In order to understand the physical and chemical processes which produce the observed spatial morphology of the cometary coma, it is necessary to analyze observational data with physically meaningful models. Thus, a coupled program of theoretical modeling and complementary observational data analysis was undertaken regarding the spatial distributions of neutral gases in the coma. More, specifically, the particular topics of interest are: (1) the theoretical modeling of the nonequilibrium...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC CHEMISTRY, COMETARY ATMOSPHERES, COMETS,...
Journal of Research of the National Institute of Standards and Technology
Topics: free molecular flow theory, aerodynamic drag, aerodynamic eccentricity, aerodynamic torque
264
264
May 6, 2010
05/10
by
Reynolds, T. W.; Richley, E. A
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Numerical solutions of free molecular flow in converging and diverging tubes and slots
Topics: CONVERGENCE, TUBE, DIVERGENCE, FREE MOLECULAR FLOW, IBM 7094 COMPUTER, NUMERICAL ANALYSIS, SLOTS,...
During Space Transportation System (STS) flight 121, higher than predicted radiator outlet temperatures were experienced from post insertion and up until nominal correction (NC) burn two. Effects from the higher than predicted heat loads on the radiator panels led to an additional 50 lbm of supply water consumed by the Flash Evaporator System (FES). Post-flight analysis and research revealed that the additional heat loads were due to Free Molecular Heating (FMH) on the radiator panels, which...
Topics: NASA Technical Reports Server (NTRS), HEAT FLUX, HEATING, SPACE SHUTTLES, SPACE TRANSPORTATION...
A rarefied-flow shuttle aerodynamic model spanning the hypersonic continuum to the free molecule-flow regime was formulated. The model development has evolved from the High Resolution Accelerometer Package (HiRAP) experiment conducted on the Orbiter since 1983. The complete model is described in detail. The model includes normal and axial hypersonic continuum coefficient equations as functions of angle-of-attack, body flap deflection, and elevon deflection. Normal and axial free molecule flow...
Topics: NASA Technical Reports Server (NTRS), ACCELEROMETERS, AERODYNAMIC CHARACTERISTICS, AERODYNAMIC...
214
214
May 23, 2011
05/11
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Romano, R.; Barone, F.; Maddalena, P.; Solimeno, S.; Zaccaria, F.; Manko, M. A.; Manko, V. I
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We discuss a model for interferometric GW antennas illuminated by a laser beam and a vacuum squeezed field. The sensitivity of the antenna will depend on the properties of the radiation entering the two ports and on the optical characteristics of the interferometer components, e.g. mirrors, beam-splitter, lenses.
Topics: AERODYNAMICS, ANGLE OF ATTACK, WIND TUNNEL TESTS, SPACECRAFT MODULES, COMPUTERIZED SIMULATION, DATA...
Results are summarized of various analyses of the exhaust plumes of the space shuttle. Specific topics discussed included: the development of the two-phase plume flow field model, including finite rate chemistry and free molecular effects; analyses of exhaust plume simulation studies; verification of the analytical two-phase plume flow field model; and complete documentation of the two-phase plume computer code.
Topics: NASA Technical Reports Server (NTRS), EXHAUST GASES, FLOW DISTRIBUTION, NOZZLE FLOW, SPACE...
Various transition methods are used here to study the viscous effects encountered in low density, hypersonic flight, through the transition from free molecular to continuum flow. Methods utilizing Viking data, Shuttle Orbiter data, a Potter number parameter, and a Shock Reynolds number were implemented in the Program to Optimize Simulated Trajectories (POST). Simulations of the Aeroassist Flight Experiment (AFE) using open loop guidance were used to assess the aerodynamic performance of the...
Topics: NASA Technical Reports Server (NTRS), AEROASSIST, AERODYNAMICS, FLIGHT TESTS, TRAJECTORY ANALYSIS,...
Two different approaches, the direct simulation Monte Carlo (DSMC) method based on molecular gasdynamics, and a finite-volume approximation of the Navier-Stokes equations, which are based on continuum gasdynamics, are employed in the analysis of a low-density gas flow in a small converging-diverging nozzle. The fluid experiences various kinds of flow regimes including continuum, slip, transition, and free-molecular. Results from the two numerical methods are compared with Rothe's experimental...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, GAS DYNAMICS, MONTE CARLO METHOD,...
