Numerical study of virtual aerodynamic shape modification of an airfoil using a synthetic jet actuator

Recently, it has been shown experimentally that the form drag of an airfoil at low angles of attack can be significantly reduced with minimum change in lift by fluidic modification of the apparent aerodynamic shape of the airfoil using synthetic jet actuators. This virtual aerodynamic shape modification is achieved by creating a small domain adjacent to the upper surface of the airfoil which displaces the local streamlines sufficiently to modify the local pressure distribution. In a recent experiment, Glezer and his co-workers deliberately created such an interaction domain adjacent to the upper surface of a 24% thick Clark-Y airfoil by employing a synthetic jet actuator placed immediately downstream of a surfacemounted passive obstruction of small dimensions. The goal of this paper is to perform numerical simulations of this experimentally observed fluidic modification of airfoil pressure distributions leading to reduced pressure drag. For performing the computations, a Reynoldsaveraged Navier-Stokes code WIND is employed. Computations are performed for subsonic flow past a 24% thick Clark-Y airfoil with a triangular bump on the upper surface with and without a synthetic jet. Reasonably good agreement is obtained between the computations and the experimental data.