Flow characteristics and stability of induced shock waves in the isolator of rotating detonation ramjet under flight Mach number 2.5 conditions

A 3D numerical simulation of a rotating detonation ramjet engine (RDRE) with isolator and combustor was performed under flight Mach number 2.5 conditions. Factors that influence the stable operation of isolator, such as equivalence ratio, length and expansion ratio of the isolator, were systematically investigated. The structure and stability mechanism of shock wave in the isolator wave were also investigated. Results show that the shock waves in the isolator are mainly composed of the spiral shock wave band (SSWB) and the leading shock wave (LSW), which are induced by the detonation wave and the strong disturbance of SSWB in the supersonic incoming flow, respectively. The airflow behind the LSW obtains the total pressure gain caused by the work of SSWB, when SSWB moves toward the isolator inlet. The speed of LSW is mainly affected by the pressure of detonation wave. The greater the pressure of the detonation wave, the faster the speed of LSW. When the total pressure at the leading edge of SSWB is lower than that of the incoming flow, LSW will stabilize in the isolator. A concept of critical pressure ratio was proposed in the present study, which is the ratio of the average total pressure of the rotating detonation wave to the total pressure at the isolator inlet. In the research configuration and working conditions of this paper, the critical pressure ratio is slightly smaller than 6 when the equivalence ratio of H2/Air premixed mixture is 0.7, below which the isolator can work continuously and stably.(c) 2022 Elsevier Masson SAS. All rights reserved.