Shock dynamics and expansion characteristics of an aerospike nozzle and its interaction with the rotating detonation combustor

Abstract

The flow of products through the aft-end of a detonation combustor is intrinsically unsteady, ultimately resulting in periodic and nonuniform flow parameters at the exit plane of a rotating detonation combustor. Therefore, the integrated design of the nozzle and combustion chamber is an important challenge in rotating detonation engines (RDEs). This paper describes a thorough three-dimensional numerical simulation of a hydrogen–air rotating detonation combustor with/without an aerospike nozzle and investigates the nozzle flow without a combustor. The simulation results allow us to analyze the coupling characteristics of the rotating detonation combustor and the aerospike nozzle. The new features of the shock wave dynamics and expansion characteristics in the nozzle with/without an integrated RDE combustor are compared. For the same rotating detonation combustor exit, the propagation mode of the detonation wave and backpressure in the RDE combustor exit are affected by the aerospike nozzle. The intensity of the shock wave and the angle with respect to the direction of the air flow are lower with the aerospike nozzle than in the nozzleless model, which is consistent with the effect of backpressure increase on the shock dynamics. Regardless of whether the nozzle is connected to the combustor, the nozzle affects the dynamic alternation of the design point state to over-expansion and under-expansion along the circumferential direction. The shock wave intensity and total pressure recovery inside the nozzle with the combustor are slightly stronger than those in the nozzle without the combustor. Consequently, the thrust and total pressure recovery of the nozzle integrated with the RDE combustor are enhanced by 7% and 5.6%, respectively. Thus, decoupling the nozzle from the rotating detonation combustor is feasible for testing the design performance of the unsteady nozzle.