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148
Jun 18, 2010
06/10
by
Zamurayev, V. P
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Steady state problem of laminar flow of radiating- absorbing grey gas in flat plate boundary layer surrounded by black walls
Topics: BOUNDARY LAYERS, GRAY GAS, STEADY STATE, FLAT PLATES, GRAY GAS, LAMINAR BOUNDARY LAYER, LAMINAR...
Investigations of deviations in local thermodynamic equilibrium in stellar atmospheres are summarized. Included are studies in gray and AO star atmospheres.
Topics: NASA Technical Reports Server (NTRS), STELLAR ATMOSPHERES, THERMODYNAMIC EQUILIBRIUM, ADIABATIC...
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159
Jun 12, 2011
06/11
by
Lada, Charles J
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This grant funds a research program to use infrared extinction measurements to probe the detailed structure of dark molecular cloud cores and investigate the physical conditions which give rise to star and planet formation. The goals of this program are to acquire, reduce and analyze deep infrared and molecular-line observations of a carefully selected sample of nearby dark clouds in order to internal structure of starless cloud cores and to quantitatively investigate the evolution of such...
Topics: JP-8 JET FUEL, FIRES, RADIATIVE TRANSFER, COMBUSTION PHYSICS, GRAY GAS, MONTE CARLO METHOD, RAY...
Analyses and numerical procedures are presented to investigate the radiative interactions in various energy transfer processes in gaseous systems. Both gray and non-gray radiative formulations for absorption and emission by molecular gases are presented. The gray gas formulations are based on the Planck mean absorption coefficient and the non-gray formulations are based on the wide band model correlations for molecular absorption. Various relations for the radiative flux and divergence of...
Topics: NASA Technical Reports Server (NTRS), GRAY GAS, INFRARED RADIATION, MOLECULAR ABSORPTION, MOLECULAR...
In this paper a new three dimensional half-moment model for radiative transfer is presented for a gray medium. It describes the evolution of the zeroth and first directional half moments of the radiative intensity. The closure is provided, similarly to Dubroca and Klar, by the maximum entropy concept. This work generalizes that model to three dimensions. The model presented here (the derivation being done in Ripoll and Wray, called the M(sup 1/2)(sub 1) model, is a hyperbolic system consisting...
Topics: NASA Technical Reports Server (NTRS), RADIATIVE TRANSFER, SOLAR ATMOSPHERE, THREE DIMENSIONAL...
A numerical study was conducted to predict the combined convective and radiative heat transfer rates on the walls of a small aspect ratio cylinder representative of the scaled model of arocket engine combustion chamber. A high-temperature, high-pressure environment was simulated in the cylinder, with gas velocities at low subsonic levels typical of the conditions leading to the entrance of the nozzle section of a rocket engine. The composition of the gases in the cylinder was determined from...
Topics: Heat, Radiation and absorption, Rocket engines, Combustion, Radiative Heat Transfer, Rocket Engine,...
Climate models based on global radiative equilibrium are normally so complicated that they require extensive computer codes to provide adequate accuracy. However, by simply modifying the concept of a gray atmosphere, a reasonably correct mean global temperature is obtained. This elementary model is then used to estimate the effects of changes in the abundances of minor infrared absorbers and changes in the solar constant or earth albedo. When applied to a Budyko-Sellers zonally averaged model,...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC HEAT BUDGET, ATMOSPHERIC MODELS, CLIMATOLOGY,...
The following subject areas are covered: the development of detailed nonequilibrium radiation models for molecules along with appropriate models for atoms; the inclusion of nongray radiation gasdynamic coupling in the VSL (Viscous Shock Layer) code; the development and evaluation of various electron-electronic energy models; and an examination of the effects of shock slip.
Topics: NASA Technical Reports Server (NTRS), AEROCAPTURE, AEROSPACE VEHICLES, CHEMICAL REACTIONS, FLOW...
Basic formulations, analyses, and numerical procedures are presented to investigate radiative heat interactions in diatomic and polyatomic gases under local and nonlocal thermodynamic equilibrium conditions. Essential governing equations are presented for both gray and nongray gases. Information is provided on absorption models, relaxation times, and transfer equations. Radiative flux equations are developed which are applicable under local and nonlocal thermodynamic equilibrium conditions. The...
Topics: NASA Technical Reports Server (NTRS), DIATOMIC GASES, GRAY GAS, HEAT FLUX, MOLECULAR GASES, NONGRAY...
Five computational methods for solution of the radiative transfer equation in an absorbing-emitting and non-scattering gray medium were compared on a 2 m JP-8 pool fire. The temperature and absorption coefficient fields were taken from a synthetic fire due to the lack of a complete set of experimental data for fires of this size. These quantities were generated by a code that has been shown to agree well with the limited quantity of relevant data in the literature. Reference solutions to the...
