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.
Underwater noise not only causes harm to marine life, but also affects the stealth of military equipment. The International Maritime Organization (IMO) issued non-mandatory noise standards for commercial ships (IMO, 2014). More and more attention has been paid to the acoustic environment. At this stage, the prediction of such noise becomes a hot topic (Deane and Stokes, 2010; Ianniello et al., 2013; Bensow and Liefvendahl, 2016).