Experimental and Numerical Investigation on a DBD Actuator for Airflow Control

Abstract

A surface dielectric barrier discharge (DBD) actuator has been experimentally investigated. An electrode pair separated by a dielectric sheet constitutes the actuator. Two types of dielectric materials and several a.c. supply conditions have been utilized to generate a surface dielectric barrier discharge with different characteristics. An Electro Hydro Dynamics (EHD) interaction was induced into still air and several fluid-dynamic regimes were obtained. Using electric and fluid dynamics measurements, the energy transfer mechanisms caused by the EHD interaction have been investigated. The visualization of the plasma boundary layer during the discharge ignition phase, characterized by hot vortexes, and during the steady regime has been obtained by means of Schlieren diagnostics technique. Vortex morphology and propagation velocities for both actuator types at all supply conditions have been evaluated. Pitot velocity profiles have been taken in the steady regime operation at several distances along a line perpendicular to the actuator surface. Along this line and as a function of the position the integral of the pixel intensities of the Schlieren image has been calculated. The function obtained matches with a good agreement the Pitot velocity profile for all distances and in all the supply conditions investigated. Numerical simulations were performed to validate theoretically this result. The calculations confirm the relationship between flow velocity distribution in the boundary layer and the gas density distribution.