A dynamics model of hydrofoil tip vortex cavitation with acoustic-flow coupling

The singing of the tip vortex cavitation (TVC) is usually observed as the strongest noise source in the experiments of cavitation noise from propeller and hydrofoil, but the acoustic-flow coupling is always neglected in existing theoretical dynamics models. In this paper, a new dynamics model of hydrofoil TVC is proposed by a new stress equilibrium condition at the cavitation wall with a coupling of the interface movement and the internal sound pressure. The sound pressure distribution inside the TVC is first shown. By solving the dynamics equations, the dispersion relations of three types of TVC motions are obtained, including radial mode motion, surface modes motion, and radial-surface coexistence motion. The acoustic-flow coupling effect on the mode frequency is found sensitively dependent on the gas content in water. In addition, the factors on the dimension of radius and mode frequency of the radial motion mode are analyzed, as well as that of the surface motion modes. The frequencies of the radial-surface coexistence motion are the obvious modulation results of the surface modes with the radial modes. When using the parameters of experiments, the proposed acoustic-flow coupling dynamics model of TVC has an accurate prediction of the modal frequencies.