Research on the aerodynamic performance and bionic application of dragonfly wing corrugation

To investigate the aerodynamic performance of dragonfly wing corrugations under gliding conditions, a new method of corrugation deformation is proposed. Firstly, the coordinate transformation functions that describe the amplitude and camber deformation of the corrugation and numerical simulation model are established. Then the effects of the corrugation structural parameters on airfoil performance are investigated by orthogonal experiment. Subsequently, the optimal structural parameters are selected sequentially, and the mechanism of the corrugation producing a high lift-to-drag ratio is analyzed. The results show that the optimized corrugation parameters are: corrugation profile as profile 5, amplitude coefficient<i>λ</i>= 0.8, vertex<i>x</i>-coordinate<i>a</i>= 0.9<i>c</i>, vertex<i>y</i>-coordinate<i>b</i>= 0.04<i>c</i>. The optimal airfoil achieves the highest lift-to-drag ratio of 5.090, which is increased by 42.82% compared with the flat airfoil (FA). The cambered corrugation airfoil can suppress flow separation. The high-pressure area generated within pressure surface corrugation can increase the pressure difference between the upper and lower surfaces, which is the main reason for the high lift-to-drag ratio. Finally, the bionic airfoils are built by arranging the corrugation on the FFA-W3-211 airfoil, which prove that the dragonfly corrugation with a low Reynolds number is also applicable to the wind turbine airfoil with a high Reynolds number, thereby increasing the lift-to-drag ratio of the prototype airfoil by 1.22%.