Destabilization mechanism of oblique detonation induced by the recirculation zone in a channel flow

The stability of flow structures is crucial for the combustion efficiency of oblique detonation waves (ODWs). Prior studies have predominantly attributed the destabilization of ODWs to the merging of subsonic regions behind detonation Mach stem. However, the flow structures of ODWs in channels are complex, probably leading to a variety of destabilization mechanisms. This study numerically investigates the ODWs under the influence of viscosity using a detailed chemical reaction model. Results show that the recirculation zone on the lower channel wall plays an important role in the stability of the detonation wave system, which has been ignored in most studies. Specifically, when the secondary reflected shock generated by the lower recirculation zone interacts with the recirculation zone on the upper wall, it triggers the continuous growth of the upper recirculation zone and the formation of an aerodynamic throat. This ultimately leads to flow choking and destabilization of the detonation waves. Based on the above findings, we further evaluate the effectiveness of a moving wedge in regulating the unstable ODWs. It is found that promptly moving the wedge downstream can suppress the upstream movement of the lower recirculation zone, preventing secondary reflected shocks from disrupting the upper recirculation zone. As a result, the unstable detonation wave system is successfully re-stabilized.