Characteristics of ethylene–air continuous rotating detonation in the cavity-based annular combustor

Characteristics of continuous rotating detonation (CRD) in a cavity-based annular combustor are studied through three-dimensional simulations, which are solved in OpenFOAM with a skeletal chemical kinetics mechanism. The results show that the continuous rotating detonation wave (CRDW) attaches to the outer wall and detaches from the inner wall in the cavity-based annular combustor. A high-temperature recirculation zone is found in the cavity with reactive intermediate species in the cavity-based annular combustor. The cavity is identified as a high-temperature ignition source, which provides heat and active intermediate radicals enhancing the detonability of the combustible gases in front of the CRDW. Consequently, the propagation performance, the propulsive performance, and the detonation combustion intensity are promoted in the cavity-based annular combustor. The propagation mode of the CRDW transforms from an unstable mode to a single-wave mode with the application of cavity. As the cavity deepens from 0 to 15 mm, the propagation velocity significantly increases from 923.21 to 1662.81 m/s and the fuel-based specific impulse increases from 941.91 to 1044.48 s as the cavity depth varies from 0 to 15 mm. Furthermore, the detonation-dominant combustion fraction remarkably improves from 27.21% to 62.29%.