This paper presents an overview of the analysis and measurements of equilibrium radiation obtained in the NASA Ames Research Center’s Electric Arc Shock Tube facility as part of testing for the multipurpose crew vehicle. These experiments were aimed at measuring the level of radiation encountered during conditions relevant to lunar return into Earth’s atmosphere. Subsequently, the targeted testing conditions ranged from 8 to and 0.1 to 1.0 torr (13.3 to 133 Pa). A comprehensive comparison between the spectrally resolved absolute radiance measured in the Electric Arc Shock Tube facility and the predictive tools (NEQAIR and HARA), is presented. To provide a more accurate representation of the uncertainty, the current predictive capability has been calculated as a function of velocity. The results of the analysis have shown that both models underpredict the experimental data at lower shock speeds (less than ), with the agreement improving with increasing shock speed. At shocks speeds greater than , the agreement between the codes and the experiment is within one standard deviation in the scatter of the experimental result. Discrepancies at lower speeds have been attributed to a higher than equilibrium level of electron number density in the Electric Arc Shock Tube flow. Furthermore, power law coefficients characterizing the radiance versus the velocity relationship measured in the Electric Arc Shock Tube are presented for ease of conducting future experimental and computational comparisons.
Uncertainty Analysis and Validation of Radiation Measurements for Earth Reentry
Journal of Thermophysics and Heat Transfer ; 29 , 2 ; 209-221
2015-01-02
13 pages
Article (Journal)
Electronic Resource
English
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