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  • 1
    Publication Date: 2019-06-27
    Description: Design, calibration, and use of radiometers to measure spectral emission in ballistic range and shock tube experiments
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TN-D-5360
    Format: application/pdf
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  • 2
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 22; 46-53
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  • 3
    Publication Date: 2019-07-13
    Description: Chemically reacting stagnation point boundary layers with wall injection of gas, comparing multicomponent solution with binary approximation and chemical simplifications
    Keywords: FLUID MECHANICS
    Type: HEAT TRANSFER AND FLUID MECHANICS INST., MEETING, 22ND, U.S. NAVAL POSTGRADUATE SCHOOL; Jun 10, 1970 - Jun 12, 1970; MONTEREY, CA
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  • 4
    Publication Date: 2019-07-10
    Description: The High Frequency Radiometer (HFR) is the only instrument on the Aeroassist Flight Experiment (AFE) with sufficient temporal resolution to discern the frequency of unsteady wake oscillations. Determining both the frequency and amplitude of wake unsteadiness during AFE atmospheric entry is essential for reliably predicting the geometry and motion of the wake of future Aeroassisted Space Transfer Vehicles (ASTV). These parameters directly affect the location and size of the pay- load and the weight of the required afterbody heat protection. The purpose of the AFE is to validate the technologies required for the design of ASTVs, which will be used to exploit Earth-lunar space. This validation will be conducted at a combination of vehicle size, altitude, and velocity not obtainable in ground-based facilities. The AFE will provide the experimental flight data needed to improve our understanding of hypersonic-wake physics and to validate computational predictions of the aerodynamic and heating loads, including afterbody radiative heating loads, on an ASTV. Reliable prediction of ASTV wake flows will ensure that payloads are located within the shear-layer envelope and will determine the amount of thermal protection the payloads require. Specifically, understanding the temporal nature of the wake unsteadiness is important for two reasons. Most importantly, analysis of ground-based experiments suggests that wake unsteadiness results in a variation of as much as +/- 5 deg in the shear-flow turning angle. This angle must be reliably predicted to avoid shear-layer impingement on the vehicle afterbody, which would result in heating rates of about 10 W/sq cm, of the same order as on the forebody stagnation point. Secondly, the energy associated with wake unsteadiness will reduce the static enthalpy of the wake fluid and cause an error of as much as 30% in the amount of predicted wake radiative heating. Therefore, the HFR flight data, which will quantify the frequency and amplitude of the wake unsteadiness, are required for the verification of computational models of ASTV flowfields. Measurement of wake unsteadiness has been endorsed by the Peer Science Steering Group and the AFE Computational Fluid Dynamics (CFD) Working Group. The Peer Science Steering Group has stressed that a reliable measurement of the wake unsteadiness is fundamental because incorporating unsteadiness represents a substantial challenge to the CFD community, and a reliable measurement will raise confidence in the computer simulation. The AFE CFD Working Group has stated that 44 any data which would prove the existence and effects of unsteady flow would be extremely valuable.
    Keywords: Aerodynamics
    Type: A-90321
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  • 5
    Publication Date: 2019-07-13
    Description: Study of the vaporization characteristics of samples of ATJ graphite, a material that has been considered for use on a Jovian probe. These samples were subjected to radiative heating loads of approximately 2 kW/sq cm in argon atmospheres of pressures from 0.00046 to 1 atm. Surface temperatures, mass loss rates, and spatially resolved emission spectral data were recorded. These data are analyzed to determine carbon vapor pressure as a function of temperature and are compared with current models for the vapor pressure of carbon. The effects of finite vaporization (i.e., nonequilibrium) rates are considered and compared with experiment. Estimates of the heat of vaporization from an energy balance are also presented.
