Interaction between Natural and Ventilated Cavitation around a Base Ventilated Hydrofoil

In more recent years, supercavitation has attracted intensive attention due to its potentials in drag reduction for underwater vehicles. Ventilation is acknowledged as an efficient way to enhance cavitation when vehicles work under low speed. That means natural and ventilated cavitation may coexist in the flow and the interaction between the natural cavitation and ventilated cavitation has to be considered. In this paper, ventilated cavitating flow with natural cavitation around a base-ventilated hydrofoil is solved by a multi-phase cavitation solver based on OpenFOAM. The Partially-Averaged Navier-Stokes method is utilized for resolving turbulence. Lengths of the natural cavities are investigated under non-ventilation and ventilation conditions. Cavity shape evolution and interface deformation have also been studied under different angle of attack. Results show that ventilation cavitation at the base of the hydrofoil tends to depress the natural cavitation on the hydrofoil surface. As the increase of the attack angle, the shedding cavity of natural cavitation have a great impact on the interface shape of the ventilation cavity. Furthermore, the research also finds that the re-entry jet is the reason for natural cavitation shedding process and the interface deformation of the ventilated cavity arises from the vortex structures induced by the shedding natural cavitation.