Active Flow Control by Surface Smooth Plasma Actuators

Surface smooth plasma actuators were used to control leading-edge flow separation on the flying wing airfoil Eppler E338 for angles of attack of up to 12° past stall at low Reynolds numbers. The plasma actuators were operated over a range of free-stream speeds from 2.2 to 6.6 m/s giving chord Reynolds numbers from 26K to 79K. The plasma actuators produced a 2-D wall jet in the flow direction along the surface of the airfoil and thus added momentum to the boundary layer. Each actuator consisted of two metal electrodes separated by a dielectric layer which was part of the airfoil surface. At all five free-stream speeds from 2.2 to 6.6 m/s, the maximum lift coefficient could be reached and the stall regime relaxed. The power to achieve this was approximately 17 watts per meter or 8.6 watts per actuator over the span width. It was found that the application of low power plasma actuators could simplify the design of mini and micro air vehicles (MAVs) by calculating with the maximum possible lift coefficients obtained from simplified fluiddynamic equations.