Propeller-shaft-hull coupling acoustic radiation characteristics induced by friction self-excitation of the stern bearing

This paper focuses on the practical engineering problem of excessive propeller-shaft-hull coupling vibration noise, which is caused by poor lubrication contact of water-lubricated stern bearings in the ship propulsion shaft system. Firstly, based on the three-dimensional sono-elasticity theory of ships, calculation models for the propeller-shaft-hull coupling acoustic radiation transfer function are established separately, considering the propeller excitation and friction excitation of the stern bearing. Secondly, by analyzing the acoustic radiation contribution of each mode, the vibration mode with the highest contribution to the typical acoustic radiation transfer function peaks of the propeller-shaft-hull coupling under the friction excitation of the stern bearing is separated. The spatial distribution and pointing characteristics of the sound field corresponding to the propeller shaft-hull coupling acoustic under friction excitation of the stern bearing are given. Finally, a quantitative evaluation model of propeller-shaft-hull coupling acoustic radiation caused by friction self-excitation of the stern bearing is established. The mechanism behind the typical acoustic radiation peaks of propeller-shaft-hull coupling under friction excitation of the stern bearing is revealed, which provides methodological guidance for the quantitative evaluation of friction vibration noise and the separation of vibration noise components in ship stern structures.