Effects of Cowl-Induced Expansion on the Wave Complex Induced by Oblique Detonation Wave Reflection

Abstract

Oblique detonation wave (ODW) reflection on the upper wall leads to a sophisticated wave complex, whose stability is critical to the application of oblique detonation engines. The unstable wave complex characterized with a continuous moving Mach stem has been observed, but the corresponding re-stability adjusting method is still unclear so far. In this study, the cowl-induced expansion wave based on the model with an upper-side expansion wall is introduced, and the ODW dynamics have been analyzed using the reactive Euler equations with a two-step induction–reaction kinetic model. With the addition of a cowl-induced expansion wave, the re-stabilized Mach stem has been distinguished. This re-stability is determined by the weakened secondary reflection wave of lower wall, while the final location of Mach stem is not sensitive to the position of the expansion corner. The re-stabilized ODW structure is also basically irrelevant to the expansion angle, while it may shift to unstable due to the merging of subsonic zones. Transient phenomena for the unstable state have been also discussed, clarifying fine wave structures further.

Special Issue on “Advances in Plasma Diagnostics and Applications”

“…This Special Issue on "Advances in Plasma Diagnostics and applications" of Processes, collects original research and review articles on the most recent plasma applications and the diagnosis of their processes, to elucidate the characteristics of plasma and mechanisms of plasma-induced processes. Wang et al introduced the cowl-induced expansion wave, based on the model with an upper-side expansion wall, and analyzed the oblique detonation wave (ODW) dynamics, employing the reactive Euler equations, with a two-step induction-reaction kinetic model [1]. The numerical results show that the upstream movement of Mach stem can be re-stabilized for the unstable structure, which suggests a feasible adjustment method and the corresponding transient phenomena deserve more attention in future work.…”