Numerical investigation of gurney flap aerodynamics over a NACA 2412 airfoil

From the time of its invention, the Gurney flap has been successfully employed as high lift augmentation device to enhance the aerodynamic performance of modern aircraft wings. These small flaps are located perpendicularly at the suction side of an airfoil near its trailing edge. By the addition of gurney flap wake is stabilized which ensures laminar flow over the suction side and thus shifts the shock. This study investigated the aerodynamic effect of a Gurney flap on a NACA 2412 airfoil for the subsonic condition. Flap height ranges from 2% to 5% of the airfoil chord length. The investigation was evaluated at 0° to 32° angle of attack under subsonic Mach number. The numerical analysis was performed using Computational Fluid Dynamics program to predict the flow field. The analysis shows that the optimal size of the device is always below the boundary-layer thickness at the trailing edge and it tends to increase lift to drag ratio significantly. The gurney flap with 2%C height provides the best performance rather than 3, 4 and 5% Gurney flap. The investigation concludes with a suggestion that Gurney flap may lead to drag reduction in high lift regions, thus, increasing the lift-to-drag ratio before the stall.