gordon Research Conference on Crystal Growth, Andover. NH, July, 1994. 

Carlson, F.M., Moosbrugger, J.C., Lee. T., and Larson, Jr., D.J. "CdZnTe crystal growth: predicitve modeling." ARPA 
Intelligent Processing of Materials Workshop. Arlington. VA. November 12, 1993. 

Casagrande, L.G., Larson, Jr.. D.J., DiMarzio, D., Wu, J., and Dudley, M. "Growth of large-area, high quality. CdZnTe 
substrates by the computer controlled vertical Bridgman method." SPIE Meeting on Producibility of II-VI Materials and 
Devices. Orlando. FL. April 5-8, 1994. 

DiMarzio. D.. Larson, Jr., D.J., Casagrande. L.G.. Wu. J.. Dudley, M., Tobin, S., and Norton, P. "Large area x-rav 
topographic screening of II-VI substrates and epilayers." SPIE Meeting on Producibility of II-VI Materials and Devices. 
Orlando, FL, April 5-8, 1994. 

Dudley, M., Wu. J., Larson, Jr., D.J., and DiMarzio, D. "Use of synchrotron white beam topography to characterize IR 
detector manufacturing processes." Fall Meeting of the Materials Research Society, Boston, MA, November 29-December 
3, 1993. 

Fedoseyev. A., Alexander, J.I.D., and Bessonov. O. "CNSPACK - Efficient solution of large sparse linear systems." First 
Southeastern Linear Algebra Conference, Chattanooga, TN, May 27-28. 1994. 

Fedoseyev, A., and Alexander, J.I.D. "Numerical modelling of solidification under microgravity conditions." 

International Aerospace Congress I AC ‘94, Moscow, August 15-19, 1994. 

Klein, J., and Larson, Jr., D.J. "Comparison of theoretical and experimental performance of a PMZF furnace for 
microgravity materials processing." Symposium on pg Solidification: Theory and Experimental Results, TMS Meeting, 
Pittsburg, PA, October 1993.. 

Klein, J., and Larson. Jr., D.J. "Evaluation of solidification process control using a programmable multizone furnace 
designed for microgravity materials processing." AIAA Space Programs and Technologies Conference and Exhibit, 
Huntsville. AL, September 27-29, 1994. 

Larson, Jr.. D.J. "Orbital processing of Zn-alloyed CdTe." 44th International Astronautical Congress, Graz, Austria, 
October 16-22, 1993. 


mu ii ■11111111111111 


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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

inn mi 


Larson. Jr., D.J. "Seeded CdZnTe vertical bndgman crystal growth and process model validation." Department of 
Materials Science and Engineering Seminar, State University of New York at Stony Brook. March 23. 1994. 

Larson. Jr.. D.J.. Alexander. J.I.D.. Gillies. D.. Carlson. F.M.. Dudley, M. "Orbital processing of high-quality cadmium 
telluride compound semiconductors." NASA Microgravity Materials Science Conference. Huntsville, AL. May 25-26. 
1994. 

Larson. Jr.. D.J., DiMarzio. D., Casagrande, L.G.. Carlson, F.M.. Lee, T.. Steiner. B.. Long, G., Seiler, D.G.. Wu. J., and 
Dudley, M. "Producibility improvements suggested by a validated process model ol seeded CdZnTe vertical Bridgman 
growth." SPIE Meeting on Producibility ot II-VI Materials and Devices. Orlando, FL. April 5-8. 1994. 

Moosbrugger, J.C., and Levy, A. "Constitutive modeling for CdTe single crystals." Seminar on Microgravity 
Solidification: Theory and Experimental Results, TMS Materials Week 4 93, Pittsburg, PA, October 18, 1993. 

Moosbrugger, J.C., and Levy, A. "Advanced constitutive modeling for CdTe single crystals." Poster presented at the 
Gordon Research Conference on Crystal Growth, Andover, NH. July, 1994. 

Moosbrugger, J.C., Levy, A., and Carlson, F.M. "Constitutive modeling for CdTe single crystals." ARPA Intelligent 
Processing of Materials Workshop. Arlington, VA. November 12, 1993. 


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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

III 1)11111111111111 lltllMHIIIIIIIIIIIIItllllllllllllllltl III! HIM I III III tlltll tlllllllllll Illllllllllllt 1 1 II III III I 111 II I II I II 1 1 1 1 1 HIM 1 1 Hill I III III I II I III IIIMIIIIIII III III III III Mil II I II 1 1 II I II I III I III I IIIHI I II I Mil II I III I HIMIM 


Crystal Growth of II-IV Semiconducting Alloys by Directional Solidification 


Principal Investigator: Dr. Sandor l. Lehoczkv 


Co-Investigators: 

F. Szofran 
C.Su 
R. Scripa 


NASA Marshall Space Flight Center (MSFC) 


NASA Marshall Space Flight Center (MSFC) 
NASA Marshall Space Right Center (MSFC) 
University of Alabama, Birmingham ((JAB) 


Task Objective: 

The objective of this research is to investigate the effects of reduced gravity on the crystal growth of mercury zinc 
telluride (HgZnTe) and mercury zinc selenide (HgZnSe) alloys with respect to their compositional, metallurgical, 
and optical properties. 

Task Description: 

The investigation includes both Bridgman-Stockbarger and solvent growth methods, as well as growth in a 
magnetic field. The alloys are prepared by reacting pure, elemental constituents in evacuated, sealed, fused-silica 
ampules. The crystals are grown in a multizone furnace. The hot zone is heated above the liquidus temperature of 
the given alloy and the cold zone is maintained at lower temperatures to provide temperature gradient sufficient to 
prevent constitutional supercooling. Crystal growth is accomplished by slowly moving the ampule from the hot 
zone to tiie cold zone of the furnace. The flight portion of the investigation is being performed by using the 
Crystal Growth Furnace (CGF). Preparation of the samples is being done in the Space Science Laboratory of 
Marshall Space Flight Center, Characterization and analysis of the samples after processing is being done primarily 
in the same laboratory with substantial microstructural analysis being done at the University of Alabama at 
Birmingham. Device fabrication and characterization will be done primarily at the Rockwell International Science 
Center. 

Task Significance: 

The anticipated results of this study will have both scientific and technological significance. The advancement in 
science will result from the increased understanding of the role of gravity on the fluid dynamic and compositional 
redistribution phenomena during the crystal growth of solid-solution semiconducting alloys having large separation 
between the liquidus and solidus of the constitutional phase diagrams, and from the more accurate values of material 
properties that can be measured using the high-quality, bulk crystals grown in space. Any advance in quality of 
these electronic materials has a great technological impact because of the application to infrared detectors for NASA 
and DOD requirements. 

Progress During FY 1 994: 

A series of HgZnTe cry stal ingots has been grown from pseudobinary melts by Bridgman-Stockbarger type 
directional solidification using the CGF Ground Control Experiment Laboratory (GCEL) furnace, as well as MSFC 
heat pipe furnaces. Several ZnTe crystals were also grow'n using a Te-solvent zone growth method. Various 
thermal boundary conditions and growth rates were employed and several of the ingots were rapidly quenched during 
the steady-state portion of growth to establish correlation between thermal conditions and melt/solid interface 
shapes. These experiments also indicated that the ingots can be successfully quenched and back melted to allow a 
rapid return to steady-state growth. The fitting of the measured crystal compositional distributions to appropriate 
theoretical models was used to obtain an estimate of the effective HgTe-ZnTe liquid diffusion coefficients. To assist 
the modeling of the pertinent heat and mass transport processes, selected portions of the pseudobinary phase 
diagram, thermal diffusivity and melt viscosity have been measured. Heat capacity and enthapy of mixing for the 
pseudobinary melts were calculated assuming an associated solution model for the liquid. Grow'th experiments for 





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II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

. .mm.., 


an Hg 0R4 Zn„ l6 Te alloy crystal were also performed in a magnetic fieldthat showed significant fluid flow effects on 
the crystal compositional distributions. 

A ground preprocessed and quenched sample was successfully back-melted and partially regrown in the CGF 
instrument during the first United States Microgravity Laboratory (USML-1) mission. The meltback interface was 
within 0.5 mm of the desired value. Because of the loss of power to the CGF, the experiment was terminated after 
approximately 39 hours into the growth period. About 5.7 mm of sample had been grown at that point. Surface 
photomicrographs of the recovered sample clearly showed significant topographical differences between the space- 
and ground-grown portions. Compositional measurements along the sample axis indicated that the desired 
steady-state growth for the axial composition was reached at about 3 mm into the growth. An X-ray diffraction and 
SEM survey of the sample showed that both the ground- and flight-portions of the ingot contained only a tew 
grains, i.e., were nearly single crystals, and the crystallographic orientation was maintained following back-melting 
and space growth. The interface shape, radial compositional variations, and the quenched-in dendritic structures of 
the flight sample all have shown an asymmetric behavior. The compositional data strongly suggest that the most 
likely cause was unanticipated transverse residual accelerations. 


Students Funded Under Research: Task Initiation: 12/92 Expiration: 9/96 

Project Identification: 963-21-08-04 
NASA Contract No.: in-house 

Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Su, C.-H., Volz, M.P., Gillies, D.C., Szofran, F.R., Lehoczky, S.L., Dudley, M., Yao, G.D., and Zhou, W. Growth of 
ZnTe by physical vapor transport and traveling heater method. J. Cryst. Growth, vol. 128, 627-632 (1993). 

Palosz, W., Szofran, F.R.. and Lehoczky, S.L. The effect of heat treatment in the magnitude and composition of residual 
gas in sealed silica glass ampoules. J. Crys. Growth, vol. 142, 215-224 (1994). 

Proceedings 

Lehoczky. S.L., Szofran, F.R.. Gillies. D.C., Cobb, S.D., Su. C.-H., Sha. Y.-G., and Andrews. R.N. "Crystal growth of 
selected E-VI semiconducting alloys by directional solidification." Proceedings of the Joint Launch + one Year Science 
Review of USML-1 and USMP-1 with the Microgravity Measurement Group, N. Ramachandran. D.O. Frazier, S.L. 
Lehoczky, and C.R. Baugher. eds., NASA Conference Publication 3272, vol. 1, 163 (1994). 


•• HIHIMIH HI, IMHH 




11-138 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

IIIMIIIIMIMMIIMIIIIIIIIIIIMIIIIHIIIIMIIMIMIMIMIIIIIIIIIIIIIIIIllMlllllllllllMIIIIIIIIIIIMIIIIIIIIIIIIIHIIIMIIMIHIIMMIIIIIMIIIIIIIIMIIIIMMIIIIMIIMIIMIIMMIMIIIIIIIIIIIMIItMIMIIMIIIIMIMMMMll IllllllMlMIIHI 


Growth of Solid Solution Single Crystals 

Principal Investigator: Dr. Sandor l. Lehoczky 

NASA Marshall Space Flight Center (MSFC) 

Co-Investigators: 


F. Szofran 
D. Gillies 

NASA Marshall Space Flight Center (MSFC) 
NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

The major objective of this research is to establish the limitations imposed by gravity during growth on the quality 
of bulk solid solution crystals having large separation between their liquidus and solidus temperatures. The 
important goal is to explore the possible advantages of growth in the absence of gravity. 

Task Description: 

The alloy system being investigated is Hg 1 . x Cd x Te with x- values appropriate for infrared detector applications in the 
8 to 14(m region. Both melt and Te-solvent growth methods as well as growth in magnetic fields are being 
considered. The study consists of flight experimentation and ground-based experimental and theoretical work needed 
to establish material properties and optimum experimental parameters for the on-going flight experiment and to 
assist material evaluation. Hg^Cc^Te is representative of several alloys which have electrical and optical properties 
that can be compositionally tuned to meet a wide range of technological applications in the areas of sensors and 
lasers with applications to optical computing and communications as well as the national defense. The 
investigation includes both Bridgman-Stockbarger and solvent growth methods, as well as growth in a magnetic 
field. The alloys are prepared by reacting pure, elemental constituents in evacuated, sealed, fused-silica ampules. 
The crystals are grown in a multizone furnace. The hot zone is heated above the liquidus temperature of the given 
alloy and the cold zone is maintained at lower temperatures to provide temperature gradient sufficient to prevent 
constitutional supercooling. Crystal growth is accomplished by slowly moving the ampule from the hot zone to 
the cold zone of the furnace. 

The majority of the ground-based studies are being performed in Space Science Laboratory of the George C. 
Marshall Space Flight Center. The flight portion of the investigation is being conducted using the Advanced 
Automatic Directional Solidification Furnace developed by the Marshall Space Flight Center and manifested for 
flights on the United States Microgravity Payload series of missions. The first flight of the instrument took place 
in March 1994. 

Task Significance: 

The anticipated results of this study will have both scientific and technological significance. The advancement in 
science will result from the increased understanding of the role of gravity on the fluid dynamic and compositional 
redistribution phenomena during the crystal growth of solid-solution semiconducting alloys having large separation 
between the liquidus and solidus of the constitutional phase diagrams, and from the more accurate values of 
materials properties that can be measured using the high-quality, bulk crystals grown in space. Any advance in 
quality of these electronic materials has a great technological impact because of the application to infrared detectors 
for NASA and DOD requirements. 

Progress During FY 1 994: 

Over the past several years, a detailed evaluation has been performed on the effects of growth parameters on the axial 
and radial compositional uniformity, defect density, and optical properties in directionally solidified Hg^Cc^Te and 
other similar compounds and pseudo-binary alloys. A series of Hg^Cd/Te alloy ingots (0<x<0.6) has been grown 


II-139 



IL MSAD Program Tasks — Flight Research 


Discipline: Materials Science 

1 1 III I ill II I II III 


from pseudobinary melts by vertical Bridgman-Stockbarger type heat-pipe tumace assembly using a wide range ol 
grow tli rates and thermal conditions. Several ol the experiments were performed in transverse and axial magnetic 
fields of up to 5T. Precision measurements were performed on the ingots to establish compositional distributions 
;uid defect density distributions for the ingots. Correlation between growth rates and thermal conditions and growth 
interface shapes have been established for die alloy system. To assist the interpretation ol the results and the 
selection of optimum in-flight growth parameters, the pseudobinary phase diagram (0<x<l), liquid and thermal 
diffusivities (0<x<0.3), melt viscosity, and the specific volumes as a tunction ol temperature (0<x<0.15) have been 
measured. From these measurements and other available data, the heat capacity, enthalpy ol mixing, and the 
thermal conductivity of pseudobinary melts have been calculated using a regular associated solution model tor the 
liquid phase. A one-dimensional diffusion model that treats the variation ol the interlace temperature, interlace 
segregation coefficient, and growth velocity has been used to establish ellective diftusion constants lor the alloy 
system. Theoretical models have been developed for the temperature distribution and the axial and radial 
compositional redistribution during directional solidification ol the alloys. These were used along with the 
experimental results to select the parameters for the first flight experiment flown on the Second United States 
Microgravity Payload (USMP-2) mission. A microscopic model for the calculation ol point-delect energies, 
charge -carrier concentrations, Fermi energy, and conduction-electron mobility as lunctions ol x, temperature, and 
both ionized and neutral defect densities has been developed. For selected samples, measurements were pertormed ol 
electron concentration and mobility from 10-300K. The experimental data were in reasonably good agreement with 
theory and were successfully analyzed to obtain donor and acceptor concentrations lor various processing conditions. 

A five zone Bridgman-Stockbarger type tumace system designated as the 1 Advanced Automatic Directional 
Solidification Furnace (AADSF)” has been designed and developed for operating in the cargo bay of the Space 
Transportation System (STS). Over 15 growth experiments were performed in the development and ground-based 
versions of the AADSF to establish optimum operating parameters and procedure lor the initial flight experiment. 
The experiment was successfully flown on STS62 mission as part ol the Second United States Microgravity 
Payload (USMP-2) mission in March 1994. An approximately 15 cm long and 0.8 cm diameter Hg 08 Cdo 2 Te alloy 
crystal was grown at a rate of 0.78 mm/h over a period ol approximately 1 1 days. Preliminary x-ray radiographs ot 
the crystal indicate dial die growth was successful. Characterization ot the crystal is in progress. 


Students Funded Under Research: Task Initiation: io/84 Expiration: 10/95 

Project Identification: 963-30-01 

NASA Contract No.: in-house 

Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Gobba. W.A.. Patterson. J.D.. and Lehoczky, S.L. A comparison between electron mobilities in Hg,. x Zn x Te and 
Hg lx Cd x Te. Infrared Phys., vol. 34(3), 311 (1993). 

Palosz, W.. Szofran, F.R., and Lehoczky, S.L. The effect of heat treatment in the magnitude and composition of residual 
gas in silica glass ampoules. J. Cryst. Growth, vol. 142, 215-224 (1994). 





11-140 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

in hi iikii in mm Illllllllllllllim • iniimtllllllllHMIltimflllllllllllHIIIIIIIIIIIIIIHIIIIIIIIIIIIIIHIIIlllllimilllllllllllllllllllllNItl 


GaAs Crystal Growth Experiment 


PRINCIPAL Investigator; Prof David H. Matthiesen Case Western Reserve University 

Co-Investigators: 

Dr. J.A. Kafalas GTE Laboratories, Inc. 

Dr. B.M. Ditchek GTE Laboratories, Inc. 


Task Objective: 

The objective is to determine the magnitude of effects of buoyancy-driven convection on the crystal growth of bulk 
gallium arsenide (GaAs). 

Task Description: 

vSelenium-doped (~10e-17) GaAs crystals are grown in controlled environments at selected environments affecting 
fluid How as follows: (a) low-gravity (minimal convection), and (b) normal gravity in three separate orientations 
(vector stabilizing the temperature gradients, vector destabilizing the thermal gradient, and vector transverse to the 
thermal gradient), and a magnetically damped flow (the three normal-gravity orientations with either axial or radial 
magnetic field). The distribution of dopant is measured and compared to numerical predictions. Selected electrical 
and chemical properties are measured and correlated with the dopant distribution. Both macro- and micro-segregation 
are determined. 

Task Significance: 

Gallium arsenide (GaAs), an electronic material, has two principle advantages over silicon for producing solid state 
electronic ’chip:” its ability to emit light, useful for making lasers, and its inherently high speed, useful in 
high-speed computers, communication satellites, etc. To fully exploit these characteristics, the material must be of 
the highest quality and be uniformly doped with traces of impurities. Typically, such uniformity is determined by 
convection in the molten material from which GaAs crystals are grown. 

This materials processing experiment, part of a larger effort to better understand and control the crystal growth 
process, was undertaken to investigate the effects of buoyancy-driven convection on crystal growth. 

Progress During FY 1 994: 

The progress in FY1994 was very limited. This was due to the fact that the project is near completion and the 
balance ol the work for FY1994 will be to complete for the Final Report. This is expected to be released near the 
end of the fiscal year. 


Students Funded Under Research: 

BS Students: 1 

MS Students: 0 

PhD Students: 0 


Task Initiation: 9/85 Expiration: 4/94 
Project Identification: 963-21 - 05-02 
Responsible Center: LeRC 


11-141 


II. MSAD Program Tasks 


Ill Mil HUM 1 1 


Flight Research Discipline: Materials Science 




1 1 III II I III! 


Diffusion Processes in Molten Semiconductors 

PRINCIPAL Investigator: Prof. David H. Matthiesen Case Western Reserve University 


Co-Investigators: 

Dr. W. Arnold 
Dr. A. Chait 
Dr. B. Dunbar 
Prof. D. Stroud 


Case Western Reserve University 
NASA Lewis Research Center (LeRC) 
NASA Johnson Space Center (JSC) 
Ohio State University 


Task Objective: 

To provide purely diffusive expenmental measurements of the isothermal diffusion coefficients of Ga, Sn and Sb in 
molten germanium with sufficient accuracy and precision to: 

a) Differentiate between model predictions of the temperature dependence. 

b) Determine the effect of dopant size and type. 

c) Determine if a ’’wall effect” is present. 

d) Provide input to continuum and atomistic model development. 


To provide purely diffusive expenmental measurements of the thermomigration diffusion coefficients of Ga, Sn and 
Sb in molten germanium with sufficient accuracy and precision to: 

a) Determine the effect of dopant size and type. 

b) Determine if a "wall effect" is present. 

c) Provide input to continuum and atomistic model development. 


To develop a 3 -dimensional, fully time dependent continuum numerical model of the germanium diffusion column, 
shear cell, cartridge and furnace for both earth-based and space-based experiments which accurately predicts the 
measured concentration profile as a function of distance in the diffusion column. 

To develop atomistic models which accurately predict: 

a) The purely diffusive isothermal diffusion coefficient of a dopant in a molten semiconductor, 

b) The temperature dependency of dopants in molten semiconductors, and which: 

c) Attempts to explain the "wall effect” 

d) Develops new empirical potentials useful for predicting other diffusion and transport properties for other molten 
semiconductor systems. 

Task Description: 

This program of study is directed at the fundamental and applied issues pertaining to diffusion of species in the 
liquid state as driven by concentration gradients (Fickian diffusion) and thermal gradients (Soret diffusion). The 
fundamental material systems of interest for near term study are the dilute binary systems of gallium (Ga), tin (Sn) 
and antimony (Sb) in germanium (Ge). Systems of commercial interest for future study include the dilute binary 
systems of dopants in gallium arsenide (GaAs). This research program consists of three major components, an 
experimental measurement portion, a continuum numerical simulation portion and an atomistic numerical 
simulation portion. 

The experimental measurement portion is designed to provide definitive measurements of the purely diffusive 
component of mass transfer in molten semiconductor systems. A shear cell technique will be used to direcdy 
measure the diffusion coefficients in semiconductor melts. For the Fickian diffusion case, isothermal measurements 
will be used to determine the diffusion coefficients. An experimental matrix will be used to determine the 






11-142 



II. MSAD Program Tasks — Flight Research 

mm it i hi hi mi it 


Discipline: Materials Science 

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dependence ot tiie diffusion coefficients on temperature, dopant type and column diameter. For the Soret diffusion 
case, measurements will be made in a thermal gradient. 

Task Significance: 

The fundamental mechanisms ot mass diffusion in the liquid state are still unclear to the degree necessary for the 
prediction ot diffusion of one species into another or even within itself. This observation is especially true with 
respect to the dependency ot diffusion mechanisms on temperature and on concentration levels, as well as on the 
dopant type. Present estimates of diffusivity in molten semiconductors can typically provide an order of magnitude 
estimate only, without any information on their dependency on concentration levels and types, and on temperature 
and temperature gradients. 

The availability ot these data is of paramount importance for practical reasons as well. The relevancy of numerical 
modeling lor the analysis and design of ground based and space experiments is directly dependent upon the accuracy 
ot the fundamental material properties used in these simulations. These data are also important for the correct 
characterization and interpretation of experimental results from ground based and space experiments. 

The subject of how a mass ot one species diffuses through a matrix of another is, at the same time, both a very old 
and very new research area. That this area can encompass the small, i.e., movement of electrons in a plasma, to the 
very large, i.e., the depletion of the global ozone layer, merely serves to emphasize the fundamental aspects of this 
subject. Most manufacturing technologies at some stage, rely on diffusion processes in the solid, liquid or gas. 

The need for precise measurements of the diffusion coefficients in molten semiconductors has been repeatedly 
pointed out. These data are required both to interpret the experimental results from previous space-based (and 
Earth-based) expenments and also to optimize newly envisioned experiments. Difficulties in experimental 
techniques and theoretical interpretations are cited lor the lack ot these data. This is a comprehensive program which 
addresses both of these issues. 

Progress During FY 1 994: 

Quantified the level of mixing between adjacent shear cell segments due to the initial fluid-fluid shear. 

• Numerically evaluated shearing rate. 

• Numerically quantified the effect of convection on the measured diffusion coefficient. 

• Established machining tolerances for shear cells. 

• Numerically evaluated Soret diffusion. 

• Numerically evaluated the use of an applied magnetic field to suppress convection. 

• Quantified error bars to establish confidence level in the measured diffusion coefficient. 


Students Funded Under Research: Task Initiation: 1/93 Expiration: 2/96 

Project Identification: 963-21 -05-04 
NASA Contract No.: NCC 3-293 
Responsible Center: LeRC 


Mil 


11-143 



II. MSAD Program Tasks — 




Flight Research 

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Discipline: Materials Science 

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The Study of Dopant Segregaton Behavior During the Groxvth of GaAs in Microgravity 


Principal Investigator: Prof. David h. Matthiesen 

Case Western Reserve University 

Co-Investigators: 

J. Kafalas 

Viable Systems, Inc. 


Task Objective: 

To characterize the two selenium doped gallium arsenide crystals which were grown in the Crystal Growth Furnace 
(CGF) aboard the first United States Microgravity Laboratory (USML-1). 

Task Description: 

During this task, the dopant distribution of the selenium in the grown gallium arsenide will be measured. Several 
complementary techniques will be used including optical (infrared transmission FTIR and QIR); electrical (Hall 
effect, C-V DLTS) and chemical (SIMS). In addition, NASA supplied acceleration measurements will be used to 
correlate any segregation events present in the crystal. 


Task Significance: 

Bv cross comparisons of the optical, electrical and chemical measurements an exacting dopant distribution will be 
measured in the crystal. When NASA supplies the appropriate acceleration data then, for the first time, an exacting 
correlation will be made between the measured segregation events and any acceleration event. 


Progress During FY 1 994: 

The segregation measurements are nearly complete. These datat indicate that initially diffusion controlled growth 
was achieved. However, after approxiamtely 1 cm of growth the data indicate that the segregation behavior 
transitioned to that of complete mixing. The acceleration data is being examined for any causes. 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: I MS Degrees: 1 

PhD Students: 0 PhD Degrees: 0 


Task Initiation: 5/92 Expiration: io/96 
Project Identification: 963-21-05-01 
NASA Contract N0.NAS8-39722 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Korpela. S.A.. Chait. A., and Matthiesen. D.H. I.aterial or radial segregation in solidification ot binary alloy with a curved 
liquid-solid interlace. J. Cryst. Growth, vol. 137. 623 (1994). 

Majewski. J.A.. and Matthiesen. D.H. Quantitative infrared imaging for the measurement of dopant distribution in gallium 
arsenide. J. Cryst. Growth, vol. 137, 249 (1994). 

Matthiesen. D.H. The total pressure of arsenic over molten gallium arsenide at 1260 °C. J. Cryst. Growth, vol. 137, 255 
(1994). 

Proceedings . . • „ r> a e 

Matthiesen. D.H. "The study of dopant segregation behavior during the growth of GaAs in microgravity. Proceedings ot 

the Joint Launch + One Year' Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group. NASA 

Conference Publication 3272. 223-259 (1994). 


hihiiih HI I mill Minimi 


11-144 



II. MSAD Program Tasks — Flight Research 

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Discipline: Materials Science 

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Temperature Dependence of Diffusivities in Liquid Metals 


Principal Investigator! Prot. Franz e. Rosenberger 

University of Alabama, Huntsville 

Co-Investigators: 


R. M. Banish 

University of Alabama, Huntsville 


Task Objective: 

This research aims ai advancing the understanding of diffusion mechanisms in liquid metals and alloys through 
accurate dilfusivity measurements over a wide range of temperatures, including the proximity of the materials 
melting points. 

Task Description: 

Toward the above objective we are pursuing the following tasks: 

• development ot an efficient technique for dynamic in-situ measurements of diffusivities in melts as a function of 
temperature; 

• development ot a flight-certified hardware package to automatically perform such diffusivitv measurements under 
reduced gravity conditions and on Earth; 

• investigation of the significance of the “wall effect” in diffusion capillaries; 

• exploration ot convective contamination of the diffusivity measurements on Earth through numerical modelling; 

• exploration ot the possibility to simulate low gravity diffusion conditions in conducting liquids on Earth through 
the application of magnetic fields; 

• measurements ot diffusivities of selected materials that will be chosen according to class-like molecular interaction 
behavior in the liquid. 

Diffusivities will be determined trom temporal records of evolving concentration profiles through multi-detector 
measurements ot radioactive tracer emission. An initially solid, cylindrical sample contains a radioactive isotope at 
one end. Alter melting, radiation escaping through small bores in an isothermal liner/radiation shield is monitored 
via a chain ot detectors. Data evaluation is facilitated by a novel algorithm, which is not limited to the simple 
initial conditions traditionally used in diffusivity studies. The algorithm permits data deduction from any sequence 
ot concentration distributions. Hence, diffusivity data can be gathered over a range of temperatures in a single 
experiment. Utilizing the different radiation absorption behavior of different photon energies, we will investmate 
the significance of the '“wall” effect. This effect is currendy believed to contaminate diffusion studies in narrow 
capillaries used to suppress convection at normal gravity. 

Task Significance: 

The diffusion ot species in melts and its temperature dependence is important for the product quality in numerous 
metallurgical and semiconductor manufacturing processes. Hence, a detailed understanding of diffusion in liquid 
metals and alloys is essential for an efficient improvement of numerous technological processes. However, the 
accurate measurement of diffusivities in liquids is hampered by difficult-to-control transport contributions from 
convection. At this point, due to the complex structure ot liquids, our theoretical understanding of diffusion in 
liquids is limited. Theoretical models ot diffusion in liquids abound. Yet, a verification of these models requires 
more accurate diffusivity data for wider temperature ranges than are currently available. This investigation will 
provide accurate data for selected materials and, hence, will further both process development as well as fundamental 
science. 




IMIIIIIMHII II IIHIHIIItlllllllltlltlltl I HUM IIMIMI I 


11-14 5 



II. MSAD Program Tasks — Flight Research 

0 1 1 ii i <i i it i it ittnt in mini i iimtiiiiMiinniH'iiimii*H*Ni»ntiiiiiii»Miini 


HIIIHIHIIMIMIIHMIMIIIMimillHIimill 


Discipline: Materials Science 

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Progress During FY 1 994: 

A novel algorithm was developed tor the evaluation of diffusive concentration profiles without use of boundary 

conditions and specialized initial conditions. . ...... . 

A conceptual design was completed based on detailed sensitivity and dimensional analyses of the optimal diffusion 
capillary and collimator geometry considering experiment time, spatial resolution and diffusivity data precision, 
detector sensitivity and minimization of the radioactive dose, isotope half-life and collimator/radiation shie d 

absorption characteristics. . . ... . „• , „ 

An isothermal diffusion oven with minimal power consumption, adequate radioactive shielding and permitting ready 

sample exchange, was designed and built. ...... . 

A boron nitride coated graphite healer cartridge was selected for its uniform radioactive absorption characteristic 

tested under oxidizing conditions over the temperature range to be used in the experiments. 

Following extensive testing of various detectors for energy resolution at the elevated operation temperatures to be 
expected in a flight experiment, CdZnTe detectors were chosen and integrated with mimtunzed data acquisition 

electronics. 

The development of software tor data acquisition and evaluation was started. . . 

Sample preparation and ampoule filling procedures were tested with particular concern tor obtaining non-we g 

conditions between the metal and ampoule material. .... 

A design verification and sensitivity testing procedure for the whole experimental setup was developed uUlizing a 
solid, radioactive sample to be mechanically moved along the diffusion direction in liquid samples. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 2/93 Expiration: 8/94 

Project Identification: 963-25-08-10 
NASA Contract No.nass-39718 
Responsible Center: msfc 







HiiiiimmniiiMiMiiimiiMMMMmmm 


11-146 



II. MSAD Program Tasks — Flight Research 

11 until 


Discipline: Materials Science 

I II I Hill Mill IIIIIHHItl 111111111111111111111111111 1 II Ml II III II I III lllltllllllMHMf It IIIIIIHIHIIHHItlHHIIIMtlllllllllll 


Double Diffusive Convection during Growth of Lead Bromide Crystals 


Principal Investigator: Dr. n. b. Singh 

Westinghouse Electric Corporation 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

The main objective ol this program is to evaluate, understand and eliminate thermosolutal convection during the 
crystal growth ot PbBr 2 -AgBr systems. The program will provide a quantitative understanding of convective effects 
and a correlation of experimental data with theories developed for thermosolutal convection will be earned out. For 
the PbBr 2 -AgBr system less dense solute causes the convective (thermosolutal) instability in addition to 
morphological instability. Also, this system is optically transparent and we can monitor the interface shape to 
study the convective and morphological instabilities. The technical objectives of this program are to define the 
parameter at normal gravity to minimize the thermosolutal convection during growth of doped lead bromide crystals 
to achieve homogeneous distribution of dopant significantly reduce the optical and acoustic scattering caused by 
convection during lead bromide crystal grov/th, and produce lead bromide crystals with unparalleled optical 
homogeneity for advanced device applications. This will be achieved by experimentally verified stability diagrams 
and direct observations on solid-liquid interface during crystal growth. 

Task Description: 

To achieve these objectives, crystal growth experiments will be conducted on earth and in space. Measurements 
involving Rayleigh number as a function of aspect ratio, and the radius of the growth tube to the length of the melt 
column, will be made. Experimental results will be compared with the stability diagram to test the validity of 
morphological and convective stability theories. 

Task Significance: 

The scientific objectives of this program are to understand the thermosolutal convection during the crystal growth of 
PbBr 2 -AgBr system. This will be achieved by growing five crystals at five different concentrations, which will lead 
to different solutal convective levels. The experimental values of the concentration distribution will be compared 
with the theories based on pure diffusional growth to evaluate the effect of convection. Also, numerical studies wall 
be carried out to study the convective and morphological instabilities, and to determine the critical concentration of 
dopant tor a particular growth velocity and gravity level. Theoretical instability diagrams will be compared with the 
experimental studies. Relevant analytical characterization techniques are to be used to evaluate the effect of 
convection on crystal quality. These studies will provide basic data on convective behavior in doped lead bromide 
crystals grown by the commercially important Bridgman process. 

Progress During FY 1 994: 

Minutes of the March 1992 Flight Science Readiness Review have been published. Dr. Singh is taking action 
based on the recommendations of the review. 


To study the effect of thermal convection, four lead bromide crystals were grown at different thermal Rayleigh 
numbers. X-ray rocking curves. X-ray contour scans and chemical etchpit studies showed that crystal quality 
decreased with increasing thermal Rayleigh number. The crystal growm at lowest thermal Rayleigh number showed 
highest quality aid the crystal grow n at highest thermal Rayleigh number showed the w'orst quality. 

Lead bromide-silver bromide crystals were grown in a Bridgman furnace at a thermal gradient of 21 K/cin and puli 
rate of 2.3 x 10' 5 cm/s. The measured concentration of silver did not match with the values predicted by theories 
based on pure diffusive or convective transport. X-ray rocking curves and contour scans for (010) plane showed that 


* "'Ml* it i it i iti i miii 1 1 mu i itm in i m mi i ti 


11-147 


II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

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crystal grown at lower dopant concentration had better quality. The crystals grown at lower solutal Rayleigh 
number exhibited small variation of lattice parameters and better homogeneity in dopant distribution. Results ot 
etchpit studies also supported these results. 

We have carried out a crystal growth run at a temperature gradient of 20 K/cm, to test the validity ot stability 
theory. We are using a charge containing 5000 ppm silver bromide. When we have steady-state conditions, the 
interlace is flat. When we start pulling the growth tube, up to the pull rate ot 0.23 micrometer per second, we did 
not observe any significant change in the shape. At the pull rate ot 0.29 or higher, we observed that the interlace 
turns concave, followed by a depression in the middle. We observed very interesting phenomena with the increasing 
time. We observed that the shape of the interface is changed significantly and can be explained on the basis ol 
toroidal flow, just as theory had predicted. A cellular or dendritic microstructure later developed within this 
depressed interface region. When we stopped the pulling ol the growth tube, the interlace recovered its original flat 
shape. We did not observe this phenomena in the pure lead bromide system and identical crystal growth conditions. 
We are excited to have experimentally confirmed the predicted region of the interlace instability under convective 
growth conditions. This type of instability can be explained on the basis of toroidal fluid flow. This type ot flow 
will not occur in the pure system and the pressed pit at the interface occurs under the point where the flow field 
converges. These results are further justification tor studying this system in low gravity. We are planning to start 
next run containing 500 ppm and we hope to increase the growth velocity 10 times to observe the instability. 


Students Funded Under Research: Task Initiation: 10/93 Expiration: 9/94 

Project Identification: 962-24-05-01 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Singh, N.B.. Stewart. A.M.. Hamacher. R.D.. Mazelsky, R., Duval, Santoro. G.J., DeWitt, R. and Lehoczky, S.L. 

Convecto-diffusive growth of lead bromide crystals: a test of theories. J. Cryst. Growth. 139. 158-164 (1994). 





11-148 



II. MSAD Program Tasks — Flight Research 

nit mi mi Minim mm 


Discipline: Materials Science 




Particle Engulfment and Pushing by Solidifying Interfaces 

Principal Investigator: Prof. Doru m. stcfanescu 

University of Alabama, Tuscaloosa 

Co-Investigators: 


P. Curreri 

NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

The primary objective ol this ta.sk is to turther develop the existing understanding on pushing and engulfment of 
particles by planar liquid/solid interfaces during solidification of metallic alloys. 


The approach towards achieving this objective is by developing an analytical and then a numerical model describing 
this phenomenon, with a parallel experimental validation effort. The numerical model is required in order to include 
die effect of convection in the liquid on interface morphology and the particle/interface interaction. The interaction 
between an insoluble ceramic particle and a liquid-solid interface during solidification is significandy influenced by 
gravitational acceleration. Since the interaction between an insoluble ceramic particle and a liquid- solid interface 
during solidiflcation is significantly influenced by gravitational acceleration, microgravity experiments will be 
performed to validate these models and to further contribute to die experimental data base for metals/ceramic 
particulate mixtures. 

Task Description: 

To acquire turther insight in the physics ol particle behavior, directional solidification experiments with transparent 
organic materials doped with polystyrene particles were scheduled. It was planned to use results from these 
experiments to validate the analytical model developed so far. 

Ground based experiments under controlled solidification conditions widi Al-SiC systems to document 
pushing/engultment phenomena in metallic systems were also scheduled. In addition several tasks required in die 
flight requirements definition effort were to be performed. 

Task Significance: 

It is of fundamental and practical importance to understand and control particle behavior at the solid-liquid interface 
during solidification. Particle behavior determines the uniformity of their distribution in the matrix. Uniformity of 
particle distribution is of great significance as it dictates the mechanical and physical properties of the composites. 

Introduction of insoluble ceramic particles in a metal matrix primarily involves three stages: transfer of particles 
from gas to liquid, interaction of particles in the liquid state and finally transfer of particles from liquid to solid. It 
is the last stage that is the most important and yet the least understood since it is the outcome of the interaction of 
numerous solidification variables. The anticipated results from this research program will provide a much better 
understanding of this stage of metal matrix composite processing and therein lies its significance. 


Progress During FY 1994 : 

Modeling: 

Through a combined thermal and torce field calculation a model has been developed to predict particle behavior at the 
interface. The derived equations predict the formation of bumps or troughs on the melt interface behind the 
particles. This was confirmed by experiments on transparent systems containing SiC. polystyrene, or gas bubbles. 
The model allows calculation of the critical velocity for particle engulfment: 

V =A(G/C 0 ) I/2 R-‘ 

where, Q, is the equilibrium solute concentration, G is the thermal gradient ahead of the interface. R is the radius of 


* 


11-149 



II. MSAD Program Tasks — Flight Research 



Discipline: Materials Science 

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curvature, and A is a constant that includes material parameters. Experimental and analytical modeling work on 
transparent systems have demonstrated that in the presence of convective fluid flow the critical velocity tor particle 
engulfment increases. This is primarily due to particles moving away from the interface with a velocity comparable 
to the fluid flow velocity. 


Progress in Experimental Work: 

Transparent organic materials doped with polystyrene particles have been directionally solidified. In-situ behavior ot 
these particles was observed under variable solidilication conditions. Results from these experiments were used to 
validate the analytical model developed so far. A better understanding of the role of interface morphology, e.g., 
planar or columnar, was also achieved. 

Metallic systems are opaque to light microscopy. Determining the position ot the particles before and after 
directional solidification is important to accurately determine the critical velocity for particle engulfment. Thus it 
was necessary to evaluate several non destructive methods. Samples have been sent out to three different 
organizations (Panametrics, Boeing, and Argonne National Laboratory) for initial evaluation. 

Water spray quenching experiments in the directional solidification furnace have been performed on both alumina 
and graphite crucibles and the corresponding cooling rates have been determined. This work was necessary tor the 
definition of flight requirements. 

A cartridge design and a method to fabricate flight samples incorporating three thermocouple tips to monitor thermal 
profile during the expenments has been developed. These samples will be tested at CNES. 

The critical velocity for maintaining a planar interface in 99.999% A1 has been determined to be 60 pm/s. 

Since spherical SiC particles required for the experiments were not available, a sputtering technique was used to coat 
spherical Ni particles with SiC. Spherical particles processed in this way have been characterized for coating 
uniformity and thickness. 


Students Funded Under Research: 

BS Studenis: 0 

MS Students: 1 

PhD Students: 1 


Task Initiation: 2/93 Expiration: 2/96 
Project Identification: 963-25-08-n 
NASA Contract No.nass-38715 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Proceedings 

Ahuja, S., Stefanescu. D.M.. and Dhindaw, B.K. M Role of processing/system parameters on the interaction between 
liquid/solid interfaces and insoluble particles.” Cast Metal Matrix Composites, Proceedings of the 2nd International 
Conference, D M. Stefanescu and S. Sen. eds.. AFS. Des Plaines. IL. 44-56 (1993). 

Pang, H.T.. Stefanescu, D M., and Dhindaw. B.K. "Influence of interface morphology on the pushing/engulfment 
transition of polystyrene particles in succinonilrile + water matrices.” Cast Metal Matrix Composites, Proceedings ot the 
2nd International Conference, D M. Stefanescu and S. Sen, eds., AFX, Des Plaines, IL, 57-69 (1993). 

Books 

Pang. H., and Stefanescu. D.M. “Influence of Interface Morphology on the Pushing/Engulment Transition of Polystyrene 
Particles in Succino nitrile + Water Systems’’ in "Experimental Methods for Microgravity Materials Science Research. 
Edited by: R.A. Schiffman and B. Andrews TMS/Warrendale. PA, pp 209-213, 1994. 


„„ 1 


11-150 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

lllltlllllllllllll lltlltlKIKIIKIKIIKIIIIKIIIIIIIIIIIIMIIIIKIKIKIIKIMIIIIIIIIIIIIIIIIKIKKIIKKIIIIKIIIIIKIIIIIIIIIIIIIIIIKIIIIIKIIIIKIIKIIIIIKII I IMMIIIHIIIIIIIIIIIIII<II<IIII<IMIMIMIIIII<IIMMIIIIIIII<IIHIIM 


Crystal Growth of ZnSe and Related Ternary Compound Semiconductors by Physical Vapor Transport 


Principal Investigator: Dr. Ching-Hua Su 

NASA Marshall Space Flight Center (MSFC) 

Co-Investigators: 


R. Brebrick 

Marquette University 

M. Volz 

NASA Marshall Space Flight Center (MSFC) 

Y, Sha 

Universities Space Research Association (USRA) 

D. Noever 

NASA Marshall Space Flight Center (MSFC) 

S. Sanghanitra 

Santa Barbara Research Center 

S. Johnson 

Santa Barbara Research Center 


Task Objective: 

The investigation consists of extensive ground-based experimental and theoretical research efforts and concurrent 
flight experimentation. The objectives of the ground-based studies are to obtain the experimental data and conduct 
the analyses required to define the optimum growth parameters for the flight experiments, perfect various 
characterization techniques to establish the standard procedure for material characterization and quantitatively 
establish the characteristics of the crystals grown on Earth as a basis for subsequent comparative evaluations of the 
crystals grown in a low-gravity environment, and develop theoretical and analytical methods required for such 
evaluations. 

Task Description: 

The crystal growth experiment will use a novel vapor transport three-thermal-zone heater translating method. The 
Crystal Growth Furnace (CGF) or Advanced Automated Directional Solidification Furnace (AADSF) will be ideal 
for this experiment because they provide two high-temperature end zones and a booster heater at the center of the 
furnace with translation capability. Using this technique, large single crystals of CdS, CdTe, PbSe, and ZnTe have 
been grown successfully in this laboratory. 

Task Significance: 

The materials to be investigated are ZnSe and related ternary semiconducting alloys, e.g., ZnS x Se Nx , ZnSe,. x Te x , 
and Zn 1 . x Cd x Se. These materials are useful for opto-electronic applications such as high efficient light emitting 
diodes and low power threshold and high temperature lasers in the blue-green region of the visible spectrum. The 
recent demonstration of its optical bistable properties also makes ZnSe a possible candidate material for digital 
optical computers. Compositional non-uniformity, microstructural crystal defects (e.g., dislocations, small-angle 
grain boundaries, and second phase precipitates), and deviation from stoichiometry can seriously limit 
state-of-the-art device performance and future device applications. The reduction of gravity-driven convective fluid 
flows in a low-gravity environment is expected to be advantageous in minimizing these compositional variations 
and structural defects. 

Progress During FY 1 994: 

1. Fundamental of transport theory was confirmed by simultaneous measurements of partial pressures and transport 
rate. 

2. Growth parameters for horizontal unseeded growth of ZnSe were optimized. 

3. Characterization methods to assess the effect of gravity on the grown crystals were established. 


IIIIIMIIIMHII I lltl II lilt I II I III I IHK I II IK I II IK IK III I III II I Kill I III III I III Mllllllllll IKI II 


11-151 




II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

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Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 2/93 Expiration: 2/96 

Project Identification: 953-21-08-09 
NASA Contract No.nass-39718 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Biao. Y., Azoulay, M., George, M.A.. Burger, A.. Collins. W.E., Silberman, E.. Su. C.H., Volz, M.P.. Szotran, F.R., and 
Gillies, D.C. Photoluminescence of vapor and solution grown ZnTe single crystals. J. Cryst. Growth, vol. 138. 219-224 
(1994). 

Sha, Y.G, Su, C.H., and Szofran, F.R. Thermodynamic analysis and mass flux ot the HgZnTe-Hgl 2 chemical vapor 
transport system, i. Cryst. Growth, vol. 131, 574-588 (1993). 

Su. C.H.. Volz. M.P.. Gillies. D.C., Szofran. F.R.. Lehoczky. S.L.. Dudley. M.. Yao. G.D.. and Zhou. W. Growth of ZnTe 
by physical vapor transport and traveling heater method. J. Cryst. Growth, vol. 128. 627-632 (1993). 

Proceedings 

Su, C.H., Sha, Y.G., Volz, M.P., Gillies, D.C., Lehoczky, S.L., Zhou, W., Dudley, M.. Liu, H.C., Brebrick, R.F., and 
Wang, J.C. "Ground based research on the growth of EL-VI compound semiconductors by physical vapor transport. 
Proceedings of the 8th Annual Symposium on Microgravity Science and Space Processing, A1AA 32nd Aerospace Sciences 
Meeting, paper no. 94-0564 (1994). 

Zhou, W.. Wu, J., Dudley. M.. Su. C.H., Volz, M.P., Gillies, D.C., Szofran, F.R., and Lehoczky, S.L. "Character ization of 
growth defects in ZnTe single crystals." Materials Research Society Proceedings, Infrared Detectors - Materials, 
Processing, and Devices, A. Applebaum and L.R. Dawson, eds., 299 (1993). 


Presentations 

Chen, K.T., George, M.A.. Zhang, Y., Burger, A.. Su, C.H., Sha, Y.G., Gillies. D.C., and Lehoczky, S.L. "Selenium 
precipitation in ZnTe crystals grown by the physical vapor transport." American Physical Society Meeting March. 
Pittsburg, PA, March 21-25. 1994. 

Ruggeri, R.T., Shepherd. W.B., Bowman, D.R., Bohnhoff-Hlavacek, G., Willenberg, H.. Su. C.H., Szofran, F.R., Rubart, 
W.S., and Stoebe, T.G. "The crystals by vapor transport experiment (CVTE): space processing and preliminary results.” 
44th International Astronautic Congress of the International Astronautic Federation. Graz. Austria, October 16-22. 1993. 

Sha, Y.G., Su, C.H., Palosz. W., Volz, M.P., Gillies, D.C., Szofran, F.R., Lehoczky. S.L.. Liu, H.C., and Brebrick. R.F. 
"Mass flux and crystal growth of ZnSe by PVT." 8th International Conference on Vapour Growth and Epitaxy (ICVGE-8), 
Freiburg, Germany, July 24-29. 1994. 

Su, C.H., Sha, Y.G., Volz, M.P., Gillies. D.C., Szofran, F.R., Lehoczky, S.L., Zhou, W.. Dudley, M.. Liu, H.C.. Brebrick, 
R.F., and Wang, J.C. "Ground based research on the growth of II -VI semiconductors by physical vapor transport." AIAA 
32nd Aerospace Sciences Meeting, 8th Annual Symposium on Microgravity Science and Space Processing, Reno, NV, 
Janaury 10-13. 1994. 





11-152 


II. MSAD Program Tasks — Flight Research Discipline: Materials Science 

" 1,1,1 Mil 


Measurement of Viscosity and Surface Tension of Undercooled Melts 


Principal Investigator; Dr. Julian Szekeiy 

Massachusetts Institute of Technology (MIT) 

Co-Investigators: 

No Co-I’s Assigned to this Task 



Task Objective: 

The objective of this investigation is to utilize the electromagnetic levitation unit, TEMPUS, on IML-2 to measure 
the viscosity and surface tension of undercooled metallic melts. To date, little study has been made of the 
thermophysical properties of undercooled melts, and a controversy exists over whether the temperature dependence of 
the viscosity obeys an Arrhenium-type or a power-law relationship. 

Task Description: 

In this investigation, a 'squeezing” force will be applied to a suitably-positioned sample to induce oscillations. The 
rate ot decay of the amplitude of these oscillations will be observed in order to measure the viscosity at a number of 
temperatures in the undercooled regime, while the frequencies of the oscillation modes will be used to deduce the 
surface tension at these temperatures. 

Our effort consists largely of a comprehensive program of mathematical modeling designed to give a detailed 
understanding of what can be expected from the flight experiment. To date, the main thrust of the modeling work 
has been to develop the methodology and to perform calculations predicting the behavior of 
levitation-melted/electromagnetically-positioned metallic droplets under both Earthbound and microgravity 
conditions. 

Task Significance: 

The main purpose of the work was to be able to predict the electromagnetic forces and heating rates, 
electromagnetically-driven velocity fields within the sample, the transient behavior of the system, and the 
deformation of the sample. The accuracy of the computational models has been checked by comparison with 
available analytical results and the results of ground-based experiments. 

Progress During FY1994: 

During the IML-2 mission this experiment was performed in the TEMPUS facility. The surface tension and 
viscosity of undercolled metallic melts - including both pure metals (Cu, Au, and Ni) and alloys (AuCu) - were 
measured. The oscillating drop technique with electromagnetic levitation was used to measure the thermophysical 
properties in a containerless fashion. By this method, a metallic sample was positioned, melted, and squeezed by 
high-trequency electromagnetic fields in TEMPUS. Once the sample is molten, it is squeezed and deformed by a 
brief current about its equilibrium free surface shape. The surface tension can be related to the frequency of the 
oscillations, and the viscosity can be derived from the rate at which the oscillations are damped. The experiments 
were performed in microgravity in order to eliminate the strong electromagnetic forces that are required to levitate 
metallic samples on Earth. These strong forces drive turbulent flow inside the sample, making it impossible to 
measure viscosity and deforming the sample to an extent that makes measurement of the surface tension more 
difficult. 

For three experiments mentioned above (Au, AuCu, and ZrNi), the digital data contained in the rau-telegram were 
analyzed with respect to the heater and positioner control voltages and temperature. The temperature data were 
rescaled using the effectives emissivities determined at the melting plateaus, which occurred at know temperatures. 
Surface tension values to Au, AuCu, and ZrNi have been determined, and the results are very promising and 
represent the first surface tension data obtained in microgravity. 


11-153 


II. MSAD Program Tasks 


Flight Research 

IHIIIIMIMIItllllMlltmlllHIlHHIH! 


Discipline: Materials Science 

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Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 12/90 Expiration: 6/95 
Project Identification: 963-25-08-08 
NASA Contract No.: nags-970 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Proceedings . 

Schwartz. H. and Szekely, J. "Some perspectives on electromagnetic levitation in space experiments. Proceedings ot 

Electromagnetic Processing of Materials. The Iron and Steel Institute ot Japan. Nagoya, Japan, 1994. 

Schwartz, E. and Szekely, J. "The shape of liquid metal droplets in electromagnetic levitation experiments considering 
internal fluid flow." Proceedings of Experimental Methods for Microgravity Materials Science, 1994 TMS Annual 
Meeting, San Francisco. CA, 1994. 73-79. 


mini * * 


11-154 


II. MSAD Program Tasks — Flight Research 

iMmiiiiiiiiiiiiiiiiiiiitimmiiiimiiiiiiiitiiiiiiiiiidiiMimMmiiiiiiuiMiiiiiMiiiiiiiiiiiiiii 


Discipline: Materials Science 

IIIIMIIIIMIIMIItmMIIIIMIMMIMMIIIimilllllllllMimilllllimiltllllllllllMIIIKIIIIIIMIIIIMIIIimilllllllllKIIKIMI 


Test of Magnetic Damping of Convective Floivs in Microgravity 


PRINCIPAL Investigator; Dr. Frank R. Szofran NASA Marshall Space Flight Center (MSFC) 


Co-Investigators: 

S. D. Cobb NASA Marshall Space Flight Center (MSFC) 

M. B. Robinson NASA Marshall Space Flight Center (MSFC) 

M. P. Volz NASA Marshall Space Flight Center (MSFC) 

S. Motakef Computer Assisted Process Engineering (CAPE) 


Task Objective: 

The objectives of this study are: to test experimentally the validity of the modeling predictions applicable to the 
magnetic damping of convective flows in conductive melts as this applies to the directional solidification of 
semiconductor and metallic materials in the reduced gravity levels available in low Earth orbit; and to assess the 
effectiveness of magnetic fields in reducing the fluid tlows occurring in these materials during space processing that 
result from density gradients (driven by the residual steady-state acceleration or g-jitter) or surface tension gradients 
(Marangoni flow). To achieve these fundamental objectives, the following specific objectives will be pursued: 

• To determine the relative effectiveness of transverse and axial magnetic fields in suppressing convective flows in 
lg driven by gravity, vibration, or surface tension gradients; 

• To test the validity of magnetohydrodynamic modeling predictions in characterizing the effectiveness of an axial 
magnetic field for suppressing convective flows in lg. 

Task Description: 

To achieve the objectives of this investigation, we will carry out a comprehensive ground-based program using a 
carefully chosen set of materials. Some of these materials have been intensely studied in environments that have 
not simultaneously included both low gravity and an applied magnetic field. These include a dilute alloy (Ga-doped 
Ge) in which solutal effects will be negligible and three solid solutions — Ge-Si, InSb-GaSb, and Cu-Ni — with 
liquid density ratios of 2.18, 1.07, and 1.012, respectively. Thus, during Bridgman-Stockbarger solidification with 
the solid on the bottom, Ge-Si has a strongly stabilizing solutal density variation, InGaSb is very mildly 
stabilizing with previous results showing substantial mixing, and Cu-Ni is even less stabilizing. All four systems 
will be processed by the Bridgman method using two diameters. In addition, the Ga-doped Ge and Ge-Si systems 
will be float-zoned to study the effects of magnetic suppression of Marangoni convection. 

Task Significance: 

During directional solidification of semiconductors, generation of destabilizing temperature gradients in the melt is 
unavoidable, resulting in buoyancy-induced convective mixing of the liquid phase. On Earth this convective 
mixing is generally very intensive and interferes with segregation of melt constituents at the growth front leading to 
less than optimum quality crystals. Crystal growth in space provides the opportunity to reduce the convective 
intensity and, for some classes of systems and charge sizes, achieve mass transfer diffusion-controlled growth. 
Magnetic damping of convection in electrically-conductive melts, however, can be used to provide a higher degree of 
control on convection in the melt. Thus our understanding of convective influences can be further advanced, and our 
ability to interpret space experimental results may be significantly improved. 

