Mach 6 Test of a Scramjet Engine with Multi-Staged Fuel Injection

Abstract

In this study, a multi-staged fuel injection was applied to a scramjet engine for improving the thrust performance without un-start transition under Mach 6 flight conditions. A boundary-layer bleeding was also applied for suppressing un-start transition. With the multi-staged fuel injection, the engine operated without un-start transition at the fuel equivalence ratio of unity or above. Especially, with fuel injection strut, the thrust increment from the no fuel condition reached to 2880 N at equivalence ratio of 1.45, which was about 1.5 times as large as the maximum thrust obtained with the single-stage injection in the previous tests in Mach 6 flight condition. It was confirmed that the multi-staged injection improved the thrust performance without un-start transition. Nomenclature Cf = friction coefficient Dint = internal drag of engines F = thrust ∆F = thrust increment from the no fuel condition ∆Fint = net thrust by combustion (∆F-Dint) Isp = specific impulse based on net thrust (∆Fint / mf) mf = fuel mass flow rate p = pressure Φ = equivalence ratio Subscripts