PERFORMANCE COMPARISON OF COMBINED FUEL INJECTION METHODS IN A STAGED-COMBUSTION SCRAMJET ENGINE

摘要

In this study, multi-stage fuel injection was applied to a scramjet engine to improve the thrust performance without unstart transition under Mach 6 flight conditions. With multi-stage fuel injection, the engine operated without unstart transition at a fuel equivalence ratio of unity (Φ= 1) or above. Of particular note, for the engine with strut first-stage fuel injection (SV1), the thrust increment from the no fuel condition (△F) reached 2880 N at an equivalence ratio of 1.45 which was about 1.5 times as large as that of the case with single-stage injection and maximum in the previous tests under Mach 6 flight conditions. It was confirmed that multi-stage injection improved the thrust performance without unstart transition. The strut first-stage fuel injection (SV1) was more effective in the multi-stage fuel injection for thrust performance, compared with the sidewall first-stage fuel injection (MV1). Fuel distribution at the engine exit of SV1 based multi-stage fuel injection was more uniform compared with MV1 based multi-stage fuel injection.