Optimal design of aeroacoustic airfoils with owl-inspired trailing-edge serrations.

The trailing-edge serration that imitates the silent owl wing is used as a flow control method to suppress the aerodynamic noise generated from the rotating wind turbine blade. Recent studies have found that the addition of serrations could degrade the overall aerodynamic performance of the airfoil. To this end, an optimal design method for airfoils with the trailing-edge serration is developed. Combined with the modeling methods of aerodynamics for serrations, the fundamental parameters of serrations are integrated into the optimal design of wind turbine airfoils. Specifically, based on the existing multidisciplinary optimization method for airfoils, the aerodynamic prediction and evaluation module for the serrated airfoil was introduced to develop an aerodynamic-structural optimal design platform. In this way, a novel serrated airfoil equipped with high aerodynamic performance can be designed. Compared with the reference airfoil, the maximum lift-to-drag ratio and lift coefficient of the optimal serrated airfoil at the design point have been increased by 1.9% and 32.5%, while the aerodynamic noise could also be reduced. Finally, experiments were conducted in an anechoic chamber to verify the noise-reduction level of the optimal serrated airfoil, which sufficiently demonstrate the capability to improve the comprehensive performance of the airfoil using such a developed optimal scheme.