Air Plasma Actuators for Effective Flow Control

An asymmetric dielectric barrier discharge model is presented for real gas eight species air chemistry using a self-consistent multi-body system of plasma, dielectric and neutral gas modeled together to predict the electrodynamic momentum imparted to the working gas. The equations governing the motion of charged and neutral species are solved with Poisson equation on finite elements using a Galerkin weak formulation. Two specific geometries were used. First the unsteady electrodynamic force development mechanism is studied over a flat plate due to charge and neutral species production from adjacent air-like N2/O2 mixtures in a radio frequency driven barrier discharge. The solutions show a dominance of O and N2 ions. The time average of the streamwise force shows mostly acceleration above the actuator but a small decelerating force downstream of the powered electrode inducing a fluctuation in the temporal evolution of streamwise velocity. This decelerating component needs further investigation as this may inherently limit the performance of a dbd plasma actuator. The computed electron temperature based on the electric field resembles the visible glow that is commonly reported in the literature. In another case, neutral gas flow is considered over a 5 deg conical crosssection for demonstration of active control using pulsed direct current and dielectric barrier discharges. The results demonstrate the need for utilization of multiple actuators for controlling a largely separated flow.