Experimental investigation on flame stabilization of a kerosene-fueled scramjet combustor with pilot hydrogen

Flame stabilization in a kerosene-fueled scramjet combustor was investigated experimentally through Schlieren, flame luminosity, and wall pressure measurement, aiming to obtain better insight into combustion characteristics. Experiments were conducted in a direct-connected supersonic combustion facility with inflow conditions of Mach number 2.0, stagnation pressure 0.82 MPa, and temperature 950 K, simulating the flight condition of Mach number 4.0. Results revealed that kerosene was able to be ignited when the equivalence ratio of pilot hydrogen reached 0.080, but was unsuccessful when the equivalence ratio was 0.040. Once ignited, the intense combustion induced high back pressure forcing the flame to spread into the isolator. The pilot flame invariably appeared in the cavity shear layer and attached to the cavity ramp under different equivalence ratios of pilot hydrogen. With the mass flux of pilot hydrogen increased, the kerosene flame located near the cavity ramp was asymmetrical and unstable since it propagated upstream repeatedly. Therefore, the kerosene could be ignited by a suitable equivalence ratio of continuous pilot hydrogen, potentially accompanied with unstable combustion.