The Next Generation Space Telescope (NGST) program and industry partners are developing extremely lightweight mirror designs. NGST development mirrors are being tested at Marshall Space Flight Center. Target temperature for development mirror testing is 35 K. Conduction and radiation are not sufficient to conduct thermal vacuum testing in a reasonable time. Helium gas is injected into the vacuum chamber to accelerate temperature transitions during testing. Free-molecular conduction can be...
Topics: NASA Technical Reports Server (NTRS), FREE MOLECULAR FLOW, MIRRORS, THERMAL ANALYSIS, COMPUTERIZED...
The equations for rigorously calculating the particle flux and density surrounding a cylindrical aperture in the free molecular flow regime are developed and presented. The fundamental equations for particle flux and density from a reservoir and a diffusely reflecting surface will initially be developed. Assumptions will include a Maxwell-Boltzmann speed distribution, equal particle and wall temperatures, and a linear flux distribution along the cylindrical aperture walls. With this...
Topics: NASA Technical Reports Server (NTRS), PARTICLE FLUX DENSITY, CYLINDRICAL BODIES, APERTURES, FLOW...
The impact of photons upon a spacecraft introduces small forces and moments. The magnitude and direction of the forces depend on the material properties of the spacecraft components being illuminated. Which components are being lit depends on the orientation of the craft with respect to the Sun as well as the gimbal angles for any significant moving external parts (solar arrays, typically). Some components may shield others from the Sun.To determine solar pressure in the presence overlapping...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC FORCES, SOLAR RADIATION, SPACECRAFT COMPONENTS,...
The aeroheating environment of the Mars Reconnaissance Orbiter (MRO) has been analyzed using the direct simulation Monte Carlo and free-molecular techniques. The results of these analyses were used to develop an aeroheating database to be used for the preflight planning and the in-flight operations support for the aerobraking phase of the MRO mission. The aeroheating predictions calculated for the MRO include the heat transfer coefficient (CH) over a range of angles-of-attack, sideslip angles,...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC HEATING, MARS RECONNAISSANCE ORBITER, MONTE CARLO...
Calculated results for the aerodynamic coefficients over the range of + or - 90 deg in both pitch and yaw attitude angles for the Aeroassist Flight Experiment (AFE) vehicle in free molecule flow are presented. The AFE body is described by a large number of small flat plate surface elements whose orientations are established in a wind axes coordinate system through the pitch and yaw attitude angles. Lift force, drag force, and three components of aerodynamic moment about a specified point are...
Topics: NASA Technical Reports Server (NTRS), AEROASSIST, FREE MOLECULAR FLOW, ORBIT TRANSFER VEHICLES,...
A proposed configuration for a Space Operations Center is presented in its eight stages of buildup. The on orbit aerodynamic force and moment characteristics were calculated for each stage based upon free molecular flow theory. Calculation of the aerodynamic characteristics was accomplished through the use of an orbital aerodynamic computer program, and the computation method is described with respect to the free molecular theory used. The aerodynamic characteristics are presented in tabulated...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC CHARACTERISTICS, AERODYNAMIC CONFIGURATIONS,...
The aerothermodynamics characteristics of the Mars Global Surveyor spacecraft are investigated and reported. These results have been used by the Mars Global Surveyor mission planners to design the aerobraking phase of the mission. Analytical and Direct Simulation Monte Carlo computer codes were used with a detailed, three dimensional model of the spacecraft to evaluate spacecraft aerobraking characteristics for flight in free molecular and transitional flow regimes. The spacecraft is found to...
Topics: NASA Technical Reports Server (NTRS), AEROTHERMODYNAMICS, TRANSITION FLOW, MONTE CARLO METHOD,...
A crossed beam apparatus has been used to measure the emission and ionization cross sections for the prominent spectral features of Na, Ca, Mg, and Fe in collisions with N2 and O2 over the velocity range of 30 to 120 km/s. From the emission and ionization cross sections, the absolute luminous efficiencies in air were determined over the range of meteor velocities. The maximum luminous efficiencies for the brightest features were: greater than 1 percent for the Na D-lines, 0.2 percent for the Ca...
Topics: NASA Technical Reports Server (NTRS), IONIZATION CROSS SECTIONS, LUMINOUS INTENSITY, METEOROID...
