Design and optimization of aerospike nozzle for rotating detonation engine

Abstract

Rotating detonation engine (RDE) is increasingly viewed as a viable technology to improve the performance of propulsion devices. At now, the design of RDE faces challenges when integrated with aerospike nozzle due to the large pressure fluctuations of rotating detonation waves. To optimize the nozzle configuration for thrust generation, the current work investigates the performance of RDE combined with various types of aerospike nozzles. The method of designing optimal aerospike nozzle for RDE with annulus combustion chamber is proposed. A series of three-dimensional numerical simulations are conducted to obtain the thrust performance of nozzles based on open-source software OpenFOAM. The flow-field structure, pressure gain in combustor and thrust performance of RDE are investigated. The results suggest that although the instantaneous flow-field in RDE is time-varying, the averaged plume field can be viewed as axisymmetric under-expanded supersonic jets. It's reasonable to use the time-averaged value of physical quantities for nozzle design. For nozzle with inward-bend cowl lip and isentropic ramp surface, the supersonic flow in nozzle undergoes approximate isentropic expansion with minimum loss. The flow at nozzle exit is basically parallel to chamber axis, generating the optimal thrust. This indicates that the aerospike nozzle is a good match for efficient expansion of rotating detonation products for propulsion. Moreover, the stagnation pressure gain in combustor has been greatly improved with the constriction nozzle throat. This suggests that in order to elevate the chamber pressure, the convergence section with nozzle throat should be adopted in RDE just as in traditional rocket engines.