An investigation of cavitation control using a porous material on a hemispherical cylinder at various cavitation numbers

In this paper, a passive control method based on a porous material is applied to the surface of a hemispherical cylinder to control a cavitating flow, and the control effect of this method at different cavitation numbers (σ) is evaluated through the cavity morphology and volume, which is important for the application in engineering. The results indicate that the control effect is improved with a reduction in the cavitation number, for the reduction of vapor volume increases from 22%–50% with σ decreasing from 0.50–0.20. Further investigation indicates that the cavity inception at different cavitation numbers is still induced by the Kelvin-Helmholtz instability, while the spatial distribution of the vapor changes significantly. Moreover, the porous material suppresses the cavitating flow in the front region but enhances it downstream at large cavitation numbers. When σ = 0.20, the cavitating flow is controlled in both the front and rear regions.