Experimental Study On Aerodynamic Coupling Characteristics Between Flapping Parameters And Geometric Parameters Of Double Wings

Flapping air vehicle has good concealment,maneuverability and low energy consumption,and has a broad application prospects in many areas.In the past 30 years,researchers have done a lot of research on the flight mechanism of insects and birds in order to develop flapping-wing aircraft.The research results provide strong support for the development of flapping air vehicle.Compared with single-winged birds and insects,double wings insects have better stability and maneuverability in flight,but their aerodynamic mechanism is also more complex.In the case of double wings,the coupling between multi-parameters has an important influence on aerodynamic force.In this paper,the dragonfly is used as a reference to establish the flapping wing model.The effects of coupling between multiple flapping parameters and geometric parameters on aerodynamic force in hovering are studied experimentally,in order to provide a reference for the development of the flapping air vehicle.Firstly,a flapping wing model was developed to simulate the hovering flight of double insects,and an experimental platform was built to measure the aerodynamic effects of coupling among multiple parameters.The experimental platform consists of four parts: double wings flapping mechanism,motion control system,bottom and upper programs,and force sensor.The flapping wing model in the experimental device completes the flapping motion under the control of a single chip computer according to the observation data of the double wings insects hovering in the literature,and the motion fitting accuracy of the model is measured.On the experimental platform,the effects of coupling among three flapping parameters,such as flapping frequency,flapping amplitude and the phase difference between front and rear wings,on aerodynamic forces were studied.The experimental results show that the coupling among the three flapping parameters has a great influence on the average lift coefficient.With the increase of flapping frequency,the average lift coefficient decreases with the increase of flapping amplitude.The coupling among the three flapping parameters has little effect on the average thrust coefficient.Then,the aerodynamic effects of coupling between distance between front and rear wings and flapping parameters are studied experimentally.The experimental results show that the coupling between distance between front and rear wings and flapping parameters has less influence on the average lift coefficient,but greater influence on the average thrust coefficient.There is a reasonable spacing between the front and rear wings,and the average thrust coefficient increases with the increase of the flapping amplitude when distance between the front and rear wings is within this range.When the distance between the front and rear wings is larger or smaller,the average thrust coefficient first increases and then decreases with the increase of the flapping amplitude.This paper reveals the aerodynamic disturbance caused by the coupling of multi-parameters of the bionic flapping air vehicle,and the research results provide a theoretical reference for making the flapping-wing prototype.