Numerical modelling of oblique shock and detonation waves induced in a wedged channel

摘要

A computational study of wedge-induced oblique shock and detonation wave phenomena in the flow of a combustible mixture over a wedged channel is presented with the purpose of understanding the fundamental gasdynamics of the waves and their interactions. A two-dimensional, time accurate, finite-volume-based method was used to perform the computations, and a five-species, two-step chemical reaction is assumed for a stoichiometric hydrogen–air mixture. The combustion channel is made of a wedged section followed by a constant area section. The simulation was performed with wedges of up to 20° semi-angle and Mach numbers from 1.25 to 6, with other inflow parameters fixed. Within the computational domain either propagating or standing shock and detonation wave configurations were obtained depending on the flow Mach number and the wedge semi-angle. Four flow modes, namely, a propagating detonation wave, a standing detonation wave, a propagating shock wave, and a standing shock wave mode were identified. The two detonation-based modes were emphasized. Detonation initiation, propagation, and the induced wave interactions of these modes were investigated. The shock-based modes were also studied briefly. Phenomena explored included overall wave structures, detonation initiation arising from shock coalescence, location of initiation, and double detonation initiation. The physical mechanisms of these phenomena were analysed.