Experimental Research Of Aerodynamic Characteristics For Half-Rotating Wing

Flapping wing aircraft has some functions of lifting,hovering and propulsion.It has become the focus of researchers all over the world for its unique mobility and flexibility,while some great achievements have been got in flapping wing aerodynamics.Half-rotating wing(HRW)is a new flapping-imitating wing system with rotating-type flapping instead of oscillating-type flapping.Theoretical analysis and numerical calculation of aerodynamic characteristics have been conducted.The mean lift coefficient of HRW is an important parameter of aerodynamic performance in hovering and forward flight,which could only be obtained from the experimental results.Besides,the influence of law of wing layout,wing phase and material properties for HRW on aerodynamic characteristics needs to be analyzed in order to obtain better aerodynamic characteristics and lift.Therefore,the experimental research on aerodynamic characteristics of HRW in hovering and forward flight was carried out by self-developed experimental platform,which would provide practical guidance for the theoretical design of HRW.The second generation contralateral-type HRW was developed on the basis of unidirectional rotation.The working principle of HRW was introduced,and the second generation contralateral-type HRW structure layout was proposed to solve the existing problem in the first generation contralateral-type HRW driving mechanism.The prototypes of double-wing HRW and fourth-wing HRW were manufactured and experimented.The high speed movement of double-wing HRW engendered small amplitude vibration of the fuselage,so the shape,size and installation position of distributed weight were redesigned on the basis of HRW dynamic balance principle.The test devices of balance and rotating aerodynamic characteristic were developed.When the general scheme of the test device was determined,the main mechanism was introduced in detail.The test device was manufactured,while its principle and the mean lift calculation model were determined.In addition,the error analysis of the two test devices was conducted.According to the character and form of error,the balance test device was analyzed from three aspects about system error,random error and gross error to verify the accuracy and effectiveness of experimental data of the test device.Dynamic performance analysis on the rotating test device was performed by ADAMS.Based on the virtual prototype,the aerodynamic force was exerted to HRW,and the dynamic simulation was conducted to verify the correctness of the mean lift calculation model.The experimental research of aerodynamic characteristics for HRW in hovering flight was carried out.The composition of the balance test system and experimental scheme were determined.Research on the influence of wing layout and material properties on aerodynamic characteristics was conducted using the single-wing,double-wing and fourth-wing HRW as experimental subject.It was indicated that the flow field generated by the motion of the wing arranged symmetrically would interfere with each other,resulting in that the mean lift coefficient of the double-wing HRW was less than the single-wing HRW.Meanwhile,the mean lift coefficient of flexible wing was larger than the rigid wing,and the mean lift of the flexible wing would go up with the increasing of looseness when it was within the appropriate range.The experimental research of aerodynamic characteristics for HRW in forward flight was carried out.The composition of the rotating test system and experimental scheme were determined.Research on the influence of the pitch angle and crank speed on aerodynamic characteristics of the double-wing HRW was conducted.The experiment results showed that the lift generated by HRW in forward flight was larger than in hovering flight at the same crank speed.The lift coefficient of HRW in forward flight would change constantly.The lift coefficient of HRW increased with the increasing of crank speed as it was in a certain range,while the lift coefficient of HRW decreased with the increasing of crank speed as it exceeded a certain range when HRW flew forward with a certain pitch angle.