The effect of trailing edge flaps length on aerodynamics of wind turbine airfoil

The goal of the study was to investigate the effect of trailing edge flaps length on aerodynamics of wind turbine airfoil, airfoil S809 and DU series airfoil were selected as research objects, and six kinds of flap length airfoil model were designed, have the same chord length of 1000mm, and the same deflect angle of 10°, the gap between the flap and the main airfoil body was optimized to make the width of gap as even 1mm. The grids near the trailing edge are refined, and the grid independence is verified through the comparison of the calculated results with grid scales three, which a 148000 grid model was selected for further calculation. The k-ω two equation turbulence model for commercial software Fluent was used here to calculate the aerodynamics of the flap models at different attack angles, the streamline, pressure contour and pressure coefficient near border of airfoil were analyzed and compared. The result shows that the flaps length of airfoil with trailing edge flaps has great effect on the aerodynamic performance of the airfoil, not only the streamline near the flap is influenced but also the whole streamline near the airfoil are influenced. The lift coefficient of airfoil with flap is bigger than that of airfoil without flap, and the lift coefficient increases with the increasing of flap length. The drag coefficient of flap model is also bigger than that of airfoil without flap, and the drag coefficient of flap model also increases with the increasing of angle of attack. The lift to drag ratio is bigger than that of airfoil without flap at some range of angles of attack.