This report discusses an investigation into the effect of a porous plate covering a cavity, on an oblique shock wave-boundary layer interaction. Four porous plates with different hole sizes and porosities, as well as a solid, 'dummy', plate, have been tested in a Mach 2 wind tunn
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This report discusses an investigation into the effect of a porous plate covering a cavity, on an oblique shock wave-boundary layer interaction. Four porous plates with different hole sizes and porosities, as well as a solid, 'dummy', plate, have been tested in a Mach 2 wind tunnel whereby an oblique shock wave (produced by a wedge) impinged on its surface, for two different wedge angles. Particle Image Velocimetry measurements, and Schlieren images, were recorded and used to analyze the interaction. The effect of the porous-plate covered cavity on the interaction's downstream boundary layer thickness and turbulence, flow separation and interaction length were analyzed and explained. The results showed that first of all, concerning the effect on boundary layer thickness, an increase in boundary layer thickness is induced by from the presence of a porous plate-covered cavity, that the effect of plate hole size, porosity and shock strength on this increase are insignificant. The turbulent kinetic energy of the downstream boundary layer could be observed to increase for a low shock strength, and decrease for a higher shock strength. This leads to the presumption that under specific circumstances a porous plate-covered cavity could lead to a beneficial application as a turbulence decreasing flow control device, but further research will have to validate this. The results showed that flow separation is increased for all plates tested, especially for higher hole sizes and lower porosities. Finally, interaction length was shown to increase due to the presence of the porous plate in all cases measured, although this result is likely highly specific to the design tested in this investigation, as is discussed in the Conclusions chapter. Keeping this in mind, interaction length seemed to increase with decreasing hole size and with increasing porosity. In order to be able to prove the abovementioned correlations with more certainty, performing a future investigation with a larger parameter range is recommended.
