Numerical study on stabilization of wedge-induced oblique detonation waves in premixing kerosene-air mixtures

The initiation and stabilization features of oblique detonation wave (ODW) in kerosene-air premixing flows are investigated numerically based on the Navier-Stokes equations with a two-step reaction model. The effects of fuel-air equivalence ratios and inflow Mach numbers are considered by a parametric study. The present results indicate that the dependence of ODW initiation distance for kerosene fuel with high density on the equivalence ratio, Φ0, is quasi-linear, which is different from the previous study on the low-density fuel such as hydrogen, but the local transition pressure from the oblique shock wave (OSW) to ODW is non-linear with a critical equivalence ratio around 1.0. In particular, as the equivalence ratio increases from the fuel-lean to fuel-rich conditions, the transition pattern from the OSW to ODW varies: a smooth transition with a curved shock shifts to an abrupt one with a multi-wave point, and the initiation distance decreases, associated with the increase of transition pressure and the unstable detonation front. These are due to combined effects of the increasing inflow Mach number and the increasing fuel-rich mixtures for the exothermic reaction. The former accelerates the chemical reaction rate due to the increase of pressure/temperature of the post-OSW flow, and the latter enlarges the heat release. In particular, a double-ODW wave structure occurs for the fuel-rich mixture with Φ0=1.4, since the inflow reactive mixture cannot be consumed as it crosses the first ODW, resulting in a downstream second ODW. The increasing inflow Mach number results in the acceleration of ODW initiation and stabilizes the ODW within the inflow conditions in this study.