A numerical study of oblique detonation re-stabilization by expansion waves

Abstract

Oblique detonation engines have significant potential as air-breathing propulsion units because they can undergo self-ignition while providing high combustion efficiency. A key design aspect of such engines is the formation of a stationary oblique detonation wave in the combustor. In the present work, the re-stabilization of oblique detonation by expansion waves induced using a finite wedge was simulated by solving Euler equations in conjunction with an induction-exothermic kinetics model. The numerical results showed that expansion waves interacting with the subsonic region behind the unstable oblique detonation wave can produce a stationary oblique detonation wave on the wedge by eliminating thermal choking. The initiation position was also found to move downstream with decreases in wedge length, while the location of the expansion waves moved upstream. And the critical locations of expansion waves that re-stabilize and initiate an oblique detonation wave were also proposed. A special field structure that comprising two parts separated by unburned gas was observed at the incident Mach number M0=7.5 when the expansion waves located near initiation critical location. The upper and lower parts comprised the detonation and deflagration fields, respectively. In others, the interaction of expansion waves leads to a smaller total pressure loss, so that is beneficial to improve the performance of oblique detonation engine in theory.