Progress During FY 1994: 

During FY94 a new thermal control system was installed to provide excellent temperature control at all fields up to 
5 T and samples of Ge:Ga, InGaSb, and GeSi were grown and analyzed. Emphasis was on the Ge:Ga system. 


11-15 5 


II. MSAD Program Tasks — Flight Research 

„„„„„ mu iitiumi 


Discipline: Materials Science 







The initial thermal control system used time proportioning and ac current and, while adequate tor zero field work, 
was not satisfactory for use in high magnetic fields. The current system uses dc current that is slowly varied but 
not turned off and on to achieve temperature control. Temperature control ot better than ±0.5 C at all fields is 
routine. 

The significant accomplishments of the project include: 

• Demonstrated mechanical interface demarcation in Ge:Ga at fields up to 5 T; 

• Reproducibly observed diffusion limited growth at 5 T in Ge:Ga; 

• Developed a furnace-specific model for Ge:Ga growth which correctly predicted the field needed to achieve 
diffusion-controlled growth; 

• Demonstrated the growth of single-crystal Ge:Ga at 5 T; 

• Observed major difference in growth characteristics in Ge0.95Si0.05 between 0 and 5 T, 

• Observed significant departure from complete mixing behavior in In 02 Gao 8Sb 


Students Funded Under Research: Task Initiation: 10/92 Expiration: 10/95 

Project Identification: 963-21-08-10 
NASA Contract No.: in-house 

Responsible Center: msfc 


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11-156 



II. MSAD Program Tasks — Flight Research Discipline: Materials Science 


Vapor Growth of Alloy-Type Semiconductor Crystals 


Principal Investigator: Dr. Heribert wiedemeier 

Rensselaer Polytechnic Institute 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objectives of this research are: the establishment of expenmentaJ trends for the relation between convective 
flow, mass flux, and crystal morphology; and the identification of microgravitv effects and crystal properties for the 
ternary semiconductor mercury cadmium telluride (HgCdTe). 

For this purpose, thin epitaxial layers of Hg^Cd/Te will be grown on (100)CdTe substrates during die USML-2 
mission to observe the effects of microgravity on the morphology of the substrate-layer interface and of die 
epitaxial layer. 

Task Description: 

This experiment requires the hot zone to be 625 °C and the cold zone to be 455 °C. The total duration of the 
experiment is 16 hours. The ampoule assembly is designed to be 160 mm in length, 18 mm outer dnuneter, and 
about 31 grams total weight. A cadmium telluride single crystal and a sapphire disc are used for die epitaxial 
crystal growth as substrate and substrate support, respectively. Four time intervals are required for crystal growth, 
namely, heat-up, annealing, growth, and cool-down periods. 

Identical experiments, except for the level of gravity, are performed on ground and in space to provide a direct 
comparison of results. 

Task Significance: 

The lateral and axial compositional homogeneity (distribution) of the major and dopant components is expected to 
be more uniform for the space-grown epitaxial layers. The density of dislocations, of strain-induced defects, and 
possibly the number of inclusions are expected to be considerably reduced relative to ground-control specimens. 

In addition, observations of the effects of reduced gravity on the formation of defects at the growth interface and on 
the propagation of these "birth defects" into the layer are of basic scientific and technological significance. 

Progress During FY 1 994: 

On-going ground-based experiments in the P.I.'s laboratory and in the GCEL furnace revealed the effects of growth 
temperature on the critical transient time of layer growth. These experiments provide the basis for the definition mid 
refinement of flight experiment parameters. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 1 

PhD Students: 3 


Task Initiation: 10/90 Expiration: io /96 
Project Identification: 953-21 -08-03 
NASA Contract No.nash -39723 
Responsible Center: msfc 


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Flight Research Discipline: Materials Science 

HI. Hill... Ml. mum. 


Bibliographic Citations for FY 1994: 

Journals 

Palosz, W.. and Wiedemeier. H. Residual gas pressures in sealed fused silica glass ampoules. J. Cryst. Growth, vol. 131 
193 (1993). 

Wiedemeier. H.. and Wu. G.H. Fast vapor growth of cadmium telluride single crystals. J. Electronic Materials, vol. 22. 
1121 (1993). 

Wiedemeier. H.. and Wu. G.H. Fast growth of Cd, ,Zn x Te single crystals by physical vapor transport. J. Electronic 
Materials, vol. 22, 1369 (1993). 

Presentations 

Wiedemeier, H. "Vapor growth of Hg tx Cd x Te epitaxial layers on ( 100)CdTe substrates under normal and reduced gravity 
conditions." 8th International Conference on Vapor Growth and Epitaxy. Stuttgart, Germany. 

Wiedemeier, H. "Vapor growth of Hg,. x Cd x Te epitaxial layers on (100)CdTe substrates under normal and reduced gravity 
conditions." Max-Planck-Institute, Stuttgart, Germany. 

Wiedemeier. H. "Vapor growth of Hg, ,Cd,Te epitaxial layers on (100)CdTe substrates under normal and reduced gravity 
conditions.” Solid State Research Symposium, University of Munster. Munster. Germany. 


• •mu III llllllll. II. •tillllHIMIIIM.MIIIIIIlll. limit 


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II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

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Superfluid Transition of 4 He in the Presence of a Heat Current 


Principal Investigator: Prof. Guenter Ahiers 

University of California, Santa Barbara 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objective of this project is to study the superfluid transition in a heat current. One issue which we are 
addressing is whether the superfluid transition remains continuous in the presence of a heat current. A second 
objective is to make measurements of the effective conductivity of the system very close to but slightly above the 
transition temperature T x as a function of the current. 


Task Description: 

Theoretical work by Onuki has predicted that the transition will be hysteretic. We are looking for this hysteresis in 
a finite current. Onuki’s theory does not take the effect of gravity into consideration, and it is not clear to what 
extent the gravitationally induced inhomogenity will hide the predicted effect. Recent calculations by Haussmann 
and Dohm have indicated that a nonlinear range of parameter space should be accessible where the conductivity will 
depend upon the current. This range will be exceedingly close to T x where the ultra-high resolution thermometry 
developed previously in our laboratory will be essential, and where gravity effects will play an important role. 


Task Significance: 

We expect that our earth-bound measurements will yield information about possible advantages to be gained from 
micro-gravity experiments. We will have to determine whether gravity effects completely obscure the nonlinear 
regime, thus necessitating microgravity experiments in order to make these nonlinear effects observable, or whether 
useful information can be obtained in an earth-bound laboratory. 

Progress During FY 1994 : 

Since January 1, 1994 we have continued to study the finite heat current effect on the thermal conductivity of 4 He 
near the lambda transition. The following progress has been made: 

We finished developing a computer code to calculate the two-dimensional temperature field in our cell. The 
simulation gave results in agreement with known experimental results and enhanced our understanding of our 
experimental data, particularly in the Hel-Hell coexistence region. Furthermore, it indicates that the side wall of our 
cell has a negligible effect in studying the nonlinear thermal conductivity of 4 He. 

To analyze the experimental data we obtained last year, we have developed a computer code to do nonlinear least 
squares fitting of our experimental data. This is nontrivial due to the complexity of the model which involves a 
number of numerical procedures. With this program we have perf ormed extensive data analysis using different trial 
models of conductivity. 

Quantitative comparison of our data with the theoretical prediction by Haussmann and Dohm requires the numerical 
evaluation of the Haussmann and Dohm formulas. With generous support from Dr. Haussmann and Professor 
Dohm we have developed a computer program to evaluate the theoretical predictions for the thermal conductivity of 
4 He as a function of heat current and distance from T,. This enabled us to make quantitative comparison between our 
experimental data and the Haussmann and Dohm theory. We shared our code with Dr. Rob Duncan’s group at 
Sandia National Lab, since it is equally important to their NASA sponsored research. 


mmiii 


III 


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II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

mill! 


Our initial data analysis indicated that further experimental data with cells ol dilterent thicknesses are needed. We 
constructed an experimental cell with 0 . 4 mm thickness, as compared to 1 . 1 mm in the previous experiment. This 
cell was installed in our apparatus, cooled down, and used to take data. The analysis ot this second set ol results in 
now well under way. A third cell, ot thickness 0.8 mm, will also be used in the near luture. 

Finally, a detailed written report was completed and submitted to JPL following the January 1994 NASA workshop 
in Washigton DC where we (Professor Guenter Alders and Dr. Feng-Chuan Liu) 
each presented an oral report. 


Students Funded Under Research: Task Initiation: 1/93 Expiration: 12/95 

Project Identification: 962-24-07-17 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Proceedings 

Ahlers. G. "Dynamics of the supertluid transition of 4He." Proceedings ol the NASA/JPL 1994 Microgravity Low 
Temperature Physics Workshop. 

Liu, F.C., and Ahlers, G. "The effect of a finite heat current on the lambda-transition and on the thermal conductivity ol 
4He.” Proceedings of the NASA/JPL 1994 Microgravtty Low Temperature Physics Workshop. 


IIIIMMII.tlMI.il. .ItllM.HMMm.lMimimill.M.K 


11-160 



II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

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Microgravitv Test of Universality and Scaling Predictions Near the 'He Critical Point 

PRINCIPAL INVESTIGATOR! Dr. Martin B. Barmatz Jet Propulsion Laboratory (JPL) 

Co-Investigators: 

U.E. Israelsson Jet Propulsion Laboratory (JPL) 

J. Rudnick University of California , Los Angeles 


Task Objective: 

The objective ot this task is to test the universality and scaling laws at the liquid-gas critical point of 3 He in a 
microgravity environment. The task objectives will include 1) precision measurements of the isothermal 
compressibility along the critical isochore to determine the critical exponent g and 2) precision measurements of the 
constant volume specific heat along the critical isochore to determine the critical exponent a. 

Task Description: 

Theories describing the behavior of thermophysical properties near critical points were developed using die concept 
ot scaling laws. These models led to the definition of universality classes where critical points of the same class arc 
predicted to have the same critical exponents. Efforts to validate the scaling law predictions near a liquid-gas critical 
point in ground-based laboratories are limited due to the gravity induced vertical density gradient associated with die 
divergence of the isothermal compressibility. This density gradient becomes appreciable as the critical point is 
approached leading to a significant smearing of the transition. Calculations have shown that in a microgravity 
environment (10' 6 g) accurate specific heat and isothermal compressibility measurements could be obtained two 
orders of magnitude in reduced temperature closer to the critical point. Techniques are being developed for the 
simultaneous measurement of both static (specific heat, sound velocity, and compressibility) and dynamic (sound 
attenuation and dispersion) properdes. These studies will require accurate measurements of pressure (Dp/p - 1 O ' ‘), 
density (Dp/p - 10‘ 9 ), and temperature (DT/T ~10‘ 9 ). ). 

Task Significance: 

The ability to perform these simultaneous measurements in microgravity should provide a very stringent test of the 
universality predictions. 

Progress During FY 1 994: 

During FY94, we designed , fabricated, and tested a GdCl 3 high resolution thermometer for operation at the He 3 
critical point, T C =3.3K. This GdCl 3 HRT was shown to have the same sensitivity at the He 3 critial point as a CAB 
HRT has at the Lambda Point. A new magnetostrictive fluid transfer valve was also demonstrated at liquid helium 
temperatures for use at the He 3 critical point. 


Students Funded Under Research: Task Initiation: 12/92 Expiration: 11/95 

Project Identification: 962-24-04-07 
Responsible Center: jpl 


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II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

„„„ 


Bibliographic Citations for FY 1994: 

Proceedings 

Barmatz. M.. and Hahn. I. "Microgravity test of universality and scaling theory predictions near the liquid-gas critical 
point of 3He." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 

Hahn, I.. and Barmatz. M. 'Application of GdC13 thermometry at temperatures near the liquid gas critical point ot 3He. 
Proceedings of the NASA JPL 1994 Microgravity Low Temperature Physics Workshop. 

Rudnick. J., and Barmatz. M. "Effects of random motions on critical point measurements." Proceedings of the NASA/JPL 
1994 Microgravity Low Temperature Physics Workshop. 




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II. MS AD Program Tasks — Ground-based Research Discipline: Benchmark Science 


Measurement of the Heat Capacity of Superfluid Helium in a Persistent-Current State 


Principal Investigator: Dr. Taiso c. Chui 

Jet Propulsion Laboratory (JPL) 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objective of the task is to detect any changes in the heat capacity of helium as result of superfluid flow very 
near the superfluid transition temperature. 

Task Description: 

The flow will be created in a toroidal shaped calorimeter in the form of persistent current. The heat capacity is then 
measured from below to above the transition, where the persistent current will decay to zero. The heat capacity will 
subsequently be remeasured below the transition to detect any difference. If the experiment shows that the heat 
capacity is different with superfluid flow, then a space experiment can be designed to map out the heat capacity 
curves as a function of temperature and superfluid velocity. 

Task Significance: 

The results will be compared to the dynamic renormalization group theory, which have recently been applied to 
calculate the expected results. The theory, which involves three adjustable parameters, is remarkably successful in 
explaining the thermal conductivity and the second sound damping near the lambda transition. The proposed 
experiment will give a much more stringent test of the theory because this new experimental situation allows die 
theory to make precise predictions without any additional adjustable parameters. 

Progress During FY 1 994: 

Recently there was new experimental evidence supporting the idea initially proposed by us that in heat flow 
experiment near the lambda transition, the first rise in temperature is associated with vortex creating of the type 
proposed by Langer and Fisher to explain the intrinsic critical velocity observed by Clow and Reppy in a superfluid 
gyroscope. If this interpretation is correct, it would affect the experiment design significantly. First, the real shift 
in the lambda transition temperature as predicted by the renormalization group theory (RG) cannot be easily reached. 
Second, the region where vortex creation is not important, and the RG prediction can be realized may be at It I < 10' K 
where t is the reduced temperature. Therefore in a heat current arrangement, measurement of the heat capacity at It I 
> 10 4 would probe the effect of vorticities on the heat capacity rather than the effect of RG. 

Based on these development, the emphasis of the experiment has shifted to charting the region of experimental 
interest where the RG prediction can be realized. And then designing an experiment that would work in this region. 
An experimental cell has been fabricated for this purpose. The apparatus has been in operation for over a year with 
high resolution thermometers capable of resolving temperature to 5xl0' n K/Hz 1/2 . The germanium resistance 
thermometers and the high resolution thermometers are fully interfaced to a computer with real time graphic 
software based on LabView G language. The PCD temperature controllers are based on software digital control 
implemented with Labview. We are current working at integrating the cell and all the software and hardware 
together. A first run is planed early next year. 


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II. MSAD Program Tasks 




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Ground-based Research 

Itllllllll 


Discipline: Benchmark Science 

mini, mu HIM 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 12/92 Expiration: 11/95 
Project Identification: 962-24-04-08 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Proceedings 

Chui TCP Day P„ Hahn. I., Nash. A.E.. Swanson. D.R.. Nissen. J.A.. Williamson. PR. and Lipa. J.A. High 
resolution thermometers for ground and space applications.” Proceedings of the 15th International Cryogenic 
Engineering Conference. Genova Italy 1994. 

Day, P., Chui, T„ and Israelsson. U. "Heat capacity of helium under superfluid flow conditions." Proceedings of the 
NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 

Tonucci R J Chui. TCP.. Israelsson. J.A. and Lipa. J.A.. "Application of nanochannel array for the studies of finite 
size effects near a second order phase transition." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature 
Physics Workshop. 

Yeh N C Strayer. D M.. Chui. T.C.P.. and Lysek. M.J. "Exploring the helium lambda transition using a high-Q 
microwave cavi'ty." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 




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II. MSAD Program Tasks 

"" 


— Ground-based Research 

Illll Mil 


Discipline: Benchmark Science 

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Nonequilibrium Phenomena Near the Lambda Transition of ‘He 

Principal Investigator: Dr. TaJso c. Chui 

Jet Propulsion Laboratory (JPL) 

Co-Investigators: 


Dr. Ulf Israelsson 

Jet Propulsion Laboratory (JPL) 


Task Objective: 


The objective of this project is to obtain information on the order-parameter relaxation time in superfluid helium 
near the lambda transition. 

Task Description: 

The experiment will measure the heat capacity of superfluid helium near the lambda transition under a pressure 
oscillation at variable frequency. There will be a small change in the averaged heat capacity when the frequency is 
increased above the reciprocal of the order-parameter relaxation time, thus allowing a measurement of the relaxation 
time. The proposed technique is well suited for performance in space where close approach to the transition is 
possible without the smearing effect of gravity induced inhomogeneity. Since the relaxation time is predicted to 
slow down considerable near the transition, geting closer to the transition will avoid problems on earth assiciated 
with extremely fast relaxation. 

Task Significance: 

The order-parameter relaxation time is an important parameter characterizing all dynamic processes in a phase 
transition. Accurate measurement ol this quantity will allow a stringent test of the dynamic renormalization group 
theory which can be applied to predict the behavior of this quantity with no adjustable parameters. 

Progress During FY 1 994: 

Parts have been fabricated for the experimental probe, This probe is a duplication one that is currently in service for 
mother project. A new post doctoral associate will join the group and begin conducting experiments in March 1995. 
Some calculations were performed to understand thermodynamics of helium under a sudden pressure quench. 


Students Funded Under Research: Task Initiation: 9/94 Expiration: 8/96 

Project Identification: 962-24-04-12 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Proceedings 

Chui, T.C.P. and Israelsson, U.E. Heat capacity under pressure oscillations- a proposal to measure the order-parameter 
relaxation time in space. Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 


IIIIIIMM<miMIMIHIIIIIIIIMI||||IIIIIIIIIHIIIII|IIIIHIII«MIIII|IIHmiHHlll 


miHIMImail IIIMIIMMIHIIIIHiniHIIHMIimMIM Hill Ill Hill 


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II. MSAD Program Tasks - Ground-based Research PlKlpItem BmKhmrir 








Determination of the Correlation Length in Helium II in a Microgravity Environment 


Principal Investigator: Prof. Russell j. Donnelly 

University of Oregon 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

The objective of this research is to measure finite size effects in the isobaric expansion coefficient near the lambda 
transition in liquid helium. We will measure the thermal expansion coefficient tor liquid helium confined between 
parallel plates for a range of temperatures very near the lambda transition temperature (both above and below), a 
range of pressures from SVP to about 25 bar, and a range of plate separation distances. 

Task Description: 

We will measure the dielectric constant of helium confined between parallel plates as a function ot temperature at 
constant pressure. Using the Clausius-Mossotti relation, the density and thus the expansion coefficient of hqui 
helium will be calculated. The experimental method involves two measurements (at a given temperature) o e 
balancing ratio of an audio-frequency ratio-transformer capacitance bridge, one with the sample capacitor empty an 
then one with it filled with liquid helium. Appropnate division of these ratios then yields directly the dielectric 

constant at that temperature. 

The capacitor used to measure the dielectric constant is a parallel-plate design operated as a three-terminal device in a 
1-kHz ratio-transformer bridge. The spacing between the electrodes is determined by a precision shun which can be 
easily changed. An identical capacitor is also mounted on the experimental platform and is operated empty as a 
reference capacitor. We expect to vary the thickness of the shims between 5 microns and 50 microns. 

Initially germanium thermometry will be used for temperature control and measurement. This will allow us to 
easily cover a wide range of temperature and to gain familiarity with the experiment. At this stage we wi wan 
reconcile our results with older, published data. High- resolution measurements will be made after installing a 
paramagnetic salt thermometer identical to that used by John Lipa in his lambda-point heat capacity experiment 
(LPE), which successfully flew on STS-52 in October ot 1992. 

Task Significance: 

Finite size effects are manifested as a rounding of the divergence in thermodynamic functions near a critical point as 
the correlation length increases toward the system size. We can thus test renormalization group theory predictions, 
universality assumptions, and boundary conditions. 

Progress During FY 1994: 

The bulk measurements of density and expansion coefficient have been completed and will appear in J. Low Temp. 
Phys vol 98, nos. 1/2, 1995. This work has identified interelectrode stray capacitance as the major source ot error 
af fecting the many experiments measuring dielectric constant of helium, and helps to explain the wide discrepancy 
in reported values of the deduced density over the last several decades. We are presently working with Dr John Lipa 
of Stanford University to ascertain the possibility of taking the cryostat to Stanford to be fitted with high 
resolution thermometers there and then returned to Oregon for use in measuring density in finite-size gap capacitors 
in support of the CHEX experiment. Our experience with the bulk measurements should be invaluable in 
eliminating sources of error which would ruin any tinite-size experiment. 


mm. iHiimmmimmiii minimi 

11-166 






H MSAD Program Tasks — Ground-based Research 

iiimmi n Mini. .mum, , , 


Discipline: Benchmark Science 

IMIlllli.llMIMMMIIIIIIimMIIIMIIMIIIIIIIMIIIIIIIMIIIIIIIIIIIMIMIMIIMIMIIMIIimilllll 


Students Funded Under Research: 

BS Degrees: 0 

MS Degrees: 0 

PhD Degrees: 4 


Task Initiation: io/89 Expiration: 9/94 
Project Identification: 962-24-04-04 
Responsible Center: jpl 


Bibliographic Citations for FY 1994 : 

Proceedings 

Niemela, J.J., and Donnelly, R.J. 'Density and dielectric constant measurements in liquid helium." The Proceedinds of the 
NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 


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II MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 




Nucleation of Quantized Vortices from Rotating Superfluid Drops 


Principal Investigator: Prof. Russel) J. Donnelly 

University of Oregon 

Co-Investigators: 


J. Niemela 

University of Oregon 

W-K Rhim 

Jet Propulsion Laboratory (JPL) 


Task Objective: 

The objective of this research is to study die nucleation of quantized vortices in helium II by investigating the 
behavior of rotating droplets of helium II in a reduced gravity environment. 

Task Description: 

Two methods well-suited for levitating the helium drop in the near vacuum environment are electrostatic and/or 
magnetic levitation. A pure electrostatic scheme requires active feedback control. whUe a purely magnetic levitation 
requires large fields. A hybrid system is probably the best choice. Rotation can be accomplished by coupling to a 
charge distribution on the drop surface. We will initially use purely electrostatic levitation tor studying drops. The 
required charging of the drops can be accomplished by forming the drops around a sharp electrode tip held at a high 
voltage. Film How of helium II can be utilized to create drops at the bottom of a suitable container which can be 
filled by a fountain pump and situated above a pair of capictor plates having an appropriate voltage difference 
between them. 

Task Significance: 

Nucleation phenomena, in general, are fundamental to many fields ot physics and engineering. In the case ol a 
rotating supertluid drop it will be possible to produce a state of zero nucleation, analogous to growing a perfect 
defect-free crystal. It should also be possible to add a controlled impurity to cause nucleation of a quantized vortez 
line in the drop. At low enough temperatures, this will be a pure quantum mechanical tunnelling phenomenon. At 
higher temperatures it should be possible to see thermally activated nucleation taking over, tor a demonstration ot 
nucleation under more familiar classical conditions. In conventional systems it is evident that vortex lines come 
from some preexisting source, probably vortices trapped by pinning sites on the walls. While this kind ot source 
of vorticity is undoubtedly important, it is not as fundamental as the "extrinsic nucleation" problem where vortex 
line appears when none was present before. 

Progress During FY1994: 

We have improved the drop forming process to have variable control over the drop rate using a small uniformly 
distributed heater on the film flow vessel. The upper limit is dteimined by the smallest perimeter of the vessel 
above the free surface of helium contained in it, which tor 1 mm size diameter drops produced from a nominally 1 
cm diameter vessel is about 1 drop/s. The use of various tapers at the tip of the film flow vessel enables us to vary 
the drop size. We have produced both positive ions (ionized helium atoms) and negative ions (electron bubbles) 
using sharp tungsten field ionization or emission tips respectively. The best tips produce negative ions at a 
threshold voltage of about 400V and positive ions at a threshold of approximately 1500 V. Currents are in the 
range of picoamps for pure ionization or emission, but can increase to microamps by increasing the voltage enough 
that a vapor bubble troms around the tungsten tip. The tips are tested in the bath and the presence of ions is 
indicated either by observing the current flowing from a collector plate to an electrometer or by observing an 
"electric fountain" which forms in response to an ion stream. The amount ot current measured tor pure ionization is 
sufficient to charge the drops of 1 mm diameter, and at a rate of 1 drop/s. Very small micron size droplets have 
been briefly levitated, but in an uncontrolled manner, by picking up charge from a glow discharge of the tips or an 
arcing discharge through the helium vapor. We are currently working on charging single large diameter drops by 
pulsing the voltage to the ionization tips to avoid secondary cascading effects in the vapor which "bum out" the 




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II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

ii turn 


tips. We have completed a theoretical study of the equlibrium configuration of a single vortex in a freely rotating 
superfluid drop (JLTP Vol. 98, Nos 1/2, 1995) and are working on extending these calculations to include 
multiple vortices. 


Students Funded Under Research: Task Initiation: 1/93 Expiration: 12/95 

Project Identification: 962-24-07-12 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Proceedings 

Bauer, G., Donnelly. R.J., and Vinen, W.F "Vortex configurations in a freely rotating superfluid drop.’’ Proceedings of the 
NASA\JPL 1994 Microgravity Low Temperature Physics Workshop. 

Donnelly, R.J. "Superfluid Drops: An Overview." Proceedings of the NASAVJPL 1994 Microgravity Low Temperature 
Physics Workshop. 


HIHIIIIIIIIII I ill li'illit 1111111111 hi IIIIIIIMIMIIIIIIIIIIIIIIIIIIIIIIIIIIMIMIIIIIIIIIIIIIIIIIIIIMIIIIIII 


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II. MS AD Program Tasks — Ground-based Research Discipline: Benchmark Science 

mm 


Kinetic and Thermodynamic Studies of Melting-Freezing of Helium in Microgravity 


Principal Investigator: Prof. Charles Eibaum 

Brown University 

Co-Investigators: 


J.M. Kosterlitz 

Brown University 

Task Objective: 


The objective of this project is to study, experimentally and theoretically, the effects of gravity on the 
melting-freezing transitions, including kinetic processes and the equilibrium shape of solids. The research is earned 
out on helium, whose unique properties render such investigations possible on a time scale consistent with 
experiments in space, under microgravity conditions. Indeed, morphological changes of the solid-liquid interface 
(i.e., the "surface" of helium) generally occur fast enough to satisfy the time constraints mentioned above. 

Task Description: 

An optical system with special lighting applied to a growth cell contained in a liquid helium dewar allows viewing 
of the solid-liquid Interface (SLI) and of crystal shapes. Rapid image capture equipment allows recording of the 
evolution of the SLI and of the crystal shapes in response to changes in temperature and pressure. 

Task Significance: 

These studies are addressing a number of fundamental questions, especially as they relate to the effects of gravity. 
These questions include the kinetics of first order phase transitions, the critical behavior in the evolution of crystal 
shapes as they approach equilibrium, faceting-roughening phenomena on various surfaces, relative and absolute 
values of interfacial free energy for different crystal faces, and the minimization of a system's free energy subject to 
various constraints. Furthermore, many applications should benefit from a deeper understanding of the above 
phenomena, among them crystal growth, surface configurations, sintering, and surface reactivity. 

Progress During FY1994: 

In our quarterly report submitted in May, 1994, we discussed our observations and some preliminary conclusions on 
crystal growth of body-centered cubic (b.c.c.) helium-four. These studies have continued, with the addition of 
nucleation, growth, and morphology of hexagonal close-packed (h.c.p.) crystals ot helium-tour. 


We have extended these investigations to cover wider ranges of temperature, pressure, and rates of crystal growth. 
Our observations on both b.c.c. and h.c.p. helium four can be summarized as follows. 

1. b.c.c. solid helium-four 

In the temperature, , and pressure, P, range of existence of the b.c.c. helium-four phase (1.43K < T < 1.76K and 
26.1 atm < P < 30.1 atm), this solid behaves, in many respects, like viscous fluid. It should be emphasized that 
b.c.c. solid helium is characterized by translational symmetry and long range order typical of ordinary solids, as 
demonstrated by x-ray diffraction. Furthermore, the solid supports high frequency elastic shear waves and its 
smallest elastic shear modulus, measured at high frequency, is of the same order of magnitude as the longitudinal 
modulus. In particular, it is found that b.c.c. crystals formed at the top of a container filled with liquid (superfluid) 
helium, deforms under gravity into a pseudo-spherical shape. This observation indicates that the solid-liquid 
interfacial tension is essentially isotropic, in agreement with earlier findings. The time constant involved in this 
deformation (spherical shape acquisition) is of the order of a few seconds. The mass transport mechanism involved 
in this process is now being investigated. Our preliminary conjecture is that quantum mechanical tunneling of 
defects (primarily vacancies) is the predominant mechanism. Additional experiments to test this hypothesis are in 
progress. 


iiiiiitimmi* iiihiihihihhhiihhihiii •mmiim.iiuihhi mil 


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II. MS AD Program Tasks — Ground-based Research Discipline: Benchmark Science 

* * * * MIII(IIMI 


II. The study of h.c.p. helium-tour crystal growth from the normal fluid yields results in sharp contrast to those 
lound tor the b.c.c. case. Indeed, the shapes of h.c.p. crystals and the characteristics of the solid following 
solidification are remarkably different. In particular there is no evidence of the solid undergoing any measurable 
deformation under gravity, within the observation times available; this restricts any possible deformation rates to at 
least three orders of magnitude lower values that what is observed in the b.c.c. solid. 

Another important factor emerging from the comparison of the behavior of b.c.c. and h.c.p. helium-four during and 
immediately following solidification concerns the effects of temperature on the processes under study. As 
mentioned above, the solidification of the h.c.p. phase took place from normal fluid, i.e. at higher temperatures than 
those of the b.c.c. phase. There is, however, no evidence of mass transport resulting in observable flow and 
deformation of the solid, while these characteristics are very prominent in (the lower temperature) b.c.c. phase. This 
indicates that the flow processes are not the same in the two phases and that if they are thermally activated, their 
activation energies are drastically different. Moreover, since the flow rates appear to be independent of temperature 
in the b.c.c. phase (over the limited range investigated), our tentative conclusion is that quantum mechanical 
tunneling of vacancies in the predominant mechanism of mass transport in the deformation of b.c.c. helium-four. 


The theoretical studies earned out since the last report consist of two parts. The first consists of numerical 
simulations of growth of a solid from a liquid in the presence of impurities which tend to concentrate at the 
interface. This was modelled by modifying the free energy F( f, c) by adding a term that is a function of the 
conserved impurity concentration,^ and the order parameter f (-1 in the bulk liquid, +1 in the solid). The function 
was chosen to make c large at the interlace when the gradient of f is large. Simulations were performed with initial 
conditions corresponding to a uniformly undercooled liquid. The results are in accord with our most naive 
expectations that this new interlace term is just equivalent to reducing the stiffness constant or surface tension at the 
interface so no qualitative differences were observed. The interface became rougher and more convoluted but this is 
just a quantitative change and no new and unexpected effects were observed. 

Some progress has been made on the problem of dealing with advection of mass from the liquid to the solid and the 
density difference between the two phases. Since experiments indicate that the b.c.c. phase of solid 4 He allows for 
mass flow, the superfluid/b.c.c. solid system can be treated as a binary fluid mixture where the kinematic viscosity 
of the supertluid vanishes and is large in the solid. There is also a 10% density difference between the two phases, 
so gravity has significant effects. We have constructed a free energy functional F(r,f ) and dynamical equations 
accounting for advection. We are intending to carry out numerical analysis of these equations starting from initial 
conditions for a uniformly undercooled superfluid and study the evolution of the solid. Gravitational effects can be 
included in our equations of motion. This constitutes a fairly realistic description of the solidification process. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 1/93 Expiration: 12/95 
Project Identification: 962-24-07-13 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Proceedings 

Elbaum, C., and Kosterlitz. J.M. "Kinetic and thermodynamic studies of melting-freezing of helium in microgravity." 
Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 


11-171 



II. MSAD Program Tasks — Ground-based Research 


Discipline: Benchmark Science 


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Theoretical Influence of Microgravity on Critical Fluid Measurements 


Principal Investigator: Prof. Richard a. Ferrell 

University of Maryland 

Co-Investigators: 

No Co-I’s Assigned to this Task 



Task Objective: 

This endeavor is tailored to provide theoretical support for these current critical fluid microgravity Space Shuttle 
experiments: the Critical Fluid Light Scattering Experiment (ZENO), the LeRC Critical Fluid Thermal 
Equilibration Experiment (CFTE), and several other microgravity experiments are now in the definition phase. 

Task Description: 

The science activity will examines six areas; three each for classical fluids and three each for super-fluid Helium. 
Regarding classical fluids, they are: 

1 . Short and long time scale equilibration driving torces. 

2. The anomalous dimension critical exponent ot the density fluctuation correlation length. 

3. Shear viscosity near the liquid- vapor critical point . 

Regarding super-fluids, they are: 

1 . A better prediction of the thermal conductivity temperature scaling. 

2. The frequency dependence of the shear viscosity. 

3. Theoretical insight into the unexpected temperature dependence of the second-sound velocity ot 4 He near its 
Lambda transition. 

This effort will employ a graduate student, a part-time post-doctoral fellow, and a visiting faculty fellow to assist in 
this work. 

Task Significance: 

The results of the proposed study will both aid the interpretation ot the data and demonstrate the need tor the data 
from the objective microgravity experiments, confirming science conclusions. The conclusions will greatly 
improve the cost effectiveness of the science from identified flight experiments. 

Progress During FY 1 994: 

This task was extended only slightly into FY94 to allow administrative closeout. All objectives were accomplished 
by the end of FY93 and reported previously. 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 0 MS Degrees: 0 

PhD Students: 2 PhD Degrees: 2 


Task Initiation: 1/91 Expiration: i/94 
Project Identification: 962-24-05-32 
NASA Contract No.:nag3-H80 
Responsible Center: LeRC 





11-172 



II. MSAD Program Tasks — Ground-based Research 

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Discipline: Benchmark Science 

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Condensate Fraction in Superfluid Helium Droplets 
Principal Investigator: Prof. j. woods H;diey 


Co-Investigators: 

C. Giese 
C. Campbell 
K. Goetz 


University of Minnesota 


University of Minnesota 
University of Minnesota 
University of Minnesota 


Task Objective: 

The scientific goal ol the proposed project is to obtain information about the condensate fraction in supertluid 
helium tour by studying elastic scattering of helium atoms from a freely floating macroscopic sphere of the fluid. 

Task Description: 

During the second year we have initiated experiments on the use of C s covered surfaces to partially suspend He for a 
ground based experiment. We are making computational studies of various magnetic suspension methods. Many 
body calculations of transmission rates in the experiment have reached the stage of explicit numerical simulation, 
which is under way in collaboration with S. Chin of Texas A and M. 

Task Significance: 

The condensate traction ot the supertluid helium wavetunction is the microscopic manifestation of bose 
condensation which is universally believed to be the origin of the fluid's supertluid properties (as originally 
proposed by London more than 50 years ago). If successful, the experiment would be important because direct 
experimental study of the condensate traction has proved extremely elusive. Only neutron scattering experiments 
give direct information and interpretation of these has proved difficult. 

Our basic idea is that in a microgravity environment, it will be possible to do a tunneling experiment (analogous to 
a Josephson tunneling experiment in some respects) in order to study the condensate. We envision sending pulses 
ot gaseous helium atoms at one side of a suspended sphere of supertluid helium four and detecting helium atoms 
emerging in coincidence from the other side of the sphere. 


Progress During FY 1 994: 

The objective of this project is the completion of a ground based study of the scientific and technical feasibility of 
an experiment in which the presence and nature of the long range quantum coherence (condensate) in supertluid 
helium four is detected. Pulses of gaseous helium will be fired at a suspended droplet of supertluid helium four and 
the resulting emission of helium atoms will be detected. 

Theoretical results from the previous fiscal year are reported in Halley and Campbell (PRL 1993), Campbell (JLTP 
1993), Halley (JLTP 1993), and Halley (Physica 1994). This work suggested the existence of a large effect but also 
clarified the need for a more complete many body analysis of the problem. Analytical aspects of this analysis have 
been completed in the past year and numerical work has been undertaken to make the needed variational calculations 
with post doctoral visitor Sang Hoon Kim. 

The first ground based experiment, undertaken in collaboration with I. Silvera of Harvard University, was finished 
during this fiscal year. In this experiment, pulses of helium were fired at the horizontal surface of liquid helium at 
one end of a U-shaped copper tube about 3 in in length and 0.25 in in diameter. A detector at the horizontal liquid 
helium surface at the other end ot the tube can detect re-emitted helium atoms. Mark Williams of this group spent 
several months in Cambridge working on this experiment. The experiment, which was not ideal in several respects 

. ........ 


II— 1 7 3 



II. MSAD Program Tasks — Ground-based Research 

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Discipline: Benchmark Science 



with regard to observing the effect, did not show evidence tor prompt re-emission of helium atoms from the surface 
at the remote end of U tube. 

We are engaged in studies for two further types of ground based experiments. M. Williams is carrying out an 
experiment at Minnesota to test the feasibility of a method for producing two parallel helium surfaces using the tact 
that cesium surfaces are not wet by supertluid helium four. A capacitive bridge for measunng liquid levels has been 
constructed and a preliminary experiment testing this idea will be run very soon. 

Magnetic supsension has often been suggested as a method for droplet suspension of liquid helium in a microgravity 
environment. Experiments at Brown are currendy under way to achieve magnetic suspension ot helium droplets on 
earth using superconducting magnets. As an alternative J. Schmidt of this group has initiated a study ot the 
possibility of using permanent magnets for this purpose. If it can be achieved this method would have great 
advantages with respect to simplicity and expense. It may even be possible to achieve suspension ot helium droplets 
on earth using permanent magnets. To study these possibilities, Mr. Schmidt has been developing computer codes 
for determination of the optimum configuration of permanent magnets. 


Students Funded Under Research: 

BS Studeius: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: i/93 Expiration: 12/95 

Project Identification: 962-24-07-14 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals . , T ■-»-> D . 

Campbell C. E. Remnants of bose condensation and off-diagonal long range order in hmte systems. J. Low Temp Rhys,, 

Vol 93, 907 (1993). 

Halley, J. W. Structure of the condensate and some possible ways to observe it.. J. Low Temp. Phys.. Vol. 93, 893 
(1993). 

Halley, J. W. A novel approach to the observation of the condensate fraction in superfluid helium-four. Physica, Vol B97 
175 (1994). 


Proceedings . . . 

J. W. Halley 'Theoretical studies of manifestations of long range quantum coherence in He in atom-droplet interactions. 

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 


J. W. Halley ’ Ground based experiments to observe long range quantum coherence in superfluid He using atomic beams. 
NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 


Presentations 

Campbell. C.E. "Recent developments in liquid helium-four Eighth International Conference on Recent Progress in 
Many Body Theories, August 1994. 

Giese, C. "A novel approach to the observation of the condensate fraction in superfluid helium-four. Eighth AIAA 
Symposium on Microgravity Science, Reno, Nevada, January 10-13. 1994. 

Halley, J.W. "Formulations of the many body atom-droplet scattering problem." Workshop on Future Directions of 
Quantum Many Body Theory, January 14-16, 1994. 

Halley, J.W. "Looking for new experimental manifestations of long range quantum coherence in superfluid Helium-4. 
Physics Colloquium, North Dakota State University, Fargo, ND, February 2, 1994. 

Halley, J.W. "Looking for long range quantum coherence in superfluid helium." Physics Seminar at St. Olaf College, 
Northfield, MN, March 23, 1994. 


* ...» * «""« *" H " * 


11-174 



II. MSAD Program Tasks 

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— Ground-based Research 


Discipline: Benchmark Science 

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Halley. J.W. Evaluating experimental ideas tor observing long range quantum coherence in superfluid helium." Invited 
talk at the American Physical Society Washington meeting. Apnl 19. 1994. 

Halltv. J.W. Looking tor long range quantum coherence in superfluid helium." Condensed Matter Theory Seminar Ohio 
State University. Columbus. OH. April 18. 1994. 

Halley, J.W. 'Evaluating experimental ideas for observing long range quantum coherence in superfluid helium." 
Workshop on Quantum Fluid Clusters. Ringberg, Schloss. Kreuth-Oberhof, Bavaria, June 12-15, 1994. 

Williams. M. "Ground based experiments on quantum coherence in helium-four." NASA Graduate Student Researchers 
Program 1994 Annual Symposium, Washington, DC, May 11-13, 1994. 





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11-175 



II. MSAD Program Tasks — Ground-based Research 

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Discipline: Benchmark Science 

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Ultra Precise Measurements with Trapped Atoms in a Microgravity Environment 


Principal Investigator: Dr. Daniel j. Heinzen 

University of Texas, Austin 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The task objective tor FY94 is to trap laser-cooled Cs atoms in an "optical box" atom trap. Dunng our preliminary 
work, we have already demonstrated the trapping of 10 7 Cs atoms at a temperature ot 100 pK in a magneto-optical 
atom trap (MOT). During the upcoming year we plan to design and to implement the lasers and optics required to 
generate an "optical box", which will be formed by six intersecting, elliptically focussed laser beams. We also plan 
to demonstrate that atoms from the MOT can be confined to the interior of this box. This constitutes the first step 
to realize our ultimate goal, which is to develop instruments and techniques that can be used to carry out precise 
measurements with atoms trapped in such a box, in a zero-gravity environment. 

Task Description: 

In order to demonstrate the "box" trap, the Cs atoms will first be captured in a magneto-optical atom trap (MOT). 
This trap can easily capture about 10 7 atoms into a 1 mm 3 volume directly from a very dilute room temperature Cs 
vapor. The Cs atoms will then be released from the MOT, and begin to tall under the influence of gravity. At the 
instant they are released, the optical box trap will be turned on, thus capturing a large fraction ot the atoms from the 
MOT. The box trap will be formed by six laser beams of elliptical cross section, that are tuned to the high 
frequency side of a Cs optical resonance line. These beams will be generated from a Ti:sapphire laser, prism beam 
expanders, and focussing optics. They will be intersected so as to form a cubical surface ot light. Atoms striking 
the "walls" of the cubical surface will experience a repulsive optical dipole force that confines them to the interior 

of the box. 

Task Significance: 

Precision atomic resonance devices have tremendous practical and scientific importance. An important example is 
the atomic clock, which has widespread applications to navigation, geophysical measurement, and astrophysics. 
Precise tests of fundamental scientific principles such as time-reversal symmetry are also carried out with such 
devices. Substantial advances in the accuracy of these devices are therefore ot great importance. One very promising 
avenue is to make use of ultracold, laser-cooled atoms. These atoms can move as much as 10,000 times more 
slowly than the atoms in conventional devices. This very low velocity can in principle substantially increase the 
accuracy of an atomic resonance device. This is because certain measurement errors are proportional to the velocity 
of the atoms. Unfortunately, gravity seriously limits the usefulness ot laser-cooled atoms tor this purpose, because 
it quickly accelerates the atoms to back to high velocities. Thus, only in the gravity-free environment of space can 
the full potential of these ultracold atoms be realized. Our goal is to develop techniques that could be used to 
produce and store a large number of ultracold atoms in the gravity free-environment of space. If successful, atomic 
resonance devices based on these techniques could lead to dramatic increases in accuracy. 


Progress During FY 1 994: 

The start date for this project was Sept. 7, 1994, and only a few weeks have elapsed since this date. However, some 
initial work on this project was carried out prior to the start date. During this time, we have built a magnetically 
shielded magneto-opucal atom trap, and used it to trap 10 7 Cs atoms at a temperature of about 100 |lK. The trap 
consists of a Cs vapor cell that is evacuated to a pressure of 10' 8 torr with an ion pump. Laser beams from two 
frequency-stabilized, grating-tuned diode lasers are used in conjunction with a quadrupole magnetic field to trap and 
cool that atoms from the background Cs vapor. We are currently carrying out Zeeman resonance experiments on 
these atoms, and are designing the optics to produce the "box” trap discussed in the task objective. 




11-176 


II. MSAD Program Tasks — Ground-based Research 


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Discipline: Benchmark Science 




Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 9/94 Expiration: 9 /% 
Project Identification: 962-24-08-14 
NASA Contract No.:nag8-io90 
Responsible Center: msfc 


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11-177 


II. MSAD Program Tasks — Ground-based Research 

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Discipline: Benchmark Science 

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Principal Investigator: Dr. uif e. israeisson 

Jet Propulsion Laboratory (JPL) 

Co-Investigators: 

R.V. Duncan 

Sandia National Laboratory 

Task Objective: 



The objective of this work is to perform dynamic measurements on a short cylindrical sample ot helium very near 
the lambda-point in an effective gravity environment of about 0.01 g. Dynamic conditions will be create y 
passing a heat current through the sample. The effective low-gravity environment will be created by applying a 
magnetic field gradient which closely cancels hydrostatic pressure differences m the sample. Specifically, the 
reduced gravity conditions will enable a test of theoretical predictions of the effect ot small heat currents on the 
nature of the lambda-transition and will allow probing of the interface region between co-existing normal and 
superfluid portions of the fluid. These measurements are not possible to perform in a regular lab environment on 
the earth due to the influence of hvdrostatic pressure effects and the need to apply large heat currents toovercome 
hydrostatic effects, tending to perturb the fluid sufficiently to render the measurements questionable. The 
suppression of the lambda-transition due to heat currents will also be investigated at lower values ot the heat curren 
than possible in a one-g environment. The magnet will be procured from a magnet winding company and installed 
in a thermal platform under construction at JPL. Melting curve thermometers, which can operate well in strong 
magnetic fields, will be used for high resolution thermometry. 

Task Description: 

The magnet will be designed and constructed by a magnet winding company. An experimental cell will be 
constructed with attachment points for melting curve thermometers to enable high resolution thermometry to be 
performed in the high field conditions of the experimental cell. The melting curve thermometers will be construe 
at Sandia under a sub-contract to JPL. A high performance theimal platform will have the experimental cell and the 
magnet installed into it for performing the measurements. A vibration isolated and magnetically shielded he mm 
dewar will be used to cool the thermal platform in order to minimize noise generation and improve the fidelity ot 

the collected data. 


Task Significance: 

Recent investigations of the influence of an applied heat current on the properties of helium near the superfluid 
transition have revealed many new phenomena. Agreement with theories based on scaled mean field calculations 
and dynamic renormalization group calculations is not good. The disagreement may stem trom the tact that theories 
assume zero-gravity conditions, while experiments are performed in a one-g environment. To overcome the 
influence of gravity on properties near the transition in a heat current, large values ot heat current are required which 
has detrimental effects on the very properties in need of study. It has also been predicted that imposition ot a eat 
current will change the very nature of the lambda-transition from continuous to first order. InvesUgating these 
phenomena in a simulated low-gravity environment would enable lower heat currents to be used and would enable 
observation of phenomena washed out by gravity effects. 

Progress During FY 1994: 

The high field gradient superconducting magnet was delivered from the manufacturer in FY 94. Prior to delivery, 
the magnet was tested at the vendor facility to verify that all requirements had been met. The magnet was 
successfully operated up to 16.5 tesla at 2.2 K without quenching for a maximum field times held gradient product 
of 23 T 2 /cm. This is exceeding the requirement by nearly 10%. At JPL the magnet was installed in the thermal 
platform, cooled down, and performance tested. We experienced some quenching problems, releasing about 150,000 
Joules of energy, when operating the magnet at near full field. The quenching problem was traced to a design flaw 




11-178 



II. MSAD Program Tasks — Ground-based Research 


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Mimitimu 


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Discipline: Benchmark Science 

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with the "home made” current leads which we now believe to be solved. Field profile data was gathered using a hail 
probe device which was movable along the axis of the magnet. A second probe was used slightly off-axis to verify 
the performance over the entire experimental region. 


The design and component fabrication of the thermal conductivity cell to he used in the experiments was also 
completed. The cell is 0.5 cm long and 0.5 cm in diameter and is made of stainless steel with copper end plates. 
The stainless steel side wall is 0.005 cm thick and ha is two circumferential temperature probes spaced evenly along 
the length of the cell. Final assembly of the cell is underway. 


Six melting curve thermometers complete with reference capacitors have been constructed. Four of these 
thermometers will be used to measure the temperature of the two mid-plane thermometers, the top copper end plate, 
and the heat current control platform to near nanokelvin resolution. 

To be able to better plan and analyze the low gravity simulator experiments, we have developed computer code to 
numerically simulate a one-dimensional thermal conductivity cell of helium near the lambda point. The basic time 
dependent heat flow equations and the known thermodynamic properties of helium at the lambda point were used. 
The etiect ot gravity was included by varying the spatial distribution of the local transition temperature in the cell 
accordingly. The results clearly demonstrate that a reduced gravity environment more closely achieves a quasi-static 
experimental condition. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 12/92 Expiration: 11/95 
Project Identification: 962-24-04-09 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals 

Israelsson. U.E., Strayer. DM., Chui, T.C.P.. Larson. M . and Duncan. R.V. Dynamic measurements near the 
lambda-point in a low-gravity simulator on the ground. Physica B, vol 194-196, 593-594 (1994). 

Presentations 

Larson, M.. and Israelsson. U.E. 'Simulations of the lambda transition of Helium-4 with an applied heat How for Ig and 
reduced gravity environments. 1994 March meeting ot the American Physical Society. 

Larson, M., and Israelsson, U.E. The lambda point in a low-g simulator - progress report. The 1994 Microgravity Low 
Temperature Physics Workshop, Washington D.C.. January. 1994. 


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11-179 


II. MSAD Program Tasks — Ground-based Research 

mini mi 


Discipline: Benchmark Science 




Turbidity of a Binary Mixture Very Close to the Critical Point 


Principal Investigator: Prof. Donald t. Jacobs 

The College of Wooster 

Co-Investigators: 

No Co-l’s Assigned to this Task 



Task Objective: 

This experimental activity is intended to measure the light transmitted through a near critical fluid consolute point 
of a density matched binary mixture. 

Task Description: 

1. Develop a room temperature thermal control system for the sample that enables temperature control inside ot ± 
3|iK. 

2. Assemble and use a phase sensitive detection system to detect the small light intensity variations expected close 
to the consolute point. 

3. The turbidity data will be reduced according to the formalism ol P. Calmettes et al.(Phys. Rev. Lett. 28, 4Z& 
(1972)};. 

4. Undergraduate students will assist Prof. Jacobs, making his activity a strong educational experience tor the 
students. 


Task Significance: 

The resulting data will be used to confirm and quantify a small exponent "if in a denominator { l+(?$ ) 1 ) that 
describes the correlation length dependent distribution of scattered light from near critical fluids. Also, two-scale 
universality" can be tested trom the data set. 


Progress During FY 1 994: 

The optical svstem can now resolve the small light intensity variations anticipated in this experiment. The optical 
components rest on a vibration-isolated optics table. Using an intensity stabilized laser beam that is split and then 
chopped into a reference and signal beam, the stability of measured intensities is less than the requisite O.lpercent. 
Lock-in amplifiers provide the sensitive detection ot the photodiode signals. 


The cell was redesigned to reliably seal the fluids yet allow light to pass through a 2mm thick slab ol fluid. Once 
the critical composition for the liquid mixture is loaded into the cell, it will be suspended in a series ot nested 
cylinders, each of which will stabilize the temperature fluctuations ot the adjacent outer stage by a tactor ot 100 
using an active temperature controller. The temperature controllers have been built and tested and the temperature 
sensors have been calibrated. 


The computer software that accesses the instruments used in the experiment has been written in the language 
LabVIEW. Each portion of the program has been tested and debugged and the main controlling program that in 
the many sub-elements is being developed. 

Associated experimental investigations that provide comparative information on other properties ot binary liquids 
are being used to test "two factor universality.” Coexistence curve and heat capacity data have been taken and are 
being analyzed for publication. 


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Research Discipline: Benchmark Science 




Students Funded Under Research: 

BS Students: 7 BS Degrees: 2 

MS Students: 0 MS Degrees: 0 

PhD Students: 0 PhD Degrees: 0 


Task Initiation: 1/93 Expiration: 12/95 

Project Identification: 962-24-05-74 
NASA Contract No. nag 3-1404 
Responsible Center: LeRC 





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11-181 



II. MSAD Program Tasks — Ground-based Research 


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Discipline: Benchmark Science 


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Atom Interferometry in a Micro^ravity Environment 


Principal Investigator; Dr. Mark a. Kasevich 

Stanford University 

Co-Investigators; 

No Co-I's Assigned to this Task 



Task Objective: 

Our scientific objectives are: ( 1 ) to develop a nigged laser cooled source of atoms using DBR (distributed Bragg 
reflector) laser technology; (2) to use this source and these lasers to demonstrate coherent atom wavepacket 
manipulation techniques; and (3) to incorporate these techniques into an atom interferometer gravity gradiometer. 
We plan to experimentally study the performance of the prototype device to evaluate the feasibility ot a space-based 

system. 


Task Description: 

In year one of the grant period we will develop the laser sources and apparatus needed for the proposed experiments. 
We will employ standard laser cooling and trapping techniques with atomic cesium to create the cold atomic source. 
Our first experfiments, to be carried out near the end of year one, will focus on demonstration and characatenzation 
of the proposed coherent atom manipulation techniques. In year two we will demonstrate and characterize an 
interferometer accelerometer - first in a low sensitivity regime in order to study potential systemauc phase shifts and 
subsequently in a high sensitivity configuration to explore the potential accuracy and resolution of the evice^ 

Since vibrational noise will severely hamper the performance of an Earth bound accelerometer, we will switch to a 
more complicated gradiometer geometry which is far less sensitive to vibrational noise in the final stages of the 

proposed work. 


Task Significance: 

The convergence of recent advances in the field of laser manipulation of atoms with technological developments in 
the electronics/opto-electronics industry opens the possibility of a new class of experiments involving laser 
manipulated atoms in a microgravity environment. In the past five years, light-induced forces have been used to 
cool ensembles of atoms to temperatures below 1 pK, providing researchers with a novel source ot ultra-cold 
atoms These laser cooled sources have revolutionized experimental atomic physics and have led to new classes of 
precision time standards and inertial sensors. Application of these techniques in a microgravity environment could 
result in robust gravity gradiometers and gyroscopes with sensitivities exceeding current state-of-the-art devices by 
several orders of magnitude. Such instruments would have important applications in a number ot fields, or 
example, satellite gradiometry studies yield important geophysical data concerning Earth and ocean dynamics. A 
satellite borne accelerometer/gravimeter used in conjunction with the GPS system could be used to obtain highly 
accurate maps of the global Earth gravity field. In addition, techniques developed for satellite interferometer sensors 
might also have terrestrial applications in , for example, mineral/oil exploration and navigation. Final y, wi 
minor modification, the techniques could be employed to develop atomic standards with unprecedented accuracy. 

Progress During FY 1 994; 

This grant has recently been initiated, and budgeting arrangements are still in process. 


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II— 1 8 2 



II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

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Students Funded Under Research: Task Initiation: 9/94 Expiration: 9/96 

Project Identification: 962-24-08-15 
NASA Contract No.:nags-1088 
Responsible Center: msfc 


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11-183 


II. MSAD Program Tasks — Ground-based Research 

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Discipline: Benchmark Science 

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Effect of Confinement on Transport Properties by Making use of Heium Near the Lambda Point 


Principal Investigator: Prof. John a. Lipa 

Stanford University 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

The objective of this project is to study the effect of confinement on the thermal conductivity of helium near the 
lambda point. The thermal conductivity is a transport property most readily accessible to precision measurement, 
allowing the effects of confinement to be quantified. The extent to which the results could be unproved in a 
micron gravity environment will also be studied. 

