Force enhancement of gurney flaps on a wing in ground effect

A study was performed of a single element, high-lift wing fitted with Gurney flaps in ground effect. The effect of the Gurney has been quantified in terms of aerodynamic performance and flowfield characteristics. The results are of direct relevance to both aeronautical and racing car applications. The qualitative performance of the Gurney in ground effect compares with freestream; the normal force of the wing is increased and a sharper stall results. Laser Doppler Anemometry was used to investigate the effect of the Gurney on the turbulent wake characteristics behind the wing. Particle Image Velocimetry was employed to elucidate the unsteady flow behind the Gurney, which is characterized by a street of alternately shedding, discrete, vortices away from the ground. When flow starts to separate from the trailing edge of the suction surface, the stall mechanism in ground effect, an unsteady wake results and the aerodynamic performance deteriorates.