Refraction and reflection of detonation waves at inclined gas interfaces

This numerical study investigates the two-dimensional refraction of detonation waves at inclined gas interfaces separating two hydrogen–oxygen mixtures with different argon dilutions. One-dimensional analysis of shock transmission reveals the relationship between the post-shock states and the argon dilution of the receiver gas, serving as a benchmark for the two-dimensional numerical study. In two-dimensional refraction at gas interfaces, regular or irregular reflections can occur depending on the argon dilution and interface incline angle, with self-similarity for inert shocks and nonself-similarity for detonations due to chemical reactions. For argon-rich interfaces, an oblique detonation is observed connecting the incident detonation above the interface to the transmitted detonation below it. The results also show that a larger interface incline angle and argon dilution strengthen reflected waves and Mach stems. At argon-lean interfaces, the transmitted detonation undergoes re-ignition due to the sudden temperature drop across the interface. A transition from mild to violent initiation modes is found with the increase in the mixture activity. These findings provide insight into the evolution of detonation in a gas with inhomogeneities.