Influences of mounting angles and locations on the effects of Gurney flaps

Experimental investigations were conducted on a NACA0012 airfoil to determine the influences of mounting angles and mounting locations on the lift-enhancing effects of Gurney flaps at a Reynolds number of 2.1 × 10⁶. The results revealed that all flaps of different mounting angles increased the lift coefficient, and an increment of maximum lift coefficient of 12.3, 15.1, and 17.4% was obtained by 45-, 60-, and 90-deg Gurney flap, respectively. There was a drag penalty associated with the lift enhancement. The best performance was obtained by the 45-deg Gurney flap for all flap deflections tested. When shifted forward from the trailing edge of the airfoil, the Gurney flap led to a decrease in lift, and an increment in drag, and thus a reduction in lift-to-drag ratio.