Numerical Research Of Fluid-Structure-Acoustics Coupling Characteristics Of Marine Composite Propellers

For military ships,the excellent noise performance of propeller can improve its stealthiness.For civil ships,good noise performance can improve the comfort of living.Therefore,it is of great significance to study the propeller noise for both military and civil ships.The composite propellers have the advantages of light weight,high damping effect,enhanced impact resistance,low noise and strong designability.The composite propellers have been widely applied at abroad,but their investigation and application are relatively insufficient in China.In the current study,the numerical method was mainly used to study the fluid-structure interaction and noise performance of composite propellers.Firstly,the bidirectional fluid-structure interaction of the marine composite propeller in the uniform flow were calculated by solving the flow field and structure field based on the Reynolds-averaged Navier-Stokes equations(RANS)and finite element method(FEM),respectively.The ACP model was used to build the finite element model of composite propellers,while the Frame Motion and Dynamic Mesh technology were used to simulate the rotation motion of the propeller and the deformation of the propeller blade.The open-water performance of the highly flexible resin propeller was calculated considering the fluid-structure interaction effect.The numerical results are in good agreement with the model test results,which verifies the validity of the fluidstructure coupling calculation method of the propeller in the uniform flow field.The numerical analysis of the open-water performance and structural steady-state response of CFP composite propeller were then carried out based on the fluid-structure interaction calculation platform.It shows that the pitch,thrust coefficients and torque coefficients of the propeller under low advance coefficients have small increases by comparison with those of the rigid propeller,while the hydrodynamic coefficients of the two propellers are basically the same under high advance coefficients because of the small deformation.Then,the bidirectional transient fluid-structure interaction calculation of composite propellers were carried out by using the coupling RANS-FEM combined with the Sliding Mesh and Dynamic Mesh technology.Firstly,the hydrodynamic performance of the HSP rigid propeller in the non-uniform flow field was numerically calculated without consideration of the coupling effect.The results agrees well with the experimental results.On this basis,the effects of the fiber material and fiber layup angle on the dynamic response of the hydrodynamic performance,dynamic structural response and structural strength of the propeller were studied by changing the fiber material and the fiber layup angles with consideration of the fluid-structure interaction.Finally,the structural vibration response of the composite propeller blade and the unsteady fluctuating pressure of the blade surface in the non-uniform flow field were used as the input data for the calculation of the vibration noise and the flow noise,respectively.The acoustic boundary element method and fan acoustic source theory were used to calculate the vibration noise and flow noise of the composite propeller.The results show that the fluid-structure interaction effect has significant effects on both of the vibration noise and the flow noise,while the blade fiber material and fiber layup angle have less influence on the flow noise,but have greater impact on the vibration noise.Therefore,appropriate selection of the fiber material and optimized fiber layup angle can reduce the structural vibration noise without increasing the flow noise,thus reducing the total noise.It can provide reference for the reduction of the total noise of the composite propeller.