Numerical investigations were conducted on the fuel mixing and stabilized combustion processes of an oblique detonation engine under Mach number at Section 8 (Ma8) actual injection conditions. Analysis was performed on how different equivalence ratio distribution ratios affect fuel mixing in the flow channel, identifying the critical ranges for three geometric parameters: the upper wall inflection point, wedge angle, and wedge height, essential for initiating and stabilizing oblique detonation wave. The results indicate that the highest mixing efficiency occurs when the equivalence ratio between the strut injector and the wall injector is 1:1 under conditions of a global equivalence ratio of 1. The upper wall inflection point affects detonation stabilization through its impact on oblique detonation reflection and area expansion. In contrast, the wedge angle and height influence the stable combustion of the oblique detonation by affecting the blockage level. Differing from direct initiation on the wedge face, the stability of oblique detonation combustion in this study is influenced by the level of blockage in the flow channel. In the cases studied in this paper, an oblique detonation wave can achieve initiation and stable combustion when the wedge angle is between 18° and 19° and the wedge height is at least 28 mm.

The stability of oblique detonation waves (ODWs) is a fundamental problem, and resistance of ODWs against disturbances is crucial for oblique detonation engines in high-speed propulsion. In this work, numerical studies on ODW stability in disturbed flows are conducted using the two-dimensional reactive Euler equations with a two-step induction-reaction kinetic model. Two kinds of flow disturbances are, respectively, introduced into the steady flow field to assess ODW stability, including upstream transient high-pressure disturbance (UTHD) and downstream jet flow disturbance (DJFD) with different durations. Generally, an ODW is susceptible to disturbances at larger wedge angles and stable at smaller wedge angles. In the unstable wedge angle range, different ODW structures and transition patterns are obtained after disturbances, including different locations of the primary triple points, different numbers of the steady triple points on the wave surface, and different transition patterns from the leading oblique shock wave to the ODW. It is found that the primary triple point tends to move upstream for the disturbances that can form a local strong detached bow shock wave near the wedge tip. In contrast, the wave surface and the transition pattern are susceptible to all of the disturbances introduced in this study. Despite the unstable responses of the ODWs to the disturbances, the ODWs can keep standing stability after disturbances, which is beneficial to the propulsion application of ODWs.

The typical structure of an oblique detonation wave (ODW) consists of a leading shock wave followed by a coupled shock-flame complex. The distance from the leading shock’s originating point to the ignition onset is referred to as the induction length. This work numerically studies the induction length effect using a two-step induction-reaction kinetic model. Results reveal that the induction length governs the transition pattern of ODWs. By testing four distinct induction lengths, four ODW regimes are identified, including a prompt ODW, a delayed smooth ODW, a delayed abrupt ODW, and a delayed abrupt ODW with an upstream triple point in oscillatory motion. The mechanisms behind these regimes are analyzed in detail. Additionally, hysteresis is observed when the induction length decreases from a larger value, demonstrating that this phenomenon can be influenced by the kinetic process.