Research On The Influence Of Limited Space On Propeller Noise Measurement

Mechanical noise,propeller noise and hydrodynamic noise are the three main noise sources of ships.The propeller noise of a ship is usually measured in the open waters of the sea or lake.However,in the development stage of warship or propeller,because of the high cost and long period of sea test or lake test,it is necessary to measure propeller noise in the limited space of water tank or water cistern.In this kind of limited space,because of the reflection of the wall,whether it has an impact on the propeller noise and wake field.In order to solve this problem,this paper studies the impact of the limited space on the propeller noise in the reverberation pool.At the same time,the author also uses the hydrodynamic test method of the hydrodynamic model of the water tunnel circulating tank in our school for reference,and establishes the external circulation pipeline system outside the reverberation tank to provide the wake flow field for the propeller model,and studies whether the external circulation diversion can reduce the influence of the limited space on the propeller noise.In this paper,the influence of limited space on propeller noise is studied by combining simulation and experiment.The simulation is divided into flow field simulation and sound field simulation1.The flow field environment near the propeller in free space and limited space is simulated.The hydrodynamic performance of the propeller blade,such as the pressure and velocity nephogram,and the flow field parameters,such as viscosity coefficient and turbulent Reynolds number,reflecting the flow field environment are compared.The influence of limited space on the wake field of the propeller is studied.2.The propeller noise in free space and finite space is simulated.Based on the sound field calibration of reverberation water tank,the sound pressure of propeller blades in two sides of plane and upper and lower sides of propeller hub are compared.The propeller noise in finite space and free space is compared,and the influence of finite space on propeller noise is analyzed.3.Combined with the simulation,the external circulation diversion system of reverberation pool(limited space)is designed to provide relatively stable flow field for propeller.The influence of external circulation diversion on the noise of propeller in finite space is compared.The paper attempts to study whether the influence of limited space on propeller noise can be reduced by the external circulation guide device.The simulation and experimental results show that: compared with the free space,the limited space will cause the wake field disorder of the propeller,and the limited space will cause the overall increase of the propeller noise,so that the directivity of the propeller noise is not obvious;the external circulation diversion of the reverberation water tank(Limited space)can reduce the influence of the limited space on the propeller noise.