Numerical Investigation of Gurney Flap Effects on Supercritical Airfoils for Transonic Speeds

Effects of a gurney flap was investigated on the supercritical NASA airfoil by solving two-dimensional Reynolds-averaged Navier–Stokes equations for a range of transonic Mach numbers and angle of attacks. It can be concluded that, the gurney flap has a remarkable influence on the aerodynamic coefficients (below the drag divergence Mach number) especially at -1 and 0 degrees angle of attack resulting in 50% increase in L/D ratio. At high Mach numbers and angle of attacks, Gurney flap loses its effects and the clean airfoil has better aerodynamic performance.