Numerical Study of Mitigating Cloud Cavitation Shedding Using Biomimetic Protuberant Stripes
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Cloud cavitation usually appears on impeller blades of hydraulic machinery. When unsteady cloud cavitation travels downstream to a high-pressure region and collapses, performance drops and cavitation erosion appears. It is important to develop effective methods to mitigate the undesirable effects. By million years of natural selection, bird feather has presented excellent flow performance. As typical characteristic structure of bird feather, a number of barbs are supported by a central hollow shaft. Under inspiration of bird feathers, we presented a method of passive cavitation control. This method of passive cavitation control uses biomimetic protuberant stripes mounted on a NACA66 hydrofoil. The effects of various biomimetic protuberant stripe arrangements on the cavitation pattern, pressure fluctuation, and hydrodynamic load are numerically studied. Then the cavitation control mechanism of the biomimetic protuberant stripe is analyzed in detail. We observe that the biomimetic protuberant stripes not only inhibit the shedding of large-scale cloud cavitation, but also reduce the cavitation size. Moreover, analysis shows that turbulence velocity fluctuation may be mitigated and boundary layer thickness is reduced with biomimetic protuberant stripes, which enhances the flow intensity in the main flow direction.