Masters Theses

Date of Award

8-1998

Degree Type

Thesis

Degree Name

Master of Science

Major

Physics

Major Professor

J. Reece Roth

Committee Members

Stuart B. Elston, A. J. Baker, Marshall O. Pace,

Abstract

In this study the ability of a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) to modify aerodynamic boundary layers is demonstrated. In early 1996, the staff at the University of Tennessee's Plasma Sciences Laboratory designed and had fabricated circuit board electrodes capable of producing thin, flat sheets of its proprietary One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). Since then, these OAUGDP panels have been repeatedly and successfully operated in the NASA Langley Research Center's 7 x 11 (17.8 x 27.9 cm) Low Speed Wind Tunnel. Experimental results will be presented from exploratory investigations of the OAUGDP panel's aerodynamic properties utilizing an air bearing drag balance, pitot tube velocity profiles, smoke-wire flow visualization, and a hot-wire anemometer.

The OAUGDP panels consist of parallel linear arrays of RF electrode strips on opposite sides of standard circuit board material. The OAUGDP panels have been energized by a RF power supply operating at frequencies between 0.4 - 6.0 kHz, and RMS voltages between 2.2 - 5.6 kV. These panels have had a variety of electrode geometries with different electrode spacings and electrode widths, and with the strip electrodes oriented both parallel and perpendicular to the airflow. While the number of possible electrode geometries is limitless, our investigations have identified two types of electrode strips with interesting aerodynamic properties.

Symmetric OAUGDP panels (plasma panels in which the plasma is generated on each side of the electrode strips) are found to increase the aerodynamic drag and boundary layer thickness by creating vortical structures and inducing turbulence.

Asymmetric OAUGDP panels (plasma panels in which the plasma is generated predominately on one side of an electrode) are found to be capable of either increasing or decreasing the aerodynamic drag and boundary layer thickness by inducing a unidirectional airflow immediately above the surface of the OAUDGP panel, either against (counter-flow) or with (co-flow) the free stream airflow, respectively.

In either case, the degree to which the aerodynamic boundary layer is affected is dependent on the electrode strip's orientation with respect to the airflow (parallel or perpendicular), relative electrode spacing, electrode width, and applied voltage. The data also suggest that the frequency of the applied RF voltage and the plasma power also strongly influence the panel's performance.

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