Study On Cavitation And Cavitation Noise Performance Of Composite Propeller Under Non-uniform Flow Field

In recent years,with the development of modern detection equipment and various underwater weapons towards high precision and long distance,the survival and combat ability of ships have been seriously threatened.In order to reduce the probability of ships being detected by sonar of the other side,the noise source of ships must be reduced as much as possible.In the process of high-speed navigation,cavitation phenomenon will occur on the surface of propeller blades.With the development of cavitation,cavitation noise is the most important noise source of the total noise of ships,which greatly reduces the stealth performance of underwater ships.Therefore,people have been looking for ways to improve the performance of propeller cavitation noise.Compared with traditional metal propeller,composite propeller has the advantages of easy molding,corrosion resistance,light weight and high damping.The unique designability of composite materials,on the one hand,can improve the hydrodynamic performance of the propeller and on the other hand,can delay the initial cavitation velocity of the propeller,which is conducive to reducing cavitation damage and reducing cavitation noise.Therefore,it is of great significance to study the cavitation and cavitation noise of composite propeller.Based on the above research background,this topic for general DTMB4381 propeller blade type,using the CFD method,the finite element method combined with acoustic method,towing experiments are used to get the non-uniform wake of figure,in non-uniform wake field of composite propeller cavitation and cavitation noise performance of the related research,and with the metal materials of propeller cavitation and cavitation noise,comparing the calculation results of specific research contents are as follows:Through the research of computational fluid mechanics method and cavitation theory,the acoustic calculation method is analyzed,the cavitation numerical simulation calculation idea suitable for composite material propeller is clarified,and the calculation method of cavitation noise of composite material propeller is determined,so as to provide a foundation for subsequent research.Firstly,based on the existing propeller geometry mode,the hydrodynamic performance of the propeller under different working conditions is calculated.The hydrodynamic model was created in finite element software,and then the rotation domain grid was divided by Poly method based on Mosaic technology,and the external flow field grid was connected by overlapping grid technology.Combined with CFD method,the hydrodynamic performance of propeller under different working conditions was calculated,and the grid independence was verified.Finally,the results of hydrodynamic performance calculation are compared with theexperimental results in relevant literatures to verify the correctness of the finite element analysis method.For in non-uniform propeller wake field of composite materials,different advance coefficient was calculated under different cavitation number and the cavitation performance of the propeller blade surface under different iteration time is studied cavitation area as well as the change of the cavity shape,analyzed the non-uniform wake for the influence of propeller cavitation performance,and with the same metal materials under the condition of the propeller calculation results were compared.Finally,the hydrodynamic performance of composite propeller before and after cavitation is calculated,and the influence of cavitation on the hydrodynamic performance of propeller is investigated.Based on composite propeller cavitation performance calculation results,combined with acoustic analysis method,calculation of composite material under different into the coefficient of propeller cavitation noise performance,compared in different monitoring location size of cavitation noise,the analysis of factors affecting the propeller noise,then the same metal materials under the condition of the propeller,comparing the calculation results obtained composite propeller cavitation noise characteristics.