Hydrodynamic Analysis And Experimental Study On Swinging Propulsion Of Two-dimensional Rigid Wing

With the development of marine resources,the requirements of underwater aircraft for propulsion are more and more high.And in bionic research,most of the fish move forward through their own torso or fin,which can maintain an efficient movement and compared with the propeller has better flexibility,so researchers began to study bionic propulsion,hoping to develop a more efficient,high mobility,low perturbation of the propulsion method.As the main propulsion mode of the fish propulsion mode,hydrofoil propulsion has a better industrial transplant and practical,and the structure is relatively simple.The propulsion mode of hydrofoil method is divided into single degree of freedom,two degrees of freedom and many degrees of freedom motion propulsion,in which the two-DOF coupled motion mode is considered as the most practical scheme.Because the flexible hydrofoil theoretically has the infinite freedom movement form,the controllability is poor,the design difficulty is high,therefore this paper uses the rigid hydrofoil to complete two degrees of freedom coupling motion advancement.In order to achieve the optimal propulsion performance,it is necessary to study the working characteristics and flow field characteristics of two-degree-of-freedom rigid swinging hydrofoil,so as to provide theoretical reference for the practical design of hydrofoil propulsion.The method of fluid simulation and experimental analysis is used in the research.Fluid simulation analysis uses the hydrodynamic analysis software FINE/Marine to solve the N-S equation.In this paper,the NACA0012 hydrofoil airfoil which is widely used in the research of hydrofoil propulsion is first selected to carry out kinematics modeling,and the two-DOF coupling motion of the bow swaying and horizontal pendulum are defined,the dimensionless parameters of hydrodynamic performance of hydrofoil are defined by the definition method of propeller hydrodynamic parameters,such as propulsion efficiency,average thrust coefficient and load coefficient,etc.Then,in order to simulate the large swing of airfoil,the flexible dynamic grid technology is used,the thrust,liftand torqueof different bow swaying amplitude and horizontal pendulum amplitude are calculated respectively,and the hydrodynamic performance curve is obtained according to the parameter definition,and the influence law of the first swing amplitude and the horizontal swing amplitude on the propulsion performance of Hydrofoil is summed up.Finally,the wake flow field of hydrofoil under different operating conditions is analyzed,and it is found that the presence of dispersed vortex and long vortex in vortex field can significantly improve the propulsion efficiency of hydrofoil.In this paper,a simple and feasible hydrofoil propulsion device is designed to carry out the experimental research of hydrofoil propulsion,and the main purpose is to provide experimental verification for hydrofoil propulsion simulation.The device is driven by a stepper motor,the two-DOF movement of the water wing is realized by the classic model of slider plus connecting rod.The three-part force sensor,which has completed the strain gage paste,wiring and calibration experiment,is used as the force measuring instrument,and the thrust,lift and torque in the motion of the hydrofoil are measured by hydrodynamic experiments.The experimental results are compared with the corresponding simulation results,which proved that the software FINE/Marine is reliable to simulate the unsteady hydrodynamic performance of hydrofoil.