Analysis Of Propeller Force And Vibro-acousitc Characteristics Of Propeller-shaft-ship Coupling System

In the propeller-shaft-hull coupling system,the excitation forces induced by propellers operating in non-uniform,unsteady flow fields can be divided into two main types,including fluctuating surface pressure acting on the hulls and the excitation force acting on the blade,both of which are transmitted to the hull through different channels,causing the vibration of the hull and radiating noise into the flow field,which will greatly affect the stealth performance of the hull.In order to better understand the characteristics of excitation force and vibro-acoustic response of surface ships,and provide theoretical support for the design of vibration-control and noise-reduction of coupling systems,this paper mainly to study the propeller-shaft-hull coupled system induced by propellers and its low frequency vibration and acoustic radiation characteristic.In this paper,a Kirchhoff-Helmholtz equation based propeller-noisesource equivalent-parameter method is used to predict fluctuating pressure,and a propeller-noise-source model under twin propeller propulsion case is established.This model is used in the simulation and the prediction of surface pressure of the ship driven by the double-propeller propulsion system.The accurancy is improved compared with the traditional monopole interpolation method.On the other hand,the wideband excitation force of the propeller is calculated according to the strip correlation function method,and the effectiveness of the method is verified by experiments.Based on these,the transfer characteristics and acousticvibration characteristics of the propeller-shaft-hull coupling system under different excitations are studied based on the coupled finite element/boundary element method.On this basis,this paper studies the influence of local parameter changes of the key areas on the acoustic radiation characteristics of the ship,and the parameters-combination optimization approach of the low-noise design of the propeller-shaft-hull system is given.In the research,the transfer characteristics of the power flow of the coupled system under different directions excitation and the influence of the changes of the parameters of different subsystems on the radiated sound power of the coupled system are described.It is pointed out that the dynamic characteristics of the sub-structure of the hull,especially the propeller-shaft system,play a leading role in the peak of the acoustic radiation characteristics of the hull.Based on this,the noise control method based on bearing stiffness is given,which provides theoretical guidance for the low noise design of the multi-support propulsion shafting driven propeller-shaft-hull coupling system.