Assessment of Reflected Shock Tunnels for Mars Entry Vehicle Ground Testing

Abstract

Recent carbon dioxide studies in reflected shock tunnel testing have noted discrepancies in the shock shapes between experiments and simulations. These have been attributed to freezing vibrational modes unaccounted for in the simulations during the rapid expansion through the nozzle. This study focuses on blunt body CO_2 experiments and simulations in the T5 Reflected Shock Tunnel to examine possible sources of error when making standoff distance and heat flux measurements. The effect of increasing the nozzle area ration to further expand the flow in the nozzle is examined and a method for making consistent standoff distance comparisons from experiments and simulations is developed. Finally, experiments and simulations are compared to theoretical models.