Plasma flow control simulations of a low-Reynolds number low-aspect-ratio wing

Abstract

Large-eddy simulation (LES) is employed to investigate use of plasma-based control in order to improve aerodynamic performance of a flat-plate wing. The wing has a rectangular planform, a thickness to chord ratio of 0.016, and an aspect ratio of 2.0. Computations are carried out at a chord-based Reynolds number of 20,000, such that the configuration and flow conditions are typical of those commonly utilized in micro air vehicle (MAV) applications. Solutions are obtained to the Navier–Stokes equations, that were augmented by source terms used to represent body forces imparted by plasma actuators on the fluid. A simple phenomenological model provided these body forces resulting from the electric field generated by the plasma. The numerical method is based upon a high-fidelity time-implicit scheme and an implicit LES approach, which are applied to obtain solutions on an overset mesh system. The control strategy explores plasma actuators that are distributed in the spanwise direction along the wing leading edge, and actuators extending in the chordwise direction along the wing tip. The investigation considers plasma-induced forces that are imposed in either the co-flowing or counter-flow directions for the former arrangement, and directed inboard or outboard for the latter. Both continuous and pulsed operation of actuators are simulated, and the magnitude of the plasma force is varied in order to establish the most efficient means of control. Computations are carried out at angles of attack that are below (8.0deg) and above (25.0deg) the stall value. Control solutions are compared with baseline results without actuation to determine the most beneficial control strategies. It was found that actuation is effective only for sufficiently large values of the plasma force. A favorable comparison is shown with the limited available experimental data.