Comparison of theory with experiment for the bow shock ultraviolet rocket flight

Abstract

Comparison is made between the results obtained from a state-of-the-art thermochemical nonequilibrium flowfield and radiation code and data obtained from a recent experiment. The experiment obtained the first measurements of ultraviolet radiation from the shock-heated gas in the nose region of a 0.1016-m nose radius vehicle traveling at about 3.5 km/s at altitudes between 37-75 km. The preflight computations agree at low altitudes but underpredict the data at high altitudes. Postflight flowfield and radiation sensitivity studies suggest improvements for the models at high altitudes. Specifically, excitation mechanisms that contribute to production of NO gamma-band emission need to be revised. Altitude dependence of the radiation observed from the OH radical can be understood in terms of nonequilibrium chemistry in the flow.