Investigations of Mach Reflection of a Shock Wave : 4th Report, The Transition between Regular and Mach Reflections

The transition between regular and Mach reflections of an oblique shock wave has been investigated by many researchers for steady, pseudo-steady and unsteady flows. However the problem for unsteady flows such as the reflection of a shock wave at cylindrical concave or convex walls has not been fully understood. The problem, considered in this report, is that of transition from Mach to regular reflection of a shock wave over a concave wall. Experimental investigations have been performed using a model of concave wall. The wall is composed of two straight sections, and the downstream second section is more inclined than the upstream first one. The process of shock reflection over this wall has been observed in detail, and the transition criterion from Mach to regular reflection in this case has been presented experimentally.