Task Description: 

Dohm and collaborators have predicted the first order departures of the thermal conductivity from the bulk behavior 
as on approaches the lambda point. As the transition is approached, the relevant length scale increases dramatically, 
allowing the effect to be measured in conventional apparatus. Higher order, nonlinear effects are also predicted, but 
quantitative information is not yet available. We plan to measure these ellects tor confinement in parallel plate 
geometry as a function of plate separation. Earlier measurements indicated that the first order ettect was different to 
that predicted. This needs to be verified, and higher order contributions need to be explored. 

Task Significance: 

The results will be used to test the emerging theory of transport properties in confined geometries, which has 
application to physical and chemical processes near surfaces or in small channels. 

Progress During FY 1 994: 

Funding for this research became available at the beginning of FY95. Progress to date included investivations ol 
previous thermal conductivity data to look for possible finite size effects. Experiments with helium confined within 
gaps as small as 70 microns have been examined. 


Students Funded Under Research: 


Task Initiation: 9/94 Expiration: 8/96 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 962-24-04-14 

MS Students: 

0 

MS Degrees: 

0 

Responsible Center: jpl 

PhD Students: 

3 

PhD Degrees: 

1 



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11-184 


II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 


Theoretical Studies of the Lambda Transition of Liquid 4He 


Principal Investigator; Prof. Efstratios Manousakis 

Florida Shite University 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

We study the critical properties of liquid helium near the superfluid transition temperature using recently 
developed numerical simulation techniques and finite-size scaling. In particular, we are interested in the scaling 
behavior of the superfluid density and the specific heat. We shall study different finite geometries, namely pure 
two-dimensional, pure three-dimensional and the crossover from two-dimensional to three-dimensional superfluidity 
in order to verify the validity of scaling and to determine the universal functions associated with scaling. 

Task Description: 

A recently developed updating technique called cluster Monte Carlo, which elliminates the long-standing problem of 
critical-slowing-down will allows us to approach close to the lambda point for large size lattices and, thus, extract 
the critical exponents and scaling properties of the physical quantities of interest. We shall study the temperature 
and the finite-size dependence of the superfluid density and the specific heat. From these studies we can determine 
the critical exponent using finite-size scaling techniques. 

In addition we shall determine the superfluid/normal phase boundary' T x ( h ) for films of thickness h . We shall 
calculate the superfluid density as a function of the film thickness and we shall examine the validity of the 
finite-size scaling theory. We shall also calculate the specific heat as a function of h and this will be used to 
understand the results of the CHeX experiment. 

Finally, the role of vortices and the Kosteriitz-Thouless scenario will be also examined in the course of this work. 
We shall calculate the renormalization group beta function for two-dimensional superfluids and we shall compare it 
to that predicted by the Kosteriitz-Thouless theory. In addition, we shall study with our simulation technique the 
intimate connection between the superfluid transition and the unbinding of vortices. 

Task Significance: 

The results of these studies are relevant and will be compared to the experimental measurements obtained from the 
lambda-point experiment (LPE) and to the confined helium experiment (CHeX). 


Progress During FY 1 994: 

Using the x - y model and a non-local updating scheme called cluster Monte Carlo, we calculated the superfluid 
density r and the specific heat c of a superfluid in a film geometry, i.e. on a finite lattice of size L x L x H (where L 
» H). In this geometry the superfluid density shows a three to two-dimensional crossover behavior. This means 
that below a certain crossover temperature the helium film behaves as if it was infinitely thick and, thus, it exhibits 
three-dimensional behavior. Above the crossover temperature and still below the bulk critical temperature T, the 
helium film shows two-dimensional behavior. Because of that the critical temperature is reduced, the superfluid 
phase transition occurs at temperatures T C (H) smaller than T } . These reduced temperatures depend on the thickness of 
the helium film. In order to determine the critical temperatures T C (H) we applied the Kosterlitz-Thouless-Nelson 
(KTN) theory, which was formulated for purely two-dimensional helium films, to the quantity T/(Hr). Namely, by 
solving the KTN renormalization group equations for this quantiyy we were able to obtain the values T/(Hr) in the 
limit as L tends twards infinity; thus, the dependence on the planar dimensions L of the lattice was completely 
eliminated and T/(Hr)(H) is a function of the film thickness only. We found that for a fixed film thickness H the 
ratio T/(Hr)(H) close to T C (H) obeys a simple functional form. Fitting this functional form to the computed values 


11-185 


II. MSAD Program Tasks 

iiiiiiiiiiiiMimmiiiHiiiiitiiimiiHiiHtmimiHmi 


Ground-based Research Discipline: Benchmark Science 




lor T/(Hr) we found estimates tor the critical temperatures T C (H). Tlic detailed results ol this work have been 
submitted for publication in Phvs. Rev. B. 

The crossover behavior for the specific heat c is much less pronounced. Lattices with L=60 are large enough to 
represent the infinite film thickness limit. For the films with H=6,8,10 we obtain a universal curve that relates the 
heat capacity for films of finite thicknes to the heat capacity ot intinitly thick films. We are in the process of 
comparing our universal function with experimental results. The results of this investigation will be submitted to 
Phys. Rev. B. 

The computations described above were carried out on the x-v model with periodic boundary conditions in all 
directions. This ensures the homogeneity of the physical quantities along the film thickness. For such a system we 
verify the validity of the finite-size scaling theory as reported above. However, in experiments on thin helium films 
which test the finite-size scaling theory, 4 He is supported by substrates which impose different boundary conditions 
on the film. It appears therefore necessary to investigate the influence of other boundary conditions on the scaling 
behavior of the superfluid density and the specific heat with respect to the film thickness. From these investigations 
we hope to gain insight as to why recent experiments on thin helium films seem to yield results contradicting the 
finite-size scaling theory. 

We have repeated the calculations described above tor the x-y model in a film geometry with staggered 
(Dirichlet-like) boundary conditions in the top and bottom layer ot the film. The supertluid density develops a 
profile with the maximum value in the middle ot the film. At the boundaries the supertluid density vanishes. We 
have identified the temperature region where the model displays two-dimensional behavior and have used the KTN 
theory to determine the critical temperatures T C (H). Furthermore our data tor the supertluid density and the specific 
heat do not collapse onto one universal curve until we applied an effective critical exponent n=0.923. It seems that 
these preliminary' results show the same situation here as was described by Rhee, Gasparini and Bishop who had to 
use an effective critical exponent n=l .14 to achieve scaling of their data for the supertluid density with film 
thickness. However, we are in (he process of trying to understand these results further. 

The calculations reported above were performed on a heterogeneous environment ot workstations which include 
DEC Alpha, Sun, and IBM RS/6000 workstations and on the Cray-YMP supercomputer and took several months ot 

CPU time. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 01/93 Expiration: 12/95 
Project Identification: 962-24-07-15 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals 

Schultka, N., and Manousakis E. Finite-size scaling in two-dimensional supertluids. Phys. Rev. B, vol 49, 12071 (1994). 

Schultka, N., and Manousakis, E. Crossover from two-dimensional to three-dimensional behavior in superfluids. Phys. 
Rev. B. (submitted). 

Schultka, N., and Manousakis, E. Finite-size scaling of the specific of supertluids. Phys. Rev. B, (submitted). 

Schultka, N., and Manousakis, E. Crossover from two-dimensional to three-dimensional behavior in superfluids-boundary 
effects. Phys. Rev. B., (submitted). 





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II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 




Proceedings 

Manousakis. E. 'Numerical simulation ot scaling in supertluid films.” Proceedings of the NASA/JPL 1994 Microgravitv 
Low Temperature Physics Workshop. 

Schultka. N.. and Manousakis E. Finite-size scaling of the supertluid density in two-dimensional supertluids." 
Proceedings ot the 20th International Conference on Low Temperature Physics. 

Presentations 

Manousakis. E. "Numerical simulation of scaling in supertluid films.” 1994 Microgravity Low Temperature Physics 
Workshop, Washington, D.C. January 18-21, 1994. 

Schultka, N. "Finite-scaling of the supertluid density in two dimensions and thin films." Max Planck Institut fur Physik. 
Munich, Germany, December 1993. 

Schultka. N. "Finite-scaling of the supertluid density in two dimensions and thin films.” Institut fur Theoretische Physik, 
RWTH Aachen, Aachen, Germany, December 1993. 

Schultka. N. "Finite-scaling of the supertluid density in two dimensions and thin films.” Institut fur Kemphysik. TU 
Wien, Vienna. Austria, December 1993. 

Schultka, N., and Manousakis. E. "Crossover from two to three dimensions in supertluid films.” APS Meeting, Pittsburgh 
PA. March 1994. 

Schultka, N., and Manousakis. E. "Finite size scaling in two-dimensional supertluids." APS Meeting, Pittsburgh PA, 
March 1994. 





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II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

«... 


Dynamics and Morphology of Superfluid Helium Drops in a Microgravity Environment 


Principal Investigator: Prof. Humphrey J. Maris 

Brown University 

Co-Investigators: 


G. Seidel 

Brown University 

Task Objective: 


The long range goal of our research is the study ot the hydrodynamics ot drops ot superfluid liquid helium by means 
of microgravity experiments conducted in space. At the present time we are developing a series ot earth-based 
experiments to levitate superfluid drops so that we can acquire data and experience that will be needed tor the design 
of experiments in space. 

Task Description: 

We are conducting a series of earth-based experiments to study the behavior of superfluid drops. We will develop a 
means to levitate helium drops in earth gravity, primarily by magnetic levitation. We will then investigate 1) how 
to inject and position drops in a microgravity chamber, 2) how to manipulate drops and to give them angular 
momentum, 3) how to observe accurately the vibrations and rotations ol the drops, and 4) what drop sizes are best 
suited for the study of a variety of phenomena. 

Task Significance: 

The goal is to achieve data and experience critical for the design of experiments in space. 

Progress During FY 1994: 

optical Levitation Experiment: We have completed our experiments on optical levitation of superfluid heiium-4. 
Drops of diameter approximately 20 microns were levitated using an optical trap formed by a tocussed Nd:YAG 
laser beam of wavelength 1.06 micron. It was possible to levitate drops for as long as three minutes. We have 
carried out a detailed analysis of a number of phenomena observed during this experiment. Several factors that might 
control the rate at which the drops evaporated were analyzed, including laser heating, evaporation due to the curved 
surface of the drop, and non-equilibrium conditions inside the experimental cell. We performed detailed computer 
calculations of the potential energy in the vicinity of the optical trap. The experiment revealed that it was possible 
for several drops to be held in the trap at the same time without coalescence occuring. We considered a number ot 
possible explanations for this remarkable result. A paper on the optical levitation experiment will appear in the 
Journal of Low Temperature Physics. In addition, the staff of Scientific American have written a short article about 
the experiment to be included in a forthcoming issue of their magazine. 

Magnetic Levitation Apparatus: We have continued construction of the apparatus to magnetically-levitate helium. 
The magnet constructed by Oxford Instruments has been delivered. The large Janis dewar for the magnet has been 
mounted and the cryostat is under construction. The cryostat is mounted adjacent to a large optical table on which 
we can mount lasers for illumination and an optical recording system. This cryostat has been designed to be suitable 
for a variety of experiments on helium drops, at temperature down to 0.5 K. 

Fluid Mechanics of Drops in Micro-Gravity: We have started a calculation designed to determine the morphology ot 
a superftuid drop with angular momentum under micor-gravity conditions. The goal is to determine how the shape 
of the drop changes as the angular momentum is increased. For the moment we are restricting attention to 
consideration of the shape with lowest energy for a given angular momentum. 


.....I'*.. .............. 


II-188 



II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 1/93 Expiration: 12/95 

Project Identification: 962-24-07-16 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Proceedings 

Weilert, M.A., Whitaker. D.L., Maris. H.J., and Seidel. G.M. ’’Optical and magnetic levitation of superfluid helium 
drops.” Proceedings of the NASA7JPL 1994 Microgravity Low Temperature Physics Workshop. 


11-189 



II. MSAD Program Tasks — 


Ground-based Research Discipline: Benchmark Science 

hiiiimi 


Critical Transport Phenomena in Fluid Helium Under Low Gravity 


Principal Investigator: Prof. Horst Meyer 

Duke University 

Co-Investigators: 


F. Zhong 

Duke University 

Task Objective: 


Ground-based experiments will be carried out to study the density equilibration process at constant average density r 
in a pure fluid, ( 3 He), near its liquid-vapor critical point (T c , r c ) alter a step change in temperature DT ot the 
container walls. Measurements are to be carried out tor both the region above T c (one phase) and below T 
(coexisting phases). Numerical simulations are to be performed of the density, temperature and pressure 
equilibration processes in 3 He for the regime above T c , both ground-based and under reduced gravity. The 
measurements are to be extended to binary ( 3 He- 4 He) mixtures near their liquid vapor critical point ("plait point"). 

Task Description: 

Two flat, horizontal cells of somewhat different geometry are used in different series of experiments. The fluid is 
contained between two parallel flat OFHC copper plates with high thermal conductivity, kept at the same 
temperature that is regulated to within a few mK before and after the step DT . In both cells, the fluid layer height is 
approximately 4 mm, the diameter is 30mm and the density is measured by two thin horizontal superposed 
capacitive sensors, spaced by 2 mm that record the dielectric constant The density is then derived via the 
Clausius-Mossotti relation, and is recorded by both sensors, r, op (t) and r KjUO!U (t) , as a function time t after a 
programmed small temperature step ot the cell walls. At temperatures above T c , immediately after the step DT, the 
fast density change from adiabatic energy transfer ("piston effect") followed by the slow stratification change at each 
sensor are recorded by computer. Experiments 

are carried out along several near-critical isochores and along several isotherms. Below T c , the two sensors detect 
respectively the coexisting liquid and vapor phases. An induced temperature change in the cell walls will permit 
following the density evolution in both phases with time. 

With help of the known scaled expressions for the static and transport properties of 3 He above T c , numerical 
simulations in one dimension are carried out to predict the temporal and spatial evolution of the thermodynamic 
parameters (density, temperature, pressure and their derivatives) and predict the asymptotic relaxation times. This 
simulation is to be done at arbitrary values of the gravitational acceleration g. 

After completion of the 3 He program, measurements and numerical simulations are to be extended to binary ( 3 He 
- 4 He ) mixtures. 

Task Significance: 

Such studies - both for pure fluids and binary mixtures - are very relevant to experiments on fluids under mg 
conditions, where investigations of static and dynamic properties near critical points are to be carried out. It is 
important to know how long a fluid system takes to approach closely enough thermodynamic equilibrium, and 
what are the basic mechanisms that control the equilibrium process. The numerical computations above T c are to be 
compared with experiments. Simulations under microgravity conditions will be able to assess the permissible 
temperature ramping rate in experimental data taking that will enable measurements of critical properties in a 
quasi-equilibrium state. In the two-phase regime below T , tittle is known about the equilibration dynamics and the 
proposed experiments are expected to substantially help in understanding these processes. 



II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 


Progress During FY 1 994: 

During spring '92, the existing cryostat tor work over a temperature range 1-5 K (previously used in the 
NAS A- sponsored viscosity measurements) was modified to incorporate a temperature-regulated platform supporting 
the density equilibration cell. Electronic circuitry was installed for high-resolution stable temperature and dielectric 
constant measurement arrangement. Computer programs for temperature step control and automatic data acquisition 
and reduction were developed. The apparatus was tested over a period of several months, and data-taking routine was 
developed and gradually perfected. Initial density stratification data were taken in the one-phase regime along the 
critical isochore and also in the two-phase regime. Temperature steps of different sizes and sign were used and the 
stratification data were analysed in a preliminary fashion. Stratification time was found to diverge as the critical 
point is approached from both the single and the two-phase regimes. At a given temperature, it was found to be the 
same coming from either the colder or the warmer side. We expect to continue with data taking along other 
isochores and along isotherms, and hope to present a scaling scheme of our data. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 2/92 Expiration: 1/94 

Project Identification: 962-24-02-01 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals 

Howald, C., Qin, X., Nham, H.S., and Meyer, H. Shear viscosity measurements of liquid 4He and 3He-4He mixtures near 
the tricritical point. J. Low Temp. Phys., vol 86, (1994). 






II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

in i iti i in mu i it mu mm 


Equilibration in Density and Temperature Near the Liquid-Vapor Critical Point 


Principal Investigator: Prot. Horst Meyer 

Duke University 

Co-Investigators: 


F. Zhong 

Duke University 


Task Objective: 

Ground-based experiments will be carried out to study the density equilibration process at constant average density r 
in a pure fluid, ( 3 He), near its liquid- vapor critical point (T c ,r c ) after a step change in temperature DT of the 
container walls. Measurements are to be carried out for both the region above T c (one phase) and below T c 
(coexisting phases). Numerical simulations are to be performed of the density, temperature and pressure 
equilibration processes 3 He for the regime above T c , both ground-based and under reduced gravity. The measurements 
are to be extended to binary ( 3 He- 4 He) mixtures near their liquid vapor critical point ( plait point ). 

Task Description: 

Two flat, horizontal cells of somewhat different geometry are used in different series of experiments. The fluid is 
contained between two parallel flat OFHC copper plates with high thermal conductivity, kept at the same 
temperature that is regulated to within a few mK betore and alter the step DT. In both cells, the fluid layer height is 
approximately 4mm, the diameter is 30mm and the density is measured by two thin horizontal superposed 
capacitive sensors, spaced by 2 mm that record the dielectric constant The density is then derived via the 
Clausius-Mossotti relation, and is recorded by both sensors, r lop and r*^ (t), as a function time t alter a 
programmed small temperature step of the cell walls. At temperature above T c , immediately alter the step DT, die 
fast density change from adiabatic energy transfer ("piston effect") followed by the slow stratification change at each 
sensor are recorded by computer. Experiments are carried out along several near-critical isochores and along severed 
isotherms. Below T c , the two sensors detect respectively the coexisting liquid and vapor phases. An induced 
temperature change in the cell walls will permit following the density evolution in both phases with time. 


With help of the known scaled expressions for the static and transport properties of 3 He above T c , numerical 
simulations in one dimension are carried out to predict the temporal and spatial evolution ot the thermodynamic 
parameters (density, temperature, pressure and their derivatives) and predict the asymptotic relaxation times. This 
simulation is to be done at arbitrary values of the gravitational acceleration g. 

After completion of the 3 He program, measurements and numerical simulations are to be extended to binary 
( 3 He- 4 He) mixtures. 

Task Significance: 

Such studies - both for pure fluids and binary mixtures - are very relevant to experiments on fluids under mg 
conditions, where investigations of static and dynamic properties near critical points are to be carried out. It is 
important to know how long a fluid system takes to approach closely enough thermodynamic equilibrium, and 
what are the basic mechanisms that control the equilibrium process. The numerical computations above T c are to be 
compared with experiments. Simulations under microgravity conditions will be able to assess the permissible 
temperature ramping rate in experimental data taking that will enable measurements of critical properties in a 
quasi-equilibrium state. In the two-phase regime below T c , little is known about the equilibration dynamics and the 
proposed experiments are expected to substantially help in understanding these processes. 



II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

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Progress During FY 1 994: 

There have been three main projects in this penod: 

A) Processing and analyzing temporal density evolution r data in 3 He after a programmed temperature step of the 
cell. These data had been obtained throughout 1993. 

B) Developing and improving the computer simulation program that calculates the spatial and temporal evolution 
of thermodynamic coefficients of 3 He. 

C) Writing a detailed paper describing both the experimental and die computed results for 3 He above the critical 
point, and also writing papers tor Proceedings. 

A) Data analysis. In the experiments that had lasted approximately 12 months, very systematic measurements of 
the density equilibration were carried out both above and below the liquid vapor critical point (T c , r c , P c ). During 
this lengthy data taking, measurements were performed of the density evolution in time r(t) at two superposed 
locations in a cylindrical cell after a programmed temperature step on the fluid container. This density evolution 
towards equilibrium was automatically stored in a computer. Experiments were carried out along several isochores, 
one of them being the critical one. Also experiments were performed along several isotherms both above and below 
the critical point below which both the liquid and the coexisting vapor phases could be sampled. Of this very large 
amount of data , those along the critical isochore and several isotherms have been processed and displayed 
graphically versus time. The superposed location of the two density sensors in the cell permitted the observation of 
the density stratification in die cell, under the effect of the earth’s gravity. 

B) Computer simulations. Together with the data analysis, the computer simulation of the temporal and spatial 
evolution of temperature T(z,t), density r(z,t) and pressure P(z,t) has been significantly improved. This simulation, 
which is restricted to the region above the critical point (single phase), uses the published static and dynamic 
critical properties of 3He obtained in this laboratory, and calculates the equilibration of T, r and P following the 
programmed temperature step of the fluid container. This is done for an arbitrary gravitational acceleration g. Hence 
the computer simulation can yield results for the density evolution that can be directly compared with experiments 
in a ground-based laboratory, and it also predicts the evolution of the coefficients during an experiments under 
microgravity conditions. Much effort was spent comparing experimental data and computations and the results can 
be briefly summarized as follows: 1) There is an impressive agreement between the observed and predicted 
amplitudes and shapes of the density evolution. In particular at temperatures well above the critical point, the 
predicted sharp spike resulting from the adiabatic energy transfer ("piston effect”) was clearly observed and the 
predicted and observed amplitudes were in good agreement. The same good agreement was found for the amplitude 
of the stratification. 2) However there is a systematic discrepancy in the time scales involved. While the observed 
and predicted relaxation times agree far above T c , there is a systematic departure as T c is approached, whereby the 
computed relaxation time diverges more strongly than the experimental one. Close enough to T c , the stratification 
causes a leveling off of the relaxation time curve versus (T-T c ) , both predicted and observed. Under microgravity 
conditions, the computer simulation shows that the relaxation time continues diverging. 3) Furthermore 
simulations in calculating the properties inside the fluid in the course of temperature ramping - both upwards and 
downwards were conducted, which gave remarkable results. In particular the rms density variation thoughout the 
fluid was predicted as a function of ramping rate and temperature. 

C) Manuscripts. Several drafts of a long and detailed manuscript "Density equilibration near the Liquid-Vapor 
critical point of a pure fluid: I Single phase T>T C " have been produced, and we hope that the final paper will be 
ready for submission to Physical Review sometime by middle of November. A first draft of the sequel of this paper 
II- coexisting phases T<T C has been written. 


imitiiiiii 


LI-193 



II. MSAD Proeram Tasks — Ground-based Research Discipline: Benchmark Science 

5 .HIM* till IIIIH Ml... * til III lltltll 111. Mill I .Ml... I 


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Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: i/94 Expiration: 12/95 

Project Identification: 962-24-07-20 
Responsible Center: jpl 


Bibliographic Citations for FY 1994: 

Journals t il, 

Zhong, F., and Meyer, H. Density equilibration near the liquid-vapor critical point of a pure fluid: I-smgle phase T>Tc. 

Phys Rev B, (submitted). 

Proceedings 

Zhong, F., and H. Meyer. H. "Density equilibration near the liquid-vapor critical point in 3He ." Fluid Mechanics 
Phenomena in Microgravity, American Society of Mechanical Engineers. 

Zhong, F.. and Meyer, H. "Densisty equilibration near the liquid-vapor critical point in 3He. Proceedings of the 
NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 

Zhong, F.. and Meyer, H. "Numerical calculation of density equilibration above the 3He liquid-vapor critical point. 
Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop. 

Zhong, F. and Meyer, H. "Density equilibration for a pure fluid near Tc: Application to 3He. Proceedings ol the 12th 
Symposium on Thermophysical Properties. 


11-194 


II. MSAD Program Tasks — Ground-based Research Discipline: Benchmark Science 

itmiiiiiiiiiiiiiii imiMiHiMiiimiiiiHMiiiiiiimiiiimmmiiHiiiiHiiiiniHmiMHMiiimmiiiHiimiHHimimiiiii'imii mum 


Nonlinear Dynamics and Nucleation Kinetics in Near-Critical Liquids 


Principal Investigator: Prof. Alexander z. Patashinski 


Northwestern University 


Co-Investigators: 

M. Ratner Northwestern University 

V. Pines Case Western Reserve University 


Task Objective: 

This grant activity is an early definition study to establish the theoretical foundations of the nonlinear response to 
strong perturbations in near critical fluids. This is a subset of a larger goal to develop an understanding of the many 
nonequilibrium states of strongly interacting systems. Critical fluids are to provide the experimental and theoretical 
model systems. This early definition work will be the basis for one or more future low gravity experiments. 

Task Description: 

The Principal Investigator will work on a description of the non linear formation and relaxation of inhomogeneities 
in liquid-vapor and binary mixtures near their critical points. The perturbations from homogeneity may occur from 
stable and unstable initial thermodynamic states. There is a need for the inhomogeneities to be large and long lived. 
Renormalization group formalism will be used to describe the non-Gibbsian distribution functions of the critical 
fluctuations. Three experiments have been suggested in the proposal. They are as follows: 

1 . Relaxation of large inhomogeneities to a one-phase final state. 

2. Nucleation kinetics during the formation of a final two-phase state starting from an initial unstable state. 

3. Nucleation kinetics and the influence of spinodal decomposition dynamics on domain nuclei in a state near the 
spinodal line. 

Task Significance: 

This is fundamental research into the non linear understanding of nucleation phenomena. Its long term 
technological value rests on application to nucleation phenomena in a myriad of common phenomena at small 
space and time scales. 

Broader fundamental knowledge of strongly interacting systems in non-equilibrium can open up new technologies. 
Our lack of knowledge in this area limits our current technological imagination. 

Progress During FY 1 994: 

Since funding was initiated in June 1994, the investigators have quantitatively analyzed weak pertubadons in the 
linear regime to confirm their formalism yields and adiabatic fast heat transfer. They are now advancing their efforts 
to apply the formalism to the non linear heat transfer in the vicinity of a strongly pertubing hot body in a very 
compressible critical fluid. 


Students Funded Under Research: Task Initiation: 6/94 Expiration: 6/96 

Project Identification: 962-24-05-07 
Responsible Center: LeRC 




11-195 




II. MSAD Program Tasks 

Ill 


— Ground-based Research Discipline: Benchmark Science 




Precise Measurements of the Density and Thermal Expansion of 4He Near the Lambda Transition 


Principal Investigator: Dr. Donald m. strayer 

Jet Propulsion Laboratory (JPL) 

Co-Investigators: 


Dr. Talso Chui 
Prof. Nai-Chang Yeh 
Dr. Mark Lysek 

Jet Propulsion Laboratory (JPL) 
California Institute of Technology 
Jet Propulsion Laboratory (JPL) 

Task Objective: 


The objective of this ground-based Annual NRA project is to demonstrate the value of high-precision density 
measurements in the study of the lambda transition ot liquid helium. During the two years ot Annual NRA 
funding, we shall demonstrate the capability to perform high-precision density measurements using superconducting 
cavities, applying high resolution thermometers (HRTs) for temperature control. We shall also demonstrate the 
ability to deconvolve nonuniformities caused by gravity from the density data. 

Task Description: 

We shall employ superconducting microwave cavities having Q-values near 10 1 , operated in modes that have 
standing wave patterns that are axially symmetric and whose z-dependences are well known. Upon tilling the cavity 
with liquid helium, and adjusting the temperature near to T„ measurements of the cavity resonant frequency will 
reflect the helium density. Very near the transition a normal-superiluid interface will form in the cavity. Moving 
this interface across antinodes of the standing wave pattern by high resolution temperature control will allow the 
density to be probed in the interfacial region. Measurements at many temperatures will provide density data for 
deconvolving the temperature dependence of the density from the gravity-induced effects. 

Task Significance: 

We expect that our earth-bound measurements will demonstrate the value of precision density measurements to 
exploration of the lambda transition, and to study of cooperative transitions in general. The preliminary 
measurements to be conducted in this Annual NRA task will provide useful information about future exploration ot 
related experiments to be conducted in the microgravity experiments. The results will lead to applications ot the 
technique to problems that include studies at many pressures, studies of nonequilibrium effects, or studies in 
confined geometries. 

Progress During FY 1994: 

This task has very recently been provided with funds. Since that time, the design of a probe on which to perform 
the demonstration measurements has progressed through development of a rudimentary thermal model, plus the 
determination of required frequency resolution in the microwave components. Obtaining those microwave 
components is now underway, with all major pieces in hand, and only some smaller pieces yet to be procured. As 
stated in the proposal, an existing superconducting cavity and a cryoprobe already in Prof. Yeh's laboratory will be 
modified for use in these measurements. The thermal model will be improved, and then will be used to design the 
modifications to yield the necessary thermal stability on the platform. 

The postdoctoral fellow who will perform the measurements is identified, has participated in the design of the 
microwave measurement system, and will be on board by the start ot 1995. 


* * 


11-196 



II. MSAD Program Tasks 

imiimiiiitiiiMMiiiHiiiiimiiiiHimiifimHHiiiHi 


— Ground-based Research 


Discipline: Benchmark Science 

mum 


Students Funded Under Research: Task Initiation: 9/94 Expiration: x/96 

Project Identification: 952-24-04-12 
Responsible Center: jpl 


...... 


11-197 



II. MSAD Program Tasks — Ground-based Research 


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Discipline: Biotechnology 





Evaluation of Ovarian Tumor Cell Groivth and Gene Expression 


Principal Investigator: Prof. Jeanne l. Becker. Ph.D. 

University ot South Florida 

Co-Investigators: 


G.F. Spaulding 
R.H. Widen 

NASA Johnson Space Center (JSC) 
University of South Florida (Tampa Gen. Hospital) 


Task Objective: 

Examine growth and gene expression of LN1 ovarian tumor cells cultured in the Rotating-Wall Vessel (RWV). 

Task Description: 

A model for the growth of human ovarian tumor cells has been developed. This model allows tor three-dimensional 
growth of LN1 ovarian tumor cells, facilitating the generation of tissue-like aggregates ot cells exhibiting complex 
architecture. The cell populations generated during RWV culture morphologically and histochemically resemble 
those characteristics exhibited by the original patient tumor specimen from which this cell line was developed. 

Task Significance: 

In vitro growth of human ovarian tumor cells is not readily accomplished using traditional culture methodologies. 
Using the low shear, low turbulence conditions provided by the microgravity environment ot the NASA RWV, we 
have developed a model which supports the culture of these cells under conditions that simulate in vivo-like growth. 
We have used this model to study growth characteristics in conjunction with changing patterns ot gene expression 
and oncoprotein production occurring during complex cellular aggregate formation in vitro. 

Progress During FY1994: 

During this year, my laboratory has received two rotating-wall vessels, a slow-turning lateral vessel (STLV) and a 
high aspect rotating-wall vessel (HARV). We have become familiar with the care, set-up and operation ot these 
vessels in our hands and the growth of LN1 in these vessels. During culture in the RWV, LNl cells become highly 
metabolic, exhibiting greatly increased rates of glucose utilization during continued three-dimensional growth. 
Because of the greater oxygenation capacity of the HARV, the growth of LNl cells in the HARV is superior to 
growth in the STLV. In conjunction with an increased rate of glucose utilization. LN1 also exhibits an increase in 
the percentages of cells undergoing DNA synthesis (S phase of cell cycle) and mitosis (G 2 +M phases) with time in 

HARV culture. 

We have demonstrated that the LN1 cell line has the capacity to differentiate into multiple cell populations during 
three-dimensional culture in the RWV. These populations have been characterized both immunocytochemically and 
flow cytometrically. Recent studies have evaluated staining patterns of intermediate filaments and oncoproteins in 
LN1 cells grown in the RWV, as compared to cells present in the original tumor specimen from which LN1 was 
derived. Staining patterns for cytokeratin, vimentin and chondroitin sulfate present in LN1 grown 
three-dimensionally in the HARV were remarkably similar to that observed in the original tumor, in contrast to 
patterns observed in control Petri dish cultures and monolayer culture. LN1 cells grown in the HARV also 
demonstrated increased staining for TAG-72 carcinoma antigen and c-erbB2 oncoprotein, as exhibited by the original 

specimen. 

LNl cells in monolayer culture exhibit constitutive expression of mRNA and protein for c-erbB2, c-ras and mutant 
p53. Analysis of LNl grown three-dimensionally also revealed constitutive expression of mRNA for c-erbB2, c-ras 
and mutant p53, although differential expression of the corresponding oncoproteins, pl85 c " bB2 , p21 c H r “, p2P “ 
and mutant p53 protein, was observed within individual cell populations generated during RWV culture. Additional 
studies have revealed that LNl expression of TGF-beta is altered in RWV culture, relative to two-dimensional 
growth in monolayer culture. 





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Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 11/92 Expiration: 11/95 
Project Identification: 962-23-01-15 
NASA Contract No.: nag -648 
Responsible Center: jsc 


Bibliographic Citations for FY 1994 : 

Journals 

Becker, J.L. Women's health issues and space based medical technologies. Earth Space Review, 3, 15-19 (1994). 

Journal Becker, J.L. Microgravity model of ovarian tumor cell growth. Low G, 5, 12 (1994). 

Presentations 

Anderson- S.M., Becker, J.L., Papenhausen, P.R. "Verification of an i(5p) marker chromosome in a mixed mullerian tumor 
of the ovary by fluorescence in situ hybridization." Internatl. Conf. Immunogenet, 1994. 

Becker. J.L., Goodwin, T.J.. Prewett. T.L., and Spaulding, G.F. "Growth and gene expression in human ovarian cancer." 
Workshop on Cell Culture Applications in Biotechnology, World Cong. Cell Tiss. Culture, 1994. 


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II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 


Crystallographic Studies of Proteins Part U 


Principal Investigator: Dr. Daniel c. Carter 


NASA Marshall Space Right Center (MSFC) 


Co-Investigators: 

J. Ho (X. He) NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

This research involves the atomic structure determination of several protein structures. Key areas ol study involve 
serum albumin structure and chemistry and HIV antibody complexes and structure. Aspects ot this research generate 
tlight experiment problems and contribute to facilities for the evaluation of flight experiment activities. 

Task Description: 

The overall goal of this research is to utilize ground-based and microgravity-grown protein crystals to improve our 
understanding in two important areas of structural molecular biology. The first involves the determination ot the 
definitive structure of serum albumin together with the chemical basis for the molecules' tremendous ability to bind 
and transport an immense variety of ligands throughout the circulatory system. The second area which is also broad 
in scope involves the structure determinauon of a series of human monoclonal antibodies expressed against the 
AIDS virus together with their respective antigen complexes. Both of these project areas are in an advanced stage 
where improvements in crystal quality will have significant impact on our understanding of the underlying 
chemistry. 

Screens for optimum crystallization conditions or to determine crystallization conditions for new proteins will be 
conducted by the hanging-drop vapor-diffusion method. A Micromedics robotic crystal growth system is available 
to aid systematic surveys of pH, precipitant type, precipitant concentration, and protein concentration. The 
monoclonal antibodies expressed against the AIDS virus will be supplied by collaborator Professor Forian Rucker 
of The Institute of Applied Microbiology in Vienna, Austria. Cleavage of the antibody with papain or pepsin to 
produce the Fab fragments and subsequent purification will continue to be conducted. Antigenic peptides will be 
provided by Dr. Rucker and/or as a gift from IAF Biochemicals of Canada. X-ray diffraction data will be collected 
from both ground-based and tlight crystals using a multi- wire area detector (Nicolet) and an imaging plate system 
(R-Axis) mounted on a Rigaku RU200 rotating anode generator. In favorable cases where'the logistics can be 
arranged, diffraction data will be collected at synchrotron sources. 

Task Significance: 

High quality, single crystals are of tremendous value for a variety of industrial and research applications. Crystals 
of sufficient size and quality also provide invaluable avenues to understanding the detailed atomic structure and 
function of biological macromolecules and other substances. Efforts to produce higher quality protein crystals for 
application in x-ray crystallography have spawned numerous experimental approaches which range from the 
application of automated screening to the growth of protein crystals in microgravity. 

Progress During FY 1 994: 

The structure of Schistosoma japonica glutathione-S -transferase fusion protein was determined. This structure has 
several important implications: 

1. The protein contains the principal portion of an epitope of gp41 of the human immunodeficiency virus type 1 
which is recognized by a neutralizing antibody, 2F5. 

2. The protein is from a parasitic flatworm which is the causative agent of schistosomiasis, the second leading cause 
of death and suffering in the world (malaria is primary). According to the scientific literature, this protein was a 
leading candidate for the development of a vaccine against this disease. 


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II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

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3. The protein is part of an important commercial protein expression system. We have proposed that fusing 
proteins which have proven difficult to crystallize to GST may provide a new and expeditious route to Lheir structure 
determination. Verification is in progress. 

The refinement ot several structures is nearing completion. Cytochrome c5 from Azotobacter vitilandii has been 
refined to 1.9 angstroms resolution. HEW lysozyme grown in microgravity is refined to previously unreported high 
resolution. Additional high quality flight crystals are required to finish this work. A new myoglobin structure is 
solved and in the final stages ol refinement. The nature ol long-chain fatty acid binding to albumin was determined. 

Several new and important proteins have been crystallized. Several manuscripts are in preparation. 

Also, this year an authoritative review on the structure of albumin was published by Academic Press. 

We completed the first year of two govemment/industry cooperative agreements. Both are interested in extending 
and/or expanding the agreements. Three additional agreements are under consideration. 


Students Funded Under Research: Task Initiation: 1/93 Expiration: i/96 

Project Identification: 962-23-08-17 
NASA Contract No.: in-house 

Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Carter. D.C., and Ho. J.X. Structure of albumin. Advances in Protein Chemistry, vol. 45. 153-203 (1994). 


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II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

in 


Microgravity Studies of Cell-Polymer Cartilage Implants 


Principal Investigator: Dr. Lisa e. Freed 


Massachusetts Institute of Technology (MIT) 


Co-Investigators: 

R. Langer 
G.F. Spaulding 
T.J. Goodwin 
D. lngber 


Massachusetts Institute of Technology (MIT) 
NASA Johnson Space Center (JSC) 
NASA Johnson Space Center (JSC) 
Harvard University 


Task Objective: 

The long-term objectives of our current studies are: (1) to assess the effects of in vitro culture conditions, 
microgravity in particular, on tissue morphogenesis, (2) to correlate the characteristics ot engineered tissues with 
bioreactor fluid dynamics in the form ot physically and biologically sound mathematical models, and (3) to elucidate 
the mechanisms underlying the effects of microgravity on the structure and function ot the engineered tissues. 
Related practical objectives are to optimize bioreactor design and develop operating strategies tor cultivating tissues 
under conditions of simulated and actual microgravity. 

Task Description: 

A simulated microgravity environment can be used to engineer cell-polymer tissue constructs, the size and shape ot 
which are determined by an FDA approved, biocompatible, biodegradable scaffold with a defined three dimensional 
(3D) shape and structure. In particular, fibrous polyglycolic acid (PGA) can be seeded with isolated cells 
(chondrocytes) and cultivated in rotating bioreactors to make cartilaginous tissue constructs for in vitro studies of 
tissue morphogenesis and/or in vivo implantation. 

Task Significance: 

Engineering cartilage (i.e., tissue constructs grown in vitro using isolated cells and biomaterial scaltolds) can be 
used in vivo, to create subcutaneous neocartilage (in nude mice) and lor joint resurfacing (in rabbits), and thus 
represents a biologically based therapy for repairing cartilage damaged by congenital defects, arthritis, or trauma. 

We have shown that the structure of engineered cartilage depends on hydrodynamic forces during in vitro cultivation, 
this is similar to the known effects of environmental forces on the tissue morphogenesis in vivo. For example, 
structural organization of bone and cartilage depends on the mechanical distribution of compressive and tensile 
stresses. Ground-based research utilizing rotating vessels (simulated microgravily) is expected to enhance our 
understanding the principles governing tissue morphogenesis. Space studies (actual microgravity) can further extend 
the operating limits of these vessels. The same approaches and methodologies can also be applied to other 
cell-polymer model systems, in order to engineer other clinically useful tissues. 

Progress During FY 1 994: 

Specific Aim (1): 

Establish methods to culture chondrocytes in 3D synthetic, biodegradable polymer scaffolds in a rotating vessel to 
regenerate cartilaginous tissue. 

Chondrocytes were uniformly seeded and cultivated on polymer scaffolds in two rotating vessels, the Slow Turning 
Lateral Vessel and the High Aspect Ratio Vessel (STLV, HARV). One week cell-polymer constructs grown in 
rotating vessels contained more GAG (total and per gram) and did not have fibrous outer capsules, as compared to 
control constructs grown in a previously established spinner flask system. These findings can be attributed to 
effects of bioreactor fluid dynamics, and indicate that differentiated cell function is promoted under conditions of 
simulated microgravity. As compared to natural bovine articular cartilage, 1 week cell-polymer constructs had three 
times more cells, 75% as much GAG, and 10% as much collagen per gram dry weight 


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II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

iHiiiiimiitiiMiiiimHiMiitiiiimiiHtiiHiiHMmiiHiiMiimiHHiiiiHiHiiiiiiiiHiiHimiiimiiiimiiiMiiiimmiiiiiMiiimiiiiiiiiiiiMi 


Specific Aim (2): 

Amplify chondrocytes isolated from small cartilage biopsy specimens to obtain the cell mass required to seed 
clinically sized polymer scaffolds. 

Cells can be amplified using petri dishes (serially passaged monolayers) or bioreactors (cell spheroids), but these 
processes can be associated with loss of differentiated cell function (e.g., secretion of type I instead of type II 
collagen). We are developing an ELISA to quantitate the type the collagen extracted from chondrocytes after 
amplification, in order to assess whether rotating vessels can be effectively used for cell amplification. 

Specific Aim (3): 

Correlate the characteristics of engineered tissues with specific fluid dynamic parameters in order to optimize 
bioreactor operating conditions. 

Rotating bioreactors represent a model system for in vitro tissue engineering because hydrodynamic forces can be 
quantitated and controlled. Viscous coupling induces a steady fluid flow field which entrains inoculated cells, 
suspends polymer scaf folds, and maintains nascent cell-polymer constructs in a state of continual free-fall. Under 
these conditions, the relative velocity between the construct and the surrounding fluid can be determined (both 
numerically and experimentally), used to calculate acting hydrodynamic forces and stresses, and correlated with the 
biochemical and physical properties of the engineered tissue. In pilot studies, a relative construct-fluid velocity of 
2-3 cm/sec and an average hydrodynamic stress of 1 .5 dyn/cnr promoted chondrocytes to attach to polymer scaffolds 
and regenerate cartilaginous tissue. 

Collaborations: 

1) Extension from chondrocytes to other cell types: Our group at M.I.T. is now working with Dr. Hartzell at 
duPont to culture cardiac myocytes on PGA scaffolds in rotating vessels. In the pilot study, cell-polymer constructs 
formed that contracted spontaneously and synchronously at rates of 30-130 beats per min.; such constructs could 
potentially be used for in vitro physiological and pharmacological studies. We also plan to collaborate with Dr. 
Lelkes at the University of Wisconsin to use other cell types in a similar model system. Optimal culture 
conditions are expected to depend on the cell type, with respect to mass transfer requirements and shear sensitivity, 
and on the desired clinical application, with respect to tissue dimensions, structure and function. 

2) Extension from simulated to actual microgravity: Right studies could potentially be done relatively soon using 
existing NASA hardware, as the first space studies have already been done in parallel to the ongoing ground-based 
research. Bovine chondrocytes obtained from M.I.T. were flown aboard STS-62 (February, 1994) in an experiment 
done at the Johnson Space Center. In brief, chondrocytes plated tissue culture dishes were flown in the 
Biotechnology Specimen Temperature Controller (BSTC) and the cells were cultivated at 37° C for various time 
intervals (1-4 days). These pilot studies demonstrated chondrocyte growth and metabolism under conditions of 
actual microgravity. 


Students Funded Under Research: 

BS Students: 1 

MS Students: 0 

PhD Students: 0 


Task Initiation: 3/94 Expiration: 3/95 
Project Identification: 962-23-oi-u 
NASA Contract No.: nag -9655 
Responsible Center: jsc 





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II. MSAD Program Tasks 

HitimiuimiiimiitiHHtiiitiiiHiiHiimitiHiiitiiiii 


Ground-based Research Discipline: Biotechnology 

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Bibliographic Citations for FY 1994: 

Journals 

Freed, L.E. Grande. D.A. Lingbin. Z. Emmanual. J. Marquis J.C. Langer. R. Joint resurfacing using allograft chondrocytes 

and synthetic biodegradable polymer scaffolds. J. Biomed. Mater. Res., 28, 891-899 (1994). 

Freed, L.E. Marquis, J.C. Vanjak. G. Emmanual. J. Langer, R. Composition of cell-polymer cartilage implants. Biotech. 
Biocng., 43, 605-614 (1994). 

Freed, L.E. Vanjak, G. Biron. R.J., Eagles, D. Lesnoy, D. Barlow. S.K. Langer R. Biogradable scaffolds for tissue 
engineering. Bio/Technology, 12, 689-693 (1994). 

Freed, L.E. Vanjak-Novakovic. G. Marquis, J.C. Langer, R. Kinetics of chondrocyte growth in cell-polymer implants. 
Biotech. Bioeng., 43, 597-604 (1994). 

Freed, L.E. Vunjak-Novakovic. G. “Tissue engineering of cartilage”. In: Brozino, J.D. (ed). The Biomedical Engineering 
Handbook, CRC Press., (In press 1994). 

Freed, L.E. Vunjak-Novakovic. G. Microgravity Tissue Engineering. In Vitro Cell. Dev. Biol., (Submitted 8/94). 

Freed, L.E. Vunjak-Novakovic. G. Cultivation of cell-polymer implants in bioreactors. In: J.B. Griffiths. A Doyle, D.G. 

Newell (eds). Cell and Tissue Culture Laboratory Procedures. Wiley & Sons (invited chapter), (September 1994). 

Freed, L.E. Vunjak-Novakovic. G. Cultivation of cell-polymer constructs in simulated microgravity. Biotech. Bioeng., 
(Submitted August 1994). 

Presentations 

Freed, L.E.,Vunjak-Novakoic. G. Blum, J.K. Emmanual, J. "Effects of shear on in vitro chondrogenesis." Tissue Culture 
Association, Durham. NC (June 1994). 

Freed, L.E., Vunjak-Novakovic. G. "Chondrocytes cultured on biodegradable polymers form neocartilage in vitro and in 
vivo." European Society for Osteoarthrology, Bari. Italy (September 1994). 

Freed, L.E. Vunjak-Novakovic. G. "Tissue engineered cartilage: bioreactor cultivation and in vivo implantation." 
Biomedical Engineering Society, Tempe, AZ (October 1994). 

Freed. L.E. Vunjak-Novakovic. G. Grande, D.A. Emmanual. J. Langer, R. "Cell-Polymer Cartilage Implants. Keystone 
Tissue Engineering Conference. Taos, NM (February 1994). 

Vunjak-Novakovic, G. Freed. L.E. "Hydrodynamic forces determine in vitro chondrogenesis in a three-dimensional 
cell-polymer model system.' European Society for Osteoarthrology, Bari, Italy (September 1994). 


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Discipline: Biotechnology 

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Excitable Cells and Growth Factors under Microgravity Conditions 


Principal Investigator: Dr. Charles r. Hartzeii 

Alfred 1. duPont Institute 

Co-Investigators: 


N. SchroedI 
S. Gonda 

Alfred I. duPont Institute 
NASA Johnson Space Center (JSC) 

Task Objective: 


Peptide growth factors are intimately involved in the regulation of normal muscle growth and differentiation. 
Invaluable ground work has been laid by investigators using numerous muscle cell lines to elucidate the 
contributions made by these growth factors in myogenesis, and significant advances in understanding these 
mechanistic pathways have been achieved. We underscore, however, the importance of confirming these results in 
primary muscle cultures. 

Task Description: 

Using the NASA bioreactor, we will examine the effects of a three-dimensional architecture on the growth and 
differentiation of neonatal rat heart cells and young adult muscle satellite cells. The bioreactor allows muscle cells 
to orient and grow within constraints normally determined by the basal lamina in vivo , yet permits experimental 
parameters to be cleanly delineated. Once muscle cultures are established, the role of neuromuscular junction 
formation on myogenesis will be explored by co-culture of heart or skeletal muscle cells with cholinergic neurons. 
Alterations in the differentiation program induced by fibroblast growth factor, insulin-like growth factor-I and 
transforming growth factor-b will be evaluated. 

Task Significance: 

The two-dimensional, unit-gravity constraints of conventional cell culture do not optimally model the 
three- dimensional cytoarchitectural design of the in vivo system. Limitations inherent in standard cell culture 
systems encourage us to continue the development of an innovative in vitro model system that is not limited by 
gravity-induced constraints and that promotes die formation of diree -dimensional, in vnr;-like tissue that is critical 
to understanding myogenic regulation. 

Progress During FY 1 994: 

1 Neonatal Rat Heart Cells Cultured in HARV Bioreactor 

In vitro characteristics of cardiac cells cultured in simulated microgravity are reported. Tissue culture methods 
performed at unit gravity constrain andiorage-dependent cells to propagate, differentiate, and interact in a 
two-dimensional (2D) plane. Neonatal rat cardiac cells in 2D culture organize predominantly as bundles of 
cardiomyocytes with the intervening areas filled by non-myocyte ceil types. Such cardiac cell cultures respond 
predictably to the addition of exogenous compounds, and in many ways, they represent an excellent in vitro model 
system. The gravity-induced 2D organization of the cells, however, does not accurately reflect the distribution of 
cells in the intact heart tissue. The NASA designed High- Aspect-Ratio- Vessel (HARV) bioreactors provide a low 
shear environment which allows cells to be cultured in static suspension. To evaluate the potential changes induced 
by the culture conditions of the HARV, neonatal rat heart cells are currently being characterized by a combination of 
biochemical and cell biological techniques. Since, at the preliminary level, the coordinated activity of the heart 
depends on specific, sequential events (including cytosolic Ca 2+ elevation, conformational changes and interactions 
among the contractile proteins, energy availability, and the alignment of myocytes and organization of cellular 
structures), we are in the process of examining: 1) Contractile Function: cardiac cell beat frequency and strength; 2) 
Ca 2+ Handling: Ca i+ distribution, mobilization, and sequestration; 3) Protein Composition: the expression of 
essential proteins; 4) Energy Metabolism: shifts in metabolism or ATP availability; 5) Cellular Morphology: the 


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II. MSAD Program Tasks — Ground-based Research 


Discipline: Biotechnology 

IIIIIIIMIKMtlltllllltKIItlMIMIlIXMlIKilMKIMtHIHIIMMMMIHIIIIIIIIIIIIItilllllllllliailll 


spatial distribution of cardiac cell types; 6) Ultrastructural Morphology: the organization of cellular components and 
organelles. HARV-3D cultures were prepared on microcarrier beads and compared to control-2D cultures using a 
combination of microscopic and biochemical techniques. Both systems were uniformly inoculated at 1x10 cells per 
milliliter medium per 4.8cm 2 surface area (polystyrene). The serum-free defined medium was exchanged at standard 
48 hr intervals after day one in culture. Cells in control culture dishes adhered to the polystyrene surface of the 
tissue culture dishes and exhibited typical 2D organization. Cells cultured in HARVs adhered to the Nunc D-Si 
polystyrene microcarrier beads, the beads aggregated into defined clusters containing 8 to 15 beads per cluster, and 
the clusters exhibited distinct 3D layers: myocytes and fibroblasts appeared attached to the surfaces of the beads and 
were overlaid by an outer cell type. In addition, cultures prepared in HARVs using alternative support matrices also 
displayed morphological formations not seen in control cultures. Generally, the cells prepared in HARV and control 
cultures were similar; however, the dramatic alterations in 3D organization gives credence to the generation ot 
tissue-like organizations of cardiac cells in simulated microgravity. 

2. Rat Skeletal Muscle Satellite Cells Cultured in the HARV Bioreactor 

Satellite cells are postnatal myoblasts responsible for providing additional nuclei to growing or regenerating muscle 
cells. Satellite cells retain the capacity to proliferate and differentiate in vitro and, therefore, provide a useful model 
to study postnatal muscle development. Limiting proliferation and differentiation of satellite cells in 2-D could 
potentially limit cell-cell contacts important for developing the level of organization in skeletal muscle obtained in 
vivo. Culturing satellite cells on microcarrier beads suspended in the High-Aspect-Ratio- Vessel (HARV) designed 
by NASA provided a low sheer, three-dimensional (3-D) environment to study muscle development. Primary 
cultures established from anterior tibialis muscles of growing rats (- 200 gm) were used for all studies and were 
composed of greater than 75% satellite cells. Different inoculation densities ranging from 0.5xl0 6 to 2xl0 6 cells 
with a cell/bead ratio 20:1 did not affect the proliferation potential of satellite cells in the HARV. Plating 
efficiency, proliferation, and glucose utilization were determined and compared between 2-D flat culture and 3-D 
HARV culture. Plating efficiency (cells attached + cells plated x 100) was similar between the two culture systems 
and generally was greater than 70%. Proliferation was reduced in 30% of HARV cultures and this reduction was 
apparent for both satellite cells and non-satellite cells. Furthermore, reduction in proliferation within the HARV 
could not be attributed to reduced substrate availability since glucose levels in media from HARV and 2-D cell 
culture were measured to be similar. Morphologically, microcamer beads within the HARV s were joined together 
by cells into three-dimensional aggregates composed on 10-15 beads/aggregate. Aggregation of beads did not occur 
in the absence of cells. Myotubes were often seen on individual beads or spanning the surface of two beads. In 
summary, proliferation and differentiation of satellite cells on microcarrier beads within the HARV bioreactor results 
in the formation of a three-dimensional level of organization that provides a suitable model to study postnatal 
muscle development. 

3. Myogenic Gene Expression During Postnatal Myogenesis 

Rat skeletal satellite cells (postnatal myoblasts) express an intrinsic genetic program that defines them as belonging 
to the myogenic lineage. This intrinsic program is best exemplified by the ability of satellite cells to differentiate 
and form contraction-competent myotubes in vitro. MyoD, myogenin, MRF4 and myt5 represent a class ot 
muscle-specific transcription factors that modulate the myogenic program during embryonic development, but their 
role during postnatal myogenesis remains unclear. We have determined the expression pattern for each myogenic 
factor, and quantitated the level of each factor during different stages of postnatal myogenesis using satellite cells 
isolated from young adult rats. Reverse transcription polymerase chain reaction (RT-PCR) was used to determine if 
mRNA for each myogenic factor was present. cDNAs generated by RT-PCR were subcloned and used as specific 
probes to quantitate the level of each myogenic factor. The following stages of myogenesis were characterized: 
freshly isolated cells prior to plating (time 0); proliferation (3 day post-plating); day 1 of myotube formation (5 day 
post-plating), early myotubes (8 day post-plating); late myotubes (13 day post-plating). All myogenic factors were 
present at each stage examined using RT-PCR. However, levels for each myogenic factor mRNA differed. MyoD 
level was highest in mononucleated cells. The myogenin level increased 15 fold between day 3 and day 5. MRF4 
and myf5 were not detectable until day 1 of myotube formation (using slot blots). In summary, satellite cells 
isolated from growing rats expressed myogenic factors in a different pattern than what has been reported for 
embryonic myoblasts and established cell lines. 


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II. MSAD Program Tasks — Ground-based Research 


• • IIIHHI mill Ill III II lilt I 


Discipline: Biotechnology 

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Students Funded Under Research: Task Initiation: 11/92 Expiration: io/96 

Project Identification: 962-23-01-07 
NASA Contract No.: nag-656 

Responsible Center: jsc 


Bibliographic Citations for FY 1994: 

Journals 

Akins. R.E. Schroedl. N.A. Gonda, S.R. and Hartzell. C.R. Neonatal rat heart cells cultured in simulated microgravity. In 
Vitro Cell Diff., (Submitted 8/94). 

