Aerodynamic Drag and Aeroacoustic Noise Mitigation of Flatback Airfoil with Spanwise Wavy Trailing Edge

Abstract

Spanwise wavy trailing edge designs are proposed as a way of reducing aerodynamic drag and aeroacoustic noise on flatback airfoils for future wind turbine blades. The wavy trailing edges are designed by varying sinusoidally the trailing edge thicknesses of flatback airfoils in the spanwise direction. Three dimensional Computational Fluid Dynamics (CFD) simulations are performed to verify the aerodynamic performance and aeroacoustic behaviors of the proposed wavy trailing edge flatback airfoils. Delayed Detached-Eddy Simulations (DDES) are used to resolve the attached turbulent boundary layer as well as the detailed vortex shedding behaviors around the airfoil trailing-edge region and nearby wake. GPU-accelerated simulations are conducted to reduce the otherwise massive computational costs. The effects of the wavy trailing edge design have been studied with two major design factors on the wave distribution: wave length and amplitude. The flow field results and vortex shedding behavior are presented for each different design case of wavy trailing edge airfoils and compared with typical flatback and sharp trailing edge airfoils. Potential acoustic noise levels resulting from the wavy trailing edge airfoils are studied and also compared with that predicted from typical flatback airfoil cases.