Research Of The Hydrodynamic Performance Of Bionic Propeller

Propeller is the most widely used propulsor,people focus more on the performance of it with the developing of science and productivity.Conventional propellers can not satisfied the demand of complex conditions gradually,thus,a serious of special form of propeller have been put forward and many of them draw on the experience of bionics.This paper drawing inspiration from fins with protrusion of humpback,designs a leading edge of propeller with concave-convex framework,and studies the performance of the propeller.The curved surface of propeller is very complex and the size and location of concave-convex framework is hard to confirm,but propeller can be simplified as a twisted wing.According to the above,this paper used NACA 0020 as the prototype wing for independent research and developed bionic concave convex wing firstly.We designed seven models with the difference of aspect ratio,concave-convex type,and the wing type.By comparing the experiment results of the hydrodynamic and flow characteristics of the concave-convex influence on the wings,we discover that the stall performance of concave-convex wings is more smooth compared to conventional wings and there is no obvious stall angle.Given that airfoil of the original NACA0020 stalls,the lift coefficient and the lift drag ratio of uneven airfoil on the same angle are well improved.The studies above lay the theoretical foundation for the design and research of bionic propeller.Then,based on the impact of the concave-convex framework on wings,we used CATIA to design eight bionic propellers with different concave-convex framework size,different distribution and established the CFD numerical simulation method of bionic propeller performance.STAR CCM+ was used to mesh the model and compute the hydrodynamic performance of the bionic propellers.The computational result of prototype propellers was compared to the experiment result and the error was in an acceptable range that proves the correctness of numerical simulation.Then the hydrodynamic performance of the eight concavo-convex bionic propellers was computed and the propeller with best performance was chosen to carry out propeller open water test.Results of the experiment and numerical calculation are consistent and the following conclusions are obtained: the thrust and torque coefficients of bionic propeller are lower than prototype propeller;the open water efficiency of bionic propeller is higher than the prototype propeller when the advance coefficient is between 0.1-0.5;energy consumption and noise can be reduced due to the large decrease of blade plane vortex;vibration of the bionic propeller is lower than the prototype propeller because of a more uniform blade plane pressure.