Ho, M.L.. Molnar, G. Funanage, V.L. Schroedl. N.A. Expression and quantitation of myogenic factors during postnatal 
myogenesi s. Dev. Biol., (Submitted 9/94). 

Holshek. J.G. and Akins, R.E. Acetonitrile: A superior dehydrating agent in cellular preparations for SEM. Microscopy 
Research and Techniques, (Submitted 7/94). 

Holshek. J.G. and Akins. R.E. Acetronitrile is better than ethanol as a dehydrating agent for cells prepared for SEM. Proc. 
Micros. Soc. Ainer., 52. 324-325 (1994). 

Molnar, G. Schroedl, N.A. Gonda, S.R. and Hartzell, C.R. Skeletal muscle satellite cells cultured in simulated 
microgravity. In Vitro Ceil. Diff., (Submitted 8/94). 

Presentations 

Akins, R.E. Neonatal rat heart cells cultured in simulated microgravity. " Gordon Research Conference: Gravitational 
Effects on Living Systems. August 1994. 

Akins, R.E., Schroedl, N.A. Gonda. S.R. and Hartzell, C.R. 'Characterization of a novel three-dimensional culture system 
for cardiac cells." Mol. Biol. Cell.. American Society for Cell Biology’s 34th Annual Meeting, San Francisco, CA, 
December 1994. 

Ho, M.L.. Molnar, G. Funanage, V.L. and Schroedl, N.A. "Myogenic gene expression during postnatal myogenesis." 

Mol. Biol. Cell., American Society for Cell Biology’s 34th Annual Meeting, San Francisco, CA. December 1994. 


Molnar, G., Schroedl, N.A. Gonda, S.R. and Hartzell. C.R. "Characterization of postnatal myogenesis in a 
three-dimensional system." Mil. Biol. Cell, American Society for Cell Biology’s 35th Annual Meeting, San Francisco. 
CA, December 1994. 


Schroedl, N.A.. Akins, R.E. Molnar, G. Gonda, S.R. and Hartzell. C.R. "Culture of cardiac and muscle cells in simulated 
gravity. In Vitro Cell Diff.. in press; (1994). Society for In Vitro Biology’s Annual Meeting, Research Triangle, NC, 
June 1994. 


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II. MSAD Program Tasks — Ground-based Research 




Discipline: Biotechnology 

II I 


Sensitized Lymphocytes for Tumor Therapy Grown in Microgravity 

PRINCIPAL Investigator: Dr. Marylou Ingram Huntington Medtcal Research Institutes 


Co-Investigators: 

G. Techy 

R. Saroufeem 

S. Narayan 
O. Yazan 

T. Goodwin 


HMRI 

HMRI 

HMRI 

HMRI 

NASA Johnson Space Center 


Task Objective: 

The NASA High Aspect Ratio Vessel (H ARV) bioreactor is used to generate spheroids of human tumor cells. 

These spheroids are then used to sensitize the patient's lymphocytes to the patient’s own tumor .The population ot 
tumor-sensitized lymphocytes (TSL) is then expanded in culture in the presence ot interleukin-2 (IL-2) and used u 
immunotherapy of the patient. 

Task Description: 

This is a small scale, in depth pilot study in which nonspecifically stimulated autologous lymphocytes (ASL) and 
tumor-sensitized lymphocytes (TSL) are administered serially by intralesional injection as local immunotherapy ot 
invasive carcinoma of the urinary bladder. This is a modification of cellular immunotherapy that we have applied 
with encouraging results in clinical trials to treat recurrent malignant gliomas (1). For the bladder cancer, the 
urological surgeon will inject cells intralesionally at intervals of approximately three weeks. Response to therapy 
will be determined by direct observation of the lesions, serial biopsies for histological and cytological studies, 
clinical evaluations and radiological exams. The ability to biopsy lesions at various times after injection ot 
stimulated immune cells is an important advantage in understanding response to therapy and in retming the therapy. 
Serial evaluation of lesions bv histology, measuring the expression of major oncogenes and tumor suppressor 
genes, assays of cytotoxic effectiveness of ASL and TSL to tumor obtained from unne specimens or bladder 
washings can provide additional information between biopsy specimens. The pilot study provides an excellent 
opportunity to evaluate the NASA H ARV bioreactor as a method for culturing tumors as spheroids as contrasted 
with conventional monolayer cultures. Tumor spheroids in vitro have a number ot characteristics present in vivo 
but absent from monolayer cell cultures. These characteristics, some of which will undoubtedly be unporiant in the 
generation of TSL cells, include the presence of specific tumor markers, angiogenesis and growth tactors. bio ogic 
response modifiers, gap junctions and tumor suppressor gene expression. Changes in the level ot expression an 
distribution of intermediate filaments and the extracellular matrix elements have also been observed. 


Task Significance: 

Cancer of the urinary bladder is of special interest in immunotherapy because it has already been shown that 
immunotherapy in the form of BCG treatment is efficacious. It is now widely used in clinical management o 
invasive bladder cancer. Thus, there is sound evidence that appropriate mobilization of the patients own cellular 
immune mechanisms can have therapeutic efficacy. A number of investigators have recognized the possibility that 
TSL may offer significant advantages in adoptive immunotherapy and there has been a recent resurgence ot interest 
in this approach (2). TSL can be expected to show increased tumor cell killing, as do tumor-mtiltrating 
lymphocytes (TIL) and they also hold forth the promise of serving as probes for identifying immunogenic gene 

products in the tumor. 

Many elderly patients with multiple tumors of the urinary bladder cannot tolerate extensive surgery or extensive 
chemotherapy and may either have failed to respond to BCG immunotherapy or are too unwell to tolerate side 
effects of that therapy. These patients present a frustrating therapeutic problem to the urologist. We believe that 


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local immunotherapy would he well tolerated by these patients and that it is a rational therapeutic strategy. A 
clinical trial ot this therapy will also provide valuable information about how stimulated immune cells select and 
identity their target cells, migrate through tissue, whether or not they continue to proliferate after injection and 
other important considerations that will advance our understanding of cellular immunotherapy and aid in refining it 
tor treatment of bladder cancer and ultimately other cancers. 

Bladder cancer has many advantages as a model for refining methodology. It permits serial administration of 
immunologically stimulated cells into the bladder lesions and yields serial biopsy specimens in which the 
interactions of immune cells and their tumor targets can be studied directly. 

1) Ingram, M., Buckwalter. J.G., Jacques, D.G., et al. Neurological Research 12:265-273 (1990) 

2) Greenberg, P.D.. Riddell. S.R.J., Natl. Cancer Inst. 84: 1059-61 (1992) 

Progress During FY 1 994 : 

During FY 94 we have had considerable success in culturing a variety of otherwise "anchorage-dependent” cells lines 
under conditions ot simulated microgravity in the NASA HARV (high aspect ratio vessel) bioreactor. These cells 
include relatively early passages os some cell lines. To avoid anchorage effects, no microcarrier beads are used. The 
bioreactor is simply filled with a monodisperse suspension containing 1-2 million cells per ml of nutrient medium. 
The cultures are maintained for periods ot a tew days to approximately a month. The spheroids produced are fixed in 
Camoy s/Bouin s fixative, then sectioned and stained. Some sections of each specimen are stained with 
hematoxyline and eosin and other sections trom the same specimen are stained immunohistochemically to 
demonstrate various markers of interest. 

When cultured in the bioreactor, each cell line produces spheroids that demonstrate cell line-specific microscopic 
architecture. Thus, gliomas tend to form small, compact spheroids that sometimes fuse to form larger bodies; die 
PC3 cell line that was developed from prostate carcinoma metatstatic in bone forms discrete spheroids in which cells 
are very loosely associated. Another prostatic carcinoma cell line, LNCaP, typically forms elongated tubule-line or 
folded structures. The bladder carcinoma cell line, HBL2, recendy developed here, shows a definite tendency towards 
epithelial differentiadon. The tendency tor the HBL2 cells to assemble in such a pattern suggests that various 
adhesion molecules play a role in determining spheroid morphology. Immunohistochemical staining to demonstrate 
tibronectin, collagen, vimentin, CD44 and other cell adhesion molecules can be expected to provide further insight 
into spheroid formadon and differentiation. These studies are in progress. 

An abstract and poster describing results ot cell culture in the NASA bioreactor were accepted for presentation in the 
"Hot Topic" poster session at the Congress on Cell and Tissue Culture Regulation, Cell and Tissue Differentiadon 
convened by the Tissue Culture Association, June 4-7, 1994 at Research Triangle Park, N.C. Dr. Ramez 
Saroufeem, who had primary responsibility for the bioreactor cultures of the HBL2 cancer cell line, attended the 
meedng and presented the poster. 


Our clinical collaborator. Dr. Michael Bishai, urological surgeon, has provided fifteen surgical specimens of bladder 
tumors and these have been invaluable. They have allowed us to refine ussue culture methods specifically for 
bladder cancer. Most ot the padents from whom the specimens were obtained did not meet protocol requirements 
(patient selecuon criteria) tor the immunotherapy trial and Dr. Bishai managed these padents clinically using other 
therapeutic modalities. The titteenth pauent does meet protocol requirements and has just been entered as the first 
protocol patient. 


From the bladder cancer specimens obtained so tar, we have established one bladder cancer cell line and, at least one 
additional specimen may also yield a permanent cell line. The new cell line, designated HBL2, has been cultured in 
both monolayer culture and in the NASA bioreactor culture vessel HBL2 cells, as well as minced tumor from some 
ot the other bladder cancers and glioma and prostate cancer cell lines, provide important experimental and reference 
specimens for immunohistochemical demonstrauon of "markers” of interest and for comparison of "marker” 
expression in cells grown in monolayer as contrasted with the same cell lines grown as spheroids or examined in 


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11-209 


II. MSAD Program Tasks — Ground-based Research 

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Discipline: Biotechnology 

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tumor mice specimens. Although we cannot, of course, expect to establish a permanent cell line (t.e., at least 25 
passages) from every tumor, primary cultures and tumor mince will be available tor use in preparing TS m 
cases. Where possible, lymphocytes to be tumor-sensitized for bladder cancer immunotherapy will be exposed to 
tumor mince, monolayer cultures, and tumor spheroids in parallel so that we may compare the relative 
immunological effectiveness of the tliree inodes of tumor presentation. We also hope to establish, trom a least one 
tumor, a line of fibroblasts and a line of endothelial cells as well as tumor cells and to use these autologous cells in 
a structured series of co-cultures to observe histogenesis and the effects ot active histogenesis on the expression ot 
antigenic gene products. 


Students Funded Under Research: Task Initiation: 11/92 Expiration, 11/95 

Project Identification: 962-23-01-14 
NASA Contract No.: nag -649 
Responsible Center: jsc 


Bibliographic Citations for FY 1994: 


Incram. M.. Techy, G.B.. Naravan. S.. Saroufeem. R.. Bishai. M.. Spaulding, G.F. and Goodwin. T J. Epithelial 
differentiation of early passage human bladder cancer cells in simulated microgravity of the NASA HARV bioreactor. (In 
preparation). 

Ingram. M.. Techym, G.B.. Narayan. S.. Saroufeen. R.. Spaulding, G.F.. and Goodwin. T.J. Variable three-dimensional 
growth of human malignant tumors in simulated microgravity of the NASA HARV bioreactor. (In preparation). 

Presentations 

Saroufeem. R„ Ingram, M. Techy. G.B., Narayan. S.. Bishai. M.. Craft. J.. Spaulding. G.. and Goodwin. T 
■Three-dimensional growth and differentiation of early passages of human tumor cells in simulated microgravity in NASA 
bioreactor.'' Annual Meeting of the Tissue Culture Association. June 4-7. 1994 at Research Triangle Park. Abstract 
SV-1006, Hot Topics Addendum Booklet. 


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II. MSAD Program Tasks — Ground-based Research 




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Discipline: Biotechnology 

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Three-Dimensional Modeling of Human Colon Tissues 

Principal Investigator: Dr. j. m. Jessup 

New England Deaconess Hospital 

Co-Investigators: 


P. Thomas 

Harvard Medical School, Deaconess Hospital 


Task Objective: 

The objectives ol this project are to determine whether 1) microgravity permits unique, three-dimensional cultures 

ol neoplastic human colon tissue and 2) this culture interaction produces novel intestinal growth and differentiation 
t actors. 


Task Description: 

The initial phase ot this project will test the feasibility of microgravity for the cultivation and differentiation of 
human colon carcinoma. We propose to do this in rotating wall vessels (RWVs) which provide a low shear stress 
environment in unit gravity. In tins environment, early experiments have demonstrated normal human colon 
tibroblasts stimulate tire differentiation ol certain human colon carcinoma cell lines so that diev produce 
three-dimensional tissue masses that are similar to neoplasms in patients or in xenografts in athvmic nude mice. 

Task Significance: 

The important question is whether this differentiation induced by fibroblasts is due to die low shear stress 
environment ol the RWV or whether suspension cultures in die RWVs are similar to cultures in standard culture 
systems in unit gravity. Should the low shear stress environment of die RWV be supernn to that of conventional 
culture systems, then the co-culture experiments should he attempted in an actual imcrogravity environment. 

Progress During FY 1 994. 

This grant w'as completed in May 1994, and its purpose was to determine whether normal stromal cells coated with 
epithelial cells would torm three-dimensional structures that were similar to tissues that developed in mice or 
humans. We studied adenocarcinomas ot the colon and began studies with normal colonic epithelium. We did not 
culture normal colonic epithelium in die rotating wall vessel (RWV) because we were not able to obtain a small 
(50ml) RWV. Nonetheless, we did demonstrate that normal colonic epithelial cells isolated from colonic crypts 
adhered to collagen Type IV and to carcinoembryonic antigen (CEA)-coalcd surfaces. This suggests that CEA is an 
intercellular adhesion molecule that may be used by human normal colonic epithelial cells, while normal 
colonocytes use collagen Type IV as a ligand in their basement membrane. This work resulted in a publication in 
Gastroenterology. As indicated in that publication, normal colonocytes do not survive more th;m 24-4X hours when 
cultured on either CEA or collagen Type IV. Their ability to remain viable is better on collagen Tvpe IV dtan on 
any other substrate including laminin and tibronectin-coated surfaces. However, because survival is so short for 
these isolated colonocytes, we did not feel that we could put diese cells into the RWV unless they were cultured in 
small volumes so that we could use sufficient spent medium to u v to prolong dieir suivival. 

We have attempted to isolate normal human stromal cells from colonic surgical specimens. However, the 
amount ot tissue that we have obtained from our pathology department has been too small to initiate primary 
cultures of colonic fibroblasts in sufficient quantity to allow stromal cell cultures. As a result, we attempted to use 
a mouse embryonic fibroblast cell line, BALB/c 3T3 cells as the stromal feeder cell. When we did this, die 
3T3;MIP-101 cells did not interact well and did not grow together in suspension. The M1P- 101 cells actually 
shunned the 3T3-coated microcarrier heads and the MIP-101 colon carcinoma cells grew in suspension. 

Our rational for this experiment is that these human colonic adenocarcinoma cell lines develop different degrees 
ot differentiation when grown as xenografts in mice and this requires interaction with mouse stromal cells. We also 
reasoned that an immortal embryonic fibroblast line may numic colonic fibroblast function under appropriate in 


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11-21 1 



II MSAD Program Tasks — Ground-based Research 

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Discipline: Biotechnology 

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vitro conditions. We did not repeat this with the other cell lines because they will behave much like HT-29. We 
did culture HT-29 KM with 3T3 cells and found that they behave similarly to the human colonic tibroblast.HT-29 

K *TOs sWdTwas to investigate the production of novel intestinal growth factors. We had initially developed a 
cumbersome bioassay in which potential factors were encapsulated in liposomes and injected into the cecal wall ot 
mice Growth and differentiation of mucin-filled goblet cells was evaluated by morphological assay of colonic 
crypts overlying the liposomal implant. This assay was extremely operator-dependent and was not easily reproduced 
in Boston As a result we attempted to develop a series of in vitro bioassays which examined the amount o 
antigen expressed on the cell surface by a ceU based enzyme immunoassay. The difficulty with this type ot assay is 
that none of the six colorectal cell lines that we examined had stable expression of the mucin re ate epitopes a 
we were evaluating. Thus, the ability to demonstrate the goblet cell differentiating factor <GCDF) activity that 
initially been defined in the in vivo bioassay was not supported by a subsequent in vitro assay. Nonetheless, we did 
evaluate the expression of EGF, bFGF, and TGF-p 1 were released by these colon carcinoma cell lines into the 
surrounding medium. Interestingly, recent data from other laboratories suggest that well or moderately ddferenuated 
carcinomas are inhibited by TGF-P 1, whereas poorly differentiated cell lines may be stimulated b >' TGF 'P • 
results indicate that LS-174T cultures plateaus as the TGF-P 1 concentration increases. However, the other three 
colon carcinoma cell lines did not demonstrate a consistent relationship among the proliferation, viability and 
TGF-P 1 level. MIP-101 cultures, for instance, demonstrate a decrease in TGF-p 1 concentrations even as they enter 

a plateau phase. 


Students Funded Under Research: 


Task Initiation: 4/9 i Expiration: 4/94 

Project Identification: 962-23-01-05 
NASA Contract No.: nag-520 
Responsible Center: jsc 


Bibliographic Citations for FY 1994: 

hTssep" J.M. Goodwin. T.J. and Spaulding G. Prospects for use of microgravity-based bioreactor to study 
three-dimensional host-tumor interactions in human neoplasia. J. Cell Biochem., 51. 290-300 (199.). 

Jessup, J.M. Brown K. Ishii S. Ford R. Goodwin T.J. Spaulding G.F. Simulated microgravity does not alter epithelial cell 
adhesion to matrix and other molecules. . Adv. Space Res.. 14(8), 71-76 (1994). 

Spaulding, G.F. Jessup J.M. and Goodwin T.J. Advances in cellular construction. J. Cell Biochem., 51, 249-251 (1993). 

Jessup J Goodwin T. "Simulated microgravity improves production of colonic growth factors." AIAA Space Programs 
and Technologies Conference and Exhibit. September 21-23, 1993, Huntsville, AL. AIAA-93-4098. 

Jessup, J.M. Fitzgerald W. Polanec J. Ford R. Goodwin T. Spaulding G.F. Brown D. "CEA production in human colon 
cancer." 1994 Meeting of the Tissue Culture Association. Research Triangle Park. NC. June, 1994. 

Jessup, J.M. Thomas P. Ford R.D. Ishii S. "Homotypic adhesion mediated by carcmoembryomc antigen (CEA) in 
colorectal carcinoma cells involves CD44 and NCA." Keystone Symposium. Cell Surface and Tissue Engineering Meeting, 
Taos. NM, February, 1994. 


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11-212 



II. MSAD Program Tasks — Ground-based 

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Research Discipline: Biotechnology 

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Three Dimensional Tissue Interactions in Colorectal Cancer Metastasis 


Principal Investigator: Dr. j. m. Jessup 

New England Deaconess Hospital 

Co-Investigators: 

No Co-I’s Assigned to this Task 



Task Objective: 

The objective ot this project is to test the fidelity with which microgravity models three-dimensional tissues by 

assessing how well microgravity effects the molecular and biological function of MIP-101, a human colorectal 
carcinoma. 


Task Description: 

MIP-101 is a poorly differentiated adenocarcinoma ot the colon that was derived from the ascites of a patient who 
had widespread metastases within the abdominal cavity. MIP-101 cells are grown in the rotating wall vessel 
(RWV) with or without normal host cells and assessed for the production of carcinoembryonic antigen (CEA - a 
180 kDa glycoprotein that is produced by carcinomas and used clinically as a tumor marker) and for biological 
behavior including adhesion and metastasis. Cells grown in microcarrier bead cultures in the RWV under simulated 
microgravity are compared to similar MIP-101 cultures grown on microcamer beads in stationary culture as well as 
in conventional monolayer cultures. 


Task Significance: 

One of the prime goals of the biotechnology program at NASA/Johnson Space Center is to determine whether 
cultivation ot cells in microgravity produces three-dimensional cultures that mimic the morphology and function of 
tissues in living animals or humans. The MIP-101 cells are an excellent test of this because they are poorly 
metastatic in experimental models of metastasis in athymic nude mice and do not produce CEA in conventional 
monolayer culture systems. We have shown that CEA injected into mice enhances production of liver metastases 
by MIP-101 cells and that MIP-101 cells will metastasize when implanted into the abdominal cavity after producing 
CEA. MIP-101 cells placed in the subcutaneous tissue of the mouse do not metastasize and do not produce CEA. 
Furthermore, cells grown on plastic or conventional substrates such as Matngel or laminin are neither metastatic 
nor induced to produce CEA. 

The conventional interpretation of these results is that the microenvironment (the three-dimensional environment) 
ot the abdominal cavity induces MIP-101 cells first to produce CEA and then to develop blood-borne metastases in 
the liver and lungs of nude mice. Early experiments in the RWV question this conventional interpretation of the 
ettects ot host microenvironment, because they demonstrated that CEA production may be induced in MIP-101 cells 
when they are grown in the RWV in the absence of any abdominal cavity stromal cells. This suggests that the 
MIP-101 cells may produce CEA when they are allowed to grow in three dimensions. Thus, the absence of CEA 
production in subcutaneous tumors is due to an inhibition of CEA production by the subcutaneous tissue rather 
than promotion of CEA production and metastatic potential by the abdominal cavity. 

This system is an excellent model in which to test the fidelity of the RWV culture system because the first stage in 
metastasis by MIP-101 cells appears to be the induction of CEA production, followed by the acquisition of the 
ability to develop experimental metastases after injection into the spleen of nude mice. Assessment of fidelity of 

the RWV culture system is simplified by first testing for the production of CEA, tumor marker, then assessing the 
biological aspects of metastasis. 


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II— 2 1 3 


II. MSAD Program Tasks - 





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Progress During FY 1994: 

The Drimarv aoal of the Biotechnology Program at NASA/Johnson Space Center is to determine whether cells 
cultivated in microgravitv produce three-dimensional cultures that mimic the morphology and function of tissues in 
ZZmZToT , tains The MIP-101 cells are a» excellent .extol this because !hey are poorly tTteutxtauc m 
experimental models of metastasis in adiymit nude mice and do nol produce CEA in convenuonal monolayer 
culture systems. We have shown that CEA injected into mice enhances production ot liver metasue.es by MIP- 
ce “and that MIP-101 cells will metastasize when implanted into die abdomtnal cavtty as they produce CEA. 
Recently a CEA-producing transfectant of MIP-101 cells was found to be metastatic in nude mice. However, 
parenteral MIP-101 cells placed in the subcutaneous tissue of the mouse do not metastasize and do not produce 
CEA. Furthermore, cells grown in plastic or conventional substrates such as Matngel or laminin are neither 
metastatic nor produce CEA at detectable levels by either RT-PCR or western blots. 

Since the three-dimensional growth in the peritoneal cavity induces the production of CEA it was thought that 
penToneal shomal cells were able to induce CEA production by MIP-101 cells. Interestingly, when MIP-101 cells 
were grown as three-dimensional colonies in the rotating wall vessel (RWV), CEA was released into the medium 
and immunoperoxidase staining of MIP-101 cultures revealed that MIP-101 cells is 

CEA cells forming three-dimensional aggregates. Thus, it appears that produc on y 

enhanced by three-dimensional growth as opposed to two-dimensional growth in monolayers. 

Recently, more data has been obtained to support this mterpretation. Interestingly, some 

that growth in Petri dishes or m T-25 flasks leads to CEA production as determined by western b ot analysis as well 
ashy enzyme immunoassay ol hie spent culture medium. RT-PCR demonstrates .gene mmsctpts .te 
convenuonal culture systems when MIP-101 cells have been cultivated * < ** ' ^^J^er 
however, shows that the s ene transepts are still quite low ,n number and Utah .1 KT-PCR as ^°"™1 'g™ 
stringent conditions, the quantity of mRNA for CEA is below the limits ot detection. In contfast RT-PCR and 
western blots clearly demonstrate the presence of the 180 kDa protein in RWV cultures ot MIP-101 as early ^as 4 
days after the initiation of RWV cultures. In addition, CEA proteins are identified by inmunoperoxtdase stammg 
day 4 as well as by western blots of extracts of MIP-101 cells beginning at day 8. The findings ot low CEA 
production by MIP-101 cells in Petri dishes and T-25 flasks was somewhat unexpected, but was found to be 
associated with overcrowding and "piling up"' of MIP-101 cells as the cultures grew vertically. Tims, in the late 
phases of the MIP-101 cultures, since thev are not contact-inhibited, the cells assume a three-dimensional formation 
S somewhat shnUar to the aggregates that are formed in the RWV. Thus, it is clear that there is a very low 
amount of CEA produced in MIP-101 cells which can be dramatically increased as the cells enter a three-dimensional 

culture formation. 

The factors that regulate the three-dimensional formauon and how this alters cell growth are being S ^esUgated It 
is clear that, in the three-dimensional aggregates formed in the RWV, the metabolic : rate of J^MIP-lOUell 
dramatically increased. A comparison of the MIP-101 cells grown in zero head-space T-25 flasks widi the RWV 
similar cell concentrations indicates that far more H* ion and C0 2 are produced in the RWV than m the mono ayer 

culture. However, the amount of glucose utilized is not significantly different. This f^u^T 

fuel source is being used by these cells in the RWV that leads to the production ot acid metabolites. Future 
experiments are designed to determine how these different metabolic pathways are activated because they may impac 

on the regulation of CEA production. 

In addition, studies are underway to identify how the peritoneal cavity improves die metastatic potential of these 
MIP cells and notwithstanding the effects of MIP cells grown m isolation on CEA production, there are su 
stromal cell MIP cell interactions. Recent work with Dr. Catherine Chen, who is doing a research fellowship in 
Dr Judah Folkman s laboratory, indicates that MIP-101 cells grow preferentially along the gneater curvature ^ the 
stomach of nude mice. Dr. Chen has found that most human neoplasms prefer to grow in dnspart ot the peritoneal 
St compared to the mesentery or other peritoneal surfaces in die abdominal cavity, f this is mie dien it 
should be possible to isolate the cells that support this growth and use them as stromal tells in future 
co-cultures with MIP-101 cells. We plan to do this in the next part ot the fiscal year as well as to investigate the 
metabolic pathways that are involved with induction of CEA production by MIP-101. 


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II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 


Students Funded Under Research: Task Initiation: 1/93 Expiration: i/96 

Project Identification: 962-23-01-13 
NASA Contract No.: nag-650 
Responsible Center: jsc 


Bibliographic Citations for FY 1994: 

Journals 

Jessup, J.M. Brown K. Ishii S. Ford R. Goodwin T.J. Spaulding G.F. Simulated microgravity does not alter epithelial cell 
adhesion to matrix and other molecules. Adv. Space Res.. 14(8), 71-76 (1994). 

Jessup, J.M. Goodwin T.J. and Spaulding G. Prospects for use of microgravity-based bioreactors to study 
three-dimensional host-tumor interactions in human neoplasia. J. Cell. Biochem.. 51. 290-300 (1993). 

Spaulding, G.F. Jessup J.M. and Goodwin T.J. Advances in cellular construction. J. Cell. Biochem.. 51, 249-251 (1993). 

Presentations 

Jessup, J. Goodwin T. "Simulated microgravity improves production of colonic growth factors." AIAA Space Programs 
and Technologies Conference and Exhibit. September 21-23. 1993, Huntsville, AL. AIAA-93-4098. 

Jessup, J.M. Fitzgerald W. Polanec J. Ford R. Goodwin T. Spaulding G.F. Brown D. "CEA production in human colon 
cancer." 1994 Meeting of the Tissue Culture Association. Research Triangle Park, NC, June 1994. 

Jessup, J.M., Thomas P. Ford R.D. Ishii S. "Homotypic adhesion mediated by carcinoembryonic antigen (CEA) in 
colorectal carcinoma cells involves CD44 and NCA." Keystone Symposium, Cell Surface and Tissue Engineering Meeting, 
Taso, NM, February 1994. 


I Mil I 


11-215 


II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

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Applications of Atomic Force Microscopy to Investigate Mechanisms of Protein Crystal Growth 


Principal Investigator: Dr. John h. Konnert 

Naval Research Laboratory (NRL) 

Co-Investigators: 


K. Ward 

Naval Research Laboratory (NRL) 

P. D’ Antonio 

Naval Research Laboratory (NRL) 


Task Objective: 

The research objective is to use Atomic Force Microscopy to study protein crystal growth mechanisms by 
extending the pioneering work of Durbin et al (1992) to include crystals other than lysozyme, and by applying 
image analysis methods not generally available to others to aid in the interpretation of crystal face images observed 
by this technique. Specific objectives include: 

• To modify an AFM liquid sample cell for use as a crystal growth cell for protein crystals. This ceil has a 
flow-through system which will allow protein supersaturation to be controlled by varying the temperature ot the 
crystallization solution bathing the crystal being observed; 

• To determine by direct observation of developing crystal faces the mechanism of crystal face growth for a variety 
of growth conditions including solution composition, degree of protein supersaturation, temperature, growth rate, 
and microgravity; 

• To use crystal etch figures methods and direct observation of growing crystal faces observed by AFM to classify 
and determine the number of crystal imperfections which occur under a variety of crystal growth rates and 
conditions, including the examination of faces of single crystals prepared under microgravity conditions; 

• To demonstrate that the observed diffraction quality of protein crystals prepared under a variety of conditions can 
be correlated with the number and type of crystal defects observed using AFM; and 

• To determine whether any observed changes in the appearance of the surface ol protein crystals can be correlated 
with the growth cessation phenomena of protein crystals. 

Task Description: 

Proteins will be prepared for examination by AFM using conventional vapor diffusion, hanging drop methods, and 
in the temperature-controlled crystallization cell described by Ward, Perozzo and Zuk (1992). 

The goal will be to prepare crystals of a given protein using different growth rates by carefully controlling the 
degree of supersaturation and other growth parameters. Single crystals prepared for these studies will be 
characterized by x-ray diffraction analyses using standard data reduction and analysis techniques. The dit fraction 
quality will be quantified using the relative Wilson plot analyses described by DeLucas etal (1991). 

In addition to preparing crystals under unit gravity conditions, we also intend to submit these proteins lor 
crystallization experiments under microgravity conditions. These experiments will be performed by Keith Ward 
either as part of the co- investigator protein crystallization program at the University of Alabama-Birmingham or as 
part of his own Flight Investigation Project which has been submitted in response to the recent NRA. 

A number of proteins have been selected for this application of AFM to protein crystal growth studies. Each one is 
readily available, easily crystallized, and exhibits unique crystallization properties. 


iiitiitiiiiMiiimHiHimiiidiiiimmiiiiiiHiHiHiiiiHiti 


11-216 


II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

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Task Significance: 

This project will, for the first time, provide unique information about protein crystal growth processes by direct 
observation of crystal faces in their growth medium. Successful results will provide new evidence for the effect of 
crystal growth conditions, including microgravity, on the defect structures and diffraction quality of protein crystals. 
Results derived from this project will, therefore, be of direct significance to NASA-funded efforts aimed at preparing 
high-quality protein crystals for structural investigations by effectively utilizing the unique microgravity 
environment of space platforms. 

Progress During FY 1 994: 

Techniques have been developed to directly observe with the AFM the growth kinetics of protein crystals in 
solution whose concentrations span those employed for the growth of crystals suitable for single crystal diffraction 
experiments. These observations at the molecular level permit the macroscopically observed crystal growth rates to 
be factored into two components: 

1. The growth of existing features as a function of crystallographic orientations. 

2. The nucleation of new features on the existing surface as a function of crystallographic orientation. In addition, 
our system allows both components to be investigated as a function of composition and temperature of the 
solutions from which the crystals grow. A journal article is being prepared. 

During the next fiscal year, we will extend our studies to other protein crystals, in order to test the general 
applicability of this method for discerning details about protein crystal growth mechanisms. 


Students Funded Under Research: Task Initiation: 1/93 Expiration: i/96 

Project Identification: 962-23 -08-25 
NASA Contract No.: H-07973D 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Konnert, J.H., D’ Antonio, P.. and Ward. K.B. Observation of growth steps, spiral dislocations and molecular packing on 
the surface of lysozyme crystals with the atomic force microscope. Acta Cryst., vol. D50, 603-613 (1994). 

Konnert, J.H., D’Antonio, P.. and Ward. K.B. Observing the growth of protein crystals. NRL Review. 130-132 (1994). 




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II. MSAD Program Tasks 


Ground-based Research 


Discipline: Biotechnology 


Neuro-endocrine Organoid Assembly in Vitro 


Principal Investigator: Dr. Peter i. Leikes 

University of Wisconsin, Milwaukee 

Co-Investigators: 

B.R. Unsworth 

Marquette University 


Task Objective: 

The specific aims of our project, entitled "Neuro-endocrine Organoid Assembly In vitro are as follows: 

1. To assemble adrenal medullary endothelial and parenchymal cells into functional organoids. Progress will be 
monitored by evaluating, a) morphology (light microscopy and ultrastructure), b) intercellular communication 
(immunocytochemistry), c) functional maturation and its hormonal control by corticosteroids, d) the expression ot 
phenotypic, biochemical, and molecular markers. 

2) To compare the usefulness and efficacy of NASA vessels with conventional co-culture systems (monolayer 
culture, suspension culture and 3-dimensional gel assembly). The time course, and the extent of neuro-endocrine 
cell differentiation, under the different culture conditions will be evaluated (as in 1). 


Task Description: 

Our lone term research goal is to understand the fundamental mechanisms ot neuro-endocrine gland assembly and 
differentiation. In our particular model system, the adrenal medulla, neural crest-derived cells ot the 
sympathoadrenal lineage differentiate into neuro-endocrine chromaffin cells. We are particularly interested in the 
role of the microenvironment in this process. We have previously shown that during assembly and maturation ot 
the adrenal medulla as in other endocrine organs, parenchymal cells and endothelial cells interact through reciprocal, 
intercellular signals. Such signals may constitute soluble factors, heterotypic cell contacts, or may be derived from 
organ-specific extracellular matrix components. These cues comprise part ot the epigenetic repertoire, which 
induces the ordered differentiation of both cell types into what is known as the "endocrine structure . 


Using conventional 2-D culture techniques, we have shown that in co-culture w r ith adrenomedullary endothelial 
cells, chromaffin-ccl 1-derivcd pluripotent PC 12 cells differentiate towards the neuroendocrine phenotype. We, 
therefore, hypothesize that capillary endothelial cells in the adrenal medulla provide some ol the organ-specific, 
differenuative cues which contribute to the neuroendocrine differentiation ol the cliromaftin precursor cells. 


In this project we extend our on-going in vitro studies on the mechanisms of organ-specific differentiation by using 
alternate methods of co-culture. We are exploiting the enhanced potential offered by the NASA vessels to analyze 
the temporal assembly of co-cultured adrenomedullary endothelial and parenchymal cells into functional, 
organe lie 1- like structures (organoids). The simulated microgravity environment ot the NASA vessels has been 
shown to randomize gravitational vectors and minimize detrimental shear torces routinely encountered in 
conventional three-dimensional suspension cultures in spinner flasks. We anticipate that the favorable culture 
conditions in the NASA vessel will accelerate differentiative, heterotypic cell-cell contacts and thus lead to 
differentiated organoid-assembly in vitro. 

Task Significance: 

In this study, we attempt, for the first time, to generate neuro-endocrine organoids in vitro by co-culturing dilferent 
cells isolated from the same organ under simulated microgravity conditions. By using the NASA cell culture 
vessels as a novel, alternate approach to conventional suspension culture in spinner flasks, we are participating in 
NASA's assessment of simulated microgravity conditions for organ-specific culture and cellular differentiation. As 
previously shown, a major advantage of using the Rotating Wall Cell Culture Vessels (RWVs) developed by 
NASA is the enhanced cell viability and tissue differentiation under conditions of simulated microgravity and 
minimized shear stress. 




mill'll, 


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FL MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

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The unique conditions in the NASA vessels are believed to enhance cellular interactions and thus differentially 
accelerate and/or facilitate these processes. In complementing a number of other parallel studies within this 
program, our project is the first one specifically designed to examine the effects of microgravity on heterotypic 
interactions between parenchymal cells and microvascular endothelial cells isolated from the same organ, namely the 
rat adrenal medulla. Such intercellular interactions are believed to be of importance during all phases of the 
development of endocrine organs, from the earliest stages of embryonic genesis through postnatal maturation. 

By using NASA's RWVs as the prime cell culture environment, we will be able to assess whether the spatial 
arrangement of the functional organ is affected by gravitational forces/vectors. Based on our preliminary 
observations, we hypothesize that by using the RWVs, we will be able to eliminate gravitational vectors, such as 
those present in static two-dimensional monolayers or in suspension cultures, and thus obtain a more realistic 
representation of tissue assembly, as seen in vivo. 

Our co-culture system is ideally suited for dissecting the microenvironmental effects (heterotypic cell interactions, 
microgravity, etc.) on neuro-endocrine differentiation of adrenal medullary chromaffin cells, since many of the 
phenotypic and genotyhpic markers for organ specific differentiation of these cells are well characterized. 
Furthermore, our model system of heterotypic co-culture of adrenal medullary cells is of particular relevance in view 
of our recent finding that microgravity specifically alters the expression of pivotal enzymes in the catecholamine 
synthesizing cascade. Tlius, our model system is also suitable to explore the cellular and molecular basis for 
(micro)gravity sensitivity, e.g. t of signal transduction mechanisms involved in neuroendocrine hormone synthesis 
and secretion. 

Based on the first year of practical experience with one of the RWVs, we are confident that the enhanced cellular 
viability and differentiation achieved by culturing the cells under similar microgravity conditions will be of general 
advantage for developing new concepts for tissue culture and tissue engineering. Specifically, we anticipate that 
this novel environment will be beneficial for cuitunng and/or co-culturing fragile cell types, e.g., when isolated at 
early stages of embryonic development. We anticipate that within a reasonable time period, we w ill be able to test 
our model for organogenesis mid differentiation during one of the future Space Shuttle missions. 

Progress During FY 1994 : 

1. As indicated in last year's progress report, we spent the first year of the grant on refining our basic heterotypic 
cell culture systems using conventional monolayer and suspension cultures. In collaboration w'ith scientists at 
JSC, (specifically the group of T. Goodwin) we explored the suitability of the various available rotating -wall 
vessels (RWVs) for growing adrenal medullary' parenchymal and endothelial cells, alone and in co-culture, under 
simulated microgravity conditions. Based on those preliminary findings, we decided to continue our studies in the 
Slow Turning Latenal Vessel (STLV) type RWV. 

2. Alter in-servicing a graduate (Ph.D.) student, Daniel Galvan, at JSC, two STL Vs were shipped to Milwaukee in 
the beginning of 1994. We are currently carrying out the expenments according to the plans detailed in the specific 
aims; we are assessing the effects of simulated microgravity on neuro-endocrine organ-assembly by co-culturing 
transformed rat adrenal medullary parenchymal cells (PC 12 pheochromocytoma cells) with organ-specific 
microvascular endothelial cells (RAME, rat adrenal medullary endothelial cells). In spite of some technical 
difficulties with the device drive units, the prolonged duration of each of these experiments (up to 3 weeks), and the 
limited number of vessels available (two), we have obtained some encouraging preliminary results: 

a) We optimized the conditions for culturing each of the cell types alone and in co-culture on microcarrier beads in 
the STLV. The elliciency of cell culture w as assessed, e.g., by the rates of glucose utilization rate and proliferation, 
respectively. 

b) Preliminary visualization by routine histological staining of the ensuing three-dimensional cell aggregates 
suggests that both PC 12 and RAME cells from histiotypic assemblies on the beads; large clumps/aggregates of 
viable PC12 cells reminiscent of parenchymal acini and con tact- inhibited monolayers of RAME cells. By contrast, 
in the co-cultures, we observed organotypic assemblies of mixed populations, in which homotypic interactions 
prevail. Thus, PC12 remain clustered into nest-like assemblies, surrounding (or surrounded by) RAMEs. 


MIHIIIIIIIHIIHtl iifiilllllllllllllllttlllllllllllltlltllllllliaillllltlllllllllllflllllllllllll 





II. MSAD Program Tasks — 

it 


Ground-based Research Discipline: Biotechnology 




Importantly, for the first time, we also observed in these co-cultures, the assembly of RAM Es into what appear to 
be capillary structures. These experiments are currently being repeated to establish the reproducibility ot the 
exciting observation that co-culture, under simulated microgravity, results in organotypic assembly ot adrenal 
medullary cells and enhances organ-specific differentiation of both parenchymal and endothelial cells. Currently, the 
findings are being substantiated by molecular biological and immunochemical techniques ot the light and electron 
microscopic level. As described below, we implemented a novel quantitative PCR technique tor measuring the 
expression of genes related to neuroendocrine differentiation. In addition, studies are under way to assess, by 
immunohistochemical means, whether the seemingly histotypic assembly of neuro-endocrine "organoids' in the 
STLV is accompanied by the enhanced expression of organ-specific differentiation markers, such as the 
catecholamine synthesizing enzymes in adrenomedullary PC12 cells. 

c) We previously reported that PC 12 cells and RAME formed organ-specific assemblies in conventional suspension 
cultures which were maintained at low speed with minimal shear forces in the absence of microcamer beads. In 
repeating the experiments, we now have substantiated these findings. Specifically, RAME cells were found to 
attain configurations which are reminiscent of the formation of new blood vessels (angiogenesis). Since, in the 
STLV cells cannot be cultured without beads, we have begun to optimize conditions tor culturing the cells in a 
small (10 ml) High Aspect Ratio Vessel (HARV). These experiments are designed to permit direct comparison 
between different "beadless" cell cultures in stirred fermentors vs. in a RWV. We expect that this comparison will 
yield relevant information on the beneficial effects of simulated microgravity on organ-specific differentiation. 

3. As detailed above, the focus of our studies is to assess differential expression ol organ-specific marker genes by 
using molecular biological techniques. In the past year, we have made significant progress in several 

complementary areas: D t dtd 

a) We continue to assess the effects ol simulated microgravity on differential gene expression, mainly via RT-PC . 
To increase die reliability of our results and to eliminate the possibility of false positives, we have synthesized, 
verified, and tested a number of previously not available species (rat)-specific PCR primer pairs tor the following 
rat-specific genes: 

Comparator genes for relative quantitation : glyceraldehyde-phosphate-dehydrogenase (GAPDH), p-actin and 
(mitochondrial) rRNA 

Catpoholamine. synthesizing enzymes : tyrosine hydroxylase (TH), phenylethanolamine-N-methyltranslerase 
(PNMT), dopamine-p-hydroxylase (DBH), aromatic-dopa-decarboxylase (DDC) 

Protooncoeenes: c-fos 

Catpcholaminp mptaholizinp enzymes : monoamine-oxidase A (MAO- A), and B (MAO-B) 

Fvtrarpilnlar matrix proteins : fibronectin (FN). Currently, rat-specific PCR primer pairs and RNA/DNA probes are 
being established for other extracellular matrix proteins, such as collagens I and IV. laminin A and B1 chains, tor 
which so far only the murine sequences are known. 

b) Having established species-specific PCR primer pairs and probes, we are currently constructing species-specific 
sense and antisense RNA probes for Northern blotting, RNAse protection assays and for in situ hybridization 
studies. These techniques will complement our quantitative PCR approach (see below). 

4. In the past, we have semi-quantitated differential gene expression by RT-PCR using established comparator 
genes, such as GAPDH, p-actin or rRNA (Lelkes, et. al., FASEB J. in press, see appendix). Recently, we 
established a rigorous, quantitative PCR-assay, termed competitive RT-PCR. In this assay, a so-called PCR mimic 
DNA template is added to the reaction buffer prior to the PCR step. This mimic uses the same primers as the 
endogenous MRNA sequence, but slightly differs in size, which allows its separation from the endogenous one on 
the DNA gel. Therefore, mimic templates compete with endogenous cDNA for PCR substrates. By adding a 
known number of mimic templates equal to the number of endogenous templates into the PCR reaction, two 
products are obtained of equal intensity and slightly different sizes as visualized on a DNA electrophoresis gel. To 
date, we have generated and successfully tested PCR mimics for TH, PMNT and FN (see below). 

5. As detailed above, our long term goal is to study the molecular mechanisms by which microgravity might affect 
cellular differentiation. Specifically, we want to discover novel molecule(s) involved in the microgravity-induced 
neuroendocrine differentiation. Towards that goal, we have in the last year implemented the most recently developed 
molecular technique, called Differential Display. Using this technique, the RNA populations of both 
microgravity-treated and control samples can be displayed on a 2-D sequencing gel. The identities of any known or 
unknown RNAs which are differentially expressed in the PC12 cell culture in microgravity vessel can be revealed by 






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II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 




further PCR, cloning and sequencing. So fir, we have successfully tested this technique and optimized the assay 
conditions. Current experiments ;ire under way to employ the differential display assay for studying die genes which 
tire differentially activated in the PC 12 cells exposed to microgravity. 

6. Other related studies: 

a) As described in last year's report, we used some of the biochemical and molecular techniques to assess the effects 
of microgravity on the expression of catecholamine synthesizing enzymes in the adrenal medulla of rats flown 
aboard the Space Shuttle Mission STS-54. In addition to presenting these results at the annual meeting of die 
American Society of Cell Biology (Lelkes, et al.. Mol. Boil. Cell, vol 4 Supply:109a, sec appendix), a paper 
entitled "Microgravity Decreases Tyrosine Hydroxylase Expression in Rat Adrenals" is currently in press in die 
FASEB Journal (see appendix). In brief, our data show that the expression and specific activity of tyrosine 
hydroxylase (TH), die rate limiting step in catecholamine synthesis was specifically affected by microgravity. By 
contrast, phenylethanolamme-N-methyl-Transferase (PNMT), die chromaffin cell-specific enzyme which converts 
norepinephrine to epinephrine was not affected during space fight. We hypothesized that these observed effects of 
space fight were not due to stress response during reentry because of the relatively long time course (about 12 
hours) of TH depression and lowered catecholamine contents. Furthermore, based on evidence in the literature, we 
speculated that microgravity may be exerting its effect on catecholamine synthesis by acting on specific, 
microgravity -sensitive signal transduction pathways. 

We have now further substantiated these conclusions by analyzing adrenals of (10 days) tail-suspended rats, a 
putative, ground-based control for weightlessness. For these studies, we used for the first time our new ly developed 
method of competitive PCR to quantitate TH and PNMT expression. In contrast to the pattern of TH and PNMT 
expression in the adrenals of space-flown animals, we found that in the adrenals of tail -suspended rats, the 
expression (and specific activities) of both TH and PNMT were increased by, respectively, 30% and 100%. This 
pattern of elevated catecholamine synthesizing enzyme levels is typical for stress situations, suggesting that 
prolonged tail suspension, while presumably suited for studying the effects of simulated weightlessness on muscle 
physiology, might not be suited to model any effects of microgravity on the (neuro) endocrine system. 

b) In order to simplify cell culture in the RW Vs, the biotechnology group at JSC recently developed a novel cell 
culture medium called GTSF-2. In collaboration with the scientists in that group, we completed our evaluation of 
GTSF-2 using a number of different cell types and other with our cells. A paper, entitled "GTSF: A New , 

Versatile Cell Culture Medium for Diverse Normal and Transformed Mammalian Cells " is currently in press in the 
Journal In Vitro. Our data suggest that GTSF-2, by itself or with minor modifications, is well suited to maintain 
the growth of a variety of cell types including neuronal cells, primary cultures of endothelial cells from humans and 
rodents, and several lines of transformed cells. 

c) An exciting spinoff of our ongoing studies is the use of RWVs to culture normal proximal tubular epithelial 
cells isolated from human kidneys. These cells are notoriously difficult to handle and very rapidly de -differentiate in 
conventional 2-D cultures. In collaboration with Dr. T. Hammond (U. Wise. Med. School) and Clonctics Co. (San 
Diego), we have used the simulated microgravity in an STLV to establish both morphologically and functionally 
highly differentiated cultures of these cells. An abstract (Human Renal Epithelial Cells in Culture Differentiate 
Under Simulated Microgravity) will be presented at the upcoming Annual Meeting of the American Society for Cell 
Biology. A manuscript detailing our results is in preparation. Moreover, the budding collaboration with a small 
business company raises the prospect that, besides their usefulness as novel research tools. RWVs can be used for 
developing a commerciali zable product which w ill be important for basic and applied biomedical studies. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 11/92 Expiration: 11/95 
Project Identification: 952-23-01-12 
NASA Contract No.: NAG 9-651 
Responsible Center: jsc 


11-221 




II. MSAD Program Tasks 


— Ground-based Research 


Discipline: Biotechnology 


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Bibliographic Citations for FY 1994: 

Journals 

Lelkes. P.I.. Ramos. E.M.. Chick. D M.. Liu. J. and Unsworth. B R. Microgravity decreases tyrosine hydroxylase 
expression in rat adrenals. FASEB J., in press. (1994). 

Lelkes, P.I., Ramos, E.M.. Nikolaychik. V.V., Wankowski. D.M.. Unsworth. B.R. and Goodwin. T.J. A new, versatile 
cell culture medium for diverse normal and transformed mammalian cells. In Vitro, in press. (1994). 

Presentations 

Galvan. D.L., Wankowski. D.M., Bacciao, Dillberger, A.. Karmiol. S.. Hammond. T.G. and Lelkes P I, 'Human renal 
epithelial cells in culture differentiate under simulated microgravity. " To be presented at the Annual ASCB Meeting, Dec. 
1994. 

Lelkes. P.I., Ramos, E.M., Chick. D.M.. Liu. i. and Unsworth B.R. "Space Bight alters catecholamine-synthesizing 
enzyme expression and activity in the rat adrenal medulla. Annual ASCB meeting, Dec. 1993. 



II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 


Formation of Ordered Arrays of Proteins on Surfaces 


Principal Investigator: prof. Abraham m. Lenhoff 

University of Delaware 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The goal of the project is to investigate the formation of ordered arrays of proteins at solid surfaces. Two parallel 
approaches are employed: 


1. An empirical study, by scanning probe microscopy (SPM), of the effects of protein and surface parameters on 
array formation; 

2. A fundamental examination, by molecular simulations and surface forces apparatus measurements, of the protein 
- protein and protein - surface interactions that give rise to protein adsorption and ordering. 

Although our primary interest is in proteins, insight can be provided in both the simulations and experiments by 
corresponding experiments on spheres. For this purpose, the FY94 task included study of amidinated polystyrene 
latex particles. 

Task Description: 

The tasks begun in FY94 fall into three categories: 

1. Atomic force microscopy (AFM) of proteins and latex spheres on surfaces, complementing the purely 
protein-related work performed and proposed previously. Use of AFM makes possible the investigation of behavior 
at non-conducting surfaces, specifically mica, while examination of latex spheres makes possible discrimination 
among multiple possible explanations for changes in adsorption extent as a function of salt strength. 

2. Calculation of the energetics and hence the isotherms for adsorption of ordered arrays of particles at charged 
surfaces. Our computations to date on ordered arrays have examined only spherically symmetric particles, and the 
additional studies are intended to investigate the effects of charge asymmetry and possibly of particle shape. 

3. Surface forces measurements of protein - surface interactions. Experimental measurements of the interaction 
energy of ordered arrays of streptavidin, immobilized on one surface, with a second charged surface. 

Task Significance: 

Ordered arrays of proteins are of interest for two main reasons: 

1. Protein structure determination. X-ray crystallography is still the workhorse for determination of protein 3-D 
structures, but other techniques have begun to emerge. One class of methods that emerged during the 1980s is that 
of structure determination on two-dimensional crystals, with techniques such as electron microscopy employed to 
probe the structures of the constituent molecules. The 2-D arrays we will study would be suitable for such 
investigations. Furthermore, it is possible that such arrays can serve as templates for the epitaxial growth of 3-D 
crystals. 

2. Synthesis of novel materials. The complex 3-D structures of proteins give them functional properties that are 
also complex, and in addition can be produced reproducibly. Given proteins with the appropriate functions, ordered 
monolayers of protein molecules at solid surfaces may represent materials with useful properties that make various 
applications possible. Examples include electronic devices and "biocomposite" materials. 


till Ill 


11-223 





II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

in, huh. 


Apart from these applications, our studies of self-assembly have a further, more fundamental purpose: the colloidal 
forces driving 2-D self-assembly are the same as those giving rise to 3-D crystal growth, so understanding these 
forces and their interactions is expected to lead ultimately to insights into manipulation ot both 2-D and 3-D 
structures. It is also the isolation ot these colloidal torces trom other disturbances that provides the incentive tor 
microgravity -based research in this area, as in protein crystal growth. 

Progress During FY 1 994: 

Progress is summarized separately tor the three areas listed above. 

1 . AFM studies of adsorption: We have studied both kinetic and equilibrium aspects of adsorption of positively 
charged latex particles on mica, which is negatively charged; ol particular interest is the etfect ol ionic strength. 
Adsorption kinetics are observed to be diffusion-limited. The equilibrium structures display relatively little 
periodicity, but a fair degree ol long-range order; in particular, the interparticle spacing decreases with increasing 
ionic strength, and hence surface coverage increases with increasing ionic strength. This trend is opposite to that 
observed for proteins, and the explanation tor this could shed considerable light on the mechanisms involved in array 
formation and, more generally, on protein crystallization. This aspect is still under investigation, but a likely 
reason lies in the relative contributions ot electrostatic and van der Waals interactions to the overall interaction 
energy. 

2. Interaction energy calculations: Our calculations ot interaction energy and adsorbed amounts tor arrays ot 
spheres have been completed (paper to appear in Langmuir ). Work to extend these calculations to more realistic 
arrays of protein molecules is in progress. 

3. Surface force measurements: We have successfully performed measurements of the interaction energy between 
an immobilized array of streptavidin molecules and a lipid bilayer coated on mica. These measurements show 
evidence of long-range repulsion, presumably due to electrostatic interactions, but a more detailed interpretation and 
comparison with protein - surface electrostatics computations is difficult because the charge on the bilayer side, 
which is actually due to the residual charge on the underlying mica, cannot be fixed reproducibly. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 4/94 Expiration: 4/95 
Project Identification: 962-23-08-30 
NASA Contract No.:nag8-1038 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

Palkar, S.A., and Lenhoff, A.M. Energetic and entropic contributions to the interaction of unequal spherical double layers. 
J. Coll. Inter!'. Sci., vol. 165, 177-194 (1994). 

Presentations 

Johnson. C.A., and Lenhoff. A.M. "An AFM study of latex particle adsorption on mica.” ACS Colloid and Surface Science 
Symposium, Stanford, CA, 1994. 

Johnson, C.A., Haggerty, L„ Wu, P., Lenhoff. A.M., and Wagner, N.J. "Ordered arrays of adsorbed proteins: modelling 
and observation by scanning probe microscopy." 8th International Conference on Surface and Colloid Sciences, Adelaide, 
South Australia, February 13-18, 1994. 

Johnson, C.A., Wu, P„ Lenhoff, A.M., and Wagner, N.J. "Modelling of the formation of ordered protein arrays at 
liquid-solid interfaces." AIChE Annual Meeting, St. Louis, MO, 1993. 

Palkar, S.A., and Lenhoff. A.M. "Characterization of protein-surface interactions using surface forces apparatus.” 8th 
International Conference on Surface and Colloid Sciences, Adelaide, South Australia, February 13-18, 1994. 


