Effects of Residual Radicals on Scramjet Engine Testing

Abstract

Scramjet engines are tested by using the RamJet engine Test Facility (RJTF) under Mach 4 to 8 conditions, where a storage heater (S mode) and a combustion air heater (vitiation: V mode) are used to raise the air temperature. The effects of air heating methods on scramjet engine performance were investigated using a chemical kinetic code, LSENSAt first, dependence of dissociation time of O₂ was investigated to evaluate the amounts of radicals supplied to scramjet engines in test facilities. Residual radicals in the S mode, the V mode, shock tunnels, were evaluated for the various nozzles. Then, autoignition criteria with radicals and H₂O addition were calculated for a scramjet flow. Then the possibility of autoignition in boundary layers was examined for M 6 and M 8 conditions. No differences in the S and V modes were found in chemical and flow fields in the engine tests in the RJTF.