Prediction of ultraviolet radiation in nonequilibrium hypersonic bow-shock waves

Ultraviolet emissions radiated by nitric oxide and atomic oxygen are computed for hypersonic nonequilibrium flow conditions corresponding to the Bow-Shock Ultra-Violet-2 flight experiment. The flowfield is analyzed using the direct simulation Monte Carlo method. Radiation is then estimated using a nonequilibrium radiation code. New results are presented that incorporate a number of recent physical and numerical models. Good agreement is obtained between flight data and predictions over a range of altitudes for both nitric-oxide and atomic-oxygen emissions. Sensitivity to a number of modeling assumptions of the emissions predicted at altitudes above 70 km is considered. It is found that the emission is very sensitive to the translational energy accommodation coefficient. It is also extremely sensitive to the freestream chemical composition assumed. By contrast, the high-altitude emission is insensitive to dissociation and exchange reaction models.