Topics: NASA Technical Reports Server (NTRS), JP-8 JET FUEL, FIRES, RADIATIVE TRANSFER, COMBUSTION PHYSICS,...
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142
May 26, 2011
05/11
by
Hollis, J. M.; Pedelty, J. A.; Kafatos, M
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The R Aqr jet was observed with the VLA B-configuration at two epochs separated by approximately 13.2 yr. Comparison of the resulting 6 cm continuum images show that the radio jet has undergone a lateral counterclockwise rotation of approximately 6 deg-12 deg on the plane of the sky. The model of jet parcels on independent trajectories is difficult to reconcile with these observations and leads us to consider a path-oriented jet (i.e., younger parcels follow the same path as older parcels)....
Topics: AEROSPIKE ENGINES, X-33 REUSABLE LAUNCH VEHICLE, COMPUTATIONAL FLUID DYNAMICS, FINITE DIFFERENCE...
Basic formulations, analyses, and numerical procedures are presented to study radiative interactions in gray as well as nongray gases under different physical and flow conditions. After preliminary fluid-dynamical considerations, essential governing equations for radiative transport are presented that are applicable under local and nonlocal thermodynamic equilibrium conditions. Auxiliary relations for relaxation times and spectral absorption models are also provided. For specific applications,...
Topics: NASA Technical Reports Server (NTRS), ENERGY TRANSFER, GAS-SOLID INTERACTIONS, GRAY GAS, MOLECULAR...
A technique was developed for predicting the character and magnitude of the shock wave precursor ahead of an entry vehicle and the effect of this precursor on the vehicle flow field was ascertained. A computational method and program were developed to properly model this precursor. Expressions were developed for the mass production rates of each species due to photodissociation and photoionization reactions. Also, consideration was given to the absorption and emission of radiation and how it...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE VEHICLES, CHEMICAL REACTIONS, COMPUTER PROGRAMS,...
A computational heat transfer design methodology was developed to study tbe dual-engine linear aerospike plume-induced base-heating environment during one power-pack out, in ascent flight. It includes a three-dimensional, finite volume, viscous, chemically reacting, and pressure-based computational fluid dynamics formulation, a special base-bleed boundary condition, and a three-dimensional, finite volume, and spectral-line-based weighted-sum-of-gray-gases absorption computational radiation heat...
Topics: NASA Technical Reports Server (NTRS), AEROSPIKE ENGINES, X-33 REUSABLE LAUNCH VEHICLE, BASE...
Premixed gas flames in mixtures of CH4, O2, N2, and CO2 were studied numerically using detailed chemical and radiative emission-absorption models to establish the conditions for which radiatively induced extinction limits may exist independent of the system dimensions. It was found that reabsorption of emitted radiation led to substantially higher burning velocities and wider extinction limits than calculations using optically thin radiation models, particularly when CO2, a strong absorber, is...
Topics: NASA Technical Reports Server (NTRS), RADIATIVE HEAT TRANSFER, ABSORPTION SPECTRA, EXHAUST GASES,...
Computational analysis is conducted to study the effect of an aerospike engine plume on X-33 base-heating environment during ascent flight. To properly account for the effect of forebody and aftbody flowfield such as shocks and to allow for potential plume-induced flow-separation, thermo-flowfield of trajectory points is computed. The computational methodology is based on a three-dimensional finite-difference, viscous flow, chemically reacting, pressure-base computational fluid dynamics...
Topics: NASA Technical Reports Server (NTRS), AEROSPIKE ENGINES, PLUMES, BASE HEATING, BOUNDARY LAYER...
Analyses and numerical procedures are presented for infrared radiative energy transfer in gases when other modes of energy transfer occur simultaneously. Two types of geometries are considered, a parallel plate duct and a circular duct. Fully developed laminar incompressible flows of absorbing-emitting species in black surfaced ducts are considered under the conditions of uniform wall heat flux. The participating species considered are OH, CO, CO2, and H2O. Nongray as well as gray formulations...
Topics: NASA Technical Reports Server (NTRS), DUCTED FLOW, GAS FLOW, GRAY GAS, INFRARED RADIATION, LAMINAR...
A computational heat transfer methodology was developed to study the dual-engine linear aerospike plume induced base-heating environment during one power-pack out, in ascent flight. One power-pack out results in reduction of power levels for both engines. That, in turn, reduces the amount of base-bleed and changes the distribution of base-bleed on the two pillows. Hence, the concern of increased base-heating during power-pack out. The thermo-flowfield of the entire vehicle was computed. The...
Topics: NASA Technical Reports Server (NTRS), AEROSPIKE ENGINES, X-33 REUSABLE LAUNCH VEHICLE, BASE...
