Experimental Study of Shock Wave Interference Heating on a Cylindrical Leading Edge

An experimental study of shock wave interference heating on a cylindrical leading edge representative of the cowl of a rectangular hypersonic engine inlet at Mach numbers of 6.3, 6.5, and 8.0 is presented. Stream Reynolds numbers ranged from 0.5 x 106 to 4.9 x 106 per foot and stream total temperature ranged from 2100 °R to 3400 °R. The model consisted of a 3-inch-diameter cylinder and a shock generation wedge articulated to angles of 10, 12.5, and 15 degrees. The primary goal of this study was to obtain a fundamental understanding of the fluid mechanics of shock wave interference induced flow impingement on a cylindrical leading edge and the attendant surface pressure and heat flux distributions. The study has provided the first detailed heat transfer rate and pressure distributions for two-dimensional shock wave interference on a cylinder along with insight into the effects of specific heat variation with temperature on the phenomena. Results of the study show that the flow around a body in hypersonic flow is altered significantly by the shock wave interference pattern that is created by an oblique shock wave from an external source intersecting the bow shock wave produced in front of the body. The local heat transfer rates and pressures are amplified up to 10 times the undisturbed free-stream stagnation point level. The intense heating and high pressures occur over a narrow region where a flow disturbance from the interference pattern impinges on the surface. Variation in specific heats and hence the ratio of specific heats with temperature (thermally perfect gas) result in slightly lower peak pressures and heat transfer rates than for the corresponding calorically perfect gas (specific heats are constant) conditions