Observation of density discontinuities behind reflected shocks close to the transition from regular to Mach reflection

Density discontinuities have been observed behind the reflected shock produced by regular reflection of weak planar shock waves from rigid, smooth surfaces at various angles of incidence. These discontinuities occur behind the point where the incident and reflected shock waves meet and have been seen only for angles of incidence close to those at which transition from regular to Mach reflection takes place. The failure of two-shock theory to predict the angle of transition from regular to Mach reflection for weak shocks may be explained by the experimental observation that near the transition, a simple two-shock picture of the reflection process is not valid.