Research On The Related Problems Of Propeller Vibration And Singing

The study of propeller vibration and singing is of great significance to both passenger ships and military ships,especially submarines.The periodic rotation of the propeller makes the surface pressure and the surrounding velocity of the propeller change periodically.The periodic flow field variation of the propeller can easily cause the vibration and fatigue of the ship shafting and the stern hull plate.At the same time,the periodic vortex discharge along the side of the propeller may also be one of the sources of the flow-induced noise of the propeller.In addition,the application of new composite materials in propeller has been developed in recent years,but the application of different materials can not effectively avoid the occurrence of propeller singing phenomenon.Flow-induced vibration can cause non-linear flow-induced noise,and the phenomenon of "singing" will occur when it is serious,which will have a great impact on the operation of ships.At present,the research on numerical calculation and analysis of propeller vibration singing is relatively few.Under this background,this paper first uses the numerical simulation method,using FLUENT to simulate the open water of the propeller at different speeds,and compares it with the actual experimental results to verify the feasibility of the numerical method.Then,the boundary element method is used to analyze and compare the flow noise and the flow-induced noise of the propeller.Finally,based on the self-defined function,the pressure of the propeller blade along the edge is analyzed to obtain the discharge frequency,and the acoustic boundary element method is used to predict and compare the noise of the propeller when the discharge frequency is close to or far from the natural frequency of the propeller.The results show that there are many lines near the discharge frequency,forming a region of discharge frequency,and the propellers with different elastic modulus correspond to different natural frequencies.When the natural frequencies of a certain order are close to the region,the noise generated by the propeller is about 20 dB higher than that generated far away.