Study On The Influence Of End Plate On The Hydrodynamic And Cavitation Performance Of CLT Propeller

The CLT(Contracted and Loaded Tip)propeller has an end plate with a biasing pressure surface at the blade tip compared to the conventional propeller.The presence of the end plate separates the pressure field between the pressure surface and the suction surface,so that between the pressure surface and the suction surface,the pressure difference is greater than that of a conventional propeller,thereby increasing the thrust of the propeller,increasing the efficiency of the propeller while weakening the tip vortex strength.End plate parameters have a significant impact on the performance of the CLT propeller.Therefore,the variable parameter calculation and analysis of the CLT propeller end plate is carried out to explore the mechanism law of the end plate affecting the performance of the CLT propeller,which is of great significance for the optimization design of the CLT propeller.In order to explore the influence of end plate parameters on the performance of CLT propellers.The article takes NACA0015 airfoil as the research object.Firstly,the lift and drag are calculated numerically,and compared with the experimental values to verify the feasibility of the calculation method.Then install an end plate on the airfoil tip,and perform variable parameter calculation and analysis on the end plate.Studies have shown that the height and angle of the end plate have an important effect on the lift resistance and flow field of the airfoil.Based on the commercial computational fluid dynamics software Star-CCM+,numerical simulation was performed on the international standard model CLT propeller P1727,and the wake field and tip vortex characteristics of the CLT propeller were analyzed.The comparison and analysis with public experimental results verified the validity of the calculation method At the same time,it is found that the tip vortex structure of the CLT is very different from the evolution law of the tail vortex and the conventional propeller.Based on the research on CLT propeller P1727,the influence of end plate parameters on the open water performance and tail vortex of CLT propeller was investigated.Taking the P1727 propeller as the prototype propeller,a CLT propeller with different end plate parameters was designed based on a self-programmed program,and its open water performance and tail vortex were numerically calculated.Studies have shown that the length,angle,and width of the end plate have a certain effect on the performance of the CLT propeller.Increasing the end plate length has a limited increase in thrust coefficient,and the end plate length has little effect on efficiency.However,the length of the end plate has a certain effect on the strength and evolution of the tip vortex in the wake field.When the end plate is short,the pressure at the blade back end plate is small and the tip vortex is strong.The position where the adjacent blade tip vortex merges with each other is closer to the center of the propeller surface.The greater the thrust and torque,the less obvious the efficiency change.The smaller the pressure at the blade back end plate,the stronger the tip vortex,and the earlier the fusion between adjacent blades.When the width of the end plate is large,the There are more positive pressure areas,so the thrust is larger,and the torque is also larger,and the efficiency is basically not improved.The influence of the end plate width on the strength and evolution of the tip vortex is not significant.Finally,the effects of end plate parameters on the cavitation performance of CLT propellers and the hydrodynamic performance of the propellers were studied.The article first numerically calculates the cavitation performance of the standard-type propeller E779A,and compares it with experiments to verify the feasibility of the cavitation calculation method.Then the cavitation performance of CLT propellers with different end plate parameters is calculated and analyzed.The analysis found that the area where cavitation occurred on the blade surface was basically the same as the low-pressure area,indicating that low pressure was the cause of cavitation,and cavitation had a negative impact on the thrust coefficient.As the length of the end plate decreases,the low pressure and cavitation area gradually develops toward the blade tip end plate,and the thrust loss gradually increases;as the end plate angle increases,the low pressure and cavitation area gradually spreads toward the end plate.Thrust loss gradually increases;as the width of the end plate increases,the low pressure and cavitation areas gradually shift to the end plate,but the thrust loss is not much different.