Near-field relaxation subsequent to the onset of oblique detonations with a two-step kinetic model

Abstract

Initiation of oblique detonation wave (ODW) results in a near-field region of curved detonation wave surface, which cannot be predicted by the detonation polar theory and lacks of in-depth work on its features. In this study, Euler equations coupled with a two-step kinetic model are used to simulate ODW dynamics, and then the flow structures are analyzed by examining the asymptotic decay of local surface angle (LSA) and the flow/reaction coupling along streamlines quantified by a non-dimensional Damköhler number Das. The results demonstrate a spectrum of local strong solutions forms, which always happens when the ODW transition pattern is abrupt, but the strong solutions deviate from the isolated strong solution predicted by the polar theory. Furthermore, the abrupt transition leads to a strong peak of Das, defined by the ratio of the characteristic flow and chemical reaction length, while the smooth one leads to a bump. Various simulated cases indicate that the transition pattern becomes abrupt and the local strong solution arises when the maximum Das reaches a critical range.

Criticality for Oblique Detonation Waves Induced by a Finite Wedge in a Hydrogen–Air Mixture

“…Then, a non-dimensional Damköhler number Da s was defined to quantify the flow/reaction. A strong peak of Da s was observed in the abrupt transition, while a bump was observed in the smooth transition [26].…”