Numerical Radiated Noise Prediction of a Pre-Swirl Stator Pump-Jet Propulsor

Abstract

The requirement of low radiated noise is increasing for underwater propulsors as the noise significantly affecting the comfort and quietness of ships, submarines, and vessels. To broaden the view of noise characteristics of pump-jet propulsors (PJPs), this paper considers the radiated noise of a pre-swirl stator PJP with the effects of the advance coefficient and rotor rotational speed. Radiated noise is obtained by the “hybrid method” approach, which combines a hydrodynamic solver with a hydroacoustic solver. The turbulence flow is obtained through improved delayed detached eddy simulation (IDDES), which show good agreement with the experiment, including the performance and flow field. The solver precision, permeable surface size, and sampling frequency notably affect the noise calculation. The spectra of thrust fluctuation and radiated noise are characterized by the tonal phenomenon around the blade passing frequency and its harmonics. The spectrum of radiated noise and overall sound pressure level (OSPL) are considerably affected by both the advance coefficient and the rotor rotational speed. Overall, the numerical results and analysis given in this paper should be partly helpful in deepening the understanding of the radiated noise characteristics of PJPs.

Keywords

Pump-jet propulsor / Hydrodynamics / Turbulence modeling / Thrust fluctuation / Radiated noise / Pre-swirl stator