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11-224 


II. MSAD Program Tasks — 

mi i min 


Ground-based Research 


Discipline: Biotechnology 

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Crystallization Studies in Microgravity of an Integral Membrane Protein: The Photosynthetic 
Reaction Center 


Principal Investigator: Dr. James r. Noms 

Argonne National Laboratory 

Co-Investigators: 

J. Deisenhofer 
M. Thumauer 
D. Tiede 
P. Thivagarajan 
M. Schiffer 
R. Furrer 

Howard Hughes Medical Institute 
Argonne National Laboratory 
Argonne National Laboratory 
Argonne National Laboratory 
Argonne National Laboratory 
Free University Berlin 


Task Objective: 


The objective ot this project is to determine the effects of microgravity on the crystallization of internal membrane 
proteins. 

Task Description: 

Advances in the understanding ot membrane protein crystallization are important from both biological and 
pharmaceutical viewpoints. Membrane proteins are responsible for many of the major biological processes such as 
vision, nerve conduction, cell differentiation, photosynthesis, and respiration. Previous crystallization experiments 
in microgravity have suggested that the elimination of density-driven convection and sedimentation may generally 
lead to larger, better-ordered crystals for water-soluble proteins. The potential beneficial effects of microgravity on 
the crystallization ot integral membrane proteins have not yet been tested. The necessity of maintaining membrane 
proteins in detergent micelles during the crystallization process suggests that the deleterious effects of gravity-driven 
convection may be more significant during the crystallization of membrane proteins than water soluble proteins. 

The effects ot microgravity on crystallization of membrane proteins will be tested using the Rhodopseudomonas 
viridis and Rhodobacter sphaeroides photosynthetic reaction centers as test proteins. The two reaction centers differ 
in the proportion ot the accessible surface area that is buried in the micelle environment. The comparison of Rps. 
viridis and Rb. sphaeroids crystallization will provide a useful indicator of whether the effects of microgravity can 
be linked to differences in volume traction ot detergent in the detergent-protein complexes. The spaceflight and 
ground control crystallization experiments will be analyzed by three techniques: optical microscopy, x-ray 
diffraction, and small angle neutron (SANS) and light scattering. The optical microscopy and x-ray diffraction of 
crystals will determine the effects of microgravity on crystal growth and molecular ordering. SANS and light 
scattering studies on reaction center solutions at various extents of completion of crystallization will be used to 
determine the effects ot microgravity on the nucleation events that precede and then continue during the 
crystallization process. The results of reaction center nucleation and crystallization studies in microgravity will be 
relevant to the crystallization of integral membrane proteins in general. 

Since 1988, despite a great deal of worldwide effort, relatively few other membrane proteins have been crystallized 
m a form suitable for high-resolution structural studies. To date, only the reaction center structures have been 
solved. Many other membrane proteins have been crystallized, but the generally small crystal size and poor 
diffraction quality has prevented structural determination. A complicating factor is the presence of the detergent 
micelle. The effect of the detergents on the crystallization process is unknown. However, the effects of small 
amphiphiles on crystallization suggest that micelle size or radius may play an important role in determining 
whether protein-protein contacts predominate to produce a crystalline structure, or whether non-specific 
micelle-micelle contacts predominate to yield a less ordered array. Crystallization frequendy occurs at or near die 
phase separation of the detergent. This correladon between crystallization and detergent phase separation has led to 
the investigation ot the micelle-micelle attraction, and the role this will play in the early nucleation process. 
Ultimately, the micelle aggregation must be balanced by protein-protein interactions to result in crystal formation. 


11-22 5 


II. MSAD Program Tasks — Ground-based Research 


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Discipline: Biotechnology 

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Task Significance: 

Current results on crystallization in microgravity have shown that the minimization of convection and 
sedimentation space leads to tmproved stee and/or ordenns of crystals lor many 

cases the resolution of the x-ray diffraction was better than any crystal produced on Earth. In cases where the x ray 
diffraction quality did not exceed the best obtained on Earth, the space-grown crystals were still beuer r than .those in 
the control experiment. These results indicate the need for optimization of space hardware compared to the results 
achieved in thTlaboratory, but still point to the beneficial effects of microgravity on the crystallization process. 


Progress During FY 1 994: 

1 Determination of Micelle Structure. During this fiscal year this project completed an analysis of detergent 
micelle structure and micelle-micelle interactions under conditions used tor the crystaUization of 
membrane protein, the photosvnthetic reaction center. This is the start of a project that will used smah angle 
neutron scattering to determine structures of intermediates in crystallization pathways otmtegnd membrane 
proteins. SANS was used to analyze the structures of micelles from the detergents octyl-b-D-glucoside OG, and 
lauryl-dimethylamine-N-oxide, LDAO. To date, only these two detergents have been tound to be usetul tor 
crystallization of the reaction center. However, crystallization with each detergent requires distincdy different 
solution conditions. The physical cause for the requirement to adjust the crystallization conditions or a 
detergent was not previously known, but the differences suggest that detergent properties significantly attect the 

crystallization process . 

Work completed this year (Thiyagarajan and Tiede, 1994 J. Phys. Chem. in prerr) characterized micelle ^ture and 
inter-micelle interaction for LDAO and OG in conditions used for protein crystallization using SANS. This work 
found that LDAO and OG micelles differ significantly in size, sensitivity to heptane mol, and in nature ot 
inter-micelle interactions. Our results suggest that successful crystallization methods can be rationalized in terms o 
an optimization of micelle size, number density, flexibility of micelle radius of curvature, and suppression ot 
inter-micelle interactions. LDAO and OG micelles were found to differ significantly in size and shape. The LDAO 
micelle was found to be best fit as an ellipsoid with semiaxes of 30.6 A and 19.4 A, while the OG micel e was 
found to be spherical with a radius of 22.9 A. The addition of heptane tnol to pure LDAO resulted in the formation 
of smaller, spherical, mixed micelles with radii in the range 17 A to 21 A, depending upon condiuons^ The resuhs 
suggest that both micelle size and curvature restrictions may contribute to the mcompaubi lity ot LDAO for ^prote 
crystallization in the absence of additional amphiphiles. The mixed OG-heptane tnol micelle was found to be 
significantly smaller than that with LDAO, having radii in the range 15 A to 18 A depending upon conditions, and 
exhibited a greater number density increase. Evidence was found for interacuon between OG and 
polyethyleneglycol, PEG, that prevents micelle aggregation at high ionic strength, and likely contributes to the 
particular success of PEG as a protein precipitant when OG is used as the solubilizing detergent, lose 
measurements suggest that the chemical constituents in membrane protein crystallization can be manipulated to 
optimize micelle size, number density and inter-particle interactions. 

2 Protein Aggregation States. During this fiscal year we also initiated SANS investigations that will eventually 
be used to characterize structure and aggregation state of the reaction center protein as a tuncuon ot its progress 
through the crystallization process. During this year, initial focus was on determining the solu “ on s ™ re ° f *** 
reaction center as a function of crystallization conditions before super-saturated states are reached. SANS da 
acquisitions were completed on reaction center aggregation states in OG and LDAO. and as a function ionic strength 
in these detergents. These measurements found a striking dependence ot reaction center aggregation state on 
determent and ionic strength. The SANS results suggest that the reaction center exists in an equilibrium between a 
monodispersed form and an unusual linear aggregate. These studies found that the equilibrium is shifted tar towards 
the linear aggregate with LDAO as the solubilizing detergent at low ionic strength, but shifts to the monodispers 
form at high ionic strength ( 1 M NaCl ). Conversely, with OG as the solubilizing detergent the equilibrium was 
found to be shifted towards the aggregate at high ionic strength, while the monodispersed form is seen to 
predominate at low ionic strength. While further structural and physical chemical analyses are currently underway, 
these results show that the existence of the monomeric reaction center state in each detergent is co-mcident with 


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11-226 



II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

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conditions that eliminate micelle interactions. This work is uncovering the connections between micelle properties, 
protein solubilization and crystallization. 

Preliminary SANS data was also acquired on reaction center aggregation in OG\PEG solutions that represent 
conditions at the start ot a crystallization experiment. Although further, ongoing analysis and data acquisition are 
needed, the preliminary results clearly demonstrate that addition of PEG at concentrations below that needed to 
induce reaction center crystallization induces a significant aggregation of the reaction center. This data provides 
evidence that a majority o 1 the reaction center population is likely to exist in aggregates in the dimer to decamer 
size range at the start of the crystallization process. This data provides evident for the importance of the aggregates 
states either as competitors to productive crystallization pathways, or possibly as functional intermediates on the 
actual crystallization paths. Ongoing work will distinguish between these possibilities. 


Students Funded Under Research: Task Initiation: 4/93 Expiration: 4/96 

Project Identification: 962-23-08-29 
NASA Contract No.: H-13058D 
Responsible Center: msfc 


Bibliographic Citations for FY 1994 : 

Journals 

Thiyagarajan, P., and Tiede, D.M. SANS studies of structure and interactions of detergent micelles as applicable to 
membrane protein crystallization. Amer. Cryst. Assoc., vol. 22, 75 (1994). 


mini 


11-227 


II. MSAD Program Tasks 

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Ground-based Research - 


Discipline: Biotechnology 


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Shear Sensitivities of Human Bone Marrow Cultures 


Principal Investigator: Dr. Bernhard 0. Paisson. Ph.D. 

University of Michigan 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objective of this research is to reconstruct human bone morrow tissue ex vivo using the NASA bioreactor to 
provide the culture environment tor three-dimensional growth. 


Task Description: 


The specific aims of this program are three: 

1) To find optimal growth conditions for human bone marrow as a function ol the supplied growth factors, 

2) To develop a shear stress chamber that measures the shear stress sensitivity of human bone marrow cells; 

3) To use the information gamed from 1) and 2) to implement long-term, continuous bone marrow cultures in 

RWV. 


the 


Task Significance: 

This study will focus on the elucidating role of three-dimensionality in bone marrow stem cell differentiation. The 
development of a three-dimensional in vitro cell model will permit investigation into the biochemical signals that 
triggers cell differentiation into various stages and subtypes of human blood cells. It also will permit the 
investigation of the role of three-dimensionality in extensive cell to cell contact and exposure to growth factors. 

Progress During FY 1 994: 

Conditions for the expansion of adult human bone marrow mononuclear cells in the rotating wall vessel (RWV) 
have been established. Total cell numbers and the number of progenitor cells increase over time by a factor of 

10-20 fold Shear sensitivity of the cells does not hamper growth of these cells. At present, it is un own w e er 

stem cells are maintained or if they expand in number in the RWV. This issue will be investigated in the coming 
year. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 11/92 Expiration: 11/95 
Project Identification: 962-23-01-09 
NASA Contract No.: NAG9-652 
Responsible Center: jsc 





11-228 



II. MSAD 


Program Tasks — Ground-based Research 


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Discipline: Biotechnology 

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Mitrognnnt y Crystallization of Avian Egg White Ovostatin 


Principal Investigator: Dr. Marc l. Pusey 
Co-Investigators: 

D. Carter 


NASA Marshall Space Flight Center (MSFC) 


NASA Marshall Space Flight Center (MSFC) 


Task Objective: 

T he research objective is designed to study the ovostatin from the standpoints of its suitability as a model protein 
lor protein crystal nucleation and growth mechanisms, the bio-mechanical movements which apparendy form the 
basis ot its inhibitory activity, mid using it as a means of studying the a 2 M group of proteins. Further, the 
intention is to develop the crystallization conditions to be tried based upon studies of the physico-chemical 
parameters, such as solubility phase behavior and observed nucleation kinetics. This will be our first demonstration 
protein tor the application ot what is being learned about the crystal growth of macromolecules. 

Task Description: 

The study ot ovostatin is ot interest tor several reasons. This protein is attractive as a model for protein crystal 
nucleation and growth studies. Crystals can be easily and rapidly grown in bulk solution. With a minimum step 
height ot 25-34 nm, surface features should be readily detectable in real-time using interferometric techniques, 
allowing direct observation ot the crystal growth process. The large size would facilitate protein crystal nucleation 
studies using light scattering methods. Practically, ovostatin can be easily purified in large quantities, requiring 
about 6 dozen hen egg whites/gram ot protein. Material purified has been stable for prolonged periods (over four 
months) during crystallization trials and has been kept for over one year as a lyophilized powder. Finally, there is 
the similarity between it mid a 2 M. Currently, the only structural information extant is from electron microscopy 
studies of isolated molecules. 

Task 1: Preparation ot ovostatin to 1/94 for protein to be used in Night experiment(s). Large scale protein 
purification will lie continuous tor the duration of the project. This material will be used to establish the reference 
ground-based crystal quality against which future flight crystals will be measured. Ovostatin prepared in this 
laboratory will be made freely available to other researchers wishing to study it. 

Task 2: Screening of crystallization condition to 7/93. The best crystallization conditions determined at this time 
will be used for future flight experiment(s). These conditions will then be used for the final solubility diagram 
determinations to be used in designing the flight experiments. 

Task 3: Establishing baseline crystal quality. Multiple data sets will be acquired using the x-ray diffractometer. 
These will be used to establish the baseline ground-grown crystal quality. 

Task 4. Studies of ovostatin. These will last for the duration ot this project. These will be done using the 
instrumentation developed in the laboratory tor the study ot the protein crystal nucleation and growth processes. 

Task Significance: 

Any knowledge gained about ovostatin based on crystal structure analysis would advance the overall knowledge of 
this family of proteins. 


11-229 



II. MSAD Program Tasks - ^“P^r,,. Bl0teChn010 ^ 


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Progress During FY 1994: . 

Previous m.cogr.vU, proteur «yaa. grow* experiment have used 

diilvsis techniques with most being done using vapor diffusion. Littke and John, using tree interlace dittusion, 
moored rioToTum^Lse for beta-Galactosidase over crystals grown on Earth. In vapor diffusion expenments. 
aUeast three proteins have shown significant! v improved diffraction resolution over any of the crystals grown on 
Earth desptethe fact that, because of short flight durations, crystallization condiuons have had to be op^mize 
“ nuc Son and growth i e.. the temporal condiuons were more favorable for lower quality crystal. Current 
experiences are'tkh cfvostatin cystals nucleate and finish growing within a one- to three-day period. The process 

will have to be slowed down to lit better within the timeframe tor a (he distil 

onnosed to the usual case where the crvstal growth process must be speeded up. Based on the ovostatin crystal 
considerable room for improvement in both crystal size and diffraction resolution. 

Ovostatin purified in this laboratory has now been supplied to four other research groups as a t ^t ^teml. Dr. 
William Wilson (Mississippi State University) has found a dramatic dimenzation-tetramen^ 
ionic strensth. This has led us to an investigation of ovostatin activity vs structure which has been earned out by a 
f ltv mr n Moriaritv UAH). Ovostatin crystallizability has been lound to be very sensitive to e 
SmSonproLdure and materials employed. We are currently supplying ovostatin to the laboratory of Dr. David 
Blow (Imperial College) for extensive crystallization tnals which we hope will lead to a preliminary structural 

determination. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: i/93 Expiration: i/96 

Project Identification: 962-23-08-26 
NASA Contract No.: in-house 

Responsible Center: msfc 






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II. MSAD Program Tasks — Ground-based Research 

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Discipline: Biotechnology 


Study of Crystallization and Solution Properties of Redesigned Protein Surfaces 


Principal Investigator: p ro t. David c. Richardson 

Duke University Medical Center 

Co-Investigators: 


M. Hecht 
K. Gemert 
J. Richardson 

Princeton University 
Duke University Medical Center 
Duke University Medical Center 

Task Objective: 


The objective ot this work is to determine what combinations of protein surface features and solution factors best 
promote the growth ol highly ordered protein crystals and to seek strategies for improving control over the process. 
The experiment design is to make detailed analysis of crystal contacts in Cytochrome B 562 , construct a planned 
series ot mutations at those crystal contacts study crystal growth and solubility properties of the mutant proteins 
study resultant crystal order and use the results to further retine analyses, hypothesis, and test mutants. 

Task Description: 

High-resolution x-ray crystal structures ol proteins are the backbone of academic and industrial research efforts to 
understand and control the detailed functional properties of these important molecules. Many such studies are 
stymied, either by lack ot crystals altogether or by crystals whose degree of order is inadequate to show details at the 
level of resolution needed. 

Two sets ot factors jointly influence the growth of ordered protein crystals: the atomic-level details of the protein 
surface, including flexibility and bound waters; and the solution conditions, including concentration and identity of 
precipitants and other components, pH and ionic strength, temperature, interactions at solid or liquid interfaces, 
vibration, convection currents, etc. Traditionally, the protein surface was not variable except by trying different 
species, and the only strategy for solution conditions was simply trying as many variations as possible. The most 
general conclusion was that what worked for one protein was likely to be different than what worked for another. 
Recently, however, there has been support and encouragement, largely led by NASA, for scientific study of the 
process ot crystallization. The most notable single result so tar has been the demonstration that growth in 
microgravity can produce significantly better-ordered crystals for many proteins, presumably because of the absence 
ot convection currents at the crystal surface. The absence of convective currents, in turn, allows for the increased 
ettect ot random diffusion ot the protein molecules at the crystal surface and for the increased effective binding 
energy ot the protein molecule to the growing crystal. Both of these are presumed to lead to more accurate and 
more stable attachment of the protein molecules to the crystal, and thus a better-ordered crystal. 

Three to tour mutants will be studied per year. Each study will involve computer-aided graphics studies of crystal 
contacts and design of mutants, genetic engineering of mutants, protein purification, crystallization experiments, 
crystal solubility determinations, face growth rate measurements, calorimeteric measurements of crystal growth, and 
evaluation of crystal diffraction. 

Task Significance: 

The research aims are to contribute to the scientific understanding and the practical improvement of protein crystal 
growth by tying together a series of designed mutations at known crystal contacts with the changes in 

crystallization behavior and parameters. There are several logical levels at which the results of this research should 
be useful. 

A research study ot the relative strengths of the binding of protein molecules into their crystal is important for 
understanding which factors are improved in microgravity, whether the growth cessation phenomena can be 





llilllMliMHiiiiiimMitiiiiiim 


11-231 



II. MSAD Program Tasks — Ground-based Research 




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Discipline: Biotechnology 


alleviated in normal gravity, and how changes in crystal contacts can improve the overall order ot protein crystals. 

A detailed study of protein crystal contacts and their specific effects may also help in the future to sort our 
influences on nucleation of protein crystals versus later growth. This research is designed to collect two 
overlapping but distinct types of information: what specific side chain changes will strengthen or weaken a contact 
for a particular crystallization media; and what contact strength is optimum, relative both to the other contacts an 
to the diffusion and convection conditions. Such information will surely aid in future rational control ot the 
crystallization process. 

Progress During FY 1 994: 

The study of the solubilitv of wt-B562 crystals (grown under 3.5 M P04, pH 6.8) continues under a variety of 
buffer conditions, additivies and temperatures. A large set of proteins with random mutations to turn C (residues 
elu-81, gly82. lys+83 wt) were generated, and 39 were sequenced (Hecht lab), me sequenced proteins were 

characterized by spectroscopy, CD and denaturation studies. From this set, eleven proteins were chosen tor 

additional crystallization studies. First, mutant LGR-B562 has been found to grow diffraction quality crystals from 
3 375 M P04 pH 6 8 1 % MPD. Approximately 100 mg of LGR-B562 has been purified to begin solubility 
measurements. Additionally, approximately 20 mgs of each of the other ten proteins has been purified and initial 
crystallization trials of each have been analyzed. One. LAA-B562. has .esutad 1 in large ^ilfacuon qnahly c^slals. 
at conditions similar to wt-B562 (3.75 M P04. pH 6.0). Two other proteins (RGM-B562 and SSR-B562) have 
resulted in small, yet potentially diffraction quality crystals, in conditions neighboring that ot wt-B562 (3.75 M 
P04, pH 6.0, for both). Four other mutants grew small crystals, either plates or rods, in the presence ot needles, 
while the remainder of die mutants formed needles or microcrystallin precipitate. 


Students Funded Under Research: 

BS Students; 0 
MS Students: 0 

PhD Students: 1 


Task Initiation: 8/93 Expiration: 8/96 

Project Identification: 962-23-08-22 
NASA Contract No.: nags-966 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 


Presentations 

Richardson. D.C. "Redesigning protein surfaces and crystal contacts. 
Center Biochemistry Retreat. Beaufort. NC. November 6-8,1994. 


Poster presented at the Duke University Medical 


Richardson, D.C. "Study of crystallization and solution properties of redesigned protein surfaces." NASA Protein Crystal 
Growth Principal Investigator Planning Meeting, Panama City, FL, April 22, 1994. 








11-232 


II. MSAD Program Tasks 

tlllHItlllHHIIIIIIHIII 


— Ground-based Research 


Discipline: Biotechnology 

Ill nil 


Convective Flow Effects on Protein Crystal Growth and Diffraction Resolution 

Principal Investigator: Prof. Franz e. Rosenberger 

University of Alabama, Huntsville 

Co-Investigators: 


L. Monaco 

University of Alabama. Huntsville (UAH) 


Task Objective: 

This research aims at developing a detailed understanding of 
the nucleation and growth mechanisms involved in the crystallization of globular proteins, 
the formation mechanisms ot structural and compositional nonuniformities (defects) in protein crystals and their 
dependence on growth conditions, and 

• the dependence ot x-ray diffraction resolution ot protein crystals on defect types and concentrations and, thus, on 
crystallization conditions. 

Task Description: 

We seek to establish, tor select proteins, a correlation of well-defined solution conditions (purity, pH, buffer, 
precipitant, supersaturation, temperature, and bulk transport) with nucleation and growth behavior during 
crystallization, and the x-ray diffraction resolution of the resulting crystals. 

Towards the above goals we are pursuing the following tasks: 

• Characterization of the purity of protein solutions by gel electrophoresis. Preparation of highly homogenous 
protein samples by high pressure liquid column chromatography. 

Studies ot protein interactions and aggregation in under- and supersaturated solutions by static and dynamic light 
scattering. 

Determinations ot the precipitant repartitioning between solutions and growing protein crystals, using atomic 
absorption and optical spectroscopy, and ion selective potentiometry. 

• In-situ studies of the protein growth morphology and kinetics, with and without forced solution flow, by 
high-resolution microscopic interferometry. 

• Numerical modeling ot diffusive-convective mass and momentum transport in geometries characteristic of protein 
crystallization on Earth and in space, using experimentally determined precipitant repartitioning and growth kinetics 
data. 

Measurements ot protein/precipitant diftusivities in saturated and supersaturated solutions, employing a novel 
interferometric technique that requires only small solution volumes. 

Measurements of the kinematic viscosity ot supersaturated protein solutions, with a capillary flow technique. 

• Determination of protein solubilities as a function of precipitant concentration, pH and temperature, using a 
miniaturized optical scintillation technique. 

Characterization ot the structural quality of selected crystals by x-ray diffraction and topography to reveal the 
influence of kinetics and transport effects. 

Task Significance: 

The pharmaceutical industry needs protein structure information to facilitate rational drug design. However, many of 
die currently available protein crystals are too imperfect to yield detailed structure information The reasons for this 
low crystal perfection are not well understood. Interestingly, crystallization experiments in space have led to 
significant improvements in crystal perfection tor some proteins. Again, the physical mechanisms for this are not 
clear. Our research aims at clarifying the connection between the magnitude of gravity present during protein 
crystallization and the resulting crystal quality. This insight is expected to lead to the design of protein crystal 
growth techniques that result in larger and more perfect crystals. 


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II. MSAD Program Tasks 

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Ground-based Research Discipline: 

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Biotechnology 

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Progress During FY 1 994: 

Our electrophoretic measurements revealed that significant amounts of high molecular weight protein impurities 
exist in all commercial lysozyme stocks. These stocks are widely used without further purification in protein 
crystallization studies. The removal of these impurities, which appear to influence most kineucs and reparuuomng 
processes, is being pursued with fast protein liquid chromatography. 

Simultaneous static and dynamic light scattering measurements were performed on buffered solutions with lysozyme 
solutions of various protein and NaCl concentrations. Contrary to most earlier work, the lysozyme dittusivities 
were found to either increase or decrease with lysozyme concentrations, depending on the salt concentrations. The 
corresponding static light scattering intensities show opposite dependence on lysozyme concentration. These data 
are compatible with concentration-dependent changes of monomeric interactions. At the same time, these findings 
appear inconsistent with earlier claims of the formation of small protein aggregates prior to nucleauon. 

The high-resolution microscopic investigations of lysozyme growth morphology and kinetics without forced flow 
have revealed several novel phenomena. Depending on the impurity content of the solution, the growth step density 
is either higher or lower at the periphery of a crystal facet than in its center. We also found growth kinetics 
oscillations even at stable growth temperatures. These oscillations, which increase in amplitude with 
supersaturation and crystal size, are associated with the formation of composiUonal inhomogeneities. These 
phenomena form the first indication for mechanisms by which bulk transport conditions and. thus, gravity could 
influence the protein crystal perfection. 


The repartitioning of Na* and Cl' ions between lysozyme solutions and crystals was investigated tor a wide range of 
crystallization conditions. A nucleation-growth-segregation model was developed to interpret the large body of data 
in a unified way. The results strongly suggest that lysozyme crystals possess a salt-nch core with a diameter on the 
order of 10 urn. These results are corroborated by white beam x-ray topographs (obtained on our crystals by V. 
Stoianoff at the Brookhaven National Laboratories) which show an accumulation of defects m the crystals historical 
center. Further support for coring comes from our preliminary investigations of compositional inhomogeneities on 
cross-linked, microtomed crystals with scanning electron microscopy and energy dispersive spectroscopy. In 
addition it appears that the high molecular weight impurities preferentially partake in the coring. Although these 
findings have to undergo further scrutiny, they suggest some far-reaching connections between protein crystal 
perfection and crystal growth conditions. 


A realistic numerical model for diffusive-convective transport in lysozyme crystallizadon has been completed. The 
results indicate that even in the small crystallization cells typically employed, protein concentration nonumlormities 
and gravity-driven solutal convection can be significant. The calculated convecuon velociues are ot the same order 
of magnitude as those found in earlier experiments. As expected, convective transport enhances the growth rates. 
However, even when diffusion dominates mass transfer, i.e. at zero gravity, lysozyme crystal growth remains 
kinetically limited. The salt distribution in the crystal is predicted to be nonuniform at both 1 g and 0 g, as a 
consequence ot protein depletion in the solution. 


To provide realistic input for the modeling, and to link light scattering results with macroscopic diflusivity data, an 
interferometric diffusivity measurement setup has been completed. This setup requires only small (protein) soluuon 
volumes and is accurate to better than 1%, as shown by extensive tests with NaCl solutions. 


Also in support of the numerical modeling, the viscosity of a large number of lysozyme solutions was monitored 
over time with a temperature controlled Cannon-Fenske viscometer under conditions which lead to crystallization. 
Changes in the kinematic viscosity of aqueous solutions by \% could be detected. However, none ot the protein 
solutions studied showed a change in kinematic viscosity as the solutions aged before crystallizauon. This indicates 
the absence of a significant concentration of large clusters in lysozyme solutions prior to nuclealion. 


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11-234 


il. MSAD Program Tasks — Ground-based Research 

millllMIMIIIIMlinmiilHIIIIimiMIMIIIIIHIMHIIIIMIIIIIIlii 


Discipline: Biotechnology 




Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 2/93 Expiration: i/96 

Project Identification: 962-23-08-23 
NASA Contract No.: NAG8-950 
Responsible Center: msfc 


Bibliographic Citations for FY 1994 : 

Journals 

Fredericks. W.J., Hammonds. M.C.. Howard, S.B.. and Rosenberger, F. Density, thermal expansivity, viscosity and 
retractive index of lysozyme solutions at crystal growth concentrations. J. Cryst. Growth, vol. 141. 183-192 (1994). 

Rosenberger, F. Boundary layers in crystal growth. Prog. Crystal Growth Charact., vol. 26, 87-98 (1993), 

Rosenberger, F. Short duration low-gravity experiments - time scales, challenges and results. Micrograv Sci Technol 
vol. VI, 142-148 (1993). 

Presentations 

Rosenberger, F. Tnterpiay between anisotropic interface kinetics and nutrient bulk transport." Plenary lecture at the 
Annual Conterence of the German Mineralogical Society. Freiberg. Germany, September 17-23, 1994. 


"• 


11-235 


II. MSAD Program Tasks — Ground-based Research 


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Discipline: Biotechnology 





Enhancement of Cell Function in Culture by Controlled Aggregation 


Principal Investigator: Prof. w. m. Saitzman 

Johns Hopkins University 

Co-Investigators: 


Prof. K. Leong 

Johns Hopkins University 

Task Objective: 


| DULU im- 

Cell-cell contact within tissues is fundamental to the regulation of cell differentiation and function. Cell 
aggregates, formed in vitro and maintained in culture, have been shown to maintain many ot the functions o e 
native tissue. The main objectives of this program are: i) development of methods for controlling cell aggregation 
using bioactive polymers and polymer microspheres and ii) systematic study ot the function and be avior o 
suitably aggregated cells in culture. The discovery of new methods for improving cell growth and (unction in 
culture is critical to the development of hybrid artificial internal organs and mammalian cell bioreactors. 

Task Description: 

To achie ' ’ these goals, we have formulated the following specific objectives for a three-year period ot study: 

Obiectiv ■ • Synthesis of water soluble p olymers for controlling cell aggregat i o n. We will synthesize water 
soluble polymers with bioactive groups that are specifically recognized by certain cells and use these 
multifunctional polymers as molecular nuclei to initiate and control cell aggregation. We will use ese P° - >incrs _ 
to control aggregation by adding them to gently agitated or quiescent suspensions of single cells; this technique wi 
produce small cellular aggregates «10 cells, diameterclOO mm). By altering the properties ot the polymers and the 
conditions of aggregation, we will identify approaches for obtaining cell aggregates of different size, polydispersity, 
and morphology. We have demonstrated the feasibility of this approach using N-acetyl glucosamine (specific tor 

chicken hepatocytes) attached to vinyl polymers. ........ 

Objective. 2: Fabrication of nolvmer m icrosnheres for canrier-assififf4 Cfr l l aggregat i o n- We will fabricate 
i^CTOspheres con^ning encapsulated soluble mediators o^ We wll > use the microspheres 

to create larger aggregates with a central polymer core. We have also demonstrated the feasibility ot this approac 
using microspheres composed ot vinyl polymers and cultured hypatocytes. 

Ohi^nvp r Development of methods for culturin g cell aggre g ates under unit g ravity . In preliminary studies, we 
have encapsulated hepatocytes and hepalocyte aggregates within gels of type I collagen, cultured these encapsulated 
cells and examined subsequent cell growth, function, and viability. We will test gels ot collagen under different 
hydration conditions to find an optimal experimental system for maintaining cells in an aggregated and suspended 
state in the laboratory. The gels will be used to suspend aggregates created with water-soluble polymers and 
microspheres To develop model culture systems representing both liver and neuronal tissues, we will use primary 
cultures of hepatocytes, pnmarv cultures and fetal brain cells, neuroblastoma cell lines, and the PC 12 cell line. 
QbifiaiSS 4- Measurement of cell function under different agg re g ation conditions in ge l cu l tu re. We have already 
developed methods of monitoring cell growth and metabolism in culture by measuring cellular protein. DNA, and 
lactate dehydrogenase (LDH) content. We have also developed methods for monitoring cell function in culture by 
following albumin and uric acid secretion (for hepatocytes) and expression of specific enzymes and responsiveness 
to nerve growth factor (for PC 12 cells). Using the optimal experimental system, defined in specific objective 3, 
we will systematically examine the function of cell aggregates in culture. Aggregates will be cultured under a 
variety of conditions including i) conventional static culture, ii) static culture with aggregates suspended within gels 
of extracellular matrix molecules, and iii) microgravity culture ot aggregates within the NASA rotating-wal 

bioreactors. _ t 

nhieetive 5: Preparation of experime n ts for evaluation under micrOgTilYltV condit i o ns- In specific objecuves 
through 4, we will have identified the important variables for controlling cell aggregation and function in aggregate 
culture. In the final stages of this project, we will design methods for developing physiologically realistic cell 
aggregates under microgravity conditions and for testing the influence of aggregation on cell function in suspension 
culture under microgravity in space. 


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11-236 


II. MS AD Program Tasks — Ground-based Research 


Discipline: Biotechnology 

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Task Significance: 

These studies are uniquely suited tor study in microgravity. First, cell aggregation in zero gravity will be driven by 
migration and diffusion rather than by forced collisions as is necessary on earth. The resulting aggregates may be 
closer to those found in tissues, since tissues are formed by migration and selective adhesion. Second, gentle 
suspension culture techniques can be used to culture the aggregates in microgravity. By the end of the period of 
laboratory study proposed here, we will have developed cell aggregation techniques appropriate for testing under 
microgravity conditions in space. 


Progress During FY 1 994 : 

Objective 1: We have synthesized several water-soluble molecules as molecular nuclei for cell adhesion. These 
molecules are based on polyethylene glycol) with bioactive peptides, NH 3 -Gly-Arg-GIy-Asp (GRGD) and 
NH 3 -Gly-Tyr-Ue-Gly-Ser-Arg (GYIGSR), grafted to the termini. We have developed covalent coupling methods for 
attaching these peptides to PEG with a variety of molecular weights (5,000 to 30,000) and to polystyrene 
microspheres (0.1 to 10 mm). We have used quantitative cell adhesion assays to determine the best peptides for 
conjugation. We have examined the kinetics of cell aggregation of a number of important cell types (including 
neural cells and cell lines, fibroblasts, and genetically engineered fibroblasts). We are developing methods for 
examining cell function tor aggregates maintained in culture. The first report in this work was published this year 
(Dai, Belt, and Saltzman, 1994) and other publications are in progress. 

Objective 2: We have synthesized polystyrene polymers modified with carbohydrates and peptides at die surface. A 
manuscript describing this work was published this year (Gutsche, et. ah, 1994). These unique polystyrene-based 
polymers can be formed as microspheres, and cells attach and grow avidly to these novel microcarriers. We have 
developed similar methods tor coupling peptides to polystyrene supports with a range of sizes. 

Objectives 3 and 4: We have developed methods for culturing and forming aggregates under unit gravity. A 
manuscript that was recently accepted for publication is appended. (Krewson, C.E., Chung S.W., Dai, W., and 
Saltzman, W.M. Biotechnology and Bioengineering 43:555-562 (1994). We have adapted these methods for 
producing aggregates within the NASA rotating-wall vessels. 

Objective 5: Only applicable to the third project year. 


Students Funded Under Research: Task Initiation: 11/92 Expiration: 11/95 

Project Identification: 962-23-omo 
NASA Contract No.: nag-654 
Responsible Center: jsc 


Bibliographic Citations for FY 1994 : 

Journals 

Dai, W ., Belt J. and Saltzman. W.M. Cell-binding peptides conjugated to polyethylene glycol) promote neural cell 
aggregation. Bio/Technology, 12. 797-801 (1994). 

Gutsche. A.T.. Parsons-Wmgerter P. Chand, D. Saltzman. W.M. and Leong K.W. N-acetylglucosamine and adenosine 
derivatized surfaces for cell culture: 3T3 fibroblast and chicken hepatocyte response. Biotechnology and Bioengmeerine 
43, 801-809 (1994). 

Krewson, C.E., Chung, S.O. Dai. W. and Saltzman, W.M. Cell aggregation and neunte growth in gels of extracellular 
matrix molecules. Biotechnology and Bioengineering, 43, 555-562 (1994). 


' * •"•"•■Him.*. 


11-237 



II. MSAD Program Tasks — Ground-based Research 

it 


Discipline: Biotechnology 




Saltzman. W.M.. Belt, J. Dai, W. Krewson, C.E. Livingston, 
substrates and characterization ot cell-polymer interactions. 


T. Parkhurst. M.R. and Shin. M. Synthesis of polymeric 
Journal of Cellular Biochemistry Supplement. 18C. 240 


(1994). 


Pr esenta tions 

Saltzman. W.M, Beaty C.E. Chung S.W. and Dause R.B. 
Meeting, St. Louis. MO. November 1993. 


Polymers for stimulating neurite outgrowth. AIChE Annual 


Saltzman, W.M., Belt J., Dai W., Krewson C.E., Livingston 
substrates and characterization of cell-polymer interactions. 


T. Parkhurst M.R. and Shin M. "Synthesis of polymeric 
Keystone Symposium on Tissue Engineering, Taos. NM. 


February 1994. 


Saltzman, W.M.. Dai W. Krewson C.E. and Parkhurst M.R. "Polymers for controlling cell motility and aggregation." 1st 
International Conference on Cellular Engineering, Stoke on Trent. UK. 12-15 September 1993. 





11-238 



II. MSAD Program Tasks — Ground-based Research 

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Discipline: Biotechnology 

* 


Culture of Porcine Islet Tissue : Evaluation of Microgravity Conditions 


Principal Investigator: Dr. David w. Scharp 

Washington University School of Medicine 

Co- Investigators: 

No Co-l’s Assigned to this Task 



Task Objective: 

Porcine islet tissue is receiving new attention as an attractive, potential tissue for application in clinical islet 
transplantation in patients with Type 1, Insulin-Dependent Diabetes Mellitus (IDDM). Recent cUnical success of 
islet transplantation into patients with renal grafts using human islets and standard immunosuppression 
demonstrated that greater than one year islet graft function can be achieved off insulin therapy. As additional 
patients are being transplanted to establish how many patients can achieve insulin independence and for what 
duration, investigators are anticipating that the 4,000 human organ donors a year will be insufficient for the 
numbers ot potential transplants that can be achieved. Thus, adult porcine islet isolations are being developed. We 
have developed an adult porcine islet procedure but realize that the use ot neonatal porcine islet tissue is more suited 
tor clinical application trom a cost production viewpoint as well as from a safety viewpoint, since the neonatal 
porcine islet tissue could be obtained trom gnotobiotic donors. While this seems ideal, there has not been any 
reliable way to isolate neonatal islet tissue in any quantity nor any method to culture these islet cells. We have 
recently developed a markedly improved method for the isolation and purification of neonatal porcine islet tissue, 
but, have no reliable method to culture islet cells that can not only produce new islets, called pseudoislets, but also 
take advantage ot their inherent growth and maturation potential prior to consideration of transplantation. 

Learning ot the microgravitational culture system with low shear rate and the proven importance in producing other 
tissue types from single cells developed by Dr. Glenn Spaulding (NASA JSC), he and I have established a new 
collaboration that would combine our islet tissue. 

Task Description: 

To accomplish these three objectives, we propose the following specific aims for the investigations: 

1 To culture neonatal islet tissue by rotational, microgravitational and static methods to determine optimal ways 
ot formation and preservation ot functional pseudoislets. 

“■ To examine die ability ot cultured neonatal porcine islet tissue to develop and maintain differentiated islet 
functional characteristics. 

3. To determine the ability ot optimally cultured porcine islet tissue to be successfully transplanted into diabetic 
recipients. 

4. To examine the replication potential of neonatal porcine islet tissue through culture manipulations. These 
proposed studies combine the islet expertise with a method of rotational islet culture that has successfully formed 
neonatal porcine pseudoislets with the microgravitational expertise with a specific low shear culture system that 
seems ideally suited to the fragile neonatal islet cells. Successful completion of these proposed studies should 
provide important results that will have considerable application in the islet field as well as in the field of 
microgravitational studies important to future NASA objectives. 

Task Significance: 

The results of these studies will provide new information to three areas. The results will be important to: 1) a 
belter understanding of the development of neonatal islet tissue, 2) NASA considerations of islet tissue as a 
potential type ot tissue lor their microgravitational studies, and 3) islet transplantation for developing an effective 
culture system tor this promising new source of islet tissue. 





11-239 


II. MS AD Program Tasks 




— Ground-based Research 

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Discipline: Biotechnology 



Progress During FY 1 994: 

This project continues to utilize islet tissue isolated from 14 to 29 day neonatal pigs which have been surgically 
altered at three days of age and given feed enriched with potential growth factors to increase the beta cell production 
and maturation for the 10-day to two week period prior to harvest. So tar this year, we have performed twe ve 
separate experiments, each closely monitored at different stages by sampling tor DNA extraction, insulin 
production, glucose utilization rates, insulin extraction, and histology evaluation. 

Results show a two- to seven-fold increase in the number of aggregates at two weeks of culture Although glucose 
utilization is fairlv constant, there seems to be a maximum output of insulin at one week of culture^ Final 
viability testing shows functional islet tissue and a 95% viability by fluorescein diacetate staining. Recent studies 
have been focused on varying the culture medium used, as well as varying the tissue and bead ratios. One o our 
latest developments has to do with increasing the ability to process more tissue at a time, therefore cutung down on 
the variabilities and increasing the yield per grams of tissue, allowing us to culture more aggregates from each 
experiment. 

Although in vitro testing has been a successful tool in monitoring the progress of our tissue survival and growth, 
we have just recently begun to study the potential of this project with in vivo growth of our neonatal tissue. We 
are usimi the SCID (sever-combined immune deficient) mouse as a recipient model, in order to avoid any rejec on 
problems. The results of these experiments are too recent to draw conclusions but our expectauons tor this series 

are high. 


Students Funded Under Research: 


Task Initiation: i/93 Expiration: i/96 

Project Identification: 962-23 -oi-os 
NASA Contract No.: nag-653 
Responsible Center: jsc 


hi. 





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II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnoloev 

* .mi Him m. I.. 


Automation of Protein Crystallization Experiments: 
Temperature 

Crystallization by Dynamic Control of 

Principal Investigator: Dr. Keith b. Ward 

Naval Research Laboratory (NRL) 

Co-Investigators: 


W.M. Zuk 
M.A. Perozzo 

Geocenters, Inc./Naval Research Laboratory (NRL) 
Naval Research Laboratory (NRL) 


Task Objective: 

The goal ot this research program is lo develop a dynamically-controlled crystallization system (DCCS) in which 
protein supersaturation is controlled by varying the temperature while crystallization is monitored by optical means. 
This device will also be capable ot being controlled telerobotically. The program intends to extend its 
accomplishments in this area by continuing to enhance the DCCS, expanding the system to include multiple 
crystallization chambers and incorporating more efficient and versatile systems for monitoring the progress of 
nucleation and crystallization. A linal goal of this project is to ascertain to what extent the technique of 
temperature-controlled crystallization is applicable tor protein crystallization. 

Task Description: 

A study ol a representative sample ot well-characterized proteins that have been successfully crystallized using other 
methods is proposed. The temperature coefficient of solubility will be measured using the DCCS, and attempts to 
prepare crystals in this apparatus will allow us to judge the general usefulness of this approach. 

The proposed methods of research include further modifying the current design to incorporate video monitoring to 
provide visual observation of growth volumes, to introduce dynamic light scattering, and to expand the system to 
include multiple crystallization cells, each with separate temperature controls. Telerobotic control experiments will 
continue using enhanced control software, and the results of the experiments will be aimed at defining the 
capabilities and limitations of remotely-controlled crystallization protocols on space platforms in microgravity. 
Collection ot protein temperature solubility data will be enhanced by the development of more fully automated 
software algorithms. The temperature of a sample is slowly changed step-wise until the level of scintillation signal 
indicates that the crystallization phase boundary has been crossed. The temperature will then be recycled using a 
finer step size until the solubility temperature of the sample is detennined to within 0.1 °C. Although currently 
some ot this process is conducted manually, further development of the control software will completely automate 
the process. 

Task Significance: 

This research is important in continuing the development of dynamically-controlled crystallization systems, proving 
the usefulness ot dynamic control in conducting protein crystallization experiments in microgravity This work 
will also aid the current effort of other NASA-funded Principle Investigators in designing advanced crystallization 
apparatuses. This system will also be used, while it is being developed, to explore whether temperature control of 
supersaturation is a technique that can have wide applicability in laboratory-based protein crystallization. 

Progress During FY 1 994 : 

The DCCS has been miniaturized and redesigned to allow the use of crystallization solutions as small as 100 
microliters. Temperature is controlled through the use of small thermoelectric coolers. The new device utilizes a 
common miniature fiuonmeter cell as the growth chamber, greatly easing the preparation and clean-up of 
experiments. The system was also designed to permit easy integration of a miniature video camera for visual 
observation of growth cells. Preliminary solubility and crystallization experiments have been conducted to 
demonstrate the usefulness ot the new apparatus. Control software is continually being refined and will soon allow 
multitasking of procedures so that multiple experiments may be conducted simultaneously. 


" " 


11-241 



II. MS AD Program Tasks — Ground-based Research 

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Discipline: Biotechnology 

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Students Funded Under Research: Task Initiation: 1/93 Expiration. i/96 

Project Identification: 962-23-08-24 
NASA Contract No.: H-07975D 
Responsible Center: msfc 


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Illlllllllllltt MM* 

11-242 



II. MSAD Program Tasks — G 

1 ii 11111111111111111111 MiiiiiHimmiiiiiitmitiiMiMMmminm 


round-based Research 


Discipline: Biotechnology 

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IIIIIIIIMIIIIIIIII 


Thermal Optimization of Growth and Quality of Protein Crystals 


Principal Investigator: Dr. John m. Wiencek 

University of Iowa 

Co-Investigators: 


E. Arnold 

Rutgers University 


Task Objective: 

The overall goal of this project is to control supersaturation at constant values during protein crystal growth by 
varying the temperature in a predetermined (by simple theory.) manner. Applying the theory requires knowledge 
about specific physicochemical properties of the protein solution including the effect of supersaturation on growth 
rates and the effect of temperature on protein solubility. Our specific goals for FY94 were: 

Application ot a temperature control strategy which maintains constant supersaturation to the erowth of 
lysozyme crystals and comparison to traditional isothermal strategies. 

Investigation ot batch isothermal calorimetry as a tool to determine lvsozvme solubility as a function of 
temperature by employing the Van't Hoff equation. 

Construction of a video microscopy apparatus for determination of crystal growth rates and terminal size. 

Work tor the coming year will focus on the measurement of solubility and crystal growth rate for human serum 
albumin as well as the assessment ot the crystals grown by the developed strategies via xray diffraction. 

Task Description: 

Three protein systems have been chosen for study: lysozyme, human serum albumin (HSA), and HIV reverse 
transcriptase (RT). Each ot these proteins have unique features that make them interesting. Lysozyme and HSA 
represent fairly inexpensive and readily available proteins and will be model systems for investigations elucidatimr 
the effects ot growth rates on crystal quality. Once strategies that are optimal are available, such strategies will be 
applied to the RT system as a realistic test case. 

Experimental evidence suggests that larger and higher quality crystals can be attained in the microgravity 
environment of space. Fundamental studies have attempted to measure and model the effects of gravity-induced 
convection and sedimentation on the crystal growth process. However, the effect of growth rate on protein crystal 
quality is not well documented. If the growth rate is controlled, how much time is required to allow for interfacial 
attachment of the large protein molecule? What is the impact of this "attachment time" on crystal quality? This 
research effort is directed at measuring the effects of crystal growth rate on the ability of crystals to diffract xrays. 
We hope to link crystal quality to slow growth rates and discern 'how slow is slow enough." In addition, 
processing strategies will be developed which xray crystallographers can use to grow larger, high-quality crystals. 
The investigation requires the measurement of protein (lysozyme, HSA and RT) solubility at two or more different 
temperatures (typically 4 0 and 25 ° C) and the growth rate at two or more different supersaturations. 

Microcalonmetry is a potentially powerful technique to measure these and other (e.g nucleation) physical parameters 
ot the protein systems. 

Task Significance: 

Development ot a systematic method of protein crystallization may lead to crystallization of previously 
uncrystalhzable proteins and add to current knowledge of protein structure/function relationships. Knowledge of 
detailed protein structure is essential tor rational design of therapies and small molecule pharmaceuticals. 


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<•"*". I IIIIHIH Illllllll 

11-243 


II. MSAD Program Tasks — 

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Ground-based Research 




Discipline: Biotechnology 

MIMIIII 


Progress During FY 1 994: 

Material balances and kinetic rate laws were combined with solubility data to produce a temperature control 
algorithm designed to maximize crystal size and maintain the crystal growth conditions morclose to the metastable 
zone Several assumptions were made in the construction of the temperature algorithm, the first being that o 
constant growth rate. Because our experiments were performed in the reservoir of a temperature-controlled water 
bath, it was not feasible to measure the crystal growth rate during the course of the experiments. Studies are 
currently underway to measure the growth rate of crystals in situ , to determine whether the assumpuon ot consent 
growth rate was met in our experimental system. The second major assumpuon m the temperature control model is 
that only one crystal is present and growing throughout the experiment. With the exception ot the isotherm 
program, the predicted final size of the seeded samples corresponds closely with the measured average final size in 
the seeded systems, indicating that this may not be a limiting assumpuon. Nucleauon can also be accounted tor in 
future studies by taking additional crystals into account in the mass balance. A third assumption is that the growth 
rate model is dependent only on supersaturation. This model was used in the generation ot tour temperature control 
strategies for the growth of lysozyme crystals: curved (constant growth model), linear ramp, isothermal 20 C, and 
isothermal 4 °C. Both the linear and the curved temperature programs yielded large, well-tormed crystals. e 
isothermal 4 X program also resulted in large crystals, but they were poorly formed due to die high initial growth 
rates. The enthalpy of crystallization of hen egg-white lysozyme in two 0.05 M acetate butters (5% NaCl pH . 
and 3% NaCl, pH 5.2) was determined at 15 °C using isothermal calorimetry and was found to be -17.1 _ 3.2 
kcal/mol (5% NaCl) and -10.5 ± 2.3 kcal/mol (3% NaCl). These values were found to agree within experimental 
error with the enthalpy of crystallization determined from a Van't Hoff plot of solubility. 

In this work, we have shown that the use of controlled temperature changes leads to improved size of lysozyme 
crystals, and can limit nucleauon in a crystallizing system. These temperature ramps must have a basts in the 
physicochemical properties of the system (i.e., solubility, enthalpy and growth rate kinetics) Perhaps the major 
limitation in extending the use of this algorithm to other systems is the limited amount ot physicochemical data 
available for most proteins. However, our results show that there is some flexibility in the application ot 
temperature control, so that a linear temperature ramp may be just as effective as our "constant growth rate 
algorithm This indicates that moderately accurate physical and chemical data may be required to generate an 
appropriate temperature ramp. The use of calorimetric methods to attain solubility and enthalpic data may provide 
another source of the necessary information. It is expected that as more information becomes available, this type ot 
predictive temperature control strategy can be applied to a wide variety of systems, facihtaung the growth ot large, 
single protein crystals suitable for X-ray crystallography. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 3 


Task Initiation: 6/93 Expiration: 6/96 

Project Identification: 962-23-08-28 
NASA Contract No.: nags-975 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Schah" C* Wiencek. J.M.. Yarmush. M.L.. and Arnold, E. Lysozyme crystallization studies at high pressure. J. Cryst. 
Growth, vol. 135, 548 (1994). 


Presentations 
Wiencek, J.M. "Production 
temperature manipulations." 
NY, October 5, 1994. 


of protein crystals suitable for X-ray diffraction analysis: controlling growth rates via 
Fall Colloquia, Chemistry and Chemical Engineering, Polytechnic University, Brooklyn, 


Wiencek, J.M. "Efficient separation from dilute solution via driving force manipulation." University of Iowa. Iowa City. 
IA, December 9, 1993. 


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II— 2 4 4 


HMIHMMIIII»IIIMIIMIMIMMMIIMHMIM<MMIIIMM*miliMI 



II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 

mm 


Wiencek. J.M. Thermal optimization ol protein crystal growth. ’ NASA Protein Crystal Growth Conference, Panama 
City Beach. FL. April 26. 1994. 

Wiencek. J.M . Schall. C.A.. Li. L . and Arnold. K. "Measurement of enthalpy of fusion of lysozyme crystals by 
calorimetry and application to maximization ot crystal size." AlChH Annual Meeting, ,St. Louis, MO. November. 1993. 


mimmmmmmHMiimimmmimiiimimmimmimmmimmmmiiiimmmmmmmmmtmiMiii 


11-245 



II. MSAD Program Tasks — Ground-based Research 

....» 


Discipline: Biotechnology 

iiiiihiiiiimiiii mu 


Search for Dilute Solution Property to Predict Protein Crystallization 


Principal Investigator: Dr. w. w. Wilson 

Mississippi State University 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

The primary objective of the research is to discover a unique dilute solution parameter that universally and 
unambiguously predicts protein crystallization. 

Since most crystallographers will not have access to sophisticated laser scattering instrumentation, a secondary 
objective of this research is to construct a simple laser scattering device that determines the universal predictor 
values. The device will be miniaturized to work with sub-milliliter volumes and incorporate the latest optical fiber 
technology for beam delivery and signal detection. 

Task Description: 

Static, dynamic and electrophoretic laser scattering techniques will be used to carefully measure an array ot 
thermodynamic and hydrodynamic (not kinetic) solution parameters for each of a group of selected proteins dissolved 
under crystallizing as well as non-crystallizing solvent conditions. The proteins chosen will have a wide variation 
with respect to molecular weight and crystallizing conditions such as temperature. pH and crystallizing agent type 
(inorganic salts, PEGs and other organics). The laser scattering solution parameters will be measured in the dilute 
protein concentration regime, often 10-20 times below protein saturation. 

The research approach is to obtain comprehensive measurements of the SLS, DLS and ELS parameters from a set 
of selected proteins under both crystallizing and precipitating conditions with particular attention given to the dilute 
solution regime. The selection of the proteins is significant, and some collaboration with protein crystallographers 
will be required to totally define the set. Prior verbal agreement for such advisory collaboration has been obtained 
from Marc Pusey and Dan Carter at Marshall Space Flight Center in Huntsville, Alabama, Pat Weber at Dupont in 
Wilmington, Delaware, Alex McPherson at the University of California, Riverside, Franz Rosenberger at the 
University of Alabama, Huntsville, and Charlie Bugg and Larry DeLucas at the University of Alabama. 
Birmingham. Use will also be made of the Biological Macromolecule Crystallization Database compiled by Gary 
Gilliland at the Center for Advanced Research in Biotechnology in Rockville, Maryland. Based on years ot 
experience in performing laser scattering measurements and on the man-power requested in the budget, a target 
number of twenty proteins is projected for the set, corresponding to roughly one complete set of measurements per 
protein per month. This amount of time accounts for protein purification procedures as well as repetitions tor each 
of the SLS, DLS, and ELS experiments. 

Task Significance: 

It is anticipated that a particular solution parameter (or combination ot parameters) will be discovered that has 
quantitative values within a reasonable narrow range for crystallizing conditions and values significantly outside that 
range for non-crystallizing or precipitating conditions. If such a universal predictor can be proven, then its use will 
have an immediate impact in the protein crystal growth community in general and microgravity research in 
particular. The solution conditions for protein crystallization in a microgravity environment should be maximized 
during ground testing so that a high probability for crystallization is achieved. Having a universal predictor will 
allow crystallographers to fine tune existing crystallization protocol or discover new conditions to crystallize 
difficult proteins. 


* 


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II. MSAD Program Tasks — Ground-based Research 


Discipline: Biotechnology 


Progress During FY 1 994: 

The focus of work during this period was investigating three laser scattering methods as potential diagnostics for 
predicting solution conditions favorable for protein crystal lization. One method, electrophoretic laser scattering or 
ELS, has been found to be generally not appropriate for this work. We have determined that the resolution of ELS 
for small proteins with molecular weights less than about 100,000 daltons is poor. ELS may be useful for studying 
large particles such as viruses, but its applicability for protein crystallography is doubtful. Accordingly, our 
emphasis shifted to static laser scattering (SLS) and dynamic laser scattering (DLS), both of which seem promising. 
We have studied about fifteen different protein/solvent crystallization conditions by SLS and have found that a 
thermodynamic solution parameter called the second virial coefficient, B22, seems to be a general predictor for 
protein crystallization. DLS was used for some of the same protein/solvent pairs to determine if the diffusion virial 
coefficient, KD, could also be used as a predictor. The results for DLS are not conclusive at this time. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 7/93 Expiration: 6/96 

Project Identification: 962-23-08-21 
NASA Contract No.: nags-965 
Responsible Center: msfc 


Bibliographic Citations for FY 1994: 

Journals 

George, A., and Wilson, W.W. Predicting protein crystallization from a dilute solution property. Acta Cryst., vol. D50, 
361-365 (1994). 




iiMiiiiimiiMMiiiiiiiiiKiiiimimiiniiiiiMiiKiiiiiiiMi 


II-247 






II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 



Characterization of Solvation Potentials Between Small Particles 


Principal Investigator: Dr. Charles f. Zukoski 

University of Illinois, Urbana-Champaign 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

A combined experimental and modelling ellort is used to characterize how variations in solvent chemical potential 
alter the states of aggregation of colloidal particles. 

