Shock wave reflections off curved surfaces

Cohen, A E
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In this work two separate studies are performed on the reflections of shock waves off curved surfaces. The effect of thermal conductivity on shock wave reflection off curved surfaces and very weak shock wave reflection are investigated. Effect of thermal conductivity on shock wave reflection off curved surfaces: Previous work has shown that the properties of a shock wave reflection off a flat surface are affected by the thermal conductivity of the reflection surface. In the more complex reflection case of a curved surface, tests were done in undergraduate studies to determine whether heat transfer into the reflection surface has an effect on the shock wave reflection properties. Although the results proved promising, further testing is required to provide conclusive results. Tests are performed on concave and convex test pieces. Test pieces of different thermal conductivities (0.19 W/mK and 401 W/mK) and hydraulically smooth surfaces are used in the experimentation. The test pieces are placed in identical positions on either side of a plane of symmetry and at the same incident angles in the shock tube. Z-configuration shadowgraph and high speed imaging is used to capture the images. Tests are performed at Mach numbers in the range of 1.26≤M≤1.5. The images are analysed both quantitatively through reflection angle measurements and qualitatively by examining the symmetry of the reflection patterns. Both the qualitative and quantitative analysis performed show that the thermal conductivity of the reflecting surface affects the reflection patterns off curved surfaces. The quantitative analysis showed that heat transfer into the reflecting surface affects the reflection patterns through the measurement of various reflection angles. Significant differences in the reflection angles indicate the presence of thermal conductivity effects. In the qualitative analysis asymmetry in the reflection patterns is found at all Mach numbers, supporting the findings which are found in the quantitative analysis
A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2021