DC Glow Discharges: A Computational Study for Flow Control Applications

Abstract

A numerical study of glow discharges was carried out in order to evaluate their potential for flow control applications. As part of this project, a three-dimensional computer code has been written to solve, in an implicit, loosely-coupled fashion, the fluid conservation laws, the charged particle continuity equations under the drift-diffusion model, and the Poisson equation for the electric potential. Fully three-dimensional calculations have been carried out for DC discharges in nitrogen, and changes in the flow in the presence a discharge have been demonstrated. In computations of a three-dimensional electrode configuration mounted on a flat plate in a Mach 5 crossflow, the discharge was found to thicken the boundary layer. The resulting compression waves led to increased pressure forces at the plate surface. These changes in flow structure occurred through dissipative heating; the body force term in the fluid momentum equation was negligible. The computations are in qualitative agreement with total temperature measurements made in a similar configuration for air flow. 1 A preliminary investigation of the effect of an applied magnetic field has also been carried out. A computation of a simple discharge between parallel plates showed that an applied axial magnetic field tends to suppress the radial component of the current density.

Simulation of Direct-Current Surface Plasma Discharge Phenomena in High-Speed Flow Actuation

“…The drift-diffusion approximation [18], [24]- [27] is used to compute the species number flux density…”

“…These studies have typically emphasized either the flow physics [14], [16], [20] or the discharge physics with some models attempting to couple these two disparate phenomena self-consistently [4], [18]. Most of the discharge models, however, make significant assumptions, such as the local field approximation (LFA) [18], [21] and quasi-neutral magnetohydrodynamics approximation [22], [23], and provide a simplified treatment of discharge chemistry [4], [17], [18], [21].…”

“…Most experimental studies in the literature, however, indicate that, in the absence of magnetic fields, volumetric heating of the flow as well as plasma surface heating is primarily responsible for bare-electrode surface dc plasma actuation in high-speed flows [6], [10], [18]. We have recently performed experimental studies on nonequilibrium dc surface plasma actuators in supersonic air flows at low pressures of ∼10 torr [19].…”

Flow Control on a Three Dimensional Forebody Using Pulsed DC Plasma Actuator Operating in Air

“…[7][8][9][10] The plasma actuator can be used to increase the lift and/or reducing the drag of airfoils and fuselages through electrodynamic force. It has been shown by the experiments [7][8][9] and simulations [10][11][12] that the plasma actuator imparts momentum to the boundary layer inducing rapid flow attachment. High-frequency spark discharge plasma was used to control asymmetric vortical structures on the conical forebody.…”

Aerodynamic Optimisation Based on Stability and Sensitivity Analysis

“…Greenblatt and Wygnanski [36] documented the control of flow separation by periodic excitation with a hydrodynamic approach, ranging from acoustic wave-based approaches to flow injection and ingestion. The application of glow discharge plasma actuation on the boundary layer control has been experimentally [49] and numerically [80] proven to enhance a fast flow reattachment. Flow stability analysis [95] predicts how small flow perturbations grow or decay with respect to an equilibrium flow solution (the base flow), providing information about the onset of the physical mechanisms (reported as modes) responsible for detachments can help to determine means by which to control it.…”