The initiation characteristics of oblique detonation in acetylene-air mixtures in the finite wedge

Oblique detonation waves (ODWs) have been widely studied due to their application in hypersonic propulsion. Most of the previous studies focus on hydrogen fuel, and the induced wedge is always infinite. In this paper, based on the detailed chemical reaction model, the two-dimensional multi-component Euler equations are solved, and the finite wedge-induced oblique detonations for acetylene-air mixtures are investigated numerically and theoretically. Effects of expansion waves, inflow Mach number and equivalence ratio (ER) on initiation characteristics of ODW are studied according to the initiation criterion in the confined space. Results show that the initiation distance of acetylene is relatively larger than the hydrogen fuel, and the convergence position of deflagration waves and the originated position of expansion waves determine the initiation characteristics of ODW. As the originated position of the expansion wave is downstream of the convergence position of the deflagration, the ODW is ignited; Otherwise, the ODW is not initiated. The characteristics length of induction zone presents a U-shaped curve distribution for different ERs, both fuel-rich and lean-burn conditions will result in the non-initiation of ODW.