Numerical Study of Cavitation Noise Around NACA66 (MOD) Hydrofoil with Direct Volume Integration

Underwater noise (URN) is the focus of academic research, and cavitation is an important source of underwater noise. This paper takes NACA66 (mod) two-dimensional hydrofoil as the research object and uses the open-source software OpenFOAM to simulate the sheet cavitation and sound field. The turbulence model is DDES, and the cavitation model is the Schnerr-Sauer model. The sound field is predicted by the FW-H formulation. Unlike the traditional method, this paper solves the quadrupole term (nonlinear term) by direct volume integration, so the nonlinear term can be predicted more accurately. At the same time, a new method of changing sound wave velocity is proposed considering the two-phase medium problem caused by cavitation. Four methods are compared, including two-phase volume integration, direct volume fraction, object surface integration, and penetrable formulation. It is found that the influence of two-phase flow is greater near the closure area of the cavity, which needs to be considered separately. The linear sound shows dipole directivity and the nonlinear component exhibits quadrupole characteristics.