Performance of Airfoils at Low Angles of Attack: Trailing Edge Trapped Vortices

The aerodynamic performance of a conventional non-symmetric airfoil is manipulated at low angles of attack (when the baseline flow is fully attached) by leveraging the presence of a small flap integrated with a synthetic jet actuator. The flap is similar in some respects to a conventional Gurney flap having a characteristic scale of 0.016~ and is mounted on the pressure side of the airfoil just upstream of its trailing edge. The objective is to leverage the presence of the trapped vortices that are induced by the flap near the trailing edge to further manipulate the Kutta condition of the airfoil and thereby achieve global flow modifications and potentially improve its overall aerodynamic performance. When the control jet is activated, the aerodynamic performance of the airfoil can be continuously varied from a configuration that is essentially an airfoil with a conventional Gurney flap through an airfoil that has similar performance as that of the smooth (baseline) airfoil to an airfoil that has a higher lift to pressure drag ratio.