The aeroheating environment of the Mars Reconnaissance Orbiter (MRO) has been analyzed using the Direct Simulation Monte Carlo and free-molecular techniques. The results of these analyses were used to develop an aeroheating database to be used for the pre-flight planning and the in-flight operations support for the aerobraking phase of the MRO mission. The aeroheating predictions calculated for the MRO include the heat transfer coefficient (C(H)) over a range of angles-of-attack, side-slip...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC HEATING, MARS RECONNAISSANCE ORBITER, FREE...
This paper describes highlights of an ongoing validation effort conducted to assess the viability of applying a set of analytic point source transient free molecule equations to model behavior ranging from molecular effusion to rocket plumes. The validation effort includes encouraging comparisons to both steady and transient studies involving experimental data and direct simulation Monte Carlo results. Finally, this model is applied to describe features of two exotic transient scenarios...
Topics: NASA Technical Reports Server (NTRS), EXHAUST GASES, IMPINGEMENT, MONTE CARLO METHOD, PLUMES,...
Atmospheric entry of meteoritic bodies is conveniently and accurately simulated in the laboratory by techniques which employ the charging and electrostatic acceleration of macroscopic solid particles. Velocities from below 10 to above 50 km/s are achieved for particle materials which are elemental meteoroid constituents or mineral compounds with characteristics similar to those of meteoritic stone. The velocity, mass, and kinetic energy of each particle are measured nondestructively, after...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ENTRY SIMULATION, LUMINOUS INTENSITY, METEOR...
A method was devised and calculations were performed to determine the effects of reflected molecules on the aerodynamic force and moment coefficients for a body in free molecule flow. A procedure was developed for determining the velocity and temperature distributions of molecules reflected from a surface of arbitrary momentum and energy accommodation. A system of equations, based on momentum and energy balances for the surface, incident, and reflected molecules, was solved by a numerical...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC COEFFICIENTS, AERODYNAMIC FORCES, FORCE...
A two-dimensional Heat Pipe Transient Analysis Model, 'HPTAM,' was developed to simulate the transient operation of fully-thawed heat pipes and the startup of heat pipes from a frozen state. The model incorporates: (a) sublimation and resolidification of working fluid; (b) melting and freezing of the working fluid in the porous wick; (c) evaporation of thawed working fluid and condensation as a thin liquid film on a frozen substrate; (d) free-molecule, transition, and continuum vapor flow...
Topics: NASA Technical Reports Server (NTRS), APPLICATIONS PROGRAMS (COMPUTERS), COMPUTATIONAL FLUID...
493
493
Jun 9, 2011
06/11
by
Wing, David J.; Giuliano, Victor J
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A sub-scale experimental static investigation of an axisymmetric nozzle with fluidic injection for thrust vectoring was conducted at the NASA Langley Jet Exit Test Facility. Fluidic injection was introduced through flush-mounted injection ports in the divergent section. Geometric variables included injection-port geometry and location. Test conditions included a range of nozzle pressure ratios from 2 to 10 and a range of injection total pressure ratio from no-flow to 1.5. The results indicate...
Topics: AERODYNAMICS, BLUNT BODIES, HYPERSONIC FLOW, TRANSITION FLOW, ANGLE OF ATTACK, FREE MOLECULAR FLOW,...
A model of the Shuttle Orbiter rarefied-flow aerodynamic force coefficients has been derived from the ratio of flight acceleration measurements. The in-situ, low-frequency (less than 1Hz), low-level (approximately 1 x 10(exp -6) g) acceleration measurements are made during atmospheric re-entry. The experiment equipment designed and used for this task is the High Resolution Accelerometer Package (HiRAP), one of the sensor packages in the Orbiter Experiments Program. To date, 12 HiRAP re-entry...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMICS, RAREFIED GAS DYNAMICS, SPACECRAFT REENTRY,...
The hypersonic transitional flow aerodynamics of the Mars Pathfinder and Mars Microprobe capsules are simulated with the direct simulation Monte Carlo method. Calculations of axial, normal, and static pitching coefficients were obtained over an angle of attack range comparable to actual flight requirements. Comparisons are made with modified Newtonian and free-molecular-flow calculations. Aerothermal results were also obtained for zero incidence entry conditions.
