Masters Theses

Date of Award

8-2005

Degree Type

Thesis

Degree Name

Master of Science

Major

Electrical Engineering

Major Professor

J. Reece Roth

Committee Members

Leon Tolbert, Mostafa Howlader

Abstract

The aerodynamic applications of plasma science is a field of growing interest. Investigations using various approaches have been initiated by several research groups that are designed to manipulate the aerodynamic boundary layer and to re-attach the flow to airfoils. EHD (ElectroHydroDynamic) flow control has proven at least as effective as other methods of boundary layer flow control. In the EHD approach, glow discharge plasma actuators are placed on the wings and fuselage of the aircraft, or on the turbine blades in the engine, to influence the boundary layer flow. This thesis is concerned with plasma actuators based on the OAUGDP ® (One Atmosphere Uniform Glow Discharge Plasma). An actuator consists of two conducting electrodes separated by a dielectric plate. When a sufficiently high RF voltage is supplied to the electrodes, the surrounding air ionizes and forms plasma in regions in which the electric field is above approximately 10 kV/cm. The ionized air, in the presence of an electric field gradient, produces a body force on the neutral gas flow.

This work is concerned with two EHD effects: paraelectric flow acceleration and peristaltic flow acceleration. In the paraelectric mode, electric field gradients act on the net charge density of plasma, and the plasma drags the neutral gas along with it due to ion-neutral and electron-neutral Lorentzian collisions. In the peristaltic mode, successive actuators are energized with the same voltage, but increasing phase angles. The first part of this thesis describes experiments at the NASA Langley Research Center, Hampton, VA in the 7 x 11 Inch Low Speed Wind Tunnel in which Pitot tube velocity profile measurements and smoke flow visualization tests were conducted.

The second part of this thesis describes the development of a low cost power supply to energize OAUGDP ® plasma actuators. The power supply consists of automotive ignition coil transformers, audio amplifiers, and a DC battery. Using this power supply, plasma actuators were energized at voltages up to 8 kV, and at frequencies between 0.5 and 8 kHz. This thesis also presents illustrative paraelectric flow acceleration data obtained using the low-cost power supply.

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