Experimental study on rocket jet-driven ignition and scramjet combustion in a kerosene-fueled RBCC combustor

Stable operation of RBCC engine in the scramjet mode is important to realize its wide airspace and high-speed flight envelope. Reliable ignition and flame stabilization of secondary fuel in the RBCC combustor have vital impacts on the engine performance in the scramjet mode. With no additional auxiliary ignition, the high-temperature jet formed by the embedded rocket can serve as a pilot flame to aid in igniting and burning the secondary fuel. The function mechanism of the embedded rocket on the characteristics of ignition and flame holding of the kerosene is studied through ground direct-connect test. The experimental results show that the embedded rocket operating at a low mass flow rate and in fuel-rich state can reliably guide the flame source, enhance the mixing of the kerosene/air and improve the combustion in the combustor. The kerosene can be ignited rapidly and achieve stable combustion driven by the high-temperature rocket jet. After the embedded rocket is completely shut down, the intensity of the shock train in the isolator decreases significantly, whilst the inner pressure reduces by 34.7%. However, the scramjet combustion can still self-sustain stably through the synergistic flame stabilization of the cavity and the fuel struts, while the combustion pressure in the combustor changes slightly by only 0.64%.