Topics: NASA Technical Reports Server (NTRS), AERODYNAMICS, BLUNT BODIES, HYPERSONIC FLOW, TRANSITION FLOW,...
Heat transfer phenomena of rarefied gas flows is discussed based on a literature survey of analytical and experimental rarefied gas dynamics. Subsonic flows are emphasized for the purposes of meteorological thermometry in the high atmosphere. The heat transfer coefficients for three basic geometries are given in the regimes of free molecular flow, transition flow, slip flow, and continuum flow. Different types of heat phenomena, and the analysis of theoretical and experimental data are...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC TEMPERATURE, CONVECTIVE HEAT TRANSFER, HEAT...
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1.2K
Jun 21, 2010
06/10
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NON
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Stabilization and control systems for reentry vehicle
Topics: KNUDSEN FLOW, PARALLEL PLATES, RAREFIED GASES, BOLTZMANN TRANSPORT EQUATION, FLOW VELOCITY, FREE...
198
198
May 22, 2011
05/11
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Forkey, Joseph N.; Lempert, Walter R.; Bogdonoff, Seymour M.; Miles, Richard B.; Russell, G
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We demonstrate the use of Filtererd Rayleigh Scattering and a 3D reconstruction technique to interrogate the highly three dimensional flow field inside of a supersonic inlet model. A 3 inch by 3 inch by 2.5 inch volume is reconstructed yielding 3D visualizations of the crossing shock waves and of the boundary layer. In this paper we discuss the details of the techniques used, and present the reconstructured 3D images.
Topics: APPLICATIONS PROGRAMS (COMPUTERS), PHASE TRANSFORMATIONS, THERMAL ANALYSIS, CAPILLARY FLOW,...
The objective of this research is to numerically simulate the vacuum plume flow field in the backflow region of a low thrust nozzle exit. In space applications, the low thrust nozzles are used as a propulsion device to control the vehicle attitude, or to maneuver the vehicle flight trajectory. When the spacecraft is deployed in the orbit or cruising in a planetary mission, the vacuum plume is created behind the nozzle exit (so called backflow region), by the exhausting gas of the propulsion...
Topics: NASA Technical Reports Server (NTRS), EXHAUST GASES, FREE MOLECULAR FLOW, KNUDSEN FLOW, NOZZLE...
Acceleration data taken from the Orbital Acceleration Research Experiment (OARE) during reentry on STS-62 has been analyzed using calibration factors taken on-orbit. The data includes the flight regime from orbital altitudes down to about 100 km which covers the free-molecule-flow regime and some of the flow-transition into the hypersonic continuum. Ancillary data on orbiter position, orientation, velocity, and rotation rates have been used in models to transform the measured accelerations to...
Topics: NASA Technical Reports Server (NTRS), ACCELERATION (PHYSICS), ACCELEROMETERS, RAREFIED GAS...
234
234
Jul 12, 2010
07/10
by
Pausder, H. J.; Hummes, D
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The tests were performed with the helicopters BO 105 and UH-1D. Closely connected with tactical demands the six test pilots' task was to minimize the time and the altitude over the obstacles. The data reduction yields statistical evaluation parameters describing the control activity of the pilots and the achieved task performance. The results are shown in form of evaluation diagrams. Additionally dolphin tests with varied control strategy were performed to get more insight into the influence of...
Topics: AERODYNAMIC CHARACTERISTICS, TABLES (DATA), AERODYNAMIC CONFIGURATIONS, COMPUTER PROGRAMS, FREE...
Panel flutter is a form of dynamic aeroelastic instability resulting from the interaction between motion of an aircraft structural panel and the aerodynamic loads exerted on that panel by air flowing past one of the faces. It differs from lifting surface flutter in the sense that it is not usually catastrophic, the panel's motion being limited by nonlinear membrane stresses produced by the transverse displacement. Above some critical airflow condition, the linear instability grows to a limit...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC LOADS, FREE MOLECULAR FLOW, HYPERSONICS,...
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222
Jun 19, 2010
06/10
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Bunimovich, A. I.; Kagan, M. L
texts
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Free molecular flow of rarefied gas in plane channels and grids
Topics: CHANNEL FLOW, FREE MOLECULAR FLOW, GAS FLOW, RAREFIED GAS DYNAMICS, RAREFIED GASES, CHANNEL FLOW,...
