Parametric Design And Aerodynamic Performance Study Of Bionic Corrugated Wings

The bionic flapping-wing micro air vehicle(FMAV)is one of the research directions that has attracted much attention in recent years.It is usually designed based on insects and small birds,and has the advantages of concealment,mobility and low power consumption.As the main power source of FMAV,optimizing wing airfoil design is an effective measure to improve its structural strength and aerodynamic performance and further enhance its application.Based on the complex folding and stretching phenomenon of wings in the dragonfly evolution process to form the folded airfoil morphology,this paper studies the differences in the mechanical performance,glide and unsteady aerodynamic performance of different specifications of folded airfoils under flapping conditions.The main contents are as follows:First of all,based on the cross section fold structure at different spanwise positions of the front wing of the blue dragonfly,the position and number of folds are parameterized,and six types of folded airfoils with different characteristics are established.The mechanical properties of folded airfoil are studied by using finite element analysis,and the specific effects of different types of folded structures on bending resistance are analyzed,and the action rules of folded structures on airfoil strength are obtained.Using the method of numerical simulation,the influence of fold structure on the unsteady aerodynamic performance of wing gliding at different angles of attack within a certain range of Reynolds number is explored,and the aerodynamic performance of wing gliding at negative angles of attack is solved as a supplement to comprehensively analyze the aerodynamic performance of fold airfoil.Secondly,combined with the three-degree-of-freedom motion in space,the aerodynamic differences in different directions under a specific Reynolds number are analyzed,and the reasons for the aerodynamic differences are analyzed in combination with the characteristics of the flow field.The advantages of the change of the spanwise force of the folded airfoil in optimizing the strength of the connecting part of the flapping-wing aircraft are innovatively pointed out,and the reasons for the differences of the two aerodynamic components in the chord direction are analyzed.The aerodynamic performance of 3D series folded wing under simple harmonic motion is further studied,and the interaction mechanism between wings of folded airfoil in series and the aerodynamic performance difference of different forms of folded structure in series flutter are analyzed,so as to guide the future series wing flapping micro aircraft device and the parametric design of folded airfoil,and the various possible applications of folded airfoil in aircraft design are pointed out.At last,the experimental equipment for aerodynamic test and smoke observation was built.On this basis,aerodynamic test and numerical simulation results of various airfoils at a single angle of attack were compared.The smoke flow experiment is further designed.By comparing with the numerical simulation flow field results,it is confirmed that the low velocity vortex trapped in the folded valley further induces the aerodynamic effect of the low pressure region.Aiming at the problem that previous research on folded airfoils cannot effectively distinguish which structure has better performance,this paper established six types of folded airfoils from the two dimensions of fold distribution number and fold distribution location,studied their mechanical properties,glide,and unsteady aerodynamic performance differences under single and double wing flutter conditions,and conducted aerodynamic performance tests to verify the effectiveness of folded airfoils,providing a certain reference for the application of folded airfoils in the field of micro flapping aircraft.