Characteristic Properties of the Formation of Shock-Wave Reflection Configurations in Unsteady Flows

Abstract

Unsteady shock wave reflection can be obtained when a planar shock wave propagating with a constant velocity encounters a non-straight surface. Most attention has been paid to the shock wave reflection off convex and concave cylindrical surfaces. For a concave reflecting surface, the reflection pattern changes from irregular to regular. In the case of convex reflecting surface, the reflection pattern changes from regular to irregular. To this day the question of determination of transition parameters has been one of the unanswered questions. Until recently the unsteady reflection was generally described as a series of consequential changes of reflection configurations depending on an incident shock Mach number and a local slope angle associated with reflection of shock waves off convex/concave cylindrical surfaces [1–4]. The experimental and numerical data show that for cylindrical reflecting walls the regular-to-Mach reflection transition (RR ↔ MR) parameters do not agree with the sonic/detachment criteria provided by the von Neumann theory for the straight wedges. The question arises of whether it would be correct to use the criteria obtained for pseudo-steady flows (shock reflection from the straight wall) for the analysis of the transition in unsteady flows (shock reflection from curved reflecting surfaces).