Numerical Study of Oblique Detonation Initiation Assisted by Local Energy Deposition

TL;DR

This paper numerically investigates how local energy deposition, especially pulsatile energy, can assist in reliably initiating oblique detonation waves on finite wedges, which is vital for stable oblique detonation engine operation at low Mach numbers.

Contribution

It introduces a novel numerical analysis of plasma-based energy deposition techniques for oblique detonation wave initiation, highlighting pulsatile energy as an efficient aid under extreme conditions.

Findings

Pulsatile energy deposition achieves sustainable detonation with less power.

On-wedge initiation fails at low Mach without assistance.

Minimum pulse frequency is identified for successful initiation.

Abstract

Reliable initiation of oblique detonation waves (ODWs) is crucial for the stable operation of oblique detonation engines (ODEs), especially under flight conditions of low Mach numbers and/or high altitudes. In this case, conventional initiation approaches relying solely on a fixed-angle wedge may engender risks of initiation failure, which necessitates extra initiation assistance measures. In this study, ODW initiation over a finite wedge with local energy deposition is numerically investigated to assess the thermal effects of plasma-based initiation assistance techniques. Particular emphasis is put on the effects of forms and magnitudes of energy deposition on initiation modes and flow field structures of ODWs. The results demonstrate that on-wedge initiation of ODWs fails at a low Mach number without any energy depositions. In contrast, both continuous and pulsatile local energy depositions can effectively initiate ODWs, leading to sustainable detonation on the finite wedge. As continuous energy deposition power or pulsatile single pulse energy increases, several key detonation initiation modes emerge sequentially. Analysis of the spatiotemporal evolution of the primary wave structures under single-pulse energy deposition reveals the minimum pulse repetition frequency required for sustainable on-wedge detonation, which is subsequently verified through multi-pulse energy deposition simulations. Nevertheless, it is found that sustainable on-wedge detonation can be achieved by pulsatile energy deposition with an average power consumption of less than 10% of that required for continuous energy deposition while maintaining a same initiation length, suggesting that the pulsatile one is an efficient way of energy deposition for initiation assistance of ODWs on finite wedges under extreme flight conditions.