    Keywords: THERMODYNAMICS AND COMBUSTION
    Type: AIAA PAPER 72-296 , American Institute of Aeronautics and Astronautics, Thermophysics Conference; Apr 10, 1972 - Apr 12, 1972; San Antonio, TX
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  • 6
    Publication Date: 2019-07-13
    Description: Implicit methods developed by Beam and Warming (1978 and Briley and McDonald (1977) make it possible to overcome the hyperbolic stiffness of the conservative compressible Navier-Stokes equations in the fine wall region computational mesh for high Reynold's number flow. Certain difficulties related to the use of these methods could be overcome by employing an approach reported by Roe (1981). In the present investigation Roe's conceptual framework has been adopted for constructing globally conservative finite difference methods. A globally conservative upwind finite difference method (CSCM) consisting of both implicit interior point and boundary point equations is constructed from a new characteristics based flux difference splitting. It is found that the employed upwind eigenvector split scheme which combines fully coupled implicit interior point and boundary point approximations has the desired properties of robust stability and accuracy.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 82-0837 , Joint Thermophysics, Fluids, Plasma and Heat Transfer Conference; Jun 07, 1982 - Jun 11, 1982; St. Louis, MO
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  • 7
    Publication Date: 2019-07-13
    Description: A new code for the simulation of full (forebody and base region) flowfields about bluff bodies in the hypersonic regime of severe planetary entry is described. The present 'maximally conservative, maximally differenced' formulation of the unsteady compressible Navier-Stokes equations for 2-D axisymmetric 3-D flow is contrasted for stability with previous formulations of Viviand, Kutler, et al, and Thomas and Lombard. Discrete metric relations peculiar to the axisymmetric finite volume formulation are presented along with a general discussion of their relations to and consequences of failure to close computational cells. A computational mesh of curvilinear coordinate topology singular in the flow regime is presented that permits aligned capturing of the major physical features of the complex flowfield.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 80-0065 , Aerospace Sciences Meeting; Jan 14, 1980 - Jan 16, 1980; Pasadena, CA
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  • 8
    Publication Date: 2019-07-13
    Description: The ablation of carbonaceous materials in a hydrogen-helium stream has been simulated using a charring materials ablator computer code. These results are compared with the first ablation data to be obtained from the Ames-NASA Giant Planet Pilot Facility. Test stream diagnostics and ablation effects on convective and radiative heat transfer are discussed since these parameters constitute important input data to the numerical simulation. Graphite ablation was predicted to within 10 to 20%, and carbon-phenolic somewhat less accurately.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 78-866 , Thermophysics and Heat Transfer Conference; May 24, 1978 - May 26, 1978; Palo Alto, CA
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  • 9
    Publication Date: 2019-07-13
    Description: Real gas, inviscid supersonic flow fields over a three-dimensional configuration are determined using a factored implicit algorithm. Air in chemical equilibrium is considered and its local thermodynamic properties are computed by an equilibrium composition method. Numerical solutions are presented for both real and ideal gases at three different Mach numbers and at two different altitudes. Selected results are illustrated by contour plots and are also tabulated for future reference. Results obtained compare well with existing tabulated numerical solutions and hence validate the solution technique.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 83-0581 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 10, 1983 - Jan 13, 1983; Reno, NV
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  • 10
    Publication Date: 2019-07-13
    Description: Solutions are presented for the aerothermal heating environments and the material thermal response for the forebody heatshield on the candidate 242 kg Galileo probe entering the modeled nominal and cold-dense Jovian atmospheres. In the flowfield analysis, a finite difference procedure was employed to obtain benchmark predictions of pressure, radiation and convective heating rates (both laminar and turbulent) and the corresponding wall blowing obtained under the steady state approximation. The fluxes over the probe flank were found to be in a range where spallation is an important mass loss mechanism. The predicted heating rates were also used as boundary conditions for a charring materials ablation which was used to predict thermochemical based surface recession, mass loss and bondline temperatures. The contingency factor of 30% currently employed by NASA was found to be insufficient for entry into the cold-dense atmosphere.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ASME PAPER 80-ENAS-24 , Intersociety Environmental Systems Conference; Jul 14, 1980 - Jul 17, 1980; San Diego, CA
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