Abstract

Recent years have witnessed extensive research efforts that aim at improving the aerodynamic performance of aircraft. while most of the efforts are drawn towards high-lift systems, simple and innovative designs like Gurney flaps, trapped vortex cavities and backwardfacing steps can have a significant effect on enhancing the aerodynamic properties of airfoils. One of those simple ideas is the Kline-Fogleman modified airfoil (KFm-2), which is basically an airfoil with a backward-facing step on the upper surface located at midway the chord length. it is claimed that the step creates a low pressure recirculation region on the suction side of the airfoil that may enhance the lifting force. This study will numerically examine the ability of the KFm-2 design to enhance the lift and drag properties of a NACA 2412 at a high Reynolds number of 5.9 #xD7; 106. The effect of the step depth and the step angle will be thoroughly examined.