Initiation of oblique detonation waves induced by a blunt wedge in stoichiometric hydrogen-air mixtures

Two-dimensional, oblique detonation waves (ODWs) in a stoichiometric hydrogen-air mixture are simulated with the reactive Euler equations using a detailed chemical reaction model. This study focuses on blunt wedge induced ODWs, which are not only influenced by inflow parameters but also the size of the blunt body. With the inflow parameters of flight altitude of 30 km and flight Mach number M₀ of 8-10, the numerical results demonstrate that the blunt wedge is crucial to initiate the ODW. In the case of M₀=10, the straight wedge without the blunt forebody can initiate the detonation. However, decreasing M₀ causes the failure of initiation, which can be compensated by increasing the radius R₀ of the blunt forebody. By adjusting R₀, two initiation procedures are observed and distinguished: one is the wedge-induced initiation and the other is the blunt forebody-induced initiation. Although both have been independently studied before, in this study, their coexistence is demonstrated, and the mechanism is analyzed for the first time. A theoretical analysis based on the classic initiation theory is performed to elucidate the initiation mechanism, giving a good agreement between the critical radius with numerical results.