Task Description: 

The objective of the FY94 program is to develop a combined density fractional theory and Monte Carlo simulation 
technique to describe the phase behavior of particles where interactions are dominated by solvation forces. In 
addition, the role of solvent/particle interactions in creating hydrophobic attractions is explored. On the 
experimental side, direct links are made between interparticle forces and phase behavior through measurements of 
protein second vireal coefficients by light scattering and phase behavior as protein concentration is increased. 

Task Significance: 

Developing methods which reliably result in high quality protein crystals is of major technological significance in 
the development of fundamental understanding of biochemical phenomena and the expression of genetically altered 
therapeutic proteins. In the work carried out here, new methods of controlling protein crystallization are explored. 
The modelling effort seeks to guide the experimental program by providing understanding of the role of solvation 
interactions in controlling the state of protein aggregation. The modelling effort has shown that the rarely 
recognized variable of solvent chemical potential can be used to control protein crystallization behavior. The 
experimental program is aimed at developing methods of characterizing protein interactions as solvent chemical 
potential is altered and demonstrating links with crystallization behavior. 


Progress During FY 1 994: 

Substantial modelling progress has been made. Simulation studies show that variations in solvent chemical 
potential can strongly influence how small particles associate and the strong influence of solvent/particle 
interactions. Experimentally, light scattering techniques have been used to determine the second vireal coefficient, 
B 2 , of lysozyme molecules as a function of pH and ionic strength. B 2 is a measure of the strength of interparticle 
forces trending from positive to negative as the interactions pass from repulsive to attractive. Linking B 2 to 
conditions resulting in crystallization remains a central task in FY95. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 6/93 Expiration: 6/96 

Project Identification: 962-23-08-27 
NASA Contract No.: nags-976 
Responsible Center: msfc 


iiiiiiimimiiiiiiiMiiiHiiiiMiiimiiuMiiiiitiiitHiiitiitiiMii 


11-248 


II. MSAD Program Tasks — Ground-based Research Discipline: Biotechnology 


Bibliographic Citations for FY 1994: 

Journals 

Douglas, L.J., Lupkowski. M .. Dodd, T.L.. and van Swol, F. On the role of solvation forces in colloidal phase transitions. 
Langmuir, vol. 9. 1445 (1993). 

Frink, L.J.D., and van Swol, F. Solvation forces and colloidal stability: A combined Monte Carlo and density functional 
theory approach. J. Chem. Phys., vol, 100. 9106 (1994). 

Presentations 

Frink, L.J.D., Zamora. P., van Swol. F., and Zukoski. C.F. ’’The freezing of colloidal suspensions in confined systems." 
8th International Conference on Surface and Colloid Science, Adelaide. Australia. February, 1994. 




11-249 


II. MSAD Program Tasks — Ground-based Research 

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Discipline: Combustion Science 

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Effects of Energy Release on Near Field Flow Structure of Gas lets 


Principal Investigator: Prof. Ajay k. Agrawai 

University of Oklahoma 

Co-Investigators: 


S.R. Gollahalli 

University of Oklahoma 

Task Objective: 


The primary objective of this research is to understand how buoyancy attects the structure ot the shear layer, the 
development of fluid dynamic instabilities, and formation and characteristics of the coherent structures in the 
near-nozzle regions of burning gas jets. The secondary' objective is to understand the role ot buoyancy in the flame 
lifting and reattachment process, evaluate the scaling behavior ot dittusion flames, and aid in the development ot a 
theoretical model by providing quantitative temperature data throughout the flame in the absence ot buo\ancy 
effects. 

Task Description: 

The initial phase of this project involves the visualization of near-tield flow structures in cold jets and nonsooting 
flames at the same flow conditions or the same jet exit Reynolds number, allowing the effects of energy release on 
these structures to be identified by comparison. The experiments wall use hydrogen and hydrogen-inert gas 
mixtures as the fuel with air as the oxidizer. Energy released in the flame will be controlled by varying the 
hydrogen mole fraction in the jet stream. Attached flames, lifted flames, and flames in the transition region 
between these two extremes will be studied. Experiments tor all cases will be conducted in both normal and reduced 
gravity. 

Task Significance: 

The phenomena occurring near the exit of a gas jet nozzel determine burning characteristics and the rate ot pollutant 
generation. The effect of buoyancy on these processes is poorly understood and hence it is difficult to model when 
designing commercial combustors. This project will study the fluid dynamics ol turbulent gas jet combustion, 
applicable to commercial combustors of this type and may lead to higher efficiencies and lower pollution generation 
levels. 

Progress During FY 1 994: 

Since the award of this grant in June 1994, laboratory space was acquired and safety procedures were established to 
begin this project. 

Computer software for the generation of rainbow' filters was developed in conjunction with Dr. Fletcher Miller, 
Case Western Reserve University, and NASA LeRC equipment and personnel. The filters were printed on a high 
resolution Polaroid digital film recorder, which is capable of producing 35 mm slides. These slides are being used 
with a schlieren system interfaced with a 3^CCD color camera and a personal computer equipped with image 
processing software. 

Concurrently, experiments w-ere conducted using hydrogen as the f uel at atmospheric pressure to determine an 
appropriate size of the nozzle for drop tower experiments. The accompanying fuel supply system and test section 
for both atmospheric and low pressure studies were designed and fabrication has been initiated. 





11-250 



II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

IIIIHIHIimiHmillltlllHIIIHIHmtlllHIHIHIMMHHIlimmiMIHIinillimiMMHimiMllilllllllllMIIIIMIIIIHIItlllllMritlHIlHimillltlttlllHIMIIimiMIIHIIIIIIIIIIIHMIlltlllltllllllltlllllMIllHIHMIllllMIIIHH 


Students Funded Under Research: 
BS Students: 2 

MS Students: 0 

PhD Students: 0 


Task Initiation: 6/94 Expiration: 5/97 
Project Identification: 962-22-05-57 
Responsible Center: LeRC 


11-251 


II. MSAD Program Tasks 


- Ground-based Research Discipline: Combustion Science 

* 


Radiative Extinction of Diffusion Flames 


Principal Investigator: Prof. Arvind Au-eya 

University of Michigan 

Co-Investigators: 


Prof. I S. Wichman 

Michigan State University 

Task Objective: 


The objective of this program is to quantify the conditions under which a stabilized, laminar dillusion flame will be 
extinguished by radiative heat losses from llame-generated particulates (e.g., soot) that drain the chemically released 
energy from the flame. These tests must be conducted in microgravity because radiation-induced extinction may not 
be possible under normal-gravity conditions where buoyancy-generated convection would sweep the radiating 
sources upward and away from the flame. 

Task Description: 

The program is to have simultaneous experimental and theoretical efforts. Experimentally, normal-gravity tests 
using a quasi-one-dimensional counterflow diffusion flame burner will be studied to quantify soot production and 
oxidation rates and their optical properties. These data are needed both for the formulation ot the reduced-gravity 
testing and for the development of theoretical models. 

Subsequent reduced-gravity testing is to be pursued in the 2.2 second drop tower at NASA Lewis Research Center, 
where a laminar diffusion flame is to be stabilized about a spherical porous burner. In these tests the local fuel 
concentrations will be varied by the introduction of inerts into the fuel-flow stream. Measurements ot flame 
temperature and radiation flux will be used for comparisons with theory. 

A numerical model will be developed to simulate the reduced-gravity experimental configuration, and will include a 
chemical-kinetics-model and an emperical model of the production and consumption ot soot particulates. A model 
of the radiant emissions from the flame, associated with the particulates, will be developed. 

Task Significance: 

The microgravity flames will demonstrate the concept of radiative extinction in stabilized flames, distinct from the 
case of spreading diffusion flames. This mechanism of extinction is likely unique in microgravity, and thus may 
have application to fire safety aboard orbiting spacecraft. 

Progress During FY1994: 

During the year the following major accomplishments were achieved: 

1. Several modifications to the 2.2 second drop tower apparatus were completed. The modifications include: 1) a 
new ignition system consisting of a hydrogen flame stabilized around the spherical burner then switching the fuel 
flow from hydrogen to the test fuel; 2) three thermocouples to measure the burner surface and two gas-phase 
temperatures; and 3) a novel flame radiation measurement consisting of three band-limited photodiodes, viz., 
200-450nm, 200-1 lOOnm, and 800-1800nm, to capture the shifting wavelength distribution expected during the 
transient reduced gravity flame. 

2. Experimental observations in microgravity indicate that spherical flames can be obtained during the 2.2 second 
test time available in the drop tower, and that these flames evolve through large variations in radiative emissions as 
measured by the photodiode detectors. These measured emissions are to be compared to the theoretical model 
developed daring previous years of this work. 


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1 1 II I Ml Ml III III I II II II I I 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 




Students Funded Under Research: 

BS Students: 0 

MS Students: 2 

PhD Students: 0 


Task Initiation: 4/91 Expiration: 3/95 
Project Identification: 962-22-05-29 
Responsible Center: Lcrc 


Bibliographic Citations for FY 1994: 

Presentations 

Atreya. A., Agrawal, S.. Sacksteder. K.R.. and Baum. H. '’Observations of methane and ethylene diffusion llames 
stabilized around a blowing porous sphere under microgravity conditions. " AIAA-94-0572. presented at the 32nd A1AA 
Aerospace Sciences Meeting, Reno. January 1994. 


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11-253 


II. MSAD Program Tasks — Ground-based Research 

...mm * * 


Discipline: Combustion Science 

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Multicomponent Droplet Combustion in Microgravity: Soot Formation , Emulsions , 
Additives, and the Effect of Initial Droplet Diameter 


Principal Investigator: Prof. c. t. Avedisian 


Co-Investigators: 


Metal' Based 


Cornell University 


No Cod's Assigned to this Task 


Task Objective: 

The objective of the proposed research is to provide insights and data that supports the role ot immiscible (e.g. 
emulsion) and miscible metal-containing additives, and to examine the influence ot the initial droplet diameter on 
the combustion of fuel droplets in microgravity. In addition, the feasibility ot using a laser-based light scattering 
technique for detecting soot formed in spherically symmetric droplet flames in microgravity, and imaging droplet 
flames in microgravity by coupling UV filtering with a conventional CCD camera that is coupled with an image 
intensitier, will be examined. Initially the experiments will be pertormed in a standard atmosphere. 

Task Description: 

The burning of multicomponent droplets is complicated by the influence of composition, which can effect the 
formation of soot, lead to multistage combustion in which one component preferentially vaporizes from die droplet 
during combustion, or possibly result in the droplet exploding during combustion due to achieving an internal 
superheat condition. These problems are extremely complicated, especially that ot soot formation. A CCD camera 
coupled with an image intensitier for the purpose of recording UV light emissions from the flame droplet will be 
measuring the droplet flame diameter and a laser light scattering technique will be set-up to provide a quantitative 
measure of soot formation. The experiments will be conducted in a drop tower at Cornell that provides 
approximately 1 second of reduced gravity. 

Task Significance: 

Little data have been provided regarding the spherically symmetric burning of unsupported droplets of 
multicomponent fuels or emulsions. The importance ot examining fuel blends is that most practical fuels which 
are burned in combustion-powered devices or incinerators are multicomponent in nature, usually miscible, but 
sometimes immiscible (emulsions). 

If the mechanism for an influence of initial droplet diameter on spherically symmetric droplet burning can be 
understood and predicted for the "simple 11 spherically symmetric droplet flame, this information may be useful for 
providing insights into the influence of initial droplet size on soot formation in a convective environment. Metal 
additives can create the potential for significant reductions in particulate emissions by the possible effect of the ions 
produced on the nucleation and agglomeration of soot particles, and their possible oxidation; their effect in the 
droplet flames, especially in the spherically symmetric configuration, is unknown. 

Progress During FY1994: 

There is no progress to report at this time since work will not start until May, 1995. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 5/95 Expiration: 5/99 

Project Identification: 962-22-05-49 
Responsible Center: LeRC 


Ml 


11-254 



II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

miiiiiiiiHiiiiniiiii«imiiiiHiiiiiiiimmiiiiiiimiiimiiiHiii«iiiiiMiiiimiiHitmmiiHHiiHiHiiitiiiiiiiiiniHH»iiiiiiiHii 


Development of Advanced Diagnostics for Characterization of Burning Droplets in Microgravity 


Principal Investigator: Dr. William d. Bachaio 

Aerometrics, Inc. 

Co-Investigators: 

Subra V. Sankar 

Aerometrics, Inc. 


Task Objective: 

This research is intended to develop rainbow thermometry for quantitative radial temperature measurements in 
burning droplets and use Morph ologically-Depen dent Resonances for quantification of the radial regression rate. 
Both ot these techniques will be developed using devices amenable for use in one of NASA's reduced gravity 
aircraft; this hardware will be delivered to LeRC at the end of the project. 

Task Description: 

Rainbow thermometry utilizes the angular dependence of rainbow location. In other words, given a known droplet 
composition, the location of the rainbow generated by that drop when illuminated with a monochromatic source 
will give the refractive index of the drop, and thus, its temperature. Instrumentation and software will be developed 
that will permit quantitative droplet temperature measurement. 

Morphologically-Dependent Resonances occurs when the droplet diameter is an integral number of wavelengths of 
the illumination source. As the droplet size regresses due to combustion, this condition will be repeatedly met, 
causing the droplet to periodically "shine." The rate at which this occurs will give the diameter regression rate and 
will be accomplished using the same hardware as for the rainbow thermometry. 

Task Significance: 

Droplet combustion is an economically vital phenomenon occurring in liquid-fueled engine combustion, which 
includes both mobile and stationary combustors. Optimization of such designs has been hindered due to insufficient 
knowledge about the nature of combusting droplets. This project will develop analytic instrumentation that will 
allow measurement of the radial temperature distribution and size of combusting droplets. While the tools to be 
developed can be used in either normal or reduced gravity, the latter admits the use of much larger droplets and 
dramatically increases the information yield of the experiment. 

Progress During FY 1 994: 

The contract with Aerometrics was executed on August 1, 1994 and they were so informed on August 18, 1994. 
Since the initiation of the contract was late in the fiscal year, Aerometrics has only had time to form a Project Team 
and outline a work plan. 


Students Funded Under Research: Task Initiation: 8/94 Expiration: 9/95 

Project Identification: 962-22-05-43 
Responsible Center: LeRC 


INI 


11-255 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

8 


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Ignition and Combustion of Bulk Metals in Microgravity 


Principal Investigator: Prof. Meivyn c. Branch 

University of Colorado, Boulder 

Co-Investigators: 


Prof. J.W. Daily 

University of Colorado, Boulder 

G. ]. Fiechtner 

University of Colorado, Boulder 

A. Abbud-Madrid 

University of Colorado, Boulder 

Task Objective: 


This project is an investigation of the mechanisms of ignition and combustion ot metals in bulk-pellet lorms under 
low-pressure atmospheres over a range of gravity levels. The project extends the unique experimental features, 
database, and analytical models established in the previous normal-gravity study to the low-gravity environment. 

Task Description: 

The preceding NASA-supported project devised an apparatus with a non-disturbing ignition source and dedicated 
diagnostics to determine surface and gas temperatures and metal-oxide surface morphology. A database ot ignition 
delays and combustion behavior was obtained at normal gravity tor a number of pure metal specimens. The present 
study extends the research to cover metal ignition and combustion behavior in both elevated and low gravity. 
Elevated-gravity measurements, already underway in the Geotechnical Centrifuge operated by the University of 
Colorado, are to be completed. The observation of the metal surface during ignition and combustion is possible 
through high-speed cinematography, using a camera on loan from the Lewis Research Center. Metal-oxide 
combustion specimens are recovered after each test and analyzed physically and chemically by electron microscopy. 
The compact, remotely operated apparatus used on the centrifuge will then be modified to meet the requirements and 
limitations for low-gravity experiments, to be conducted by the investigators in the Lewis Research Center airplane 
facility. 

The analytical study involves numerical modeling ot the metal heating, ignition, and combustion processes as 
influenced by gravity level and oxygen pressure. The initial findings were verified by the normal-gravity 
measurements of metal temperature rise, with excellent agreement. Extended modeling will incorporate the 
variations in heat loss by natural convection, to be validated by the elevated- and low-gravity measurements. The 
experimental results will also contribute information essential for the addition ot surface and gas-phase reaction 
processes into the modeling. 

Task Significance: 

This study offers a novel means of observing and interpreting metal combustion using a radiant-energy ignition 
source and a simplified convection-controlled environment. The results otter new scientific information on metal 
combustion reactions, and they promise practical applications to the management and safety ot spacecraft cryogenic 
propellant systems. 


Progress During FY 1 994: 

The quantitative measurement capabilities of the normal-gravity experimental study were extended to supplement the 
temperature measurements and visual observations obtained in the preceding year. Pure-metal specimens slightly 
smaller than before, 4 mm in diameter and 4 mm high, were heated by the unique radiant source of a 1000-W Xe 
short-arc lamp. The added diagnostics included a spectrograph-array detector system, scanning electron microscope 
(SEM) metallography, and X-ray spectrometry of specimens quenched at various stages during heat-up and 
combustion. In addition, surface-temperature histories indicative of the distinct stages of heat-up, ignition, and 
combustion were obtained over an elevated acceleration range of 2 to 20 g (g=9.8 m/s 2 ) in the University ot 
Colorado Geotechnical Centrifuge. 


mi. ••...». m.im ........ .... I*. 


11-256 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

hum 


The baseline screening tests were conducted with 8 different pure metals selected to exhibit a range of igniuon and 
combustion behavior. The additional measurements were each conducted with a single metal for simplification, 
however. 

The time-resolved measurements of gas-phase emission spectra in the reaction field were conducted with magnesium 
(Mg) specimens. A spectrograph with a diode-array detector gave a refined measurement of color temperature from 
the broad-band continuum spectrum. Prominent lines in the narrow-band spectra established the abundance of Mg 
and its MgO product through identified electronic and vibration resonances. This information will be very useful in 
determining the effect of gravity-induced convection in gas-phase reactions of bulk metals. 

The SEM surface-morphology and chemical analyses of quenched specimens were conducted with copper (Cu) 
specimens. The oxidation sequence of Cu at various stages of the heating and combustion processes was determined 
from the identification and location of surface reactants and products, with further corroboration by quantitative 
electron microprobe analysis. It is anticipated that in microgravity the chemical nature of the oxide layer will be 
altered by the lack of convective transport of oxygen adjacent to the metal surface. 

The elevated-gravity measurements were conducted with titanium (Ti) specimens. The complete experimental 
system was mounted on swiveling baskets at both ends of the rotating arms of the centrifuge. Power, control, and 
data signals were transmitted through slip rings. An additional silicon photodiode was installed to monitor any 
changes in the Xe arc lamp output due to the increased acceleration environment. Results of the testing, in terms of 
the time-related temperature responses, indicate a distinct change in the heating rate of the Ti samples. At 3 and 5g, 
the heating rate decreases and the ignition delay increases, although the ignition temperature remains comparable to 
that at normal gravity. At higher accelerations, however, the trend reverses and ignition delay decreases. In fact, at 
15 and 20g, the heating rate is greater that at normal gravity and the ignition temperature appears to be higher. This 
behavior is apparently due to the competing effects of the increase in the transport rate of oxygen to the metal 
surface and the increase in convective heat loss with acceleration. This plausible mechanism will be confirmed in 
further experiments with a variety of metals and oxidizing atmospheres, along with more detailed spectroscopic 
diagnostics. 

This project is to conclude early in FY 1995 (November 1994). Design activities are initiating to modify the 
apparatus for installation in an airplane facility, for a follow-on microgravity project already approved for support by 
NASA Headquarters. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 4/91 Expiration: 11/94 
Project Identification: 952-22-05-30 
NASA Contract No.:nag 3-1257 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994 : 

Proceedings 

Abbud-Madrid, A., Fiechtner, G.J., Branch, M.C., and Daily, J.W. "A study of bulk metal ignition in oxygen 
atmospheres/' The Combustion Institute, Fall Meeting of the Western States Section. WSS/CI 93-079, October 18-19, 
1993. 

Presentations 

Abbud-Madrid, A., Fiechtner, G.J., Branch, M.C.. and Daily, J.W. "Ignition and combustion characteristics of pure bulk 
metals: Normal gravity test results." AIAA Paper 94-0574. 32nd Aerospace Sciences Meeting and Exhibit. Reno. NV. 
January 10-13, 1994. 


I IMIMIMIMt II II I I Ml Ml II 


11-257 






II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

° mm •ihhhmiiimhiiiiiihiiiiii iiiiiiiiiiiimiimM 


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Ignition and Combustion of Bulk Metals in Microgravity (Ground-Based Experiment) 


Principal Investigator: Prof. Meivvn c. Branch 

University of Colorado, Boulder 

Co- Investigators: 


Prof. J.W. Daily 
A. Abbud-Madrid 

University of Colorado, Boulder 
University of Colorado, Boulder 

Task Objective: 


This project is an investigation of the mechanisms of ignition and combustion of metals in bulk pellet forms under 
low-pressure atmospheres over a range of gravity levels. The project extends the unique experimental features, 
database, and analytical models established in the previous normal gravity study to the low gravity environment. 


Task Description: 

The preceding NASA supported project devised an apparatus with a non-disturbing ignition source and dedicated 
diagnostics to determine surface and gas temperatures and metal oxide surface morphology. A database of ignition 
delays and combustion behavior was obtained at normal gravity for a number of pure metal specimens. The present 
study extends the research to cover metal ignition and combustion behavior in both elevated and low gravity. 
Elevated gravity measurements, already underway in the Geotechnical Centrifuge operated by the University of 
Colorado, are to be completed. The observation of the metal surface during ignition and combustion is possible 
through high-speed cinematography, using a camera on loan from the Lewis Research Center. Metal oxide 
combustion specimens are recovered after each test and analyzed physically and chemically by electron microscopy. 
The compact, remotely operated apparatus used on the centrifuge will then be modified to meet the requirements and 
limitations for low gravity experiments, to be conducted by the investigators in the Lewis Research Center airplane 
facility. 

The analytical study involves numerical modeling of the metal heating, ignition, and combustion processes as 
influenced by gravity level and oxygen pressure. The initial findings were verified by the normal gravity 
measurements of metal temperature rise, with excellent agreement. Extended modeling will incorporate the 
variations in heat loss by natural convection, to be validated by the elevated and low gravity measurements. The 
experimental results will also contribute information essential for the addition of surface and gas-phase reaction 
processes into the modeling. 

Task Significance: 

This study offers a novel means of observing and interpreting metal combustion using a radiant-energy ignition 
source and a simplified convection controlled environment. The results offer new scientific information on metal 
combustion reactions, and they promise practical applications to the management and safety of spacecraft cryogenic 
propellant systems. 

Progress During FY 1 994: 

This project is not scheduled for initiation until December 1994, upon completion of the current normal and 
elevated gravity project. 


Students Funded Under Research: Task Initiation: 12/94 Expiration: 11/97 

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-30 

MS Students: 0 RESPONSIBLE CENTER: LeRC 

PhD Students: 2 




11-258 


II. MSAD Program Tasks — Ground-based Research 

* him 

Modeling of Microgravity Combustion Experiments 

Discipline: Combustion Science 

iiiiimmitiiHiiiimimMiHiiiiiiHiiiiiiiiMimMiMHmHmiiimiiHiiiiMimiiiiiiiMiiitiiHiiiHiiii 

Principal Investigator; Prof. John d. Buckmaster 

University of Illinois. Urbana-Champaign 

Co-Investigators: 


No Co-I’s Assigned to this Task 



Task Objective: 

Modeling ol existing microgravity experiments tor improving our understanding of the fundamental physics, with 
particular emphasis on (a) premixed gaseous combustion processes, particularly those involving purely diffusive and 
very slow convective velocities, and (b) chattering flame propagation in premixed particle cloud combustion. 

Task Description: 

Microgravity combustion experiments amenable to modeling are identified, and analytical and numerical models are 
developed trom first principles tor various systems and configurations. Model predictions are compared with 
experimental results and necessary adjustments and enhancements are incorporated into the models. Precise 
quantitative comparisons are made with numerical results where possible. 

Task Significance: 

Modeling provides invaluable physical insights into the experimentally observed behavior. This study is done in 
close collaboration with experimentalists with the goal of providing a clear understanding of the underlying physics. 

Progress During FY 1994 : 

A presentation entitled "Unsteady Spherical Flames Generated by Point Ignition of Combustible Mixtures 
Containing Inert Particles, " by J. Buckmaster and A. Agarwal was given by J. Buckmaster at the 5th Int. Conf. on 
Numerical Combustion in Garmisch, Sept. 27 - Oct. 1, 1993. 

A poster session presentation entitled "Unsteady Spherical Flames in Dusty Gases," by J. Buckmaster and A. 
Agarwal was given at the 25th International Symposium on Combustion, Irvine, CA, 1994. It is also submitted to 
a journal as a paper lor publication. The abstract ol the paper reads: "We examine an expanding spherical premixed 
flame propagating in a mixture containing inert dust. The presence of the dust generates a significant radiative 
energy llux that influences the flame speed. With the adoption of a hydrodynamic description in which stretch 
effects are accounted lor using an empirical formula, and with the use of the Eddington approximation to describe 
the radiation, a simple numerical problem is formulated valid for that initial time interval in which the flame 
temperature changes by 0(e) amounts where E is the small inverse activation energy. Solutions are constructed 
using parameter values appropriate to lean CH 4 /air mixtures, and for modest particle loadings. We describe the 
competition between the Zeldovich-Spalding effect in which radiative losses on the diffusive scale tend to quench the 
flame, and the Jouhn effect in which radiative preheating on the scale of the Planck length tends to strengthen the 
flame." 

The paper entitled The role ol slip in the generation of acoustic instabilities in gas turbine combustion systems," 
by M. DiCicco and J. Buckmaster was completed in December 1993 and submitted for publication. The abstract of 
the paper reads: In the context ol gas turbine combustion chambers, this study describes how slip affects the 
response time of fuel sprays to pressure fluctuations in a gaseous flow field. Slip between the condensed and gas 
phases is shown to cause fuel vapor mass fraction fluctuations upstream of the reaction zone. A resulting 
oscillating heat release can drive the pressure fluctuations, depending on the phase difference between them. This 
generates an acoustic instability. With relevance to previous experimental results, differences are explored in the 
evaporation characteristics among three different fuel sprays (JP-4, JP-5, and D-2) in relation to their effect on the 
magnitude ol the fuel vapor mass fraction perturbations. Parameters such as droplet sizes, inlet air temperatures, air 
velocities, and initial Reynolds numbers, are varied with their corresponding influence examined." 


iiiiiitiimimiHiitimitiiiMMiiiiiiiiiiMiiiiiimmiiiHiiiiiiiiiHiiiiimmii 





11-259 


II. MSAD Program Tasks 


Ground-based Research Discipline: Combustion Science 

HUH • 


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The paper entitled "Acoustic instabilities driven by slip between a condensed phase and the gas phase in combusuon 
systems." by M. DiCicco and J. Buckmaster was presented by M.DiCicco (graduate student) at the 32nd A 
Aerospace Sciences Meeting, Reno, Nevada, in January 1994. The abstract of the paper reads: In the context ot 

eas turbine combustion chambers, this study descnbes how slip affects the response time ot fuel sprays to pressure 
fluctuations in a gaseous How field. Slip between the condensed and gas phases is shown to cause the fuel vapor 
mass fraction fluctuations upstream of the reaction zone. A resulting oscillating heat release can drive the pressure 
fluctuations, depending on the phase difference between them. This generates an acoustic instability. With 
relevance to previous experimental results, differences are explored in the evaporation characteristics among three 
different fuel sprays (JP-4, JP-5, and D-2) in relation to their effect on the magnitude of the fuel vapor mass tracuon 

perturbations. H 


The paper entitled "Intrinsic and acoustic instabilities in flames fueled by multiphase mixtures, by C.J. Lee, J. 
Buckmaster, and M. DiCicco was published in Combustion Science and Technology in 1994. The abstract of the 
paper reads: "We describe linear stability results for flames fueled by mixtures of air and particles. Nonsimilanty 
between the temperature and fuel concentration fields gives rise to an intrinsic pulsating instability tor uncontined 
flames (a single mode). Acoustic interactions for confined propagating flames generate acoustic instabilities (an 
infinite number of modes) when the gas-phase velocity is different from that ot the solid phase (i.e. there is s ip). 
The confinement modes can not, in general, be classified as intrinsic, fundamental, first-harmonic, etc For 
example, for propagation in a tube with flame initiation at the open end, a mode can start as the second harmonic 
but finish, when the flame is at the closed end. as the fundamental. Instabilities tend to be suppressed in spherical 
flames generated by point ignition in a confinement vessel. The triggering of acoustic instabilities in gas turbines 
by slip between fuel drops and air is discussed, and we show that the role ot slip is quite different when the 
condensed phase is injected at a finite point rather than being dispersed throughout the gas phase. 


The paper entitled "The effects of radiation on the thermal-diffusive stability boundaries of premixed flames, by J. 
Buckmaster and T. Jackson was accepted for publication in April 1994 in Combustion Science and Technology. 

The abstract of the paper reads: "We examine the stability of premixed flames in mixtures containing significant 
amounts of fine dust wnose sole impact is upon the radiative transport. By using well-established modeling 
strategies together with a simple radiation model which preserves much of the essential physics, it is possible to 
explore to what extent radiative transport displaces the classical non-hydrodynamical stability boundaries ot the 
plane deflagration. Analysis is possible for arbitrary values of both the Planck length and the Boltzman number, t 
is shown that the pulsating/traveling- wave instability is strongly enhanced by the presence of radiation, and can be 
present even if Led. On the other hand, radiation tends to suppress the cellular instability normally associated 
with values of Le less than 1 . The latter is consistent with preliminary experimental observauons ot Abbud-Madnd 


and Ronney.” 

The paper entitled "Absolute flammability limits and flame-balls," by D. Lozinski and J. Buckmaster was published 
in Combustion and Flame in 1994. The abstract of the paper reads: "We examine flame balls that are not optically 
thin so that radiation from the hot burned gas is not lost but is reabsorbed by the surrounding cool gas The steady 
solution is shown to be multivalued in general and defines an intrinsic (apparatus independent) flammability limit 
for a sufficiently small ignition source. Beyond the flammability limit a steady solution exists tor arbitrarily weak 
mixtures, but is unrealizable since it is unstable to one-dimensional perturbations. An unsteady propagating flame 
solution is also possible for arbitrarily weak mixtures, but can only be generated by a large igniuon source. 
Observations of flame- strings in SF6-diluted mixtures are reported and suggest that the peculiar nature ot the 
radiative properties ot SF6 is responsible for peculiar dynamics. 


The paper entitled "Quenching of opposed forced flow smoulder," by D. Lozinski and J. Buckmaster was presented 
by D. Lozinski, post-doctoral associate, at the Spring Meeting of the Canadian Section of the Combustion Institute 
in May 1994. This work was subsequently completed as a paper entided "Quenching ot flames in reverse 
smoulder," by D. Lozinski and J. Buckmaster in June 1994 and submitted for publication. The abstract ot the paper 
reads: "A simple model of reverse smoulder in a porous medium is analyzed using asymptotic methods. When the 
only chemical reaction is exothermic oxidation, the burning rate is a single-valued function of the blowing rate, 
increasing from zero to a maximum, and then returning to zero. When endothermic pyrolysis is added to the 
description, the burning rate is double-valued for blowing rates less than some maximum. Beyond this maximum 


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11-260 



II. MSAD Program Tasks — Ground-based Research 


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Discipline: Combustion Science 

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there arc no solutions. The upper branch of the double-valued solution is tile physically relevant one. On it, for 
certain choices ot parameters, the burning rate increases from zero to a maximum, and then decreases until 
quenching occurs at the inaximpm blowing rate. This behavior mimics experimental observations by Torero, 
Fernandez- Pc llo, and Kitano ( 1993)." 

The paper entitled The role ot mathematical modeling in combustion,'' by J. Buckmaster was published in a book 
entitled Combustion in High Speed Flows, J. Buckmaster, T. Jackson, and A. Kumar, eds., Kluwcr Academic 
Publishers, The Netherlands, 1994. pp. 447-459. (S. Gokoglu) 

The book entitled Combustion in High Speed Rows was published, J. Buckmaster, T. Jackson, and A. Kumar 
editors, by Kluwer Academic Publishers, The Netherlands, in 1994. 

The paper entitled "Some topics in reverse smoulder, 1 " by J. Buckmaster and D. Lozinski, based on a presentation 
made by J. Buckmaster at a US/Japanese Workshop on Modeling in Combustion, held in Kauai, July 1994, was 
completed and submitted in August 1994 for the Workshop Proceedings. The abstract of the paper reads: "The role 
ot thermal non -equilibrium and endothermic pyrolysis is discussed in the context of a simple model of reverse 
smoulder combustion. It is shown that non-equilibrium has little qualitative effect on the nature of the solutions, 
but endothermic pyrolysis can lead to quenching at sufficiently large blowing rates." 

The paper entitled An elementary discussion ol forward smoldering," by J. Buckmaster, C. Femandez-Pello, and D. 
Lozinski is submitted lor publication. The abstract ot the paper reads: "We describe an elementary model of 
one-dimensional unsteady forward smoldering, purged of all unnecessary physics. Following work of Dosanjh and 
Pagni, a late time solution is constructed, characterized by two reaction fronts - an exothermic oxidation front, an 
unusual kind ol diffusion flame; and an endothermic pyrolysis front. It is shown that the flame temperature and the 
ratio ol the speeds ol the two fronts relative to the solid are independent of the blowing rate, in agreement with data 
obtained by Ohlemiller and Lucca. The structure ot the oxidadon front is described in the context of 1 -step 
Arrhenius kinedcs, and it is shown that leakage ot solid reactant through the front is possible, but not leakage of 

oxygen. An elementary pyrolysis structure is also examined which reduces to die frontal model in a certain limit, 
and cl (trifles its nature." 


Students Funded Under Research: 

BS Students: 0 BS Degrees: 0 

MS Students: 3 MS Degrees: 2 

PhD Students: 0 PhD Degrees: 0 


Task Initiation: 2/91 Expiration: 12/95 
Project Identification: 952-22-05-31 
Responsible Center: lcrc 


Bibliographic Citations for FY 1994 : 

Journals 

Buckmaster, J. The structure and stability of laminar flames. Annu. Rev. Fluid Mech. vol. 25. 21-53 (1993). 

Buckmaster. J. The role ot mathematical modeling in combustion. Combustion in High Speed Flows. Kluwer Academic 
Publishers. The Netherlands. 447-459 (1994). 

Buckmaster. J. and G. Joulin Comb. Sci. & Tech., vol. 89, 57-69 (1993). 

Buckmaster. J. and Jackson, T. The effects ot radiation on the thermal-diffusive stability boundaries of premixed flames, 
accepted by Combustion Science and Technology, (1994). 

Buckmaster, J. and Lozinski. D. Some topics in reverse smoulder, to appear in the Proc. of US/Japanese Workshop on 
Modeling in Combustion . in Kauai, (August 1994). 

DiCicco, M. and Buckmaster, J. Accountic instabilities driven by slip between a condensed phase and the gas phase in 
combustion systems. AIAA. 94-0103, (1994). 


" 


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III II I Mill HIM III III HIM Mill 


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Discipline: Combustion Science 




Lee. C.J.. Buckm aster. J. and DiCicco. M. Intrinsic and acoustic instabilities in flames fueled by multiphase mixtures. 
Comb. Sci. &. Tech, vol. 98, 161 (1994). 

Lozinski. D. and Buckmaster. J. Absolute flammability limits and flame-balls. Comb. & Flame, vol. 97. 301-316 (1994) 


Buckmaster.' J "and A. Agarwal "Unsteady spherical flames generated by point .guidon of ~mbfWom«mre, 
containing inert particles." presented at the 5th Int. Conf. on Numerical Combustion in Garmisch. September 

1. 1993. 


October 


Buckmaster. J. and A. Agarwal "'“Unsteady spherical flames in dusty gases"." presented at the 25th Int. Symp. on 
Combustion. The Combustion Institute. Irvine. CA. July 31 - August 5. 1994. 


Buckmaster, J. and Agarwal. A. "Unsteady spherical flames in dusty gases." poster session presentadon at the 25th Int 
Symp. on Combustion. Irvine. CA, July 31 - August 4. 1994. 


Buckmaster. 

combustion 


J. and DiCicco. M. "Acoustic instabilities driven by slip between a condensed phase and the gasphase in 
V s terns." presented at the AIAA 32nd Aerospace Sciences Meeting. Reno. NV. Jan. 10-13. 1994. 


Buckmaster. J. and Jackson. T. "The effect of radiative transport on the thermal-diffusive stability boundaries o^prem.xed 
flames." poster session presentation at the 25th Int. Symp. on Combustion. Irvine. CA. July 31 - August 4. 1994. 


Buckmaster. J. and Lozinski. D. "Some topics in revedrse smoulder." presented at the US/Japanese Workshop on 
Modeling in Combustion, Kauai, July, 1994. 

Lozinski, D. and Buckmaster. J. "Quenching of opposed forced flow smoulder." presented at the 1994 Spring Technical 
Meeting of the Canadian SecUon of the Combustion Institute, 10-13 May, 1994. 


Lozinski, D. and J. Buckmaster 
Spring Technical Meeting of the 


Quenching of opposed forced flow smoldering combusdon." presented 
Canadian Section of the Combustion Institute. May 10-13. 1994. 


at the 1994 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 




Buoyancy Effects on the Structure and Stability of Burke- Schumann Diffusion Flames 


Principal Investigator: Prot. l. d. Chen 

University of Iowa 

Co-Investigators: 


Dennis P. Stocker 

NASA Lewis Research Center (LeRC) 


Task Objective: 


The general goals ot the proposed research are to improve our understanding of (1) the influence of buoyancy on 
co-flow diffusion flames, e.g., Burke-Schumann diffusion flames, and (2) the effects of buoyancy on vortex-flame 
interactions in co-flow diffusion flames. The overall objectives of the proposed work are to: 

1. Verify the zero-gravity Burke-Schumann model and the gravity-dependent Hegde-Bahadori extension. 

2. Investigate the flame stability in a buoyancy-dependent flow- held as affected by the co-flow oxidizer. 

3. Examine the state relationships of co-flow diffusion flames. 

4. Study flow vortex and diffusion flame interactions. 

Task Description: 

In order to meet the objectives, die phenomena will be investigated by: 

1. Microgravity testing. 

2. Normal -gravity testing (e.g., at reduced pressure to emulate reduced gravity). 

3. Numerical modeling. 

D. Stocker (NASA LeRC) will have the lead responsibility for the microgravity testing, which will be generally 
conducted in the 2.2-second Drop Tower. The tests will be conducted in the rig fabricated for Stocker s precursor 
studies of Burke-Schumann diffusion flames. Also, D. Stocker and L.-D. Chen will consider testing in the Zero-G 
Facility and in research aircraft (e.g., DC-9) if a need is identified. In either case, the tests will most likely be 
conducted in rig(s) built for the Gas-jet Diffusion Flame (GDF) Experiment, since only limited modification would 
be required. 

Normal-gravity tests will be conducted under the direction of Prof. Chen at the University of Iowa and possibly at 
the Wright Laboratory (at WPAFB, in Dayton, OH), since the WPAFB facilities have been made available to this 
project at no cost. The normal-gravity experiments will complement the microgravity experiments, but will 
include tests that cannot be readily conducted in the microgravity facilities. For example, some instrumentation 
(e.g., NOx analyzer) that will be used in the normal-gravity testing cannot readily be used in the microgravity tests 
due to various constraints (e.g., time required for measurement, size of instrument, "ruggedness" of instrument, 
etc.). 

Prof. Chen will direct the numerical modeling which will be conducted at the University of Iowa. An existing, 
semi-implicit, transient, axisymmetric code will be modified to include gas-phase radiation, state relationships or 
reduced mechanisms tor major species, and finite chemistry for NOx. The predictions will be verified by the 
experimental measurements. 


Task Significance: 

The 1928 Burke-Schumann diffusion flame analysis is of fundamental and historical interest, and can be found in 
many, it not all, introductory combustion textbooks in the U.S. Experimental validation of this zero-gravity model 
will be an important contribution to combustion science, and it is likely to be referenced in future textbooks. 
Additionally, the study results could lead in the long-term to improved engine or furnace efficiency and reduced 
pollutant emissions. 


Mini 


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— Ground-based Research Discipline: Combustion Science 

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Progress During FY1994: 

During FY94, the work was focused on the development for upcoming tests and the modeling and analysis ot 
previous results. There were no microgravity tests conducted in FY94, due to the shut down ot the 2.2-second 
Drop Tower. The analysis of die pulsed Burke-Schumann flame tests conducted in FY93 was presented at the 
WSS/CI Fall 1993 meeting and in a poster session at the Twenty-Fifth International Symposium on Combustion, 
in August 1994. 

Hardware Development 

Whereas the previous microgravity tests have been limited to photographic studies ot the flame structure, the 
upcoming tests (to begin in FY95) will include measurements of temperature, species, etc. For this reason, a 
significant effort was focused on the hardware preparation for the upcoming microgravity tests. 

In the fall of 1993, D. Stocker was assisted in this effort by two undergraduate interns receiving design course credit 
from Worcester Polytechnic Institute. Flow visualization in the co-flow of the Burke-Schumann burner was 
demonstrated using streak imaging, by seeding the air flow with phenolic microballoons or smoke (from 
model-train smoke fluid). Shadowgraph imaging (using an expanded beam from a 15-mW HeNe laser) was used to 
visualize the hot plume above die flame. Additionally, tests were conducted with various slot burners in preparation 
for the design of slot bumer(s) to be included in upcoming tests. Slot flames are ol interest, since the analysis ot 
Roper and Hegde & Bahadori predicts that they will be more strongly dependent on buoyancy tiian the axisymmetric 
flames studied by Stocker thus far. 

J Goldmeer, a LeRC GSRP fellow, and D. Stocker conducted preliminary normal-gravity tests using dun tilament 
pyromeuy (TFP) to measure temperature profiles across a flame. Multiple fibers were imaged with a standard video 
camera, via an interference filter, providing a strong intensity and low noise with the camera at maxunum gain. 
Intensity profiles along each fiber are easily obtained using the Image Processing workstation. Calibration ot the 
video intensity vs. flame temperature will be done in FY95. TFP will be the primary method for temperature 
measurement in the upcoming drop tests. 

LeRC provided a driver for a proportional control valve to produce sinusoidal variations in the tuel flow tor pulsed 
flame studies. The droppable device sinusoidally varies the flow, and provides (nearly) independent control of the 
frequency and amplitude (both dc and ac) of the flow. Although there may be some hysteresis in the flow, the 
preliminary tests are promising. The periodic flow from the device will be characterized in FY95. 

Work is in progress on the definition of requirements and the conceptual design of circular and slot 
Burke-Schumann burners, which will be appropriate for smoke-fluid flow visualization, thin-filament pyrometry, 
absorption spectroscopy for species measurements, and traditional instrumentation (e.g., thermocouples). For the 
species measurements, a new source/detector array will be designed, that will mate with the burner chimney and be 
used with the spectroscopy system developed by Southwest Sciences, Inc. The burners will include interchangeable 
chimney segments appropriate to the different measurement techniques. 

Modeling & Analysis 

Stocker and the two WPI interns coded a computer program for predictions of the height and shape ot slot flames tor 
three conditions: (1) no gravity and no axial diffusion, (2) with gravity but no axial diffusion, and (3) no gravity but 
with axial diffusion, based on the works of (1) Burke & Schumann, (2) Chung & Law, as well as Roper, and (3) 
Hegde & Bahadori. 

Modeling was also performed at the University of Iowa for comparison with the pulsed flame tests conducted by 
Stocker in FY93. A correlation was established between the tip cutting and the appearance ot flow vortices. The 
numerical modeling showed that the tip cutting coincided with vortex formation near the tip of the flame in lg, and 
near the base of the flame in Og. Furthermore, animation of the vorticity field has shown that the baroclinic effect 
in the fuel-lean region acts as a source term in vortex dynamics, while thermal expansion is a sink term. 





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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

iiiiiim 


The modeling was unable to predict however, observed subharmonic tiame response, which presumably results 
from vortex merging. This held true despite the use of FCT correction for convective transport, various velocity 
profiles, and various waveforms in the modeling. Based on these results, differential pressure measurements were 
made of the How pulsation system, but they revealed a fundamental response, ruling out the solenoid valve as the 
cause of the subharmonic response observed in the flames. 

Nonetheless, numerical simulation of a tiame pulsed at 1 Hz has shown the effect of buoyancy on the flame's 
spectral response. The normal-gravity tiame spectrum appears to consist of linear combinations of two dominant 
frequencies, 1 and 4 Hz. The microgravity tiame spectrum showed only one dominant frequency, the 1-Hz forcing 
frequency. 

Modeling and normal-gravity experiments at University Iowa revealed a harmonic response (in tiame height and 
temperature traces) in Burke-Schumann flames pulsed at 1 to 4 Hz. Thus results thus far show' that buoyancy is an 
important parameter in this nonlinear tiame response (as suggested by Stocker’s drop tests). A paper is being 
prepared describing the numerical algorithm, that will use this finding as an example of the importance of using a 
high-order scheme (spatial) for accurately predicting tiame dynamics. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 1 

PhD Students: 2 


Task Initiation: 6/94 Expiration: 6/98 

Project Identification: 962-22-05-63 
Responsible Center: LcRC 





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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 


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Gravitational Effects on Premixed Turbulent Flames 


Principal Investigator: Dr. Robert k. Cheng 

Lawrence Berkeley Laboratory 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The overall objectives of this experiment is to investigate experimentally the dynamics of low Reynolds number 
premixed turbulent flames in a microgravity environment 

Task Description: 

The emphasis of this experimental program will be on measuring flame wrinkle scales and imaging mean flowtieid 
properties of conical Bunsen-type flames and rod-stabilized v-flames. Laser diagnostics will be used to obtain 
statistical scalar and velocity information to evaluate parameters suitable for predicting the ettects ot gravity on 
turbulent premixed flames. A 2.2 second drop tower, and Leaijet parabolas will be performed as well as parallel 
laboratory experiments. 

Task Significance: 

This research effort will provide insight to determine significant processes through which gravity affects flame 
properties such as flame speed and flame structures. The results will be used to determine the gravity-influenced 
limit for premixed turbulent flames. Such knowledge is valuable for guiding the development of turbulent 
combustion models to include the effects of gravity. This experimental study will contribute to resolving the 
inconsistencies that exist between experiments and theories and help couple chemical and fluid mechanical processes 
found in many turbulent combustion environments. If better understood, turbulent combustion can be exploited to 
enhance burning rates and volumetric power density in many heating and power generating systems. 

Progress During FY 1 994: 

An experimental rig that had been used in the 2.2-second Drop Tower was converted for the Lear jet. The behavior 
of laminar and turbulent Bunsen type conical and rod stabilized v-flames has been observed by the use of laser 
schlieren. The tests are follow-on experiments based on 2.2 second drop tower work from previous years. The 
schileren images are recorded on videotape and are analyzed by computer-controlled image processing. Comparison 
of the microgravity results with those under normal gravity shows the gravity affects flame propagation through the 
coupling of the flame dynamics and the surrounding flowfleld. Under normal gravity, buoyancy-driven flow 
instabilities are shown to induce flame flickering. 

The emphasis of the microgravity experiment was on measuring mean flame properties and compared them with 
those observed in the laboratory under normal gravity and reversed gravity. In addition to the use of laser schileren, 
the laboratory flames are also interrogated by other laser technique to measure their scalar and velocity statistics. 
These information are needed to evaluate parameters suitable for predicting the effects of gravity on premixed flames. 
The data will be useful for comparisons to theoretical models which do not include the effects of gravity. The study 
will assist in understanding the relationships between turbulence and low-gravity combustion. 

The analysis of the schileren video during the Leaijet experiments has begun. For the laminar flame cases, the 
median of the intensity is extracted to represent the mean flame position. For the turbulent flame cases, the task was 
more difficult due to the broad flame position. Different methods are being explored to obtain consistent and 
reproducible representation of the turbulent flames. The analysis of gravity-driven pulsating frequency of the 
Bunsen flame is complete. An emperical correlation is found for all the pulsating frequencies measured in our 
laboratories and those reported previously by others. The independent parameter is the square of Strouhol number 
over the Richardson number. The dependent parameter is the Reynolds number to the power of 2/3. The influence 
of gravity on the stabilization limits of Bunsen flames and rod-stabilized v-flames are also determined. These results 


in him 


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II. MS AD Program Tasks — Ground-based Research Discipline: Combustion Science 

iiiiiiiiiMiiiiiiiiiiiHmiiiiiiimiimmimmmmiMiiiiiiiHiiitmiiiiiMidiiiitMimimiMmHimH'immiiiHiiiiiiiMt 


are usetul lor designing future microgravity expenmentand to elucidate the processes important to characterizing the 
coupling between gravity and premixed names. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 6/91 Expiration: 3/95 
Project Identification: 952-22-05*32 
Responsible Center: LeRC 


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II MSAD Proeram Tasks — Ground-based Research Discipline: Combustion Science 




Gravitational Effects on Premixed Turbulent Flames: 

Microgravity Flame Structures 

Principal Investigator: Dr. Robert k. Cheng 

Lawrence Berkeley Laboratory 

Co-Investigators: 

No Co-l's Assigned to this Task 



Task Objective: 

The overall objectives of this experiment is to investigate the influence of gravity on premixed turbulent flame 
propagation. 


Task Description: 

The emphasis of this experimental program will be on measuring flame wrinkle scales and imaging mean flowtield 
properties of conical Bunsen-type flames and rod-stabilized V-flames. Laser diagnostics will be used to obtain 
statistical scalar and velocity information to evaluate parameters suitable for predicting the effects of gravity on 
turbulent premixed flames. Leaijet parabolic flights will be performed as well as parallel laboratory experiments. 

Task Significance: 

This research effort will provide insight to determine significant processes through which gravity effects flame 
properties such as flame speed and flame structures. The results will be used to determine the gravity-influenced 
limit for premixed turbulent flames. Such knowledge is valuable for guiding the development of turbulent 
combustion models to include the effects of gravity. This experimental study will contribute to resolving the 
inconsistencies that exist between experiments and theories and help couple chemical and fluid mechanical processes 
found in many turbulent combustion environments. If better understood, turbulent combustion can be exploited to 
enhance burning rates and volumetric power density in many heating and power generating systems. 

Progress During FY 1994: 

There is no progress to report at this time since work will not begin until March, 1995. 


Students Funded Under Research: Task Initiation: 3/95 Expiration: 3/97 

Project Identification: 962-22-00 

Responsible Center: LeRC 





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II. MSAD Program Tasks — Ground-based Research Discipline- Combustion Science 




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Combustion of Interacting Droplet Arrays in a Microgravity Environment 


Principal Investigator; Dr. Daniel l. Dietrich 

NYMA, Inc. 

Co-Investigators: 

No Co-fs Assigned to this Task 



Task Objective: 

This research program involves the study of one-dimensional and two-dimensional arrays of droplets in a 
buoyant-free environment. The purpose of the work is to extend the data base and theories that exist for single 
droplets into the regime wherein droplet interactions are important. 

Task Description: 

The emphasis ol the present investigation is experimental, although comparison will be made to existing 
theoretical and numerical treatments when appropriate. Both normal-gravity and low-gravity testing will be 
employed, and the results compared. 

The normal-gravity testing will utilize the classical suspended droplet technique; single droplets and droplet arrays 
will be supported on 125 pm optical libers in a combustion chamber where the ambient environment can be 
controlled. The low-gravity testing will employ droplets suspended on 15 pm Si-C fibers, a new technique 
developed during the past year, again in a combustion chamber where the ambient environment can be changed. 

Task Significance: 

The eventual goal will be to use the results of this work as inputs for models on spray combustion, wherein 
droplets seldom bum individually (the combustion history ot a droplet is strongly influenced by the presence of the 
neighboring droplets). 

Progress During FY 1994 : 

In collaboration with Dr. R. Vander Wal, data was obtained on the relative and absolute soot volume fractions 
produced during the burning of fiber supported droplets. The data was of single droplets with a 1.5 mm initial 
diameter suspended on optical fibers at 1 atm pressure in the air. The fuels used were n-heptane, n-decane, 
chlorohcptane, chlorodecane and ethanol/decane mixtures. The data consisted of simultaneous measurements of the 
soot volume traction (via LII) and natural flame images, simultaneous measurements of natural flame and OH 

chemiluminescence, and simultaneous measurements of droplet size, flame radiation measurements, and natural 
flame. 

The modifications to the experimental apparatus were completed and initial burning rate data on single droplets of 
pure fuels (decane, heptane, and methanol) with different size support fibers were taken. The effects of the support 
fiber are being investigated by comparing the experimental results to theoretical computations by M. 
Vedha-Nayagam . 

The normal gravity apparatus was reconfigured for two droplet studies. Testing began on the combustion of two 
droplets of n-decane (normal gravity). 

This effort is also part of the Fiber Supported Droplet Combustion Glovebox Experiment. The engineering model 
ot the experiment was built and tested. The flight hardware was designed and all of the parts were fabricated. All of 
the paperwork to date is complete. The experiment is manifested on USML-2. 


• 


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II. MSAD Program Tasks — Ground-based Research 

° 


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Discipline: Combustion Science 

mini 


Students Funded Under Research: T ask Initiation: io/89 Expiration. 12/94 

Project Identification: 962-22-05-33 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Dietrich.* LX ^ ^ Relative soot volume tractions in droplet combustion via laser-induced incandescence." Eastern States 
Section of the Combustion Institute Fall meeting, 1994. 

Vander Wal. R. and Dietrich, D. 'Laser-induced incandescence applied to droplet combustion. Applied Optics. 1994. 

Vander Wal. R. and Dietrich. D. "Laser-induced incandescence applied droplet combustion." Western States Section of the 
Combustion Institute. Spring Meeting. 1994. 





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II. MSAD Program Tasks — Ground-based Research 

mm mm 


Discipline: Combustion Science 

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Internal and Surface Phenomena in Heterogeneous Metal Combustion 


Principal Investigator; Dr. Edward l. Dreizin 

AeroChem Research Laboratories, Inc. 

Co-Investigators: 


Dr. H.F. Calcote 

AeroChem Research Laboratories, Inc. 

Task Objective: 


This project is an experimental and analytical study to determine the mechanisms by which oxygen penetrates 
within a burning metal droplet and attects the combustion process. Particular attention is given to disruptive 
uming, such as in micro explosions, which have been observed but never explained by current theories. 

