Numerical Investigation on the Effect of Gurney Flap Thickness on Airfoil Characteristics

A systematic numerical study is performed to determine the effect of Gurney flap (GF) thickness on the aerodynamic performance of an A821201 airfoil. In this paper, three different GF thicknesses are investigated. The Reynolds-averaged Navier-Stokes equations are solved with implementation of the Spalart-Allmaras one-equation turbulence model. It is showed that compared with the clean airfoil, all GF configurations produce increased lift coefficient, and the increments become more significant with decrease in thickness. The maximum lift coefficient is improved by 38.34%, 34.56%, and 30.61% for GF thicknesses of 1mm, 10mm, and 20mm, respectively. In addition, higher drag and pitching moment coefficients are obtained when a thinner flap is utilized. Furthermore, a detailed comparison of the predicted flowfield indicates that as the GF thickness increases, another separation bubble is formed at the bottom side of the GF. In order to use the GF efficiently, it is recommended that GF should be made as thin as possible.