Structural Design And Aerodynamic Characteristics Study Of Bionic Flapping Wing Aircraft

Bionic flapping wing flight vehicle is a kind of birds and insects in the nature as a new type of aviation aircraft,a mock object compared to the traditional fixed wing and rotor aircraft,the bionic flapping wing flight vehicle has the advantages of good energy utilization high maneuverability strong concealment,especially its unique bionic appearance,make it in the field of military and civilian fields has a broad application prospect.Birds and insects have different physiological structures,resulting in different flapping patterns of bird wings and insect wings.In order to overcome the poor aerodynamic performance of single-stage bionic flapping wing aircraft,this paper aims to design a multi-stage bionic flapping wing aircraft with the function of "expansion-fold-torsion" with large and medium-sized birds as imitation objects.This paper summarizes and studies the physiological structure and flight mode of birds and insects,analyzes the mechanism of flight lift and thrust of flapping wing,and defines the design task.In order to meet the target of imitating large and medium-sized birds,different driving modes were analyzed,conventional mechanical structure was selected as driving mode,and double crank and double rocker mechanism was adopted as driving mechanism.Through optimization and improvement,the "expansion-folding" mechanism was designed to realize the function of wing expansion and folding.The active torsional mechanism is designed so that the aileron can be torsional during the flapping of the wing.The driving mechanism is designed as a whole and its kinematics is analyzed by software ADAMS,the analysis results show that the designed drive mechanism conforms to the mechanical law and design requirements.Complete the overall size and internal structure design of the bionic flapping wing aircraft,select the appropriate power and energy source,design the gear reduction group,improve the wing type,design the full-motion tail fin to control the direction,and process and make the prototype.The method of ADAMS-XFlow joint simulation can make the wing move well.The aerodynamic simulation analysis in this paper includes the aerodynamic characteristics of the multi-stage bionic flapping wing aircraft under different flapping frequency,inflow velocity,fuselage Angle of attack and aileron torsion Angle.The simulation results show that: with the increase of flapping frequency,the lift coefficient and thrust coefficient peak gradually increase;With the increase of inlet velocity,the peak values of lift and thrust coefficients decrease gradually.With the increase of the fuselage Angle of attack,the lift peak increases and the thrust peak decreases.With the increase of aileron torsional Angle,the minimum lift and maximum thrust increase.