Influences of incoming flow on re-initiation of cellular detonations

The study of detonation initiation under supersonic incoming flow is of significance for the supersonic air-breathing propulsion based on detonation waves. By high-resolution simulations based on the 5^th order weighted essentially non-oscillatory (WENO) and a two-step reaction model, this paper addresses the effect of incoming flow on re-initiation as a detonation generated in a pre-detonator propagates into semi-infinite free or confined space. Results show that detonation re-initiation is promoted by incoming flow because the leading shock wave is strengthened at the upstream side. Furthermore, the role of the promotion is quantitatively compared between stable and unstable detonations. Responses of detonation re-initiation to incoming flow velocity are different, which associates with the instability of detonations. Since responses of ignition delay time to the variation of post-shock temperature are different, the unstable detonation is more sensitive than the stable detonation.