Non-Self-Similarity in Mach Reflection of Weak Shock Waves: Effects of Transport Properties and Surface Roughness

摘要

The effects of transport properties (viscosity and thermal conductivity) and surface roughness were compared experimentally to investigate non-self-similar Mach reflection phenomena in weak shock waves. The effect of the transport properties was changed by varying the initial pressure ahead of the incident shock in experiments conducted at Karlsruhe (KIT) and Saitama (SIT). By introducing a non-dimensional distance based on physical properties behind the Mach stem, the difference between the results under various experimental conditions was diminished, and in some cases the results almost coincide with each other within the error in angle measurement. In order to investigate the effect of surface roughness, further experiments were conducted at SIT using models with rough surfaces. The results were compared with those for smooth surfaces. The effect of surface roughness turned out to be small compared with the viscosity effect, proving the effect of transport properties to be dominant. The fact that the discrepancies between the SIT and KIT experiments vanished after introducing the non-dimensional coordinate may possibly be ascribed to inaccuracy in angle measurement at KIT.