Numerical Simulation Of Aerodynamic Performance Of A Beetle-Mimicking Flapping-Wing Micro Air Vehicle

The MAVs have the advantages of small size,high maneuverability and portability,and they have good development potential in military and civilian applications.After miniaturization,the flapping-type MAVs have superior flight performance than the rotor-type MAVs and fixed-wing MAVs,so the flapping-type MAVs have become a research hotspot.the beetle wing has superior portability and concealment,Therefore,the study of the foldable wing of the beetle is very important.Based on the four-plate theory mechanism,a four-plate foldable wing of beetle was designed,and the aerodynamic analysis of the forward flight process was carried out by using Fluent software.According to the flight mode and principle of the insect,the mechanism of the aircraft is optimized,and the simulation analysis of the gliding process of the rigid and flexible wings was carried out.The main research contents and results are as follows:Based on the four-plate mechanism theory proposed by Haas Fabian et al.,a bionic foldable wing was designed and the physical model of the bionic foldable wing was built in solidworks software.Using the dynamic mesh technology,numerical simulations of the unsteady flapping of rigid wings in Fluent,The lift coefficient,drag coefficient and the lift-to-drag ratio of the wings were analyzed under different flapping frequency,flapping amplitude,forward speed and torsion angle.Aiming at the problem that the bionic flapping wing aircraft is mostly driven by a DC motor and the motion characteristics are relatively simple,a bionic beetle flapping mechanism with variable motion characteristics is designed.The mechanism is designed with a double crank-crank slider mechanism with variable motion characteristics.The kinematics equation of the mechanism is established by the closed-loop vector method.According to the bionic characteristics of the beetle flight,aiming at the stability of the flapping flight,the flapping wing transmission mechanism is optimized by considering the flapping amplitude,frequency,angular velocity and acceleration.A multi-objective optimization model of the flapping mechanism was established,and the numerical calculation of the mechanism optimization is carried out.The influence of the flapping wing mechanism on the aerodynamic characteristics of the aircraft is analyzed.A two-way Fluid-Structure Interaction(FSI)numerical simulation method was employed and the lift and drag coefficients of the foldable wing with flexible hinges of different elastic modulus were analyzed.The gliding performance of rigid and flexible wings under different angles of attack and at different gliding speeds was simulated.The lift and the lift-to-drag ratio of the flexible wings at different gliding speeds were obtained.In this paper,the numerical simulation was used to simulate and analyze the aerodynamic performance of the bionic foldable wing in different forward and gliding states,and the design of the aircraft transmission mechanism is optimized.The results provide a basis for improving the flight capability and efficiency of the beetle-mimicking flapping wing aircraft.