Experimental and numerical investigation of cavitation control with porous material on the hemisphere cylinder

Cavitation flow control methods such as obstacles, grooves, surface roughness, and air/water jetting can effectively improve the performance of hydraulic machinery and reduce cavitation, thus being widely investigated in the past few years. Recently, the porous media is widely used in air/water jetting flow and transpiration cooling due to the permeability. Whereas, there are few researches using porous media to control the cavitation flow, and the control mechanism is still unclear. In this paper, a passive control method using a layer of porous material is proposed for the suppression of cavitating flow around a hemisphere cylinder. Experiments and numerical simulations focusing on the control effects and the dynamics of cavitation are conducted. For the controlled case, due to the high local pressure caused by the obstruction to the incoming flow at the leading edge of the porous layer, the cavitation inception near the shoulder of the cylinder is suppressed. At the trailing edge of the shear layer, the Kelvin-Helmholtz instability induces the shedding of the spanwise vortex, which alters to hairpin vortex. During this process, cluster of cloud cavity occurs, develops and disappears periodically. In porous layer, the damping effect suppresses the development of vortex, and no cavity is observed. •A control method of cavitation using porous material is proposed.•Porous layer suppresses the cavitating flow and changes the flow pattern apparently.•Local high pressure and local stable shear layer are the keys of control effect.•Instability of shear layer and variety of vortex induce the cavitation downstream.