There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC DRAG, ATMOSPHERIC DENSITY, ESTIMATING, TELEMETRY,...
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Jun 13, 2011
06/11
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Butrica, Andrew J
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Th e decades-long debate over reusable launch vehicles (RLVs) versus expendable launch vehicles (ELVs) has been less a reasoned debate than a sustained argument for the building of reusable launchers instead of the standard throwaway rocket. The single greatest touted advantage of reusable launch vehicles is that they reduce launch costs.' Comparing reusable and expendable rockets is not simple; it is a rather complicated task not unlike the proverbial comparing of apples and oranges. To...
Topics: AERODYNAMIC HEATING, DATA BASES, MARS RECONNAISSANCE ORBITER, FREE MOLECULAR FLOW, MONTE CARLO...
A model of rarefied gas flow in tubes was developed which combines a lobular distribution with diffuse reflection at the wall. The model with Monte Carlo techniques was used to explain previously observed deviations in the free molecular thermal transpiration ratio which suggest molecules can have a greater tube transmission probability in a hot-to-cold direction than in a cold-to-hot direction. The model yields correct magnitudes of transmission probability ratios for helium in Pyrex tubing...
Topics: NASA Technical Reports Server (NTRS), FREE MOLECULAR FLOW, GAS-SOLID INTERFACES, MONTE CARLO...
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253
Jun 20, 2010
06/10
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Lam, L. S.; Lundquist, C. A.; Mendes, G. M
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Satellite experiment design for atmospheric density and near-free molecule flow aerodynamics
Topics: AERODYNAMICS, SATELLITE DRAG, ATMOSPHERIC DENSITY, EXPERIMENT DESIGN, FREE MOLECULAR FLOW,...
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202
Jun 21, 2010
06/10
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Clark, V. C., Jr
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No Abstract Available
Topics: CONTRACTORS, WETTABILITY, EVAPORATION, FREE MOLECULAR FLOW, MATHEMATICAL MODELS, MECHANISM, POROUS...
Acceleration data taken from the Orbital Acceleration Research Experiment (OARE) during reentry on STS-62 have been analyzed using calibration factors taken on orbit. This is the first Orbiter mission which collected OARE data during the Orbiter reentry phase. The data examined include the flight regime from orbital altitudes down to about 90 km which covers the free-molecule-flow regime and the upper altitude fringes of the rarefied-flow transition into the hypersonic continuum. Ancillary...
Topics: NASA Technical Reports Server (NTRS), RAREFIED GAS DYNAMICS, SPACE TRANSPORTATION SYSTEM,...
Free molecular heating (FMH) is caused by the transfer of energy during collisions between the upper atmosphere molecules and a space vehicle. The dispersed free molecular heating on a surface is an important constraint for space vehicle thermal analyses since it can be a significant source of heating. To reduce FMH to a spacecraft, the parking orbit is often designed to a higher altitude at the expense of payload capability. Dispersed FMH is a function of both space vehicle velocity and...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC HEATING, ATMOSPHERIC DENSITY, CONVECTIVE HEAT...
On July 4, 1997, after traveling close to 500 million km, the Pathfinder spacecraft successfully completed entry, descent, and landing at Mars. In the present paper, the focus is on the hypersonic rarefied portion of Pathfinder's atmospheric entry where the synergy of flight measurements, aerodynamic calculations, and atmospheric modeling tools are used to extract Pathfinder's attitude and the freestream density. Accuracy of the capsule aerodynamics directly impacts the inferred atmospheric...
Topics: NASA Technical Reports Server (NTRS), MARS LANDING, MEASURING INSTRUMENTS, SPACECRAFT MOTION,...
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Jul 23, 2010
07/10
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NON
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The conference proceedings contains 14 formal papers and the results of two panel discussions. In addition, a transcript of discussion that followed the paper presentations and panels is included. The papers are of two kinds. The first seven papers were directed specifically to the correlation of industry and government mathematical models with data for rotorcraft stability from six experiments. The remaining 7 papers dealt with related topics in the prediction of rotor aeroelastic or...
Topics: CONTINUUM FLOW, ERROR ANALYSIS, FREE MOLECULAR FLOW, TEMPERATURE MEASUREMENT, THERMISTORS, HEAT...
