Aerodynamic Numerical Analysis Of Gurney Flap Applicationon Wind Turbines

In this paper,the influences of Gurney flap on airfoil aerodynamic characteristics and windturbine aerodynamic performance are investigatedusingcomputational fluid dynamic method.Airfoil S809and the Phase Ⅵ wind turbine blade of National Renewable EnergyLaboratory(NREL) are selected as prototype models for numerical analysis. The accuracy andreliability of the CFD method are confirmed through the comparison between computational andexperimental lift coefficient and lift-drag ratio of the S809airfoil and PhaseⅥ blade.Gurney flaps of1%,2%,3%, and4%chord length are virtually equipped to S809airfoil at thetrailing edge. The aerodynamic performance and flow fields of the airfoil are numerically simulatedunder different Reynolds numbers and angles of attack. The calculated results show that Gurney flapcan effectively enhance the lift coefficient and lift-drag ratio of S809airfoil. Gurney flap also changesthe flow structure around the trailing edge of airfoil by generating a separating bubble in front of theflap and a pair of reserve vortexes behind the flap. In addition, a new type of Gurney flap calledIndented Gurney flapisstudied in this paper. Indented Gurney flaps at the85%,90%, and95%chordpositionsare equipped to S809airfoil. The calculated results show that Indented Gurney flap can alsoenhance the lift coefficient and lift-drag ratio effectively while performed better in improving the stallperformance of the airfoil. For the PhaseⅥ blade, a4%chord length Gurney flap is attachedperpendicular to the local chord line at the trailing edge. The aerodynamic performance of PhaseⅥblade is calculated under different incoming wind speeds. The results show that Gurney flapeffectively increases the low-speed shaft torque of the wind turbine and reduces the separating area onthe suction surface of the blade, leading to a comprehensive enhancement of the aerodynamicperformance.