Multi-AOA optimization of variable-speed wind turbine airfoils

Considering that the operating angle of attack (AOA) of a blade element on a variable-speed wind turbine (VSWT) cannot be maintained at a single value due to the slow dynamic behavior of the turbine, the multi-AOA based airfoil design is gradually becoming a significant approach to improve the efficiency of energy capture for the blade element. However, a key issue of this method, the selection of multiple design AOAs and weight factors in the objective function, still relies on engineering experience at present, due to lack of investigation on the distribution of operating AOAs. Therefore, the operating AOA distribution of VSWTs' blade element is firstly investigated and described based on the inflow wind energy in this paper. Furthermore, by focusing on increasing the lift-to-drag ratios at the AOAs with the concentrated distribution of inflow wind energy, a multi-AOA design optimization method for VAWT airfoil is proposed. Finally, the proposed method is applied to optimize the airfoil NACA64618 and verified by simulation results.