4 . TITLE AND SUBTITLE An Analysis of Combustion Studies in Shock Expansion Tunnels and Re ected Shock Tunnels

The e ect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in highspeed ows for a simulated Mach 17 ight condition was investigated by analyzing the results of comparative combustion experiments performed in a re ected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes nite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and that the presence of the nonequilibrium partially dissociated oxygen in the re ected shock tunnel enhances the combustion. Methods of compensating for the e ect of dissociated oxygen are discussed.