Flow Mechanism Analysis And Experimental Study Of Swing Wing Propulsion

Ship propellers have evolved greatly with the evolution of ships for thousands of years.However,most modern ships and submersibles still use the traditional propeller propulsion method.In recent years,with the continuous development of bionics,the concept of bionic propulsion has gradually been introduced into the research of underwater propulsion mode.The bionic hydrofoil propulsion derived from fish swimming has a prominent advantage compared with the traditional propeller propulsion method.The bionic propeller is more maneuverable,allowing for more flexible turns,while achieving higher thrust at lower motion speeds and lower hydrodynamic noise.Therefore,it is of great significance to study the hydrodynamic performance of hydrofoil propulsion to improve the propulsion device of existing underwater vehicles.Based on the previous work of the research group,this paper mainly studies the hydrodynamic performance of the oscillating hydrofoil and discusses its flow mechanism.At the same time,the accuracy of the numerical simulation method is verified by the swing wing propulsion experiment.The specific research contents are as follows:1.Using the FINE/Marine hydrodynamic analysis software of the NUMECA series,the numerical simulation calculation of the lift coefficient of the NACA0012 airfoil widely used in the hydrofoil propulsion research under different Reynolds numbers is carried out,and the technical test data of the NACA0012 airfoil is verified.The accuracy of static analysis of numerical simulation methods.The grid generation mode and grid independence are verified.The results show that the 2D mesh generation mode can be used to simulate the hydrofoil hydrodynamics,and the calculation efficiency is high,which can greatly reduce the calculation time.2.A simulation model was established for the NACA0012 airfoil,three different thickness ratio flat airfoils and two types of NACA0012 airfoil.The hydrodynamic performance simulation study was carried out.The results show that the NACA series of airfoils have an advantage in propulsion performance.At the same time,the CFView postprocessing software is used to analyze the transient flow and airfoil flow field characteristics of the hydrofoil.The results show that the existence of the anti-Carmen vortex street is the main reason for propelling the hydrofoil forward,and also the main reason for cyclical changes in hydrofoil thrust and lateral force.3.The effects of the bow swaying amplitude,horizontal swing and motion trajectory on the hydrofoil propulsion performance are discussed.The flow field characteristics of the hydrofoil under different working conditions are analyzed.The influence factors of the oscillating hydrofoil propulsion are analyzed by the characteristics of the flow field.The results show that the size of the vortex in the flow field,the shape of the vortex,the distribution law of the vortex and the existence of the vortex are important factors affecting the propulsion performance of the hydrofoil,which also provides a certain reference for the performance optimization of the swing propulsion.4.Optimized and improved a set of swing-wing propulsion experimental institutions designed and processed by the research group,designed and improved the experimental scheme,improved the measurement and calibration of the force,and implemented the swing-wing propulsion experiment based on the circulating water tank.A number of repetitive tests were performed and a large amount of experimental data was obtained.According to the processed experimental data,the force analysis of the swing wing is carried out,and the corresponding hydrofoil numerical simulation results are compared and analyzed.The results show that the data is in good agreement,the accuracy of the numerical simulation method for unsteady hydrodynamic performance analysis is verified.