Abstract
Results of theoretical and experimental investigations on shock reflection at a fixed wall are reported in this paper. In the region of regular reflection, agreement of theory and experiment is found to be good except for the fact that experimental points extend a litter bit beyond the theoretical limit. A theoretical investigation of the flow characteristics is made on Mach reflection cases with the conclusion that a singularity would appear at the triple point, and hence, the reflected shock angle would not coincide with the theoretical one when the flow is subsonic behind the reflected shock. This theoretical prediction is fully confirmed by the results of shock angle measurement in schlieren pictures obtained by the experiment. In case of a strong incident shock, angle of the reflected shock decreases discontinuously at the transition from regular to Mach reflection as expected from the theory. In case of a weak incident shock, on the other hand, its change is continuous against the ordinary three-shock theory. It is found in the experiment that the boundary between these two cases takes place approximately at ξ=0.42, where ξ is the pressure ratio across the incident shock. This is in good agreement with the theoretically predicted value, ξ=0.433, above which the Mach reflection with a singularity at the triple point would appear. It corresponds to the condition of the stationary Mach reflection. Comparisons of theory and experiment are also made in this paper on the condition at which the flow behind the incident shock is just sonic relative to the triple point and on the angle of the Mach stem. Throughout the present study experiment was made by use of a shock tube.
