Research On Cavitation Mechanism And Cavitation Characteristics Of Composite Propeller

Cavitation will inevitably occur when the propeller operates under water.The cavitation phenomenon will not only lead to the decline of propeller hydrodynamic performance,but also cause cavitation corrosion and cavitation noise.Traditional metal propellers are widely used because of their high strength and stiffness.However,in recent years,the development of large-scale and high-speed ships has led to more and more serious cavitation of metal propellers.At the same time,composite propellers have been developed rapidly.Their different structural characteristics and working principles from metal propellers make it possible to weaken the cavitation effect and delay the initial velocity of cavitation.Therefore,the cavitation mechanism and characteristics of dtmb4381 composite propeller are studied in this paper.The specific research contents are as follows:Firstly,based on computational fluid dynamics(CFD)and finite element method(FEM),the numerical simulation method of composite propeller cavitation is established.Based on the CFD method,the propeller hydrodynamic model is established by using the hybrid grid structure.The influence of the turbulence model on the calculation results is discussed.Compared with the experimental results,the effectiveness of the hydrodynamic model is verified;Based on FEM method and hydrodynamic model,the steady-state fluid structure coupling calculation of composite propeller was carried out,and the reconstructed geometric model of composite propeller after deformation was obtained under the conditions of various advance coefficients;Based on the reconstructed geometric model and CFD method,the composite propeller cavitation numerical calculation model is established by using the hybrid grid structure.The influence of the cavitation model on the calculation results is discussed.The effectiveness of the cavitation numerical calculation model is verified by comparing the calculation results with the experimental results.Then,based on the cavitation numerical model of composite propeller,the cavitation hydrodynamic force and cavitation state are predicted,and the cavitation characteristics of composite propeller are further analyzed.According to the calculation results,the effects of cavitation number and advance coefficient on the cavitation hydrodynamic force and cavitation state of composite propeller are discussed respectively;The cavitation collapse performance diagram of composite propeller is given,and the relationship between the cavitation hydrodynamic performance and the advance coefficient is discussed when the cavitation number is fixed.Finally,the cavitation hydrodynamic force and cavitation state are predicted for each working condition within the range of the cavitation bucket.Based on the predicted cavitation distribution of the blade,combined with the cavitation incipient criterion,the incipient cavitation number of each section is obtained,the cavitation bucket Atlas of the composite propeller is given,and the cavitation characteristics of the composite propeller are discussed.At the same time,the calculated cavitation bucket diagram of metal propeller is given,and the cavitation hydrodynamic force,cavitation state and cavitation bucket diagram of the two are compared and analyzed,which shows the advantages of composite propeller in reducing cavitation effect and delaying cavitation initiation.