Numerical estimation of underwater radiated noise of a marine propeller in non-cavitating regime

The underwater radiated noise levels (RNLs) emanating from surface and underwater marine platforms are becoming a topic of significant concern for all the nations in view of the global requirement to minimise the increasing adverse impact on marine life and maintain ecological balance in the so-called silent ocean environment. The studies have reported an increase in low-frequency ambient sea noise by an average rate of about 1/2dB per year [Ross in IEEE J Ocean Eng 30(2):257–261, 2005 1] which is attributable to the growing fleet of ships. Marine propeller noise in both non-cavitating and cavitating regimes is an important component of the overall underwater radiated noise of a marine platform in addition to the machinery and flow noise. Merchant ships generally operate at low speeds, and hence, propeller noise in non-cavitating regime is an important area of concern. For military applications, design of low-noise propellers dictates the ships’ survivability and operational performance. Hence, design and development of low-noise propulsion systems and, in particular, low-noise propellers is a relevant topic of current focus which is in line with the global need of the hour to design eco-friendly ships. In this respect, the main scope of this study is to numerically calculate the propeller noise in the non-cavitating regime for the uniform flow (no wake condition). Flow around the propeller is solved with a commercial CFD software STAR-CCM+, while hydro-acoustic analysis is performed using Ffowcs Williams–Hawkings (FWH) equation. The numerical closure was achieved using k-ε Reynolds-averaged Navier–Stokes (RANS) model. The predicted hydrodynamic performance curves and radiated noise levels have been validated from the published experimental and numerical results.