Research On Vibration And Acoustic Radiation Of Propeller-driven Underwater Vehicle Stern

When the propeller works in water,it not only produces radiation noise directly,but also produces vibration force acting on the ship structure,which causes the vibration sound radiation of the stern of the underwater vehicle and affects its acoustic stealth performance.Therefore,it is of great significance to carry out the research on the vibration sound radiation of the stern of the underwater vehicle stimulated by the propeller to improve its survivability and combat ability.The change of the navigation state of underwater vehicle is accompanied by the change of incoming flow speed and propeller speed.The influence of propeller noise and propeller vibration and acoustic radiation in the stern of underwater vehicle is very complicated.Therefore,from the perspective of engineering application,this paper has carried out the research on propeller vibration force,straight sound,blade vibration sound radiation and underwater vehicle stern vibration sound radiation.Firstly,the main numerical calculation methods in this paper are verified.Taking E779 A propeller as the research object,the hydrodynamic performance of the propeller was compared with the experimental results in literature to illustrate the rationality of CFD combined with large eddy simulation method.Taking cone-cylinder-hemisphere as the research object,the FEM/AML method was validated by comparing the numerical simulation results with the experimental results.Taking the square plate as the research object,the reliability of the FEM/BEM method is proved by comparing the calculation results of the verified model’s mean square velocity and sound power with those in the public literature.Secondly,based on CFD and large eddy simulation method,the propeller excited force under stern wake was predicted numerically.The distribution of fluid velocity and vortex system near the propeller was analyzed,and the influence law of incoming flow velocity and speed on propeller bearing force was explored.Then,the influence of propeller or not on the propeller surface pulsating pressure characteristics was analyzed.Furthermore,the influence of inlet velocity and propeller speed on propeller surface force is discussed.Thirdly,taking SUBOFF standard model stern and 7-blade propeller as research objects,based on large eddy simulation method combined with FW-H equation,the propeller sound and blade surface pulsation pressure were obtained,and the spatial directivity of propeller radiated noise under different inlet velocity and speed was studied,and the influence of inlet velocity and speed on propeller sound was explored.The influence of incoming flow velocity and rotational speed on the pulsating pressure of the blade surface was analyzed,and then the influence of incoming flow velocity and rotational speed on blade vibration and radiated noise was explored based on FEM/AML method.Finally,taking the propeller bearing force and surface force calculated above as input excitation,the low-frequency vibration response and line spectrum noise in the stern of the underwater vehicle were predicted numerically based on FEM/BEM method and FEM/AML method respectively.The results showed that when propeller bearing force and surface force acted separately,The influence of incoming flow velocity and rotational speed on the aft vibration and radiated noise of underwater vehicle was analyzed by means of energy superposition method,which provides support for the prediction,evaluation and control of the vibration and radiated noise of the stern of the underwater vehicle under propeller excitation.