Study on initiation mode of oblique detonation induced by a finite wedge

Oblique detonation engines attract more and more attention due to their potential use in hypersonic propulsion, but the initiation of detonation still requires comprehensive study concerning the complicated interaction of wedge, supersonic flow, and heat release. In this study, the effects of the wedge angle on the initiation mode of oblique detonation have been investigated theoretically and with numerical simulation. Detailed chemical reaction models are used, and constant-volume combustion theory that considers the vibration excitation of the gas molecules is applied to study the characteristic length of the induction zone. It is found that the theoretical and numerical characteristic lengths in induction regions are in good agreement. Two initiation modes - kinetics-controlled and wave-controlled - are analyzed in depth at different Mach numbers and wedge angles. The results show that reducing the wedge angle can cause the initiation mode to change from kinetics-controlled to wave-controlled at different Mach numbers. The detailed induction zone length and the transit wedge angles between two initiation modes of wedge-induced oblique detonation have also been found.