Abstract: The flatback wind turbine airfoils have good structure and aerodynamic performance. Blunt trailing edge or flatback airfoils are studied especially for the inboard region of large wind turbine blades. The drawback of the flatback design is known as the production of large vortices downstream of the airfoil that tend to degrade the performance of the blade. The overall objective of the present research is to have a better understanding of the airfoil performance characteristics such as the loss in aerodynamic performance balanced by the structural performance gain. The performance of the S809-100 flatback airfoil is simulated and compared with the original thin-trailing edge S809 airfoil by using the computational fluid dynamics (CFD) technique. It is shown that the flatback airfoil can increase the sectional maximum lift coefficient and lift curve slope, and reduce the well-documented sensitivity of the lift characteristics of thin airfoils to surface soiling in comparison with the traditional thin trailing edge airfoil.

Key words: Aerodynamic performance, Computational fluid dynamics, Flatback airfoils, Wind turbine