Experimental Research on Hydrogen and Hydrocarbon Fuel Ignition for Scramjet at Ma=4

Ignition experiments of Hydrogen and Ethylene were performed on direct-connected pulse combustion facility. Air stagnation temperatures were 900 K and stagnation pressures were 0.8 MPa, the entrance Mach number was approximate 2.0 provided by a two-dimension nozzle. The experimental results indicate that: (1) Hydrogen self-ignition won’t occur at stagnation 935 K when it is injected upstream the cavity in this combustor model. But with low input power igniter, hydrogen can be ignited reliably. (2) Ethylene cannot be ignited with igniter only even at high igniter power. Under the assistant of both igniter and pilot Hydrogen, Ethylene can be ignited reliably and maintain stable combustion after the igniter and pilot hydrogen completely turned off. (3) The lowest equivalence ratio of pilot hydrogen for successful ethylene ignition is 0.05 below that ignition will fail. (4) When pilot hydrogen and igniters were both employed for ignition, the function of igniter is to ignite the hydrogen and the input power of igniter has no influence on ignition performance.