Effect of Plasma-Based Control on Low-Reynolds-Number Flapping Airfoil Performance

Large-eddy simulation (LES) is employed to investigate the use of plasma-based actuation for the control of flapping motion of a wing section at low Reynolds number. The SD7003 airfoil section and imposed oscillatory motion of the investigation are representative of micro air vehicle (MAV) applications. Dielectric-barrier-discharge (DBD) plasma actuation is utilized to modify the transitional flow and improve aerodynamic performance. Solutions are obtained to the Navier-Stokes equations, that were augmented by source terms used to represent plasma-induced body forces imparted by the actuator on the fluid. A simple phenomenological model provided the body force resulting from the electric field generated by the plasma. The numerical method is based upon a high-fidelity time-implicit scheme, an implicit LES approach, and domain decomposition in order to perform calculations on a parallel computing platform. Solutions are obtained for combined periodic pitching and plunging motion about an 8 degree mean angle of attack at chordbased Reynolds numbers of 30,000 and 60,000. Baseline simulations without control are compared to cases employing plasma actuation in order to assess eects on performance. Comparison is also made with experimental data, and a grid resolution study is performed for validation purposes. Plasma-based control is able to mitigate, but not completely eliminate, the massive separation that occurs during the unsteady motion. It is shown that plasma actuation can reduce drag by 80% over the flapping cycle, and increase the lift to drag ratio by a factor of five.