Task Description: 

The study uses a novel apparatus that generates uniformly sized metal droplets through electrical arc discharges with 
consumable, pure metal electrodes. The separated droplets are ignited and then subsequently quenched to terminate 
e reaction at prescribed times during combustion. Experimental measurements will cover droplet temperatures and 
diameters as Junctions ot time and chemical and metallurgical analyses of the quenched, solidified specimens. Test 
conditions include variations of temperature, droplet size, and atmospheric oxygen concentration, for at least three 
dilterent metals. Initial normal gravity tests are conducted at the AeroChem Laboratories facilities. Subsequent 
inicrogravity tests, using a modified version of the droplet generator apparatus, will be conducted by the 
investigators in the Lewis Research Center free-fall drop tower facility. In microgravity, the near-absence of 
settling forces permits the precise control of the droplet motion to improve the interpretation of the droplet-diameter 
and droplet-temperature histories. Concurrent with the experimental studies, analytical studies verified by the 
experimental results model the processes occurring in metal droplet combustion to provide a theoretical foundation 
ot surface and internal transport and reaction rate phenomena in the burning metal-droplet system. 

Task Significance: 

This project is a study of metal and oxygen behavior in metal-droplet combustion using a unique but demonstrated 
apparatus to generate, control, and analyze the combustion processes. The results of the study have practical 
application to the performance and improvement of metallized fuels, such as those used in solid rocket motors. 

Progress During FY 1 994: 

This project began on July 6, 1994 with the award of NASA Contract NAS 3-27259. Since the basic apparatus for 
metal-droplet generation and ignition, called the GEMMED, was available and operational, only minor 
modifications to the apparatus were required poor to the studies. These changes, already accomplished, included an 
improved consumable wire-electrode feed unit with a measuring microscope and various small changes to the power 
gas-feed, and instrumentation systems. 


The initial study used the GEMMED to generate aluminum (Al) droplets in three nominal diameters of 120 pm, 

160 pm, and 190 pm, lor ignition and combustion in a normal-gravity, air environment. Temperature histories 
were provided by three-wavelength optical pyrometry. Three stages of combustion were observed in the available 
tune tor panicle combustion (100 ms for the 160 pm particle diameter, for example). 1) An initial stage had 
spherically symmetric combustion, with temperatures increasing to near the boiling point of AL0 3 and radiation 
also increasing. 2) A second stage had non-symmetric combustion, with temperatures falling slightly but radiation 

showing a peak and oscillations. 3) A final stage had non-symmetnc combustion, with decreasing temperatures and 
radiation. 

Particles were quenched at different combustion times in the tests bv allowing them to pass into an argon 
atmosphere separated from the air by a soap-bubble film as well as by impingement. Cross-sections of quenched 




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II MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 




panicles were examined using scanning electron microscopy; internal composition was determined using 
enemy-dispersing spectroscopy. From the temperatures, composition, and observed smoke traces, the investigators 
propose a mechanism tor the combustion-stage transition based on the concentration ot oxygen dissolved in the A 
particles. Further interpretations are being advanced to understand the nature of the final combustion stage and the 
potential to create micro-explosions. 


Students Funded Under Research: Task Initiation: 7/94 Expiration: 6/98 

Project Identification: 962-22-05-46 
NASA Contract Nonas-3-27259 
Responsible Center: LeRC 





11-272 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 




iitiiiHiitit inn 


Flame-Vortex Interactions Imaged in Microgravity 

Principal Investigator: Prof. James f. Driscoll 

University of Michigan 

Co-Investigators: 

Prof. W.J.A. Dahm 
Prof. M. Sichel 

University of Michigan 
University of Michigan 


Task Objective: 


The objective ot this research is to investigate a method that will provide high quality, quantitative, color enhanced 
digital images ot a vortex exerting aerodynamic strain on a flame under microgravity conditions. This will be used 


1. Quantify how the vortex distorts the flame; 

2. Define the degree of flame curvature; 

3. Show how preferential diffusion affects temperature profiles. 

Task Description: 

The fundamental interaction between turbulence and chemistry in a combustion process will be studied by 
interacting a repeatable, well-defined vortex, or variable size and strength vortex, with premixed and nonpremixed 
flames. The complicating effects of buoyancy will be eliminated by employing the NASA LeRC 2.2-second drop 
tower. High quality, quantitative, color enhanced 2-D images will be obtained of the temperature field, the flame 
emission, and the mixture fraction (nonpremixed case). Results will be compared to full Navier-Stokes direct 
numerical simulations and to the classical theory of stretched flames. 

Task Significance: 

Images ot the flame shape and curvature will be used to assess numerical simulations which neglect buoyancy, and 
to deduce universal, buoyancy free scaling relations showing the effects of vortex size and strength. Understanding 
ot turbulent combustion, applicable to all practical combustion, will be enhanced. 


Progress During FY 1 994 : 

During the month of June a student was hired and was assigned the task of building and testing an array of Thin 
Filament Pyrometers, which is one of the diagnostics to be used on the drop tower experiment. A method was 
developed to mount 50 SiC filaments for thin filament pyrometry with the proper tension. The necessary flow 
metering equipment tor the calibration burner was purchased and assembled. An intensified CCD array camera is 
being used to image the radiated light intensity from the 16 micron diameter filaments at two wavelengths, from 
which temperature is to be deduced. Also, during the month of June some of the necessary software was written 
and an orientation visit from Jim Driscoll, Werner Dahm, Chuck Mussel, and Ron Springer, took place on 24 June 
1994 . A tour of the NASA LeRC 2.2-Second Drop Tower and SEL was conducted. 

During the month ot July a CCD array camera was used to image 10 thin filaments to determine the 2D temperature 
field in a flame, a method to be used in future drop tower tests. Images were obtained and the reduction of the data 
was begun. Software development is continuing in order to deduce the temperature and to apply small corrections 
tor conductive and radiative losses along the filament. The survivability of the filaments was tested and a way to 
separate many filaments from the initial filament bundle was developed, using acetone and water solutions. 

Dr. King from NASA Headquarters recommended that we interact with modellers in the NASA microgravity 
program, so we contacted Prof. Elghobashi from the University of California at Irvine, who agreed to provide 





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II. MSAD Program Tasks — Ground-based Research 







Discipline: Combustion Science 




computauons of unsteady strained flames with full chemistry and radiative losses We will use his compuBflons 
future data. to detennine if die tlamelet modeliug approach ,s a valid approach. W =aUo plan 

£ 5 =^ 

interactions. 

Durine the month of August the research team met to plan the design of the drop tower experiment and arrange for 

and the model to be developed. A preliminary destgn of the experiment to be 
droooed was sketched out Vendors were contacted to obtain information regarding the sizes of light sources, 
222 e^cScs and tad tanks. Calculations were performed to determine the feasibly of certain ^agnostics 
including white light PIV. Mie imaging using oil drops, and thin filament pyrometry. orts a so are ei g 
to improve and apply the software needed for the PIV and Mie imaging diagnoses. Software development s 
progressing while the experiment is being designed and fabricated. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 5/94 Expiration: 4/98 

Project Identification: 962-22-05-45 
Responsible Center: LeRC 


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11-274 



II* MSAD Program Tasks 


— Ground-based Research 


Discipline: Combustion Science 

hi minim initiiiiiiiiiii 


Aei-odynatmc, Unsteady, Kinetic, and Heat Loss Effects on the Dynamics and Structure of 
Weakly-Burning Flames in Microgravity 


Principal Investigator: Prof. Fokion n. Egoifopouios 

University of Southern California 

Co-Investigators: 


No Co-I’s Assigned to this Task 


Task Objective: 


To obtain quantitative information (flame speed, velocity field, temperature) about the characteristics of weakly 

burning flames in microgravitv, and to apply this information to analyze near-limit phenomena at normal gravity 
conditions. 


Task Description: 

The experiments will employ a counter-flow burner geometry to provide a nearly adiabatic flame with a 
well-controlled strain, tor conditions that cannot be achieved in normal gravity. Both premixed and diffusion flames 
will be studied at various pressures, and Laser Doppler Velocimetry. Particle Image Velocimetry and high-speed 
cinematography will be used to measure the flow fields. Models will be developed for these cases tor comparison 
purposes. In addition, flame interactions will be studied, and numerical simulations of flame propagation in tubes 
in spherical vessels will be performed. Experiments will be conducted at normal gravity, in the NASA LeRC 

2 . 2 - Second Drop Tower, and aboard the NAS A aircraft. 

Task Significance: 

The research will allow a first-time study of flames burning near their flammability limit (the concentration of fuel 
in air that just forms a flammable mixture) without the complications of buoyancy, wall heat losses, or 
time-varying strain. It will provide fundamental data about the flammability limits that can be used to verify 
theoretical calculations, and has applications to turbulent combustion such as that found in engines. 

Progress During FY 1 994 : 

This is a new project, so effort has thus tar been concentrated on defining the order of the experiments and designing 
hardware. Design and drawings tor the counterflow burner apparatus have been completed, and construction is 
underway. Layout of the hardware in a drop frame for the 2 . 2 -Second Drop Tower, testing of a new flame ignition 
system, and design ot a PIV test rig are underway. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 1 

PhD Students: 1 


Task Initiation: 5/94 Expiration: 4/98 
Project Identification: 962-22-05-50 
Responsible Center: LeRC 


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* * I II II I IMIllllllllll 


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II. MSAD Program Tasks — Ground-based Research 




Ml I 


Discipline: Combustion Science 




Effects of Gravity on Sheared and Nonsheared T urbulent Nonprenu xed Flames 

PRINCIPAL INVESTIGATOR! Prof. Said E. Elghobashi University Of California. Irvine 


Co-Investigators: 

Dr. Y.Y. Lee 
Mr. R. Zhong 


University of California, Irvine 
University of California Irvine 


Task Objective: 

The objective is to answer fundamental questions regarding die effect of buoyancy on turbulent combustion. These 
questions include the following: 

1 . How does buoyancy affect the small-scale structure of the scalar and velocity fields? 

2. How does buoyancy affect the distribution of scalar dissipation near the reaction zone? 

3. Under what conditions is the tlamelet model valid for buoyant turbulent diffusion flames? 

4. How does flame extinction depend on the appropriate non-dimensional numbers (Fr, Da, Re, etc.), the 
magnitude of the reaction energy, and the direction of gravity relative the fuel-air interface. 


Task Description: 

This research is entirely computational. It will focus on direct nmnerical simulation (DNS) of two cases oHlow^ 
in initially isotropic turbulent flow (without shear) and a flow with miually uniform shear. In bothcases, separate, 
parallel streams of fuel and oxidizer will enter the computational domain and react. Numerical models that 
Lady been developed by the Principal Investigator will be extended to these cases with principal addiuons to 
delude finite rate chemistry and non-zero gravity. The results will be condensed in the form of diagrams based 
the appropriate nondimensional numbers. 


Task Significance: 

This work will answer fundamental questions regarding how buoyancy induced by gravity affects turbulent 
combustion. In particular, gas, temperature, and velocity distributions can be very different m the absence of 
gravity and this research will focus on revealing the small-scale structural differences in the flame as weU as 
probing the dependence of flame extinction on the alignment between gravity and the fuel-air interface. With this 
information, mathemaucal models of turbulent diffusion flames can be modified to better account ‘or buoy^cy 
effects. Better understanding of the physical processes will lead to improved combustor designs and enhanc 
predictive capabilities regarding fires on Earth and in a space environment 

Progress During FY 1 994: 

Thic is a new research effort Thus far, the partial derivative terms in the existing computer code have been 
modified from 2nd order central differences to 5th order and 6th order accurate schemes and the results checked against 
the exact solution of the Taylor-Green vortex flow. The conclusion was that while the new approach yielded more 
« “su““ e in aJ in compos toe was no. accept, e. Cu*en.e«om « unto way » rewme £= code 
so that it can take advantage of new parallel processor computers, and to continue code addiuons to include finite 
rate chemistry and buoyancy forces. 


« 




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II. MSAD Program Tasks — Ground-based Research 

* Hill* HIM MM,,., 


Discipline: Combustion Science 

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Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 5/94 Expiration: 5/98 
Project Identification: 962-22-05-59 
Responsible Center: LeRC 


"" mu 






II. MSAD Program Tasks — Ground-based Research^ 



Combustion of Electrostatic Sprays of Liquid Fuels in Laminar and Turbulent Regime^ 


Principal Investigator: Prof. Alessandro Gomez 

Yale University 

Co-Investigators: 


Prof. M.B. Long 
Prof. M.D. Smooke 

Yale University 
Yale University 


Task Objective: 

This research is a combination of experimental and computational work by Professors Alessandro Gomez (PI, 

Marshall B. Long (Co-1. Oragnosucs, and Mitchell D. Smooke (Co-I comp™i«^ fra* Yale 
University. It involves studying the formation and burning of electrosprays of liquid fuels at both 
reduced gravity. 

Task Description: 

Normal-gravitv testing of electrostatic sprays is conducted with cold-flows (i.e. non-buoyant) t and in t countertlow 
diffusion flames. Microgravity tests of the countertlow diffusion flame are conducted m the NASA LeRC 
2.2-Second Drop Tower. A numerical model of a gas-phase countertlow diffusion tlame is being extended to 
account for the droplet spray, for comparison of predictions with experimental results. 

Task Significance: 

The goal of this investigation is to study the combustion of well-defined and well-controlled sprays in 
^nffgumtions of successively increasing levels of complexity, starting from laminar sprays to fully turbulent ones. 
This may lead to improvements in the design of diesel engines or liquid-fueled rocket engines. 

Progress During FY 1994: 

The FY94 research effort was focused on three areas: (1) tests with electrostatic sprays, (2) tests with sprays 

produced by an ultrasonic nebulizer, and (3) the development of laser diagnoses fff droplel t size i 

There were no microgravity tests conducted in FY94 due to the shut-down ot the NASA LeRC 2.2-Second Drop 

Tower. 

NomXgmvtiv test wlreTonducted with an electrostatic spray of heptane in an axisymmetnc laminar dittmsion 
flame The flames were like a candle flame in appearance (i.e., sheath combustion), with a dark core (where the 
droplets evaporate without burning), surrounded by a high-temperature soot-shell, enveloped by the blue flame. 
There was no evidence of individual droplet combustion. The results (based on phase Doppler anemometry and 
sizing as well as thermocouple measurements) indicate that the D-square law with constant evaporauon rate was 
satisfied over a significant portion of the droplet history. It was found that the average evaporauon rate could be 
determined from the height of the dark core without intrusive measurement. It was also observed tha 
droplet-droplet interactions, although present near the flame surface, were apparently not significant m the flame 

core. 

(2) Experiments with Sprays Produced by an Ultrasonic Nebulizer 

Preliminary normal-gravitv tests were conducted with an ultrasonic spray, since the electrostatic spray does not 
allow studies of flame extinction and droplet interaction under low-slip condiuons (which are more amenable to 
numerical modeling). Preliminary tests indicate that the mean droplet diameter is independent of flow rate and 
controlled by the resonant frequency of the piezoelectric crystal. Good size distributions have been attained (witii a 
relative standard deviation less than 0.3), although the droplets are not monodisperse as with the electrospray. A 
self-sustained flat flame has been established over a much wider range of conditions than possible with the 
electrostatic spray (e.g., 2 cc/min and a strain rate of 30 s-1), and work is underway to improve the burner stability. 
The researchers are now considering how to adapt the ultrasonic burner to the 2.2-second drop package. 


"" " 




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11 HI Minim iiiimiii tin mum mill min 


(3) Development of Laser Diagnostics 

Improvements have also been made in the measurement ot droplet size. By matching the angular scattering pattern 
with calculations tor spheres from Mie-Lorentz theory, size determination has been improved from an accuracy ot 
4 % to 1 % in droplet diameter (12 % to 3<7c in volume). Since the comparison of the measurements with Mie-theory 
calculations is very time-consuming, algorithms were developed based on FFT to generate a look-up table 
associating scattering patterns with measurements. The sensitivity ot the technique to the ettects ot finite laser 
beam size will be investigate in the future. A paper describing the technique is being prepared tor submission to 
Applied Optics. 


Students Funded Under Research: Task Initiation: 3/91 Expiration: 12/98 

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-34 

MS Students: 0 RESPONSIBLE CENTER: LeRC 

PhD Students: 2 


11-279 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 




Three-Dimensional Flow in a Microgravity Diffusion Flame 


Principal Investigator: Prof. Jean r. Hertzberg 

University of Colorado, Boulder 

Co-Investigators: 


Mark A. Linne 

Colorado School of Mines 


Task Objective: 

The objective is to study the influence of buoyancy on the three-dimensional fluid dynamics of the interaction 
between a diffusion flame and the elliptic vortex rings formed by pulsations of the fuel flow issuing Irom an elliptic 
nozzle. 

Task Description: 

A methane diffusion flame burning in atmospheric conditions is investigated. Elliptic vortex rings are generated by 
a combination of periodic flow perturbations (active forcing) and the elliptic geometry ot the tuel nozzle (passive 
forcing). The fuel flow is forced by an in-line 100 watt loudspeaker system at frequencies up to 1 Khz. Phase-locked 
flow visualization and particle image velocimetry (PIV) are the primary diagnostics. 

Task Significance: 

Techniques to control turbulent structures in flames are investigated with the objectives in mind such as enhancing 
combustion efficiency and reducing pollutant formation using techniques of active and passive control ot fluid 
dynamics. Potential applications include industrial and residential burners and gas/liquid tueled engines. 

Progress During FY 1 994: 

Preliminary test plans and schedule were prepared and presented to LeRC's drop tower and diagnostics personnel. 

Normal gravity studies on the prototype combustor revealed that the flow exhibits a bifurcation type phenomenon 
in the absence of flame. A nonreacting flow of air was visualized using cigarette smoke and alumina particles, 
illuminated by a strobe, phase-locked to the forcing signal. The results show that the acoustically forced jet forms a 
series of vortex rings which evolve into a complicated structure, which then splits into two or three jets several 
diameters downstream of the nozzle exit. Preliminary results suggest that this phenomenon exists over a wider range 
of flow rates and at lower forcing levels than the bifurcated flame phenomenon. The effective frequency range lor the 
nonreacting air flow is also wider and lower than the flame phenomenon. The presence of the bifurcating 
phenomenon in a nonreacting air flow suggests that the driving mechanism is not an absolute instability, but is 
more likely a combination of axial and azimuthal forcing. 

Efforts have begun to visualize the fuel jet in the bifurcated flame case. Note that techniques developed tor the 
bifurcated flame will be applied to the asymmetric forced flame as appropriate. The fuel flow was seeded with 
aluminum oxide as in the previous non-reacting air flow, using a cyclone/fluidized bed seeder. A white-light strobe 
was phase-locked to the forcing signal. However, the flame emission was several times more intense than the light 
scattered by the seed, so further development of this technique is needed. As a first step, the experiment rig was 
moved to a different room, where a 12 watt argon ion laser is available. This laser will be chopped with a chopper 
wheel and attempts will be made to phase-lock it to the forcing signal. If this is unsuccessful, a Bragg cell based 
chopping system can be developed. Eventually, a diode laser system is planned in place of the (large) ion laser. 


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11-280 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

tun tinimiiii* hi 


Students Funded Under Research: 

BS Students: 6 

MS Students: 0 

PhD Students: 1 


Task Initiation: 5/94 Expiration: 5/98 
Project Identification: 952-22-05-58 
Responsible Center: LeRC 


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II. MSAD Program Tasks — Ground-based Research 

in * 


Discipline: Combustion Science 

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Chemical Inhibitor Effects on Diffusion Flames in Microgravity 

PRINCIPAL Investigator: Prof. Simone Hochgreb Massachusetts Institute ot Technology (MIT) 


Co-Investigators: 
Gregory Linteris 


National Institute of Standards and Technology (NIST) 


Task Objective: 

The objectives of the proposed research are as follows: 

1. To determine the effects of flame inhibitors on the physical characteristics (height, shape, color, and luminosity) 
and stability limits (ignition, extinction, lift-off and blow-off) of gaseous diffusion flames in the presence of 
halogenated fire suppressants in microgravity. 

2. To develop quantitative analytical models for the observed behavior, including chemical kinetic effects, in order 
to understand the mechanisms of inhibition of halogenated compounds in gaseous diffusion flames. 

Task Description: 

The experiments will consist of normal and microgravity studies of laminar jet and co-flow diffusion flames 
inhibited by halogenated suppressant addition to the air or fuel stream. In microgravity, visual and temperature 
diagnostics will be utilized to detect flame shape, dynamics and stability limits. Normal gravity experiments will 
make use of additional chromatographic and spectroscopic diagnostics in addition to visual and temperature 
experiments. 

Analytical and computational work will be performed using existing general 2-D codes with chemical kinetic 
models for comparison with the observed results. The calculations should serve for comparison with observations, 
explanation of observations and selection of additional experimental conditions ot interest. 

Task Significance: 

Fire suppression in space is one of the mam reasons to investigate combustion phenomena in microgravitv. Since 
halogenated compounds will remain as the tire suppressant of choice in many space missions, there is clearly a need 
for experimental evidence on the effectiveness of these compounds under zero buoyancy conditions. 

The final product of the experimental and analytical work is a comprehensive and quantitative understanding of the 
physical and chemical phenomena involved in the suppression of diffusion flames through the addition ot chemical 
halogenated inhibitors. This understanding is expected to be very useful both from a fundamental viewpoint as well 
as for the practical utilization of chemical tire suppressants in space. 

Progress During FY 1994: 

In order to first examine the effects of the inhibitors CF3H and CF3Br on diffusion flames in normal gravity we 
constructed a co-flow diffusion flame burner capable of operation with variable jet diameters. Calibrated mass flow 
controllers under computer control metered the flows of air, fuel gas (propane and methane), and inhibitor. Two jet 
diameters were used in the current experiments (0.1 mm and 1.2 mm). The smaller jet produces a flame 0.3 to 0.7 
cm tall, and the larger jet 14 to 16 cm. Because of the flame's small size, the effect of buoyancy will be less using 
the smaller jet, allowing some early assessment of the effects of buoyancy on the flame characteristics. 

In these tests, we first determined the flow rate of methane necessary to cause blow-oll for each jet diameter, and 
determined the effect of the air co-flow velocity on the blow-olf condition. It appeared that the blow-otf condition 
was sensitive to the aerodynamic conditions near the jet tip which were atfected by the co-flow velocity and any 


« 


11-282 


II. MSAD Program Tasks — Ground-based Research 


HimimmiiMimimiiimiiimimmiMiMm 


MMMMIIIIIIIII 


Discipline: Combustion Science 




geometrically induced flow disturbances. We then measured the concentration of CF3H and CF3Br which caused 
blow-off at a methane flow rate ot 50*T of the fuel blow-off condition for these two jet diameters. The results of the 
experiments will help us to determine the initial test conditions of the NASA LeRC 2-Second Drop Tower tests in 
the presence ot inhibitor. We next recorded video images of the flames as a function of either the fuel flow rate or 
the inhibitor concentration in the air stream, and used these to determine the flame height. These data can be used to 
assess the utility ot simple analytical models for predicting the flame size. 

An important component of the present project will be calculations of the flame structure using a detailed chemical 
kinetic mechanism and a suitable flame model. This month we acquired a kinetic mechanism for fluorine inhibition 
ot hydrocarbon flames from Burgess/Tsang/ZachariahAVestmoreland at the National Institute of Standards and 
Technology (NIST) and combined it with GRIMECH obtained from Greg Smith at SRI. Using the premixed flame 
code ot S ANDIA, we have performed extensive tests of its performance against premixed flame speed measurements 
recently obtained as NIST and MIT. 

1) Measurements ot the effect of CF ? H and C 2 F 6 on CH d laminar flame speeds in a combustion bomb at variable 
pressure and temperature have been concluded. The experimental data, at equivalence rations of 0.8 to 1.2. pressures 
between 0.7 and 8 atm and temperatures between 300 and 500 °K show that, as shown for experiments at ambient 
conditions, both inhibitors are more effective at rich conditions, C : F 6 being twice as effective as CF 3 Br. No 
particular dependence ot the inhibition effect on temperature or pressure is apparent the effects being primarily a 
tunction ot inhibitor concentration (tested between 0 and 5 percent) and equivalence ratio, results are currently being 
prepared for publication. 

2) The chemical kinetic mechanism developed at NIST for CF 3 H and C 2 F 6 inhibition effects was used to predict 
flame speeds at the varying pressure and temperature conditions for which the tests were conducted. The results 
show remarkable agreement under lean conditions, but predictions are 10-15 percent lower than observed values at 
the richest equivalence ratio. This leads us to conclude that some difficulties are potentially to be expected in 
modeling dilfusion flames, where much of the chemistry takes place under rich fuel conditions. 

3) Belore we are able to use the NIST fluonnated species inhibition mechanism to model our inhibited inethane- 
and CO-air diffusion flames, we must first test the accuracy of the mechanism. Towards this end, we have begun 
testing the mechanism against both data collected at NIST and with data existing in the literature. This month we 
performed extensive calculations of the flame structure of premixed methane-air and CO-02-Ar flames inhibited by 
CF3H. The methane calculations were performed at phi=0.9, 1.0, and 1.1 lor inhibitor mole fractions up to 8%, 
and these were compared with recent measurements at NIST. The NIST mechanism was found to predict several of 
the important features ot the CF3H inhibition, including the strong effect of equivalence ratio on the burning rate 
reduction (rich flames are inhibited more), and a reduction in inhibitor effectiveness at higher inhibitor mole 
tractions. The kinetic mechanism, however, is predicting about 30 % more reduction in burning rate than the 
experiments show. We have been working closely with Wing Tsang and Don Burgess to try to determine the 
possible areas for improvement in the mechanism. 

4) In order to test the effectiveness of CF3Br and CF3H in micro-gravity under non-sooting conditions, we plan to 
study inhibited CO flames. The burning rate reduction of premixed CO-02- Ar flames by CF3H has been measured 
by Vandooren and co-workers. To test die model for moist CO oxidation, we have performed numerical calculations 
ol the burning rate for all ot Vandooren’s conditions (about 150 flames). In nearly all of these calculations, the 
burning rate was predicted within 10 % (flames with very low H2 concentration were not well predicted). Hence, it 
appears that the model works vcry( underlined) well for moist CO flames, but may need more work for CH4 flames. 

5) We have started to set up a counter-flow diffusion flame lor studies of CF3H and CF3Br inhibited diffusion 
flames, again, to test the mechanism, and to start to examine the mechanism to study the effects of transport on the 
inhibition. 


11-283 


II. MSAD Program Tasks 

.m.mm.mmmimmi.m... ».«»...« 


Ground-based Research Discipline: Combustion Science 

. * 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 6/94 Expiration: 6/98 

Project Identification: 962-22-05-54 
Responsible Center: LeRC 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

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Time-Dependent Computational Studies of Pre-Mixed Flames 


Principal Investigator: Dr. k. KaiiasanaUi 

Naval Research Laboratory (NRL) 

Co-Investigators: 


Dr. G. Patnaik 

Berkeley Research Associates 

Dr. E.S. Oran 

Naval Research Labs 


Task Objective: 

Study the structure (multidimensional) and dynamics (propagation, stability and extinction) of premixed flames in 
microgravity and normal gravity environments. 


Task Description: 

Pertorm detailed numerical simulations using time-dependent, one-dimensional and two-dimensional flame models. 
These models solve the multispecies-coupled, partial-differential, reactive-flow equations, including fluid, 
thermodynamic and transport properties, chemical kinetics, radiative heat transfer, buoyancy and boundary heat loss 
ettects. The investigator will a) systematically isolate and evaluate the relative importance of various physical and 
chemical processes that may be controlling the structure and dynamics of premixed flames, and b) compare 
qualitatively and quantitatively with experimental observations. 1 

Task Significance: 

Small amounts of fuel leaking from fuel cells could pose a tire hazard on the space-shuttle and similar vehicles. 
Therefore, understanding the burning and extinguishment characteristics of flames are important for the safe 
operation of space vehicles. The knowledge gained from such studies is also useful for the sale and efficient use of 
tuels on Earth. Computer simulations are a cost effective way to obtain data to corroborate limited experimental 
observations and provide additional details which arc difficult to obtain from space based experiments. 

Progress During FY1994: 

Investigations of burner-stabilized lean methane-air flames indicate that a 5% methane-air flame cannot be stabilized 
even by including the ettects of radiative losses. This is in contrast to freely-propagating flames which can be 
sustained in this mixture, with and without the inclusion of radiative losses. However, a 5.5 % methane-air flame 
can be stabilized on a burner, but only tor high inflow velocities such as 7 cm/s, which is close to the 
treely-propagating burning velocity. When the inflow velocity is reduced to 6 cm/s, the flame shows a longitudinal 
oscillation with excursions of the flame temperature above and below the planar adiabatic values and eventually dies. 
These oscillations are independent of the spatial and temporal resolution of the numerical solution. They appear to 
be a manifestation of the transition from the imposed initial condition of a propagating flame to its stable no flame 
final condition. However, these oscillations do not seem to be very significant physically since the flames 
eventually die. For lower inflow velocities, the flames extinguish more quickly. Overall, the simulations suggest 
that conductive and radiative heat losses play an important role in the stability of very lean methane-air flames and 
that such flames can be stabilized on burners only for a narrow range of inflow velocities. 


Some ot the characteristics of freely-propagating low velocity lean methane-air flames are quite distinct from those 
of lean hydrogen-air flames with similar velocities. The methane flames are thinner and have significantly higher 
flame temperatures. 

The cellular structures observed in lean methane-air mixtures (5-6%) were very weak when compared to those in lean 
hydrogen-air flames of comparable burning velocities. Therefore, alter discussions with Prof. Paul Ronney, a C02 
diluted methane-oxygen mixture, with an effective Lewis number of about 0.70, was chosen for studying a case 
which should exhibit strong cellular structures. Both the simulations and Ronney's experiments indeed indicate well 
defined cellular structures. However, the detailed structures are not quite the same in the two cases. Computed 


Mill Ill M"ltl"l IIIIMI|||||||||||||||lltlllllllimillllMilllllllHIII 


11-285 



II. MSAD Program Tasks — Ground-based Research 

.......... in. 


Discipline: Combustion Science 

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burning velocities are larger than the experimental ones; however, the llame temperatures are about the same. 
Three-dimensional effects, insufficient numerical resolution and inadequacy ot the chemical kinetics scheme to 
adequately capture the effects of C02 dilution are possible explanations for the observed differences. 

The variation of the burning velocity with dilution is being studied to see it the "skeletal mechanism used in the 
computations is adequate to represent the chem.cal effects of dilution with C02. This work is hampered by the lack 
of experimental data on C02 dilution effects. Further tests with N2 dilution are underway to check it the reaction 
scheme is adequate for any dilute mixture. Tests in which the equivalence ratio was varied showed that the scheme 
was adequate for those cases. 

Three-dimensional simulations as well as simulations using more complex chemistry schemes will need parallel 
processing to be efficient. One of the major problems in achieving efficient parallel processing is distributing the 
work-load among the various processors. The first step towards the development ot a llame code that will 
efficiendy run on massively parallel processors such as the Intel/IPSC 860 was to develop a load-balancing 
procedure for the chemistry. This has been accomplished using the newly developed Work-Parti software trom the 
University of Maryland. Stiff points are gathered into a 1-D array, and only those points are redistributed to other 
processors using gather/scatter operations. This tends to reduce the number ot points needed to be moved to achieve 
the load balance. After tackling the chemistry, the FCT fluid convection, radiation, inflow velocity control and 
timestep control routines were rewritten to make it more efficient and reduce the scratch space. David Fyte (NRL) 
and Craig Douglas (IBM) were instrumental in re-writing the multigrid part of the code for parallel implementation. 
Then, the diffusive transport modules were also parallelized. 

The development and testing of a fully parallel version of the flame code has been completed successfully. The code 
has been run on the Intel/IPSC 860 at NRL and the Intel Paragon at Air Force Wright Aeronautical Labs and shown 
to produce the same results as on the Cray C-90. 

The newly developed parallel version of the flame code is being used to study the detailed dynamics of the 
extinguishment of downward-propagating methane-air flames. The plan is to compare these observations to those 
made in the earlier NRL study of the extinguishment of hydrogen-air flames. Such a comparison will be helpful in 
isolating effects that are specific to the highly diffusive and easily combustible hydrogen-air mixtures trom those 
that are more general and applicable to a variety of fuel-air mixtures. Furthermore, it will also provide some 
information on the relative role of conductive and radiative heat losses in extinguishing flames propagating in tubes. 
The earlier NRL studies of one-dimensional, zero-gravity flames in lean methane-air mixtures showed that radiative 
losses alone can extinguish some flames. In this study of two-dimensional flames, radiative and conductive losses 
will be considered together and separately to isolate their effects. The NRL simulations to date show that a 5% 
methane-air flame propagates without extinguishment even when considering both losses, so leaner mixtures will 

be tried next. 

Currently, studies of near limit downward-propagating methane flames are continuing. Discussions with Prot. Paul 
Ronney and others at the International Combustion Symposium identified the third-body efficiencies in the 
chemistry scheme as a possible source of the differences observed earlier between Paul s results and ours tor the 
extinguishment of C02 diluted methane flames. It was decided to pursue this matter further using the FLAME ID 
code before performing more detailed multidimensional simulations ot the extinguishment ot methane- air flames. 
Different values for the third body efficiencies suggested in the literature have been incorporated into the codes. A 
repeat of stoichiometric methane-air flames shows that these parameters do not make any difference in the results. 
However, a repeat of the simulations of the C02 diluted mixtures used in Paul s experiments shows that these 
parameters have a strong influence on the flame temperatures and velocities. In fact, it has been difficult to even 
ignite some of these mixtures. Our results to date show that the burning velocities ot near-limit C02 diluted 
mixtures are now lower than prof. Ronney's. Recall that with the efficiencies set to unity, our burning velocities 
were higher than those observed in his experiments. It appears that the exact values ot the third body etticiencies 
could play a crucial role in obtaining accurate results. It is not clear how accurately these parameters are known. 
Preliminary calculations with a 5% methane-air mixture now show that it is very difficult to obtain a steadily 
propagating flaee in this mixture when radiation and non-unity third-body efficiencies are taken into account. 

Further calculations are being performed to resolve this issue. 


............. 


11-286 



II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

IIMIIilllllllMlinilllllllllllllllltlllllllllllltlllllMIMMIIIIIIIIItlllllllltllllllllllllllltlllllHIIIIIIIMIIIIIIIIItlllllllllllimHIimillllllllMlllllMllllllllllllllllHnillllllltlMMtMIIMtmiltimmiMIMiailltMIIIIMIIIII 


Students Funded Under Research: Task Initiation: 2/92 Expiration: 12/97 

Project Identification: 962-22-05-22 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994 : 

Journals 

Patnaik, G. and Kailasanath, K. On the role of gravity in burner-stabilized flames. The Eastern States Section of the 
Combustion Institute. Chemical and Physical Processes in Combustion, 417-420 (Oct.25-17. 1993). 

Patnaik, G. and Kailasanath. K. Effect of gravity on multidimensional burner-stabilized flames, in Heat Transfer in 
Microgramity, eds. C.T. Avedisian and V.A. Arpaci, HTD. the American Society of Mechanical Engineers. New York. NY. 
vol. 269. 79 (1993). 

Presentations 

Patnaik, G. and Kailasanath, K. ’’Effect of gravity on multidimensional burner-stabilized flames." ASME Winter Annual 
Meeting. New York. NY, 1993. 

Patnaik. G. and Kailasanath, K. "Celleular structure of lean hydrogen and methand flames." ASME Winter Annual 
Meeting, New York, NY, 1993. 

Patnaik, G. and Kailasanath, K. "Numerical simulations of burner-stabilized hydrogen-air flames in microgravity. M the 
25th Int. Symp. on Combustion. Irvine, CA. July 31 - August 4, 1994. 

Patnaik, G. and Kailasanath, K. "Cellular structure of lean hydrogen and methane flames." AIAA 94-3275, 30th 
AIAA/ASME/ASEE/SAE Joint Propulsion Conference, Indianapolis, IN. June 27-30, 1994. 

Patnaik, G. and Kailasanath, K, "Numerical simulations of burner-stabilized hydrogen-air flames in microgravity." 
presented at the 25th Int. Symp. on Combustion. Irvine. CA, July 31 - August 4, 1994. 


Illillllllfl 11111111111111111111111 mi MUM 


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II. MSAD Program Tasks — Ground-based Research 




Discipline: Combustion Science 

IIMtlllll 


Radiative Ignition and Transition to Flame Spread in Microgravity 


Principal Investigator: Dr. Takashi Kashiwagi 

National Institute of Standards and Technology (NIST) 

Co-Investigators: 


Dr. H. Baum 
S.L. Olson 

National Institute of Standards and Technology (NIST) 
NASA Lewis Research Center (LeRC) 

Task Objective: 


The objectives of the Middeck Glovebox RITSI Investigation is to conduct an experimental study of the radiative 
ignition and subsequent transition to flame spread in low gravity in the presence ot very low speed air flows in 2D 
and 3D configurations and to compare the experimental observations with the theoretical model. 


Although the fundamental processes involved in radiative ignition have been suggested in the literature, there have 
been no definitive experimental or modeling studies up to this point due to the flow motion generated by buoyancy 
(starting plume problem) near the heated sample. In addition, there are very lew studies ot the transition irom 
ignition to flame spread. Almost all flame spread studies are based on two-dimensional, quasi-steady or steady 
flame spread. The limit on the viability of flame spread should be controlled by the transient process trom ignition 
to flame spread. Steady- state flame spread models cannot be expected to accurately describe this limit. 

For the first time the use of a prolonged microgravity environment allows us time to conduct a definitive study on 
ignition and subsequent transition to flame spread. The model and numerical codes tor such a calculation are 
nearing the end of their development and experimental data is needed to compare with the predicted results. From 
the comparison, we will learn how accurately we understand ignition and flame spread mechanisms and where the 
deficiencies in our understanding of them might exist. 

Task Description: 

RITSI hardware uses a localized irradiated area via a radiant heater and/or hot wire to ignite samples of cellulose of 
various thickness and/or composition. The hardware will provide a means to record ignition delay time and the 
subsequent transition to flame spread at various low speed air flows. It will also provide a means to record solid and 
gas-phase temperature data as well as the radiant heater and flow intonnation. 

Variables in priority order are 1) Flow velocity (0,2,5 cm/s); 2) Irradiated sample diameter (1 cm, 2.5 cm) and/or 
power level (up to 8 W/cm 2 ) 3) Smoldering via metal ion doping of fuel 4) Geometry of sample (2D or 3D) and 5) 
Sample thickness. 

RITSI hardware consists of a flow duct with screens at both ends and a fan (pulling air through duct rather than 
pushing it) at one end along with an area reducer to provide the air flow. One side ot the duct opens tor access to 
the sample holder for changeout of samples in the glovebox. Some samples are narrow rectangles, tor upstream and 
downstream propagation only, and some will be more square, tor propagation sideways as well. 

Task Significance: 

In previous studies, ignition and flame spread were studied separately with the result that there has been little 
understanding of the transition from ignition to flame spread. In spacecraft fire safety applications this transition is 
crucial to determine whether a fire will be limited to a localized, temporary bum or will transition into a growth 
mode with the potential to become a large fire. 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 


Progress During FY1994: 

(October 1993) RJTSI: Formal approval from NASA HQ based on the September nonadvocate peer review was 
received tor continued development of a Glovebox experiment called RITSI (Radiative Ignition and Transition to 
Spread Investigation). The engineering unit assembly is beginning electrical assembly. 

(November 1993) Theoretical study: the variable mesh code is w-orking and quiescent three-dimensional calculations 
are being run. RITSI: The engineering unit assembly is complete and calibrations are underway in preparation tor 
December Learjet low gravity testing. 

(December 1993) RITSI: Six Learjet flights with 14 tests were successfully conducted. Ignition ot plain Whatman 
44 was not achieved with the lamp alone, and modifications to the ignition procedure allowed tor successful ignition 
with a soot spot and gas-phase pilot in addition to the lamp. Smolder-promoted paper ignited easily. 

(January 1994) RITSI: Data analysis of the Learjet tests by LeRC personnel is underway in preparation for a visit 
to NIST by LeRC's S. Olson. 

(February 1994) Theoretical: Axiymmetric cases were run with a variable step size, and the results documented in a 
Combustion and Flame paper ( 1994). RITSI: Preliminary results of the Learjet tests were presented to NIST 
during a February 17 visit by S. Olson. Flight hardware design has started. 

(March 1994) Formal approval of a NRA-submitted proposal was received by the PI from NASA HQ. A flight 
experiment as a follow-on to the precursor RITSI Glovebox experiment is approved. This experiment is tentatively 
entitled TIFS-3D (Transition from Ignition to Flame Spread in 3D). The Lewis team (Project Scientist and Project 
Engineer) were assigned. Theoretical: A pilot ignitor in the gas-phase was added to the code. Variations of the 
incoming velocity distribution are being studied. RITSI: Odor testing was conducted. Data analysis and upgrades 
of the engineering hardware continue. 

(April 1994) Theoretical: Numerical computations have been run to evaluate the effect ot energy distribution on the 
ignition and transition to flame spreading quiescent environments. Spot size and total energy were varied, and the 
results indicate that although the final flame spread rate is independent of energy distribution, the ignition delay and 
the transient spread rate from ignition to steady state are strong functions of the energy distribution. RITSI: Right 
hardware design is nearly complete. Engineering testing of ignition delay and ignitor wire temperature was 
conducted. Negotiations for tesung of the Engineering Unit at Brunei to determine production levels of CO and the 
Glovebox facility's ability to convert the CO to C0 2 were initiated. TTFS-3D: Project team reviewed proposal. 
Negotiations with Japan were initiated on a collaboration to conduct tests with the RITSI Engineering hardware in 
the 10 second Hokkaido JAMIC facility. 

(May 1994) Theoretical: 2D flame ignition and subsequent flame spread of a finite-width (uninhibited edges) 
thermally-thin paper were calculated with no wind. The results showed that the flame spread rate at the edge is at 
least twice as fast as the spread rate in the center of the paper. RITSI: Toxicity testing of the smolder-promoted 
paper for CO is being prepared at NIST. The output of the radiant heat lamp was experimentally characterized. 
TIFS-3D: Olson attended the kickoff meeting for the new flight NRA’s. An Objective and Scope for TIFS-3D 
were drafted. 

(June 1994) RITSI: Electrical and mechanical upgrades to the engineering hardware were complete. Verification 
documentation for the flight expenment was drafted. Additional lamp characterization tests were conducted. Status 
was reviewed with the PI during a visit by the PI on June 3. TIFS-3D: A memo was sent to HQ by the PI and 
Project Scientist requesting an expanded scope for the TIFS-3D experiment to include 02 and preheating effects. 

The PI visited the project team on June 3 to define the experiment objectives, scope, draft matrix, and diagnostics 
requirements. 


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(July 1994) RITSI: Toxicity testing was completed at NIST. The negotiations for toxicity and abatement testing 
at Brunei are continuing. A manuscript of wind effects on flame spread is being prepared (joint theoretical and 
experimental). TIFS-3D: The project obtained 2 LeRC civil servants to work on preliminary breadboard flow and 
laser heater systems. 

(August 1994) Theoretical study: A paper "Effects of Ignition and Wind on the Transition to Flame Spread in a 
Microgravity Environment" by K.B. McGratton, T. Kashiwagi, H.R. Baum, and S.L. Olson is completed and it is 
under internal review prior to submission to Combustion and Flame. RITSI: More smolder-promoted papers were 
made and sent to NASA LeRC for Leaqet testing, normal gravity ignition testing, and CO toxicity testing at 
Brunei University as part of the flight hardware verification testing. TIFS-3D: The project team met to discuss 
design options. 

(September 1994) Theoretical study: The internal review of the above paper has been completed after some 
modifications corresponding to comments by the reviewers. An extended abstract based on the paper has been 
written and submitted for presentation in the Eastern States Combustion Institute Meeting. RITSI: DC-9 Aircraft 
tests were conducted where both plain and smolder-promoted paper samples were successfully ignited in low gravity. 
The PI attended the First Meeting of NASA/NEDO Microgravity Combustion Coordinating Group for possible 
microgravity experiments using the Japanese 10 seconds drop tower. Agreement was reached that this was a fruitful 
endeavor, and a formal brief proposal will be submitted to the MCCG for formal approval of this venture. The PI 
also reviewed the flight hardware design progress and the engineering hardware test results. TIFS-3D: We had an 
informal meeting at NASA Lewis Research Center for discussing possible experimental parameters and diagnostic 
measurements. We also discussed an outline of SRD for this experiment. A C0 2 laser, a candidate radiant heater, 
was successfully used to ignite paper with no soot spot or gas-phase hot wire pilot 


Students Funded Under Research: Task Initiation: 4/91 Expiration: 12/97 

Project Identification: 962-22-05-35 
Responsible Center: LeRC 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

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Sooting Turbulent jet Diffusion Flames 

PRINCIPAL Investigator: Prof. Jerry C. Ku Wayne State University 

Co-Investigators: 

P.S. Greenberg NASA Lewis Research Center (LeRC) 


Task Objective: 

The objectives of this study are to model soot formation and radiation for turbulent jet diffusion flames and to 
determine the modeling coefficients from measured data under both normal and reduced-gravity conditions. 

Task Description: 

In regard to experimental measurements, thermophore tic particle sampling and electron microscopy are used for soot 
particle size and aggregate morphology analysis. Laser light absorption imaging provides for the determination of 
soot-volume fractions, and emission imaging and thermocouple measurements will be used for soot thermometry. 
Laser Doppler Velocimetry may possibly be employed to measure velocities and turbulence intensities, but is 
beyond the stated deliverables of this effort. 

In the area of modeling, Favre-averaged boundary layer equations with a k-e-g turbulence model and the conserved 
scalar approach with an assumed pdf (probability density function) are used to predict flow field and gaseous species 
mole fraction profiles, respectively. Transport of soot particles is described by equations for volume fraction and 
number density using rate equation models. The energy equation is included to provide coupling between flame 
structure and radiation analyses. The radiative flux is solved from the radiative transfer equation (RTE). 

Task Significance: 

Microgravity combustion is not only relevant to tire safety on-board a spacecraft but also provides a unique 
condition for better understanding of fundamentals of this common type of combustion. 

Progress During FY 1994: 

The YIX method was applied to solve radiative heat transfer in a finite cylindrical enclosure with a 
nonhomogeneous, nongray, emitting, and absorbing soot/C02 mixture. Numerical results were obtained for 
radiative heat transfer within a turbulent ethylene jet diffusion flame from precalculated flame temperature, soot 
volume fraction, and C02 concentration maps. Soot only, C02 only, and combined cases were examined over the 
spectral range of 1-20 microns. Soot absorption coefficient spectra were calculated from soot volume fraction and 
refractive indices according to die Drude-Lorentz dispersion model based on the three frequently cited dispersion 
parameter secs. Results from these three dispersion parameter sets show that the difference in maximum flux is 
51%. Thus, current uncertainties about soot spectral refractive indices are the main limitation on accurate estimates 
of the radiation heat transfer from sooting combustion systems. The exponential- wide-band model is used to 
calculate the C02 absorption coefficient spectrum. Overall, the contribution of soot radiation is only two to three 
times that of C02. Consequently, both soot and C02 contributions are significant, and must be accounted tor. For 
C02 gas, only contributions around absorption bands at 2.7 and 4.3 microns are significant. It seems that spectral 
contributions from the range above 5 microns may be neglected without any significant loss of accuracy in 
evaluating total radiation properties. This work was submitted to the ASME Journal of Heat Transfer. In addition, 
an improved method for handling the discontinuity between the velocity of fuel and co-flow has been implemented. 
The agreement between model prediction and FYofi Santoro's co-flow soot volume fraction data (already in the 
literature) is very good now. 

The fabrication of a coaxial, piloted burner for turbulent gas jet diffusion flame studies has been completed. 
Extremely small tubing diameters (n 0.75 mm inner diameter for the inner jet) were employed to obtain large 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

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Reynolds numbers while retaining a reasonable overall flame height compatible with the dimensions ot the 
combustion chamber on the present 2.2 second laser rig. The major challenge was to provide a stable, coaxial 
arrangement ot the inner jet and pilot nozzles. This was accomplished by the stall ot the LeRC instrumentation 
shop, who employed an arrangement ot laser-welded thin wire spacers to accurately control the relative position ot 
the inner and outer tubes. After welding the spacers in place, the thin wires were then ground to the appropriate 
diameter to fit accurately into the pilot tube. The spacers also serve as flow straighteners tor the pilot flow. Initial 
tests indicate that adequate symmetry has indeed been achieved. 

A series of drops were conducted in the NASA LeRC 2.2 -Second facility to obtain the soot volume traction in 
reduced gravity laminar jet diffusion flames. Tests indicated a reduction in local volume traction tor 1.5 mm jets 
using ethylene as a fuel at flow rates between 1.0 and 3,0 cc/sec. This resulted in volume fraction signals (obtained 
via light extinction measurements) with poor SNR’s. Larger diameter burners were fabricated to provide longer 
optical path lengths, thus increasing signal strengths. Limitations on flow rate due to the capacity ot the rig and 
the resulting flame lengths proved to be disadvantageous because stable flames could not be achieved in the available 
test tune. Apparently Reynolds number considerations separate two different regimes wherein these flames are 
either diffusion or momentum dominated. The former evolve too slowly to be studied in the 2.2 second facility, the 
latter produce insufficient volume fractions for tractable flow rates and flame heights. Switching to acetylene as the 
fuel increased the soot production to the level wherein reasonable SNR s could be obtained. Some issues relating to 
the stability of these flames as a function of burner diameter and flow rate under reduced gravity conditions remain, 
and are presently being pursued. The hardware has been performing consistently well, as has the facility’s newly 
refurbished air-bag deceleration system. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 1 

PhD Students: 2 


Task Initiation: 3/91 Expiration: 12/94 
Project Identification: 962-22-05-36 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Journals 

Hsu, P.F. and Ku, J.C. Radiative heat transfer in finite cylindrical enclosures with nonhomogeneous participating media, 
to appear in AIAA J. of Thermophysics and Heat Transfer, (1994). 


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11-292 


II. MSAD Program Tasks — Ground-based 

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Research 

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Discipline: Combustion Science 

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Soot and Radiation Measurements in Microgravity Turbulent jet Diffusion Flames 


Principal Investigator: Prof, jerry c. Ku 

Wayne State University 

Co-Investigators: 

No Co-I’s Assigned to this Task 



Task Objective: 


The objectives ot this study are to determine modeling coefficients from measurements of soot morphology and 
radiation in both normal and reduced-gravity turbulent gas jet diffusion llames, and to further refine models for soot 
lormation and spectrally dependent radiation properties. 

Task Description: 

In the area ot experimental measurements, thermophoretic particle sampling and subsequent transmission electron 
microscopy analysis are used tor soot particle size and analysis of aggregate morphology. Laser light absorption 
imaging provides tor the determination ot soot volume fractions. Emission imaging using isolated bandpass filters 
will be used to measure spectrally dependent soot radiation properties and possibly temperature. Rapid insertion of 
line-wire thermocouples will also be used tor the determination of temperature. 

In the area of modeling, Favre-averaged boundary layer equations with a k-e-g turbulence model and conserved scalar 
approach with an assumed probability density functions (pdt) are used to predict flow field and gaseous species mole 
fraction profiles, respectively. The soot formation model has been modified and tested to predict soot volume 
traction and number density. The energy equation is included to provide a full coupling between flame structure 
and radiation analysis. A third-order spherical harmonics approximation and the YIX method have been applied to 
solve the radiative transfer equation. In the proposed study, soot formation and radiation models will be improved, 
and methods for efficient spectral integrations and iteration between the solutions for the flame structure and the 
radiative transfer equation will be sought. 

Task Significance: 

Microgravity Combustion is not only relevant to fire safety on board a spacecraft, but also provides a unique 
condition tor a better understanding ol combustion tundamentals of this common type of combustion. 

Progress During FY 1 994 : 

There is no progress to report at this time as the project has not started yet. 


Students Funded Under Research: Task Initiation: 1/95 Expiration: 12/97 

Project Identification: 962-22-00 

Responsible Center: LeRC 





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II. MSAD Program Tasks — Ground-based Research 

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Discipline: Combustion Science 

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Studies of Flame Structure in Microgravity 


Principal Investigator: Prof. Chung k. Law 

Princeton University 

Co-Investigators: 

No Co-l’s Assigned to this Task 



Task Objective: 

The objectives of this work are to understand and quantify the structure, stabilization mechanisms, soot formation 
in, and extinction of one-dimensional premixed and nonpremixed laminar flames. 

Task Description: 

This program comprises two main elements: 

1 . A numerical simulation of one-dimensional laminar flames is to be developed that, m addition to including the 
usual fluid mechanical and heat transfer mechanisms, will include detailed chemical kinetic mechanisms tor 
comparison with the unique experimental results. 

2. A drop-tower text apparatus is to be used to observe premixed laminar flames stabilized about cylindrical and 
spherical porous burners to distinguish heat loss and flow divergence influences on flame stabilization and 
flamefront stability. 

Task Significance: 

The one-dimensional adiabactic laminar unstretched premixed flame is a fundamental precept of combustion science, 
but cannot be stabilized in normal gravity because of the straining or asymmetrical influences ot gravitational y 
induced buoyant convection. In microgravity experiments, this program demonstrates this combustion paradigm 
and provides a capability for probing the structure, chemistry, soot dynamics, and flame propagation speed ot these 
fundamental flames. 

Progress During FY 1 994: 

This task was renewed in Fiscal Year 1994 with the award of an extended ground-based program entitled, 'Studies ot 
name Structure in Microgravity," under NRA-93-OLMSA-1, "Microgravity Combustion Science: Research and 
Flight Experiment Opportunities." 

Progress on these two tasks are unseparable one from the other since the latter award is a simple continuation of the 
former, and together consist of: 

1 A series of tests were completed providing observations of cylindrical, premixed flames in microgravity. These 
tests provided the first observations of flames stabilized near a burner by virtue of the flow divergence only and not 
by heat losses to the burner surface, as observed in normal gravity flame holding devices. This experimental work 
has provided a new method for evaluating the adiabatic flame speed for premixed flames, a fundamental property ot 
fuels. 

2. The formulation of an asymptotic theory of spinning premixed flames is completed. This work extends the 
previous diffusion flame analysis by Matalon (of a spinning fuel droplet undergoing diffusional burning in an 
oxidizing environment) to the premixed flame situation, wherein a mixture of fuel and oxidizer is ejected trom a 
spherical source and subsequently bums as a premixed flame. This work is performed in anticipation of future 
experiments involving spinning premixed flames which are subjected to differing body forces and strain rates over 

the flame surface. 

I • 


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II. MSAD Program Tasks — Ground-based Research 




Discipline: Combustion Science 

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3. The theory tor spinning spherical flames was investigated including four cases that span: premixed and 
unpremixed tueis and tuels that require heat tor vaporization (as in droplet combustion or monopropellant spheres) 
or those that do not (porous burner tor gaseous fuels). This theory provides a basis for evaluating body force effects 
and flame stretch simultaneously. Preliminary results indicate a Lewis number dependence for the premixed case in 
which the flame flattens at the pole or at the equator; and a demonstration of extinction for unity Lewis number 
diffusion flames. 

4. Experimentally, a new spherical burner has been developed using sintered metal, with flow incoming from both 
polar positions. Observed flame tronts in normal gravity are not smooth, which may be caused by nonuniform 
flow or by intrinsic flamefront instabilities. 


Students Funded Under Research: Task Initiation: 5/90 Expiration: 11/94 

Project Identification: 962-22-05-37 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994 : 

Presentations 

Eng, J.A.. Law, C.K. and Zhu, D.L. "Stabilization mechanisms and burning rates of cylindrical burner flames." 
AIAA-94-0571 . presented at the 31st A1AA Aerospace Sciences Meeting, Reno, January 1994. 

Eng, J.A, Law, C.K. and Zhu, D.L. "On burner-stabilized cylindrical premixed flames in microgravity." Twenty-Fifth 
symposium (international) on Combustion, the Combustion Institute, presented, to appear, 1994. 


