Enhancing Lift on a Flat Plate using Vortex Pairs generated by Synthetic Jet

Abstract

Synthetic jets have been widely used in flow control applications of airfoils to prevent stall or reattach separated flow to enhance lift and decrease drag. In this study, a synthetic jet actuator is utilized as a generator of vortex pairs. Based on the interaction between the vortex pairs of the synthetic jet and a flat plate wing, novel active flow control strategies can be developed to manipulate vorticity generation and distribution in the flow field to realize enhanced lift. The mechanism of these control strategies is inspired by a previous study, which demonstrates that the motion of vorticities in the wake will affect lift production. To verify this idea, a 2D potential flow model is developed to model the flow field around a flapping flat plate wing with vortices in the wake. Moreover, the vortex pairs generated by a synthetic jet actuator are also modeled using point vortices in a potential flow. The validity of these potential flow models is verified through comparison with previous experimental and numerical studies. This flow model of an unsteady flat plate serves as a test case, based on which the vortex interaction and evolution around a flat plate with synthetic jet actuation are simulated. The results of this lift enhancement study indicate that a synthetic jet actuator should be placed close to the leading edge and issued in the direction of the background flow to achieve enhanced lift for low angle-of-attack cases where flow separation has not occurred. This will provide guidance for flight control of micro aerial vehicles (MAVs) during taking off or landing.