Research on Optimized Design of Structural Parameters and Aerodynamics of Wind Turbine Airfoil with Bionic Flap

In this paper, a self-expanding bionic flap is added to the suction surface of the wind turbine S809 airfoil to suppress the separation of flow around the airfoil at high angles of attack. This is inspired by the phenomenon in which birds slightly pop up their feathers at the wing trailing edge under special conditions. The sample spaces of the bionic flap structural parameters(including the flap height H, the distance from flap to the trailing edge D, and the popped up angle of flap θ)are obtained with the Box-Behnken response surface methodology(RSM). The lift-drag ratio of the airfoil under a large angle of attack is selected as the optimization target. Numerical calculation and quadratic regression analysis are also carried out to investigate the response function relationship between the structural parameters of the bionic flap and the airfoil lift-drag ratio as well as the optimal combination of bionic flap parameters. The performance of the bionic flap airfoil and clean airfoil are compared from the perspective of dynamic and static aerodynamic characteristics. The results show that D has the highest sensitivity to lift-drag ratio among all the single-factor main effects while θ -H has the highest sensitivity to lift-drag ratio among all the interaction effects; the bionic flap suppresses the flow separation on the suction surface, and changes the size and distribution of the separation vortex and the wake vortex at high angles of attack, thus suppressing the dynamic stall effect. As a result, the lift-drag ratio and lift are increased at most by 53% and 41.8% respectively under different configurations. © 2022 Xi'an Jiaotong University. All rights reserved.