Mechanisms of irregular Mach reflections in cellular gaseous detonation fronts

This paper investigated the Mach reflection behaviors in detonation fronts to address the issue of the expansion, multiplication, and breakdown of the cellular structures in a diverging detonation. It employs the reactive Euler equations with a two-step Arrhenius chemistry model. Several pairs of Mach reflection structures producing different cell patterns were used as initial conditions to simulate the propagation of cellular detonation in a rectangular channel of single-cell width. The Adaptive Mesh Refinement method is used to capture a high-resolution Zeldovich–von Neumann–Döring structure. The numerical results reveal that, in the regular cellular pattern, the collision of stronger transverse waves generates a larger cell size. In the irregular cellular pattern, we observed two triple-point-adding mechanisms: strengthening weak aerodynamic structures in detonation fronts by shock compression and generating a new Mach stem adjacent to an existing one. And we found two failure forms of the cellular pattern: the structural failure caused by the collision of Mach stems instead of transverse waves, which is due to the very strong transverse waves, and the intensity failure caused by the decay of Mach stems from a detonation to a shock. These observations and findings could, in some way, guide practical engineering applications in detonation-based propulsion systems.