超音速来流中爆轰波衍射和二次起爆过程研究

It is an effective way to initiate detonation with the aid of a pre-detonator in the detonation engines, and the initiation process by the pre-detonator has been widely investigated in static and subsonic flows. However, how to initiate a detonation wave with a pre-detonator in the supersonic flow was little dealt with in the literature and still needs to be intensively investigated. The diffraction and re-initiation processes during a planar detonation wave propagates into the supersonic inflow were numerically investigated in this paper. The detonation initiation processes both in a semi-infinite space and a confined channel were studied. The governing equations are two-dimensional in-viscid Euler equations. The high-accuracy WENO scheme was utilized in the simulations. The chemical reaction model is a two-step chain branching kinetic model with induction and reaction steps. The cellular structure of detonation wave is regular which is corresponding to the detonation wave formed in the detonable mixture highly diluted with inert gas. It was shown that the maximum distance of detonation propagation increased as the Mach number of supersonic inflow in the semi-infinite space. More transverse waves were generated outside the kernel zone. However, the re-initiation of detonation was failed in the geometry utilized in this work. In the confined channel, the re-initiation process was greatly influenced by the reflected waves. The emerged flow was compressed at the upstream side when the supersonic inflow was added and the pressure of the shock wave was increased accordingly. Compared with the failure of detonation re-initiation in the static flow, the re-initiation of detonation was successfully triggered in the supersonic inflow with Ma=2.0, despite the two cases used the same geometry. It was because that the wrinkles occurred on the reaction front and then resulted in the generation of transverse waves in the supersonic inflow. Because of the collisions between transverse waves, or between the transverse wave and the wall, the pressure decay of the leading shock wave was suppressed. Consequently, a successful re-initiation of detonation was occurred.