Study On Open Water Performance Calculation And Study On Fatigue Life Estimation Of Propeller

Propeller is one of the most commonly used marine propulsion devices.It is very necessary to conduct relevant research today when marine resources are becoming more and more important.With the development of computer technology,the numerical calculation method of propeller has been used more.This paper is carried out under such a large background.The CFD method is mainly used to calculate the open water performance of the propeller,and the finite element method is used to predict the crack propagation on the surface of the propeller.In this paper,the numerical simulation of the open water test of a certain type of propeller is carried out.The calculation accuracy of the three standard turbulence models of standard k-ε,RNG k-ε and SST k-ω is compared,and the relatively best turbulence model SST k-is obtained.ω,and verified the accuracy of the CFD calculation method.Because the propeller is sometimes in a diagonal flow when it is used in engineering practice,this article has calculated the hydrodynamic performance of the propeller in the diagonal flow.By comparing the open water performance of the propeller under different diagonal flow angles,it is found that the impact can be ignored when the diagonal flow angle is small,but the impact cannot be ignored when the diagonal flow angle is 8 °,and when the diagonal flow angle continues to increase,the propeller’s The efficiency drop can be more than one-third,and the increase in propeller torque will cause safety problems.Therefore,for some propellers that are designed at an angle to the incoming flow,the influence of diagonal flow must be taken into account.In addition,some fracture accidents indicate that the failure of the crack will cause the propeller life to be lower than expected,and the propeller stress is much lower than the yield stress of the material,which makes it possible to estimate the propeller life through numerical simulation of crack propagation.In this paper,the fatigue life of the propeller is predicted based on the crack propagation method.The stress intensity factor of the crack on the surface of the propeller is calculated to determine whether the crack propagates.The shape of the crack propagation is predicted according to the paris formula,and the propeller fatigue life is finally estimated.By changing the crack position,length,and propeller speed,the specific impact of these parameters on the life of the propeller was explored.The longer the initial crack,the closer to the propeller at 0.3r,and the faster the propeller speed,the lower the fatigue life of the propeller.