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11-295 


II. MSAD Program Tasks 

HI 


Ground-based Research Discipline: Combustion Science 

„„ HI... * 


Structure and Dynamics of Diffusion Flames in Microgravity 


Principal Investigator: Prof. Moshe Mataion 

Northwestern University 

Co-Investigators: 

No Co-l’s Assigned to this Task 



Task Objective: 

The objectives of the work are to gain insight into diffusion flames by studying simple combustion systems. The 
emphasis of the work will be to understand the structure and dynamics of stationary spherical flames, and the 
coupled processes occurring in the liquid and gas phases associated with the burning of liquid fuels. 

For gaseous flames, the Principal Investigator will investigate the processes that lead to extinction ol these flames 
either by the process of blowoff or by radiative losses. He will also examine the nature of the interactions between 
two diffusion flames, the mechanisms leading to the generation of flame front instabilities, the formation of cellular 
flames and the effect of residual gravitational acceleration on microgravity diffusion flames. 

For liquid fuel burning, the Principal Investigator will examine the possible generation of instabilities that are 
intrinsic to the vaporization process and identify the importance of thermocapillary motion on the overall burning 
process. 

Task Description: 

The program is entirely theoretical in nature. The Principal Investigator will work closely with related 
experimental investigations in the microgravity combustion science program to identify problems oi specific 
interest. 

The porous sphere will be the model problem for gaseous diffusion flames. A standard formulation of the 
conservation equations in spherical coordinates forms the base case. The model will then be extended to incorporate 
finite rate kinetics through activation energy asymptotics, enabling details of the flame structure to be elicited. The 
model can then be extended to include a standard form of a radiative loss to determine the extinction limits, blowott 
and radiative, of the combustion system. Finally, the model will be extended to determine the effects of interaction 
by modeling two spherical diffusion flames in close proximity to each other employing bi-spherical coordinates in 
the approach outlined above. 

As a next step the core model will be extended to incorporate stability theory and determine the conditions for the 
onset of flame-front instabilities similar to those that have been observed experimentally. Similarly, the effect of a 
low-magnitude, time-varying body, force (g-jitter) on the flame will be examined, by casting the disturbance as a 
sinusoidal term in the governing equations. 

The ideas developed above will then be extended to liquid fuels. The major change to the model w ill be the 
incorporation of the liquid phase, the conservation equations for the liquid phase, and the coupling ol the gas and 
liquid phases. A major addition will be the incorporation of thermocapillary motion in the liquid phase equations. 

Task Significance: 

The proposed research will lead to a greater understanding of diffusion flames in general. By working closely with 
experimental studies in the microgravity science program, the investigator will be able to give a theoretical 
foundation to many experimental observations of diffusion flames in microgravity. 




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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

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Progress During FY 1 994 : 

Currently, the participants in this program are Prof. M. Mataion (the PI) and two Ph.D. students. The work which 
has been initiated is associated with 1) flame instability in pool burning, and 2) diffusional-thermal instabilities in 
dittusion flames. For the first problem, a simple one-dimensional model has been developed describing the 
evaporation and subsequent burning from a flat bed of a liquid fuel. The evolution of small disturbances is being 
examined in order to identify possible instabilities. Experiments show that while one possible mode of burning is a 
pool burning, in some circumstances a traveling front along the fuel bed may occur. The goal of the theoretical 
investigation is to explain these observations. The analysis of the second problem requires a complete 
understanding ot the structure of a corrugated (three-dimensional) diffusion flame with arbitrary Lewis numbers (not 
necessarily = 1). Previous work, notably that of Linan, has been restricted to one-dimensional flame fronts and to 
unity Lewis numbers. It should be mentioned that while diffusional-thermal effects are reasonably well understood 
tor premixed flames, they are not well understood for diffusion flames. We have thus extended Linan's analysis and 
gave a description tor the structure of a diffusion flame of arbitrary 3D shape. Preliminary results indicate that in 
the absence ot fuel or oxidant leakage through the reaction zone, the diffusion flame is absolutely stable. 

Instabilities are possible when leakage is present for a special range of the fuel and oxidant Lewis numbers and for a 
Damkohler numbers that is near the critical value corresponding to extinction. We are currently mapping the region 
of instabilities in terms of these parameters. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 6/94 Expiration: 5/98 
Project Identification: 962-22-05-47 
Responsible Center: LeRC 


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IIIIMI 


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Discipline: Combustion Science 


Filtration Combustion for Microgravity Applications: (V Smoldering, (2) Combustion Synthesis of 


Advanced Materials 


Principal Investigator: Prof. Bernard j. Matkowsky 

Northwestern University 

Co-Investigators: 


A.Bayliss 
V.A. Volpert 

Northwestern University 
Northwestern University 

Task Objective: 


The objective is to investigate combustion in porous media with applications to (1) smoldering and (2) combustion 
synthesis of advanced materials, also referred to as self-propagating high-temperature synthesis (SHS). 

Task Description: 

1 Proposing/developing theoretical models describing the fundamental mechanisms lor the phenomena under 
consideration, (2) performing complementary analytical and numerical work on the proposed models and 
mechanisms, (3) comparing the results of these analyses to experiments. 

Task Significance: 

Both smoldering and combustion synthesis of advanced materials (SHS) contribute to fundamental science, and also 
represent important applications for microgravity combustion science; in smoldering to tire safety in both norm- 
and microgravity, and in SHS to the determination of optimal synthesis conditions in both normal and microgravity 
environments. Combustion synthesis appears to compete favorably with conventional technology, by achieving 
shorter synthesis times, and at lower cosh by employing the internal energy ot the combustion reactions rather than 
the costly external energy of a furnace, employed in conventional technology. 

Progress During FY 1 994: 

A paper entitled "Combustion of Porous Samples with Melting and Flow of Reactants," by A. Aldushin. B. 
Matkowsky K Shkadinskv, G. Shkadinskaya, and V. Volpert is accepted for publication by Combusuon Science 
and Technology. The abstract of the paper reads: "We formulate and analyze a model describing the combustion ot 
porous condensed materials in which a reactant melts and spreads through the pores ot the sample. Thus there is 
liquid motion relative to the porous solid matrix. Our model describes the cases when the melt either tills all the 
pores or spreads through only some of them. In each case the melt occupies a prescribed volume tracuon ot the 
mixture. We employ both analytical and numerical methods to find uniformly propagating combusuon waves to 
analyze their stability and to determine behavior in the instability region. The principal physical conclusion which 
follows from our analysis is that the tlow of the melted component can result in nonuniform composition ot the 
product. Unlike models which do not take into account the relative motion of the components, this model exhibits 
a dependence of the structure of the product on the mode of propagation of the combustion front. Thus, it the initial 
mixture is uniform, models which do not allow for relative motion necessarily lead to uniform structure of the 
product, while in the model employed here the structure can be nonuniform. We observe that the structure ot 
uniformly propagating combustion waves depends on whether the refractory or melting componeit is in excess in 
the initial mixture. We determine how various parameters of the system affect stability and find a pulsating 
instability of the uniformly propagating solutions. We also perform numerical simulations in order to (i) study the 
dynamical behavior of the combustion wave in the instability region, (ii) obtain a description ot the melt flow on 
the scale of the entire sample rather than on the scale of the combustion wave, i.e. to study the evolution ot the size 
of the liquid melt layer which may occupy only a part of the product region. We show, in particular, that a 
transition to relaxation oscillations may occur closer to the threshold of instability than in gasless solid tuel 
combustion. Our numerical and analytical results are in qualitative agreement." 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

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A paper entitled Propagation and Extinction of Forced Opposed Flow Smolder Waves/ by A.C. Femandez-Pello, 
B.J. Matkowsky, D.A. Schult, and V.A. Volpert is submitted to Combustion and Flame. The abstract of the paper 
reads: 'Smoldering is a slow combustion process in a porous medium in which heat is released by oxidation of the 
solid. If the material is sufficiently porous to allow the oxidizer to easily filter through the pores, a smolder wave 
can propagate through the interior of the solid. We consider samples closed to the surrounding environment except 
at the ends, with gas forced into the sample through one of the ends. A smolder wave is initiated at the other end 
and propagates in a direction opposite to the flow of the oxidizer. We employ large activation energy asymptotic 
methods to find uniformly propagating, planar smolder wave solutions. We determine their propagation velocity, 
burning temperature, final degree of fuel conversion, and extinction limits. We also determine spatial profiles of gas 
flux, oxidizer concentration, temperature, and degree of conversion of the solid, including the burning temperature 
and final degree of conversion." 


Students Funded Under Research: Task Initiation: 5/94 Expiration: 5/98 

Project Identification: 962-22-05-55 
Responsible Center: l c rc 


Bibliographic Citations for FY 1994: 

Journals 

Aldushin. A.. Matkowsky. B.. Shkadinsky. K.. Shkadinskaya. G. and Volpert. V. Combustion of porous samples with 
melting and flow of reactants, accepted by Combustion Science and Technology, (1994). 


* hi nit. 


11-299 



II. MSAD Program Tasks — Ground-based Research 




Discipline: Combustion Science 

mu 


Combustion 


of PTFE: The Effect of Gravity on the Production of Ultrafine Particles Generation 


Principal Investigator: Prof. j. t. McKinnon 


Colorado School of Mines 


Co-Investigators: 
P.W. Todd 


University of Colorado 


Task Objective: 

This project is a study of the fundamental chemical and physical mechanisms of the producuon of ultra 
particles, and the nature of the particles themselves, generated by the thermal breakdown of polytetrafluoroethylene 
(PTFE) wire insulation. PTFE is a material that normally resists ignition and tire spread, but it can degrade whe 
stressed by thermal and electrical overloads to release ultra tine (10 to 100 nm) particles as aerosols or smoke. 

Task Description: 

The experimental study will be performed in three tasks, as follows: 

1. Initial normal gravity tests, conducted at the Colorado School of Mines in a simplified apparatus, heat reference 
perfluoroalkane compounds in a tube furnace to generate ultra tine particles. These preliminary tests etermme 
effects of temperature and residence time on particle generation and develop the means tor particle capture and gas 

analysis. 

2 Subsequent normal gravity tests, also conducted at the Colorado School of Mines in a closed chamber apparatus, 
heat copper wires coated with PFFE. These advanced tests enable the detailed determination ot particle sizes and 
concentrations by nonperturbing light scattering measurements and the collection ot particles by thermop oretic 

sampling. 

3 Subsequent microgravity tests, conducted by the investigators in the NASA Lewis Research Center drop tower 
and airplane facilities, are essential for an understanding of the effect of the low convection environment on the 
production of ultra tine particles and their possible dispersion and agglomeration, as a direct representation ot 
potential hazard situations in spacecraf t. 

The accompanying analytical study seeks to develop a comprehensive predictive model to predict ultra tine particle 
production given inputs of heating rate, polymer quantity, degree of forced convection, and other factors. This 
analysis is based on elementary reaction rates from established databases, the investigator s studies on soot 
formation, and the interpretations of the results ot the experimental tests. 

Task Significance: 

This study will examine the phenomenon of ultra-tine particle generation by the thermal degradation of a class of 
spacecraft wire insulation. The results contribute to the knowledge of the physical and chemical mechanisms ot 
this process and offer practical applications in the reduction of health hazards in spacecraft and in the early warning 
detection of tire incidents by atmospheric smoke sampling. 

Progress During FY 1 994: 

This project began on June 27, 1994 with the award of NASA Grant NAG 3-1628. The initial task is to design the 
procedures of normal-gravity tests to determine the effects of temperature and resident time on the effluents produced 
by a pyrolyzing polymer and to develop a means of effluent gas analysis and particle capture. The original plan was 
to investigate the degradation of reference monomeric compounds, perfluoroalkanes, in a simple tube furnace. 
Instead, the studies initiated with investigation of the thermal reactions of the target polymer, 
polytetrafluoroethylene (PTFE), since there is an immediate application for detailed analyses ot the products ot this 




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11-300 



II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 


material. Concurrent life-science studies at the University of Rochester Medical School, supported by a NASA 
Center for Research and Testing, shows that toxic solid and gaseous products are generated by pyrolytic reactions of 
PTFE at temperatures of 410 C and above. Gaseous products evolved in the tube-furnace tests will be separated and 
identified by gas chromatography and mass spectroscopy. Ultrafine-particle products will be collected on a simple 
filter plate, with morphological- and chemical-analysis methods to be determined. 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 1 


Task Initiation: 5/94 Expiration: 4/98 

Project Identification: 962-22-05-64 
NASA Contract No.:nag3-1628 
Responsible Center: LeRC 


11-301 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

Hum 


Premixed Turbulent Flame Propagation in Microgravity 


Principal Investigator: Prof. Suresh Menon 

Georgia Institute of Technology 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The overall objective of this research is to characterize the behavior of turbulent premixed flames and to use the 
experimental data to validate a novel computational method to simulate accurately the behavior of premixed flames. 
In order to understand the behavior of turbulent flames, access to all the length scales (from the device size to the 
Kolmogorov scale) in the flow field is required. A possible method to achieve this is to reduce the flow velocity. 
However, in normal -gravity this is not possible due to gravitational acceleration and the turbulent stresses are 
overwhelmed by buoyant stresses. Therefore, experiments in microgravity will be carried out that will allow the 
study of low-speed turbulent flames without buoyancy effects. 

Task Description: 

Premixed combustion of hydrogen-air mixtures will be studied in a Couette flow configuration which is essentially 
a flow between two parallel plates moving opposite to each other. The turbulent flow field is characterized with the 
flame speed being the primary variable of interest. Additional data on pressure rise and temperature is also measured. 

Task Significance: 

Improved understanding and modeling of practical turbulent flames will lead to increased efficiency and reduced 
pollutant formation. Practical applications of technology to industrial combusters and high throughput engines 
may be anticipated. 

Progress During FY1994: 

Preliminary test plans and schedules were prepared and presented to NASA LeRC drop tower and diagnostics 
personnel. 

A detailed literature search was completed to determine what has been done related to premixed combustion and 
turbulent flows in Couette-type configuration. Relevant papers were collected and reviewed. The review of the 
literature clearly showed the following: (a) there has been no numerical and/or experimental work earned out for 
turbulent combustion (both premixed and non-premixed) in Couette flow configuration, (b) there have been quite a 
few experimental studies of plane-Couette flows, however, the configurations were quite different - - in most cases, 
it consisted of only one wall moving and hence simulated a plane shear flow in a channel. These configurations 
were quite large setups and not considered feasible for the present study. Only two cases were found (other than the 
original report from Germany), which involved setups and testing procedure relevant for the present study. In 
particular, one configuration appears quite promising to study Couette cold flows since it appears to be easily 
constructed and will allow very long testing times. Cold flow testing will be the first experimental study since it 
would allow us to resolve the various issues related to turbulence measurements in such flows, (c) there have been 
numerous numerical studies of turbulent Couette flows; however, most of the studies were for the mean 
(steady-state) flow calculations using Reynolds- Averaged methods with turbulent closure and no unsteady flows have 
been studied. In summary, the review of available literature clearly indicates that there have been no studies of 
premixed combustion in turbulent Couette flows, and it further indicates even cold (non-reacting) unsteady flows 
have not been studied. 

Based on the literature study, a numerical study of premixed combustion in a plane Couette Flow was initiated. The 
configuration is similar to the one planned for the experimental study. Premixed flame propagation is modeled using 


immtiiimtmimimmmm mi. mu. mi.mi.u. in miiiimiiii imimmi min 

11-302 


II. MSAD Program Tasks — Ground-based Research 

Mini 


Discipline: Combustion Science 


HIIHIMIIimillMIIIMHIMIIMIIMItlllllHIIIMl'immilllimiMIIHIIIItllllllllllltimmilHIHMIlllHIIIHIIimM 


the G-equation model. This approach allows the study of thin flames without requiring detailed kinetics modeling 
and there! ore, is computationally very efficient. Unsteady turbulent How is simulated using the large-eddy 
simulation methodology. The first phase involves simulations in two dimensions; however, we plan to move to 
lull 3D within the immediate tuture. The 2D code is already operational. 

A test problem was identified for the numerical code validation. This problem consisted of only one moving wall; 
however, detailed experimental data had been obtained for this case and therefore, the numerical predictions can be 
validated using the experimental data. Preliminary calculations of laminar Couette Hows were earned out and an 
excellent agreement with the classical results was obtained. Currently, simulations of the turbulent flow are 
underway by using a turbulent inflow that consists of a mean flow and isotropic turbulence. The above noted 
studies are being earned out using a 2D LES code. However, the eventual goal is to simulate full 3D flows; 
therefore, a 3D version of this code is also being set up and is planned to repeat the 2D validation studies with the 
3D code. 

On the experimental side, the design issues for the cold flow experiments are being addressed. The exact dimensions 
have not yet been finalized, but the configuration under current consideration is similar to the setup used by 
Tillmark and Altredsson in Sweden. The main differences are (a) the present study will employ gases (e.g., air and 
helium) and therefore, leakage is a serious issue, (b) the configuration will be much smaller overall in order to be 
applicable to the reacting Couette flow configuration, (c) the range of spacing between the two belts and the range 
of Reynolds number will be different and (d) it is planned to carry out detailed turbulence measurements and flow 
visualization of a no-heat release "flame" front (which will be generated by introducing in the channel center a new 
species that can be tracked - - currently acetone and byacetyl dye are being looked at). 


Students Funded Under Research: 

BS Students: 0 

MS Students: 0 

PhD Students: 2 


Task Initiation: 5/94 Expiration: 5/98 
Project Identification: 962-22-05-48 
Responsible Center: LeRC 




11-303 



II. MS AD Program Tasks — Ground-based Research Discipline: Combustion Science 

...» 


A Fundamental Study of the Combustion Syntheses of Ceramic-Metal Composite Materials Under 
Microgravity Conditions 


Principal Investigator: Prof, lohn j. Moore 

Colorado School of Mines 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objective is to obtain an improved understanding of the effect of gravity on the combustion synthesis of 
ceramic matrix-metal infiltrated composites and to develop new and improved-property materials. 

Task Description: 

Combustion synthesis reactions are conducted under normal gravity (various orientations of samples with respect to 
gravity) and in microgravitv to generate either porous or dense ceramic matrices in the presence of varying amounts 
of excess AT0 3 (diluent) and/or excess aluminum, which will be available to fill residual pores by capillary action. 
The effects of itas generation during reactions on the porous matrix formation are studied under different levels of 
gravity. The dense composite materials are produced using a one step, low cost, simultaneous 
combustion-consolidated process. The microstructure and properties of both dense and porous product composite 
materials are also characterized. 

Task Significance: 

An improved understanding of the role of gravity on the combustion synthesis of ceramic-ceramic and ceramic 
matrix-metal composite materials allows for new approaches for the development ot specified micro-structures, 
thereby resulting in improved material properties. One can also explore ways to develop brand new materials by 
microgravity processing (e.g. high surface area expanded or foamed ceramics, and fully dense interpenetrating phase 
composites). The expected benefits of such inexpensive, light, strong, and either highly porous or dense composite 
materials range from construction-support systems to liquid-metal, liltering-systems applications. 


Progress During FY 1 994: 

The B4C/A1203 system using the reaction: 

2B 2 Oj + C + (4+x)Al + yAl 2 0 3 -> B 4 C + (2+y)Al 2 0 3 + xAI 

is being persued based on the observation that this system showed expansions of approximately 150% under 2-g, 
and over 400% under 0-g conditions (Lear let), as opposed to 300% under n-g, after the combustion synthesis 
process. A new student will concentrate her efforts on the more accurate control of the combustion temperature to 
avoid melting A1 2 0 3 . If successful, this would provide an increased surface area in the expanded ceramic composite. 

Two modes of combustion are being studied: 1) simultaneous, where the mixture is ignited by heating the whole 
pellet at once, and 2) propagating, where the ignition is at one end of the pellet. Depending on the value of y and 
combustion mode, the reactions are observed to be quenching, unstable, or stable, and the product has different pore 
sizes, distribution and expansion. 

By using the simultaneous' combustion mode for cylindrical pellets they observed radial expansions of about 13% 
in addition to an axial expansion of about 15%, i.e. near three-dimensional uniform expansion. The scanning 
electron microscopy analysis shows that the samples contained a marked amount ot submicron diameter whiskers. 


Mill 


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11-304 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 


Upon an informal review of the grant, the Space Experiments Division at LeRC came up with a number of 
recommendations. Prof. Moore agreed that a student should re-analyze the x-ray radiography tapes from previous 
NASA Lear Jet flights for a better verification of reaction speed and quantification of pore formation and progression 
in samples of the B4C/A1203 system. X-ray and scanning electron microscopy (SEM) work is providing evidence 
tor the speculation that reactions are occumng ahead of the combustion front. 

Samples tor the B 4 C/AI 2 0 3 system with 20 wt% excess A1 are still planned to be flown on the Lear Jet with 
operation by LeRC personnel for about eight trajectories. After the 10 wt% excess A1 2 0 3 (diluent) samples, the 
student reacted some 5 wt% and no excess A1 2 0 3 samples in argon gas (inert atmosphere). Their SEM images also 
show the formation of shells within the sample. She will determine the interior structure and composition of the 
shells by using electron back-scatter imaging. She also plans to measure the surface area. A trend of continuous 
reduction in combustion temperature with increasing diluent is being observed. 

The vacuum pump is in place to complete reactions utilizing 25 wt% AI 2 0 3 as a diluent. The goal is to decrease 
the combustion temperature of the reaction system below the melting point of A1 2 0 3 so that the reacted samples 
exhibit a higher surface area/weight ratio. 

The other graduate student is processing the TiC/Al 2 0 3 /Al system using the reaction: 

3Ti 0 2 + 3C + (4+x)Al + yAl 2 0 3 -> 3TiC + (2+y)Al 2 0 3 + xAl 

under normal gravity conditions using a hot press. He reports that the same level of uniformity of the metal 
network readily obtained under micro-g conditions would require pressures of 4000psi under normal-g conditions. 

He will also develop physical and computer models to predict these phenomena. He is studying the effect of green 
powder particle size on the kinetics, stability, and product microstructure of the TiC/Al 2 0 3 /Al system. Larger 
particles decrease the stability of the reaction. He has determined that metallic A1 bonding between particles in 
products when excess A1 is used is the main reason for the enhancement of strength and toughness. While tine 
particles result in more homogeneous pores in the final product, they produce no whiskers. On the other hand, 
coarse particles can produce whiskers when excess A1 (x>2) is used. 

The student then has achieved fracture toughness values twice as much as that of pure A1 2 0 3 using various values of 
the stoichiometry (x and y), and consolidation pressure. The samples with higher fracture toughnesses exhibit 
smaller grain sizes and more homogeneous morphologies than their lower fracture toughness counterparts. Both 
A1 2 0 3 and AI are used in excess to control the combustion temperatures and, thereby, the microstructures and 
mechanical properties. 

Finally, he has successfully defended his PhD Thesis in June 1994 and will continue working on the same system 
as a post-doc for six more months. 


Students Funded Under Research: 

Task Initiation: 8/91 Expiration: 12/94 

BS Students: 

0 

BS Degrees: 0 

Project Identification: 962-22-05-38 

MS Students: 

2 

MS Degrees: 1 

Responsible Center: LeRC 

PhD Students: 

1 

PhD Degrees: 1 


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11-305 



II. MSAD Program Tasks — Ground-based Research 




Discipline: Combustion Science 




Bibliographic Citations for FY 1994: 

Journals . 

Feng, H.J. and Moore. J.J. Combustion synthesis of high performance ceramic-metal composits. High Performance 

Metal and Ceramic Matrix Composites, TMS. ed. K. Upadhya, 157-174 (1994). 

Feng, H.J. and Moore, J.J. In-situ combustion synthesis of dense ceramic and ceramic -metal interpenetrating phase 
composites, accepted, Met. Met. Trans. (1994). 

Feng, H.J. and Moore. J.J.. The design of an affordable one-step process for the production of a functionally-graded 
material (FGM). accepted, J. Mat. Synth. Proc., (1994). 

Feng, H.J. and Moore, J.J. Combustion synthesis of dense ceramic-metal composites, accepted, Ceramic Matrix 
Composites. Ceramics Transactions, (1994). 

Feng. H.J., Hunter. K.R.. and Moore. J.J. Combustion synthesis of ceramic and metal-matrix composites. J. Mat. Synth. 
Proc. 2, 71-86 (1994). 

Hunter. K.R. and Moore, J.J. The effect of gravity of the combustion synthesis processing of advanced materials. 6th Int. 
Symp. Experimental Methods for Microgravity Materials Science, TMS. eds. R.A. Schiffman, F.B. Andrews, 125-131 
(1994). 

Hunter. K.R. and Moore. J.J Effect of gravity on the combustion synthesis ot ceramics and ceramic-metal composites, 
accepted. J. Mat. Synth. Proc.. (1994). 

Moore, J.J. An examination of the thermochemistry of combustion synthesis reactions. Processing and Fabrication of 
Advanced Materials III, TMS, eds. V.A. Ravi, T.S. Strivalsan, J.J. Moore, 817-831 (1994). 

Moore, J.J. Self propagating reactive synthesis of advanced materials. Proc. ot Powder Matallurgy World Congress, 

Paris, June 6-9. 1994 (European Powder Metal Association), (1994). 

Moore. J.J. and Feng, H.J. Combustion synthessis of advanced materials: Part I, reaction parameters, accepted. Progress 
in Materials Science, (1994). 

Moore. J.J. and Feng, H.J. Combustion synthesis of advanced materials: Part II, classification, applications and 
modeling, accepted. Progress in Materials Science. (1994). 

Moore. J.J., Readey, D.W.. Feng, H.J. and Monroe, K. Exothermic reaction (combustion) synthesis of advanced ceramic, 
intermetailic and composite materials, accepted, J. of Metals. (1994). 

Presentations 

Feim, H.J. and Moore. J.J. "Combustion synthesis of dense ceramic-metal composits." Ann. Mtg. ot Am. Cer. Soc.. 
Indianapolis, IN. April. 1994. 

Feng, H.J. and Moore, J.J. "Combustion synthesis of high performance ceramic-metal composits.’' High Performance 
Metal and Ceramic Matrix Composites. TMS. Warrendale. PA, 1994. 

Feng, H.J. K.R. Hunter and J.J. Moore "The application ot combustion synthesis in the production of titanium-based 
ceramic and ceramic-metal composites." Eng. Found. Cont. on High Temp. Struc. Mater., Hawaii, 1993. 

Hunter. K.R. and Moore. J.J. "The effect of gravity of the combustion synthesis processing of advanced materials." 6th 
Int. Symp. Expenmental Methods for Microgravity Materials Science. TMS, Warrandale. PA. 1994. 

Hunter. K.R., J.J Moore The effect of gravity on the in-situ combustion synthesis ot ceramic-metal composites.. 

AIAA 94-0568, presented at the AIAA 32nd Aerospace Sciences Meeting at Reno. NV. Jan. 10-13. 1994. 

Moore. J.J. "Self proagating reactive synthesis of advanced materials." Keynote Lecture. 1994 Powder Matallurgy World 
Congress. Paris. June 6-9. 1994. 

Moore, J.J. "An examination of the thermochemistry of combustion synthesis reactions. Processing and Fabrication ot 
Advanced Materials HI, TMS. Warrendale, PA, 1994. 


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11-306 


II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 


Flow and Ambient Atomosphere Effects on Flame Spread at Microgravity 

PRINCIPAL INVESTIGATOR: Prof. Paul D. Ronney University of Southern California 

Co-Investigators: 

Sandra Olson NASA Lewis Research Center (LeRC) 


Task Objective: 

This program is a three-year expenmental and theoreucal study of the effects of ambient atmosphere on the 
properties of flame spread over thin and thick solid fuel beds. In particular the effect of the type of inert gas, which 
affects the Lewis numbers of fuel and oxidant, and the effect of the addition of sub-flammability-limit 
concentrations of gaseous fuels to the oxidizing atmosphere will be studied. The effect of convection will be 
studied through one-g and mg experiments with and without a forced flow. Moreover, the influence of thermal 
radiation, whose effect is known to be markedly different depending on the convection level, will be addressed. 

Task Description: 

The emphasis of this study is on thermally thin fuels because of the limited jig test time available in ground-based 
facilities, and preliminary scaling analyses suggest that thermally thick fuels can be exmnined as w r ell w hen gaseous 
fuel is added to the oxidizing atmosphere. 

The experiments will be conducted in a combustion chamber in which a convective flow of a few cm/sec can be 
imposed in the direction opposite the flame spread. The oxidizing atmosphere will be mixed by the partial pressure 
method. For tests of Lew-is number effects, inerts He, Ne, N 2 , C0 2 and SF fi will be used since they provide Lewis 
numbers from about 0.3 to 1.4. CO and CH 4 w ill be used for the gaseous fuels. Thin fuel samples will be ashless 
filter paper and thick fuel samples will be PMMA. Fuel samples of varying thickness will be ignited by the heat 
generated by a current passed through a coiled nichrome wire coated with nitrocellulose. 

The primary diagnostics tire video and an array of fine-wire thermocouples to measure the temperature 
simultaneously at several locations. The video records provide information on the spread rate and flame shape. The 
thermocouples give an independent check of the spread rates tuid the existence (or lack thereof) of a separate flame 
front in the case of added gaseous fuel. The temperature data may also be used to determine the heat llux from the 
gas phase to the fuel bed. which ciui be related to the spread rate. 

Task Significance: 

The understanding and control of accidental fires is a critical safety issue in both terrestrial and space-home 
environments. The proposed work would provide insight that could be used to assess the fire hazards associated 
wit h non-standard atmospheres that might be employed in future manned spacecraft. Also, fires in enclosures 
produce a considerable amount of unbumed vaporized fuel and partially combusted gases such as CO. One-g 
experiments have shown that the addition of combustible gases such as CO to the oxidizing atmosphere may 
increase the flame spread rate substantially. This study could provide information to improve models of fire 
development and spread in enclosures at one-g and fig. 

The influence of weak forced convection is particularly important for studies of flame spread at |ig because there is 
very little buoyancy-induced flow at fig. Experiments by Olson and collaborators show r s that the presence of forced 
convection currents ( for example due to ventilation systems in untuned spacecraft) can have a profound effect on the 
spread rate and extinction conditions. Consequently, the understanding of these effects is critical to understanding 
how fires might start spread, and be extinguished at fig conditions. 










II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

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Progress During FY1994: 

To improve (he sensitivity of the video imaging system for the very weak near— extinction flames, a shearing 
interf erometer has been designed and is being constructed for evaluation. The shearing interferometer has no parts 
that have critical alignment requirements, and thus may be especially suitable for drop tests. The interferometric 
measurements may also be useful to supplement the thermocouple temperature measurements. 

A graduate student is modifying our existing one-g flame spread apparatus for use in drop towers with regards to 
fuel sample mounting, optical access, and data acquisition. 

As a precursor to the experimental study, an analytical study has been initiated in conjunction with Dr. Mike 
Delichatsios of Factory Mutual Research Corporation in Norwood, MA. The goal of the work is to extend Dr. 
Delichatsios’s previous (1986) exact solution of flame spread over a pyrolyzing fuel bed to consider the effects 
Lewis number, finite-rate chemistry, and gaseous fuel addition on flame spread rate. A preliminary theory of Lewis 
number effects on flame spread over thin fuel beds, including finite-rate chemistry, has been obtained and compared 
with prior one-g data from Zhang et al (1992). 


Students Funded Under Research: 

BS Students: 0 

MS Students: 2 

PhD Students: 0 


Task Initiation: 5/94 Expiration: 4/98 

Project Identification: 962-22-05-61 
NASA Contract No.:nag3-1611 
Responsible Center: LeRC 


Bibliographic Citations for FY 1994: 

Presentations 

Delichatsios, M,A. and Ronney, P.D. "Horizontal and lateral flame spread on solids: closure and diffusional Lewis number 
effects." Fall Technical Meeting, Combustion Institute, Eastern States Section, Clearwater Beach. FL, December 5-7, 
1994. 


II. MSAD Program Tasks — Ground-based Research 

* . 


Discipline: Combustion Science 

it .in. in 


Combustion Research 


Principal Investigator: Dr. Howard d. Ross 

NASA Lewis Research Center (LeRC) 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 


The task objective is to advance the understanding ot fundamental combustion phenomena and/or processes that are 
affected by the presence or absence of gravity. 

Task Description: 

The research approach is to provide for limited precursor studies by external investigators and for the engineering 
and fabncauon ot hardware needed to conduct in-house research and assist in the research efforts conducted on-site at 
LeRC in support ot Code UG-sponsored Principal Investigators (Pi's) and National Research Council (NRC) 
graduate student researchers. Funds for facility overhead charges are provided through separate Research and 
Technology Operations Plans (RTOP) resources. 

Subtasks are lunded in part by this task.or are included for completeness at die request of NASA Headquarters. 

Task Significance: 

Significance varies with the various research efforts, and therefore, more focused, effort-specific, statements are 
given below. 

Progress During FY 1 994 : 

Funds were disbursed to support service contractors to perform technical analysis and assistance for selected ground-based 
microgravity combustion science research grants and cooperative agreements. In addition, a number of research activities 
were conducted by onsite staff, including NRC post-doctorate fellows and Graduate Student Research Program fellows 
associated with both ground-based and flight projects. The objective, approach, significance, and progress for each of 
these research activities are described below. 


Combustion Synthesis of Fullerenes - ,J. Brooker 

Objective: 

The objective of this research is to produce, collect, and quantify fullerenes synthesized during combustion under normal 
microgravity and com P are the results relative to: C60 and C70 composition. C60 and C70 percent of soot, and 
C70/C60 molar raUo. In phase one. acetylene will be burned in a gas-jet premixed flame; in phase two. benzene will be 
studied. 


Description: 

Flames will be used to generate fullerenes in a sub-atmospheric combustion chamber. Normal gravity tests will be 
performed to determine conditions favorable for fullerene production and to define a suitable method of collection and 
species separation/identification. Subsequent experiments will employ the 2.2 Second Drop Tower and possibly aircraft. 

Significance: 

The suggested potential applications for fullerenes include superconductors, lubricants, catalysts, high energy fuels, 
polymers, and biomatenals. Some of the emerging applications that are currently under investigation include the growth 
o lamond films on surfaces for protective coatings and electronic industries, their use as optical limiters to protect 
sensors from intense radiation sources, incorporation of fullerenes into photoconducting polymers with applications in 
light detection and electrostatic imaging, and the possible use of fullerene derivatives as drugs to combat AIDS bv 
interacting with the active site of HIV. 

Progress: 

A literature search on fullerene properties and methods of production began along with a study of combustion texts to 


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11-309 


111111111 



II. MSAD Program Tasks 

hi 1 1 


r- w or i Rpsparch Discipline: Combustion Science 




constraints. 

Design of the burner, vacuum system, collection system, and diagnostic pallet began. Various parts were >denUhed tor 
procurement/fabrication and orders were submitted. With the LeRC Chemistry Laboratory we are determining th 
analytical equipment and procedures necessary to identify fullerenes and to separate them Irom 
products. 

Investigation of Burning Droplets of Azeotropic Mixtures - Dr. R. Colantonio 

flame histories and location of the azeotropic point for a number of binary azeotropic mixtur . 

ftopw'Zine of azeotropic mtx.ure, mil be performed « 1-g and a, tbe NASA 2.2 second Drop Toww. A demoti sirated^ 

t nt» motes wilhdr.w, *. needle,. Two bo, -wire hoop, will be o.ed ,o t S m,e Ihe M drople, once *. 
neddles have been withdrawn and the droplet is suspended during reduced gravity. 

Both a color CCD camera and a high-speed 16 mm camera will be used to observe the burning characteristics of the 
azeotropic fuel mixtures. 

Experimental hardware was procured and is currently being assembled with testing tentatively scheduled for December 
\ 994 . Tetrachloroethene/propanol and ethanol/water mixtures are likely candidates for the first series of testing. 

A Transient Model of Flame Spread Over Solid Fuel in Microgravity - Dr. P. Ferkul (NRC) 

Mecrive of this effort is to deveiop an unsteady model of flame spread an 

is sought. Also, the flammability boundary, as a function ot oxygen percentage and flow velocity, is invest, g 

The detailed dynamics of flame extinction can be examined with this model. 

There are several other related objectives. The first is the development of a good algorithm to handle the interface between 
the solid and gas phases at the fuel surface when the fuel gets appreciably thick. The changing geometry due to fuel 
Hp,“p »mpta«. tb= specification of boondt, condibon, Tbe .econd i. ihc ^ 

since some of these long flames may tend to become turbulent in the downstream region. The third is he identification 
those cases where a "quasi-steady" solid formulation will be adequate, as opposed to those where the fully unsteady 
phase equations are necessary. 

An^xisfing 1 steady-state computer code will be modified. This onginal program is based on the SIMPLER ^“rithm which 
^ general fluid flow solver The full Navier-Stokes equations are used, together with conservation of energy and 1 fuel and 
oxygen species. A second-order finite-rate chemical reaction is assumed to model the combustion. Radiation tr ° m fuel 
surface serves as a heat loss mechanism. The Cray Y-MP at NASA LeRC will be used to compute, store, and process 
large amount of data which will be produced. 


mlimilMIHIMlimiMHMIMIIMH'IIIMIIMMIIHIIIIItitHiHII 


* 


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Significance: 

The purpose of this etfort is to both guide and predict related experimental work. Together with the experimental work, the 
model will provide fundamental insight into flame spread at microgravity. The work has direct application to spacecraft 
fire safety. 

Progress: 

The details of the flow around the fuel burnout point were examined. This region is important since it serves as the flame 
stabilization point and will thus have implications on extinction. Several references of cold flow in the leading edge 
region of a semi-infinite flat plate were examined. One reference suggested that using "parabolic coordinates" instead of 
the primitive cartesian coordinates may better capture details at the leading edge. 

Using this suggestion, the parabolic coordinate system has been defined. The coordinate transformation of the 
Navier-Stokes equations from cartesian to parabolic was performed, using the vector form of the unsteady, compressible 
Navier-Stokes equations. The equations for parabolic-cylindrical and parabolic-axisymmetric coordinates were derived. 

Venting Extinguishment Experiment - J. Goldmeer (GSRP) 

Objective: 

The G.S.R.P. Venting Extinguishment Experiment is examining the extinction of a solid diffusion flame at low pressures 
in reduced gravity. The experiments being conducted will yield data on the flammability of the fuel at various pressures, 
oxygen concentrations, and flow velocities. This data will provide information regarding the effectiveness of the 
depressurization process as a fire extinguishment technique in reduced gravity. 

Description: 

The Venting Extinguishment Experiment is examining the combustion and extinction behavior of a solid, horizontal, 
PMMA cylinder in a low-speed flow in reduced gravity. The depressurization process is being examined in three phases. 
The first portion involved 1-g testing to determine the appropriate test parameters. The second portion of the research 
examined the effect of reduced gravity on the selected combustion configuration utilizing the NASA Lewis 2.2 Second Drop 
Tower. 1 The third phase of the research will examine the effects of flow and depressurization on the flame in 1-g and in 
low-gravity. The low-g depressurization experiments will be conducted on board a NASA reduced gravity aircraft. (This 
research is part of J. Goldmeer’s doctoral program at Case Western Reserve University ). 

Significance: 

Combustion of solids in low-speed forced flows at reduced gravity is relevant to fire safety in spacecraft. In an emergency a 
compartment within a space vessel could be intentionally vented to space to extinguish a fire. However, the effect of the 
induced flow on the fire in the low gravity and low pressure environment is unknown. 

Progress: 

A series of tests were conducted on board the KC-135. In the combustion tests the PMMA cylinders (2.5 cm in length, 1.9 
cm in diameter) were ignited during the 2-g portion of the trajectory with flow in the chamber. A focus of the analysis has 
been the centerline temperature of the samples. 

Steady-state extinction tests (lg) were also conducted. In these tests a horizontal PMMA cylinder was ignited in a forced 
flow and the pressure was slowly reduced until flame extinction occurred. During the experiment the velocity was kept 
constant. 

In these tests three different combustion modes were evident as the pressure was reduced. The first was a flame which 
surrounds the cylinder completely. The second mode of combustion occurred when the chamber pressure was reduced to 
approximately 0.1 atm. The flame at the lower stagnation point of the cylinder experienced blow-off, and the flame which 
was still burning along the upper surface of the cylinder began to oscillate. (This behavior was previously seen in lg 
oxygen depletion experiments.) The third mode occurred after the oscillations stopped. The flame slowly transitioned 
into a wake flame. The flames along the upper surface extinguished at approximately 0.07 atm; this pressure seemed to be 
independent of the flow velocity. 

During all tests, the temperature at the center of the sample was measured by a thermocouple probe. There was a correlation 
between the measured solid temperature at the center of the cylinder pressure at extinction. As the solid temperature 
increased, the pressure required to extinguish the flame decreased. 

A series of reduced gravity tests were conducted again on board the NASA Lewis Lear Jet. Forty-four trajectories were 
accomplished in nine flights. The experiments examined the steady-state extinction with a constant forced flow in reduced 
gravity. The chamber pressure and the temperature at the center of the solid were measured during these experiments. 





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II. MSAD Program Tasks — Ground-based Research 

«,it, it ‘"" m * 


Discipline: Combustion Science 
»»**» 


Above a critical solid centerline temperature the flames did not extinguish tn reduced gravity. Examining the trend in that 
data indicated that the pressure required to obtain extinction decreased as this critical temperature increased. At 
temperatures below this range, the flames extinguished during reduced gravity. This has implications lor the possible use 
of venting (depressurization) as a method for extinguishing fires on board spacecratt. 

Heat Release Effects on Shear-Layer Instabilities - Dr. U. Hegde 


Progress: 

During FY 94. studies were conducted in primarily two areas: 

(i) Heat release ettects on shear-layer instabilities 

The effects of unsteady heat addition on instabilities of parallel shear layers in the absence of gravity was analyzed. It was 
shown that, in the linear regime, the influence of heat addition is felt only through the time-averaged velocity and 
temperature fields, that is. the unsteady component of the heat addition plays no active role. The analysis which has 
application to both premixed and diffusion flames was published in AIAA Journal. 

(ii) Effects of unsteady heat transfer to a burning solid fuel 

In collaboration with Dr. M. Vedha-Nayagam. analysis of the oscillatory behavior of opposed-jet diffusion flames was 
extended to a stacnation point solid fuel diffusion flame. This is an area where microgravity environment may be of use in 
studying the effects of turbulence on flames. The effects of velocity fluctuations in the oxidizer stream on oscillations tn 
the burning rate of the fuel and flame intensity were investigated. The analysis was carried out to second order to 
investigate the time-averaged shift away from the undisturbed flame configuration. It was found, for cases considered, that 
the velocity osc, Uations caused an increase in the flux of reactants into the flame. Results were presented at the Central 
States Section Meeting in June. 

Diffusion Flame Extinction Dynamics - V. Nayagam 


The objective of this research is to investigate the extinction dynamics of diffusion flames at small, as well as large stretch 
rates The experimental portion of this study employs a rotating fuel-disk. The diffusion flame supported by the spinning 
fuel disk is embedded in the mduced 'Von Kannan boundary layer. This novel flow configuration enables one to control 
the stretch rates precisely. The theoretical effort makes use of large activation energy asymptotics to examine the 
extinction process. The attempt is to provide a unified of high stretch extinction (blow-off) and radiation heat loss 
dominated low stretch extinction. 


A knowledge of conditions under which diffusion flames extinguish is of fundamental as well as practical importance. 
Furthermore, the concept of laminar flamelets as an embedded structure that controls turbulent diffusion flames has 
provided a new impetus to further understand laminar extinction conditions in a variety of flow configurations. In the 
present study a rotating fuel disk induces a three dimensional boundary layer in which a laminar diffusion flame is 
established A range of chemical and fluid mechanical time scales over which extinction conditions occur are produced by 
changing the environmental conditions (pressure and oxygen concentrations), fuel, and the spinning velocity of the fuel 
disk. High speed filming of the burning process, and temperature measurements provide quantitative information 
regarding the extinction dynamics. 


The large experimental apparatus used earlier for normal gravity studies has been redesigned and miniaturized to fit into the 
standard drop-tower frames. The new design is currently being built. A theoretical model for the extinction process using 
the activation energy asymptotic technique has been developed. The model predicts extinction at high stretch rates (high 
RPM) as well as radiation heat loss induced low stretch extinction. The extinction condition is characterized by a critical 
Damkohler number. 

Stability of Laminar Premixed Gas Flames - Dr. H. Pearlman (NRC) 


The objective of this study is to develop a fundamental understanding of the inherent stability of premixed gas flames at 
earth and micro -gravity. 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 

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Description: 

The research approach is to design and construct hardware used to study freely-propagating flames in tubes in both normal 
and microgravity. This experimental configuration is chosen because it eliminates the additional complexities of heat 
loss and hydrodynamic effects common to burner stabilized flames. 

Significance: 

Understanding the intrinsic stability of premixed gas flames is essential to our fundamental understanding of heat and mass 
transport in the presence of chemical reaction. This work is applicable to our understanding of combustion phenomena as 
well as to our knowledge of a broader class of chemical and biological systems known as reactive-diffusive systems, which 
include such diverse phenomena as the patterns of spots on animals, the spread of infectious disease, the formation of 
spiral galaxies, as well as the rhythmic beating of a human heart and the solitary voltage pulses which travel along nerve 
fibers. 

Progress: 

One of the most fundamental problems in premixed gas combustion is the stability of a steadily-propagating, planar flame 
in a quiescent environment in the absence of forced or natural convection (buoyancy). Its stability will depend on: (1) the 
rate at which the heat liberated by the flame diffuses into the cold reactants versus the rate at which the stoichiometrically 
scarce reactant, the rate-limiting component, diffuses into the flame (i.e.. the diffusive-thermal mechanism) and (2) the 
ratio of the heat lost to the heat generated by the flame. The first of these two effects can be characterized by the Lewis 
number (Le) of the mixture where the Le is defined as the ratio of the thermal diffusivity of the bulk mixture to the mass 
diffusivity of the stoichiometrically scarce reactant in the bulk mixture. 

Low-Le (cellular flame) instabilities have undergone extensive experimental and theoretical treatment during the past 
century, yet, the high-Le instability has managed to evade experimentalists, until now. even though theoretical treatment 
by Joulin and Clavin, Matkowsky and Olagunju, and Booty et. al. have strongly suggested that pulsating and/ or traveling 
wave instabilities arise in high Le number mixtures. 

The first observations of these instabilities were made in the 2.2 second drop tower at NASA LeRC using a lean mixture of 
butane and oxygen diluted with helium (Le_3 .0)1,2. Based on these tests, we realized that the reason the instabilities have 
not been observed earlier is because the oscillation frequency is on the order of 100 Hz (or higher); much too fast to be 
detected by the human eye or at standard video framing rates. 

Consequently, we use a high speed intensified video camera to visualize the flames. We observe two intrinsically unstable 
modes of flame propagation: (1) a pure radial pulsation and (2) a combined radial pulsation and traveling wave instability. 
These modes have been observed at lg and ug which suggests that the instabilities are not buoyantly-induced, but rather 
inherent to the flame itself, caused by an imbalance between heat and mass transport in the presence of chemical reaction. 

One of the most striking features of these high Le number instabilities is that the spatio-temporal patterns rival those 
observed in other excitable media. Specifically, this premixed gas-phase reaction exhibits many of the same features and 
analogous dynamical behavior as numerous biological and chemical systems including the well-studied, liquid-phase 
Belousov-Zhabotinskii (BZ) reaction. Both these premixed gas flames and the BZ reaction exhibit chemical fronts which 
spontaneously develop from single or multiple pacemaker sites into circular ring wave(s) or rotating spiral wave(s). This 
is indicative of self-propagating waves of chemical activity in excitable media believed to affect such diverse phenomena 
as the patterns of spots on animals, the spread of infectious disease, the formation of spiral galaxies, as well as the 
rhythmic beating of a human heart and the solitary voltage pulses which travel along nerve fibers. 

Radiative Flame Extinction at Large Droplet Radius - P. Struk (GSRP) 

Objective: 

To verify experimentally the existence of a limiting large droplet radius above which a spherical steady flame cannot be 
sustained due to gas-phase radiative loss. Large fuel droplets are simulated using a wetted porous sphere continuously 
supplied fuel by a syringe pump. 

Description: 

The research consists of two phases: a ground-based phase and a microgravity phase. The ground-based phase involves the 
development of porous spheres, hardware buildup, as well as ascertaining the feasibility and techniques of using porous 
spheres to simulate droplet burning. In the microgravity phase, wetted porous spheres are burnt in various atmospheric 
conditions to ascertain a droplet flammability map based on droplet diameter. In microgravity, the radius of the droplet is 
varied by adjusting the fuel flow rate to the porous sphere via the syringe pump. 


1 1 — 3 1 3 



II. MSAD Proeram Tasks — Ground-based Research Discipline: Combustion Science 

HtIMIMHIMtt * HI Ml I Ml Mill HI I II I I 


Significance: 

The verification of a limiting large droplet radius will contribute to our understanding of droplet burning and extinction, a 
fundamental topic in combustion. It will also support the premise that gas-phase radiative loss alone can cause diffusion 
flame extinction in fig. 

FY94 Progress: 

Hardware was designed, selected, and assembled. Two sets of experiments were performed during the ground-based phase in 
normal gravity to demonstrate the feasibility of simulating fuel droplets using a wetted porous sphere. In both sets of 
experiments, the fuel used was n-decane. The first set of experiments were performed at atmospheric pressure and used a 
porous bronze sphere, 5 mm in diameter. A wetted fuel surface was not observed during an entire burn due to an excessive 
heat feedback from the flame predominately due to the convective environment. The heat feedback, in turn, causes a high 
fuel consumption rate which the syringe pump could not supply. 

A second set of experiments were performed at roughly 1/3 atmospheric pressure and used a 4 mm porous bronze sphere. A 
wetted fuel surface was observed during an entire burn at these conditions. Reducing the pressure decreased the mass 
burning rate of the fuel (via chemical kinetics). At reduced pressure, the syringe pump could provide fuel to the porous 
sphere at a rate equal to or greater than the consumption rate of the fuel. These results indicate the feasibility of 
controlling the droplet radius in microgravity where convective effects are significantly reduced. 


Students Funded Under Research: 


Task Initiation: i/9i Expiration: 12/95 

BS Students: 

0 

BS Degrees: 

0 

Project Identification: 962-22-05-08 

MS Students: 

0 

MS Degrees: 

0 

Responsible Center: LeRC 

PhD Students: 

2 

PhD Degrees: 

1 



Bibliographic Citations for FY 1994: 

Journals 

Ferkul, P.V. and T’ien, J.S. A model of low-speed concurrent flow flame spread over a thin fuel. Combustion Science and 
Technology ( in print), (1994). 

Hegde, U. Heat release effects on the instability of parallel shear layers. AIAA Journal (accepted), voi. 31 no. 1. 206 
(January 1994). 

Presentations 

Vedha-Nayagam, M. and Hegde. U. "Effects of free stream oscillations on heat transfer to a burning fuel surface.”' Spring 
Meeting of the Combustion Institute, Central States Section. June 1994. 


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IL MSAD Program Tasks — Ground-based Research 



Discipline: Combustion Science 

iitMMimmiiiiimiiifiitiiMiHiMimiitiiiimiiiiiiiinMtMiiiiiitiiiiiiiiiiiiiiiiMiMii 


Combustion of Solid Fuel in Very Low Speed Oxygen Streams 


Principal Investigator: Dr. Kurt r. Sacksteder 

NASA Lewis Research Center (LeRC) 

Co-Investigators: 

No Co-I's Assigned to this Task 



Task Objective: 

The objective of this program is to obtain experimental experience and data to improve the understanding ot the 
mechanisms that control the spreading of flames and the flammability ot materials in low-speed oxidizing flows, 
including buoyantly-driven and forced concurrent flows and buoyantly -driven opposed flows. 

Task Description: 

New and unique experimental apparatus are to be developed to obtain flame spreading observations in partial gravity 
and in forced flows in microgravity. Partial gravity tests are to be conducted aboard NASA research aircraft flying 
parabolic trajectories, altered from the traditional condition of near free tall, to obtain the desired reduced levels ot 
acceleration. Low-speed forced flows are to be obtained in microgravitv drop towers using mechanical devices to 
establish purely-forced (non-buoyant) flows. In each instance, detailed measurements of flame ignition, spreading, 
and limiting behavior are to be made. 

Task Significance: 

This work attempts to provide a fundamental understanding of the practical flame-spreading environment ot 
low-speed flows including: purely buoyant flows in partial gravity (between microgravity and normal gravity), and 
purely forced flows only possible in microgravity. In normal gravity, buoyancy forces induce flows in spreading 
flames having velocities of no less than 20-30 cm/sec. Interactions between flames and lower speed flows, 
therefore, cannot be observed in normal gravity. In the low-speed flow regime, flow velocities approaching the 
spreading velocity of the flames can be examined. These flames are expected to demonstrate entirely new 
spread-rate limiting mechanisms, different than the normal -gravity counterpart. These tests are also expected to 
demonstrate lower flammability limits of solid fuels than any observed in normal gravity. Additionally, this work 
will attempt to distinguish between influences of buoyantly induced flows and flows ot similar intensity that are 
externally imposed. 

Progress During FY 1 994: 

This task was completed dunng fiscal year 1994 with the award of a new flight experiment project enuded, 
’’Combustion of Solid Fuel in Very Low Speed Oxygen Streams,” under NRA-93-OLMSA-1, 'Microgravity 
Combustion Science: Research and Flight Experiment Opportunities.” 

At the transition to the flight program, this task has achieved the following major accomplishments: 

1. A comprehensive testing program of flame spreading and flammability limit determinations tor a thin tuel 
burning in low-speed forced-concurrent flows has been conducted. These experiments include drop tower 
experiments in a microgravity wind tunnel, and experiments in a unique experimental device, developed under this 
program, with which the lowest speed flows are obtained by translating the burning sample through the oxidizing 
environment. In these experiments a low-speed flammability limit has been observed tor lorced flows at about 12% 
oxygen atmospheric mole fraction (normal air is 21% oxygen), far below the opposed-flow limit observed in 
microgravity of about 15% oxygen. Flame spread rates were measured over a wide range ot oxygen environments 
and flow velocities. All forced-flow results were dominated by the ignition process because of the limited testing 
time available in the ground-based facilities. 


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II. MSAD Program Tasks — Ground-based Research Discipline: Combustion Science 


2. A comprehensive testing program of flame spreading and flammability limit determinations tor a thin fuel 
burning upward in purely buoyant (concurrent) flows has been conducted. These experiments were conducted in an 
iiircratt facility operating under partial-gravity conditions. These experiments have demonstrated reduced-gravity 
upward-spreading flammability limits similar to those observed in the low-speed forced flow experiments, and 
similar to the normal gravity upward spreading limit, all approximately 12% oxygen. At the reduced-gravity levels 
obtainable in aircraft testing, (between 0.05 and 0.6 times normal Earth Gravity) the buoyant velocities are 
sufficiently high that flammability limit and flame spread behavior are similar to normal gravity behavior, le. finite 
rate chemical reactions limited by reactant residence times. At these relatively high speed flows (even at 0.05 g) 
flame spread rates are unsteady, because of either inherent unsteadiness or ignition effects. Until lower levels of 
partial-gravity are made available, a transition to "low-but-not-zero” gravity behavior in concurrent flow flame 
spreading cannot be observed. 

3. A comprehensive testing program of flame spreading and flammability limit determinations for a thin fuel 
burning downward in purely buoyant (opposed) flows have been conducted. These experiments were conducted in an 
aircraft facility operating under partial-gravity conditions. These experiments have demonstrated increases in 
flammability as the gravitational acceleration is reduced from normal Earth gravity, to a low of between 13% and 
14% oxygen near 0.05 g compar