Nonlinear noise of hydrofoil cavitation considering sound velocity variation and phase transitions

Cavitation noise is an important part of underwater radiated noise (URN). It not only reduces the concealment and comfort of ships, but also affects marine life. In this paper, a detailed study of cavitation noise is carried out for NACA0012 hydrofoil and a wavy-leading-edge hydrofoil. The nonlinear sound pressure is computed by direct volume integration in FW-H formulation, considering the sound velocity change caused by the phase transition and the spherical sound source caused by the cavity volume change. By comparing with the experiment, the acoustic prediction method proposed in this paper is verified. The acoustic study is conducted from the perspectives of streamwise distribution, spanwise distribution, far-field directivity, influence of cavitation number and geometric influence. Three components and the sound source distributions are analyzed. The results show that, for cavitation state, nonlinear sound pressure is larger than the linear one and dominates in the near field. At further distances, the spherical component dominates. The cavitation noise of the modified hydrofoil is enhanced, and the source intensity is increased by 1–2 orders of magnitude. •A new method to compute nonlinear sound pressure is proposed considering the sound velocity change.•Sound pressure caused by cavity volume change is computed by sphere source.•Modified wavy-leading-edge cavitation noise is compared with that of baseline hydrofoil.