Air Flow Control at a Boundary Layer Using a Surface Dielectric Barrier Discharge Actuator

The aerodynamic plasma actuators have shown their capability as a flow control device in different applications. This study presents an inventory design in which a power supply is used to generate a high voltage (up to 8kV) at high frequency (up to 10 kHz) output. The High voltage generator is applied to ionize ambient air at atmospheric pressure at the surface of a plasma actuator. The configuration of the plasma actuator is simple. It consists of two electrodes arranged asymmetrically. One of the electrodes was exposed to the surrounding air, and the other was on the other side of the dielectric material.. When a high AC voltage was applied, a plasma discharge appeared on the insulator surface above the insulated electrode, and directed momentum was coupled into the surrounding air. The amount of the coupling momentum was effective in substantially altering airflow over the actuator surface. The coupling momentum induced an air flow that expanded over both sides of dielectric layer. Such a coupling can increase air velocity in boundary layer from zero modifying air flow. However in this study the induced air flow was measured in the absence of external airflow using a pilot tube. The effect of frequency and dielectric material on induced air velocity was also studied. The results showed that there is an optimal frequency (7.5 kHz in this study) at which the induced air flow reaches its maximum velocity. The results revealed that the induced air velocity at the top of dielectric up to 0.5 mm reaches to 5m/s for Plexiglas dielectric and to 6m/s for Teflon. Hence, the dielectric constant plays a significant role in inducing air velocity. The advantages of the plasma actuator flow control device over traditional flow control devices are: smaller in size and weight, absence of moving parts, higher reliability, inexpensiveness, broader bandwidth (quick response), reduced drag and increased aerodynamic agility.