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  • 1
    Publication Date: 2019-11-01
    Print ISSN: 0376-0421
    Electronic ISSN: 1873-1724
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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  • 2
    Publication Date: 2019-11-15
    Description: The Hypersonic Materials Environmental Test System arc-jet facility located at the NASA Langley Research Center in Hampton, Virginia, is primarily used for the research, development, and evaluation of high-temperature thermal protection systems for hypersonic vehicles and reentry systems. In order to improve testing capabilities and knowledge of the test article environment, a detailed three-dimensional model of the arc-jet nozzle and free-jet portion of the flow field has been developed. The computational fluid dynamics model takes into account non-uniform inflow state profiles at the nozzle inlet as well as catalytic recombination efficiency effects at the probe surface. Results of the numerical simulations are compared to calibrated Pitot pressure and stagnation-point heat flux for three test conditions at low, medium, and high enthalpy. Comparing the results and test data indicates an effectively fully-catalytic copper surface on the heat flux probe of about 10% recombination efficiency and a 2-3 kPa pressure drop from the total pressure measured at the plenum section, prior to the nozzle. With these assumptions, the predictions are within the uncertainty of the stagnation pressure and heat flux measurements. The predicted velocity conditions at the nozzle exit were also compared and showed good agreement with radial and axial velocimetry data.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-29443 , Journal of Thermodynamics and Heat Transfer (e-ISSN 1533-6808); 33; 1; 199-209
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-13
    Description: This work quantifies the backshell radiative heating experienced by payloads on human- scale vehicles entering the Martian atmosphere. Three underlying configurations were studied: a generic sphere, a sphere-cone forebody with a cylindrical payload, and an ellipsled. Computational fluid dynamics simulations of the flow field and radiation were performed using the LAURA and HARA codes, respectively. Results of this work indicated the primary contributor to radiative heating is emission from the CO2 IR band system. Furthermore, the backshell radiation component of heating can persist lower than 2 km/s during entry and descent. For the sphere-cone configuration a peak heat flux of about 3.5 W/cm(exp. 2) was observed at the payload juncture during entry. At similar conditions, the ellipsled geometry experienced about 1.25 W/cm(exp. 2) on the backshell, but as much as 8 W/cm(exp. 2) on the base at very high angle of attack. Overall, this study sheds light on the potential magnitudes of backshell radiative heating that various configurations may experience. These results may serve as a starting point for thermal protection system design or configuration changes necessary to accommodate thermal radiation levels.
    Keywords: Fluid Mechanics and Thermodynamics; Numerical Analysis
    Type: NF1676L-25743 , AIAA Aviation Forum 2017; Jun 06, 2017 - Jun 09, 2017; Denver, CO; United States
    Format: application/pdf
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