Numerical simulation of gurney flap on RAE-2822 supercritical airfoil

A two-dimensional steady Reynolds-averaged Navier-Stokes equation was solved to investigate the effects of a Gurney flap on RAE-2822 (Royal Aeronautical Establishment) supercritical airfoil aerodynamic performance. The heights of Gurney flaps range from 0.25 to3%airfoil chord lengths. The incompressible/compressible Navier-Stokes equations were used to simulate the flow structure around the airfoils in subsonic/transonic flows, respectively, with the Spalart-Allmaras turbulence model. In comparison with the clean airfoil, the Gurney flap can significantly increase the prestall lift and lift-to-drag ratio of an RAE-2822 airfoil at a small angle of attack. Nosedown pitching moment also increased with the Gurney flap height. At both takeoff-and-landing status and cruise phase, the aerodynamic performance of the airfoil was significantly improved by Gurney flaps with the height below 1%airfoil chord length. In addition, the surface pressure distribution, wake flow velocity profile, and trailing-edge flow structure of the airfoil were illustrated, which helps to understand the mechanisms of the Gurney flap to improve RAE-2822 airfoil aerodynamic performance.