Pierre Magnier

Experimental study of a DBD surface discharge for the active control of subsonic airflow

The use of plasmas, created by electric discharges, as aerodynamic actuators has been an exciting research topic for more than ten years. However, investigation of these electric discharges is still incomplete. This paper presents our contribution to the study of a DBD surface discharge. Complementary and coherent electrical, optical and aerodynamic measurements as a function of various parameters and geometries were performed. We measured the influence of the frequency and applied voltage of the discharge on the dissipated power. Experimental data yielded an empirical formula to calculate dissipated power and the energy lost in the dielectric was estimated. The plasma temperatures were also evaluated by spectroscopy emission measurements of N2 molecular bands. The velocity of the airflow induced by the DBD discharge in initially still air was measured as a function of the power dissipated in the discharge for different thicknesses and types of dielectric.

Experimental Study of the Flow Induced by a Sinusoidal Dielectric Barrier Discharge Actuator and Its Effects on a Flat Plate Natural Boundary Layer

Since the mid-1990s, electrohydrodynamic actuators have been developed for modifying on subsonic airflows. The principle of plasma action is the use of the direct conversion of electrical energy into kinetic energy in order to act on the flow boundary layer. This paper presents our contribution to such an investigation concerning an electrohydrodynamic actuator consisting of several sinusoidal dielectric barrier discharges. First, the ionic wind induced by this actuator was measured with a pressure sensing probe. The induced flow velocity increased with the applied voltage and frequency. The particle image velocimetry system without external airflow showed the presence of induced swirls, generated by the ion movement in plasma. Then the action of this actuator on a flat plate boundary layer in parallel flow at zero incidence was studied in a subsonic wind tunnel. Experiments were performed for 15 m/s and 22 m/s. They showed that electric discharges (±8 kV, 1 kHz) acting on a laminar flow tripped the laminar-to-turbulent transition. Moreover, higher applied voltages (up to ±12 kV, 1 kHz) were necessary for modifying turbulent boundary layers.

Control of Subsonic Flows with High Voltage Discharges

In this paper, a DC surface corona discharge established on a rounded edge of a dielectric material was studied in atmospheric air. The flow induced by this actuator was measured and experiments on a NACA 0015 were performed in a subsonic wind tunnel. These measurements showed that this discharge modified the fully detached flow on the airfoil up to Re=267 000 and 17.5° of angle of attack.