Date of Graduation

2015

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Patrick H Browning

Committee Co-Chair

Wade Huebsch

Committee Member

John Kuhlman

Abstract

The continued high global demand for passenger and freight air traffic as well as increased use of unmanned aerial vehicles (UAVs), in spite of rising fuel costs and several tragic cases involving loss-of-control events, has resulted in researchers examining alternative technologies, which would result in safer, more reliable, and superior performing aircraft. Aerodynamic flow control may be the most promising approach to this problem having already proven its ability to enable higher flow efficiency while also simultaneously improving overall flow control. Recent research in the area of aerodynamic control is transitioning from traditional mechanical flow control devices such as slats and flaps to plasma actuators. Plasma actuators offer an inexpensive and energy efficient method of flow control. In addition, plasma actuator technology has the potential of application to a host of other aircraft performance parameters including applications in radar mitigation and in situ wing deicing.;Dielectric Barrier Discharge (DBD), one of the most widely studied forms of plasma actuation, employs an electrohydrodynamic (EHD) device, which uses dominant electric fields and the respective electrically related body forces for actuation. Unlike momentum jets or other traditional flow control methods used on wings and tail surfaces, a DBD device operates without moving components or injecting any mass into the flow stream.;Work performed focuses on qualitatively investigating experimentally the use of DBD devices for flow separation control on a NACA 0012-based 2D wing model. Flow visualization techniques illuminated flow seed particles around the model to determine the state of the flow (i.e., attached or separated) for various actuator cases. The DBD was operated in a steady-on mode as well as for three different pulsing frequencies (only for low power testing) based on the Strouhal frequency for each flight condition and compared to the clean (i.e., plasma off) case. Some of the flow control results were compared to another active flow control scheme known as dynamic roughness (DR) which consists of surface mounted time dependent deforming elements that operate as a periodic forcing device that energizes the boundary layer. The potential use of DBDs for application to existing UAVs and aircraft was also evaluated based on applicability, power consumption, and other relevant factors.;Results of this work indicate that low power gapless DBD actuators are an effective form of separation control at low Reynolds numbers Ohorn (10 4) near the angle of attack where separation begins to occur. