A summary of acoustic characteristics and control techniques of underwater non-cavitation thruster

Abstract

This paper gives a detailed description of the mechanism of sound production, acoustic characteristics and prediction methods for radiation sound spectrums (low frequency line spectrum, low frequency broadband spectrum and high frequency broadband spectrum) of non-cavitation thruster and the secondary acoustic radiation caused by the unsteady force which excited both shaft system and hull in the unsteady flow field. It indicates that the underwater thruster has a great influence on underwater noise of the navigation body with its direct or secondary radiation sound. The paper also describes two control methods, one is mostly used to control the uniformity of the flow field, while the other is used to design low-noise thruster such as pump-jet thruster and highly skewed propeller. Additionally, a new type multi-blade coupling propeller with unique features is proposed to achieve further noise reduction and open water performance improvement.