Surface dielectric barrier discharge actuator: Electrical, optical and mechanical characterization

Abstract

Surface dielectric barrier discharge (DBD) based on two electrodes mounted on both sides of a dielectric have been widely studied for ten years for their application in aerodynamic flow control by plasma actuators1,2,3. On one hand, surface DBD supplied by an ac sine high voltage (ACDBD) produces an electrohydrodynamic force that results in an electric wind based-wall jet. Typically, single DBD can produce mean force and electric wind velocity up to 1 mN/W and 7 m/s, respectively. With multi-DBD designs, velocity up to 11 m/s has been measured and force up to 350 mN/m. On the other hand, if the high voltage has a nanosecond repetitively pulsed waveform (NRP-DBD), the sudden gas heating at the dielectric wall results in a pressure wave with pressure gradient up to 1 kPa4. When the plasma actuator is mounted at the wall of an aerodynamic profile, these both mechanical phenomena (EHD force and pressure wave) can interact with the boundary layer and modify the near-wall flow, resulting in the control of the whole flow. In the present paper, we focus on surface AC-DBD actuators. Electrical, optical and mechanical characteristics of surface AC-DBD are presented. First, discharge current and energy consumption values are discussed. Secondly, the discharge formation along the dielectric wall is investigated by fast iCCD visualisations. Finally, time-resolved measurements of the electric wind by particle image velocimetry and laser Doppler velocimetry are presented. The influence of several parameters such as the electrode geometry and the voltage frequency on the discharge behavior are more especially investigated in the present experimental study. On one hand, results show that the voltage frequency does not affect significantly the discharge physics but it plays a key role in the produced force. On the other hand, the study highlights that the use of a wire active electrode instead of a plate electrode modify considerably the discharge physics and its mechanical effects.