Regions of various forms of Mach reflection and its transition to regular reflection

Abstract

Reflection of plane shock waves at a rigid wall in argon, air, nitrogen and carbon dioxide has been studied in a shock tube. Mach numbers of the incident waves have been changed from 2 to 10, the wedge angles from 15 to 60°. It has been found that the double Mach reflection type takes place at large angles and high velocities for all gases including argon. The criterion for transition between simple Mach reflection and double Mach reflection is the onset of supersonic flow downstream of the reflected shock in the system of reference connected with the primary confluence point. The transition between Mach and regular reflection has been considered. It has been found that for strong shock waves the transition from Mach reflection occurs in the form of a double Mach reflection. During transition the primary and secondary confluences approach the base of the primary Mach stem. Therefore, the pressure can change continuously during transition. A model of transition between Mach and regular reflection has been proposed. The regions of various forms of reflection have been defined in air and nitrogen depending on incident wave Mach numbers and angles of the wedge.