The Effect of Various Wedge Flap Configurations on the Performance of Wind Turbine Airfoil

Controlling turbulent flow to improve wind turbine airfoils' aerodynamic characteristics is a desirable task. The current study evaluated the potential of adding a wedge flap (WF) at the trailing edge of the NACA0021 airfoil. The effect of different WF heights and lengths on optimum height (L/H) on the aerodynamic performance and flow over the airfoil has been studied numerically using two-dimensional computational fluid dynamics simulation. The simulation solves the Reynolds-Averaged-Navier-Stokes with shear stress transport k-omega turbulent model. The results indicate that adding WF can effectively suppress flow separation and improve aerodynamic efficiency in all studied cases compared to clean airfoil. The aerodynamic performance is influenced significantly by the height of WF compared to the slight influence by the length at L/H < 1. Inclined WF achieves the highest lift and lift-to-drag values with total maximum increments of 71.67% and 45.79%, respectively, at optimum height and length with 6%c and 1%c, respectively, in comparison with the clean airfoil case. The results observed that WFs have advantages over the Gurney flaps discussed in this study. WF appears to be an effective passive flow control device that can be used in wind turbines if its dimensions are properly chosen.