Abstract
There is a dearth of information on the reflection of very weak shock waves on curved surfaces; and particularly a distinct lack of experimental data at Mach numbers below 1.03. A previous study at Mach numbers between 1.03 and 1.05 showed that there are variations in the accepted reflection evolution on curved surfaces. That work indicated the existence of an apparent regular refection pattern in the curved shock wave reflection evolution which is also predicted for very much weaker waves in acoustic studies. To improve spatial resolution, the current study is performed in a large shock tube with a test section height of 450 mm using a 520 mm radius curved test piece with zero initial ramp angle. Imaging is primarily using shadowgraphy and high-speed photography. Experiments concentrated on tests in a range of \(1.007 \le M \le 1.09\) with some tests at higher values. No shear layer is evident at the lower Mach numbers as for von Neumann and weak Mach reflection patterns. Transitioned regular reflection appears to cease at incident Mach numbers below 1.07. A reflection pattern resembling a regular reflection exists in the transition between the three-shock patterns and transitioned regular reflection.
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Acknowledgements
We wish to thank Blessing Chirewa, an undergraduate student, who, for his final year research project, explored methods in an attempt to get incident Mach numbers below 1.03. His data have been included and show consistency with the current more detailed study.
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Cohen, A., Skews, B. Very weak shock wave reflection off curved surfaces. Exp Fluids 61, 174 (2020). https://doi.org/10.1007/s00348-020-03009-2
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DOI: https://doi.org/10.1007/s00348-020-03009-2