Wavefront stability of detached detonation waves around a blunt wedge

Detached detonations generated by blunt wedges represent an important, yet incompletely understood, challenge in hypersonic reactive flows, with significant implications for the stability and efficiency of detonation-based propulsion systems. Here, we investigate the unsteady wave structures of blunt-wedge-induced detached detonations using two-dimensional reactive Euler simulations with a two-step hydrogen–oxygen kinetic model. The analysis reveals that the detached detonation front can be divided into three regimes: a quasi-ZND (Zel'dovich–von Neumann–Döring) structure, a single-triple-point structure, and a double-triple-point structure. Analysis of streamline properties shows that the quasi-ZND regime consists of mixed subsonic and supersonic zones, with a Prandtl–Meyer expansion recovering supersonic uniform flow. In the single-triple-point region, the wavefront configuration can be fully described by shock polar theory, whereas in the double-triple-point region, two distinct triple points emerge: a forward-facing triple point that produces stronger compression effects and a downstream-facing triple point characterized by weaker shock interactions. Reconstruction of triple-point trajectories further revealed region-dependent cellular morphologies, evolving from scattered arcs to straight-line cells and then to inclined fish-scale structures, with cell sizes gradually increasing downstream as the detonation weakens. These findings deepen the physical understanding of detached detonation dynamics by highlighting the critical role of triple-point asymmetry and stability transitions in shaping cellular structures, thereby providing valuable insights for developing reliable detonation-based hypersonic engines.