Research on Noncavitation Noise of Axial-Flow Pump Jet Propulsor Impellers and Biomimetic Noise Reduction Design

Abstract Propulsor noise is a major contributor to underwater radiated noise from vessels. The pump jet propulsor (PJP), widely used in underwater vehicles, is studied here for its noncavitation noise through experimental and numerical simulations. A model of the axial-flow PJP is created, and large eddy simulation (LES) with acoustic analogy methods is used to calculate flow noise. A test platform is developed with a recirculating water pipeline to measure head, shaft power, and sound pressure levels. Experimental and simulation results are compared. The head measurement error is minimal, with a maximum of 0.68%, and the flow noise frequency spectrum closely matches the experimental data. The total sound pressure level within the 10–4000 Hz range has an error of less than 5 dB, confirming the simulation's accuracy. The study proposes a biomimetic noise reduction design inspired by owl wing serrations. A parametric analysis of different serrated shapes shows that the curved serrated impeller has a maximum efficiency loss of 0.58%, significantly reducing low-frequency noise. It lowers the first four blade harmonics by 10.93 dB and reduces the total sound pressure level by 3.49 dB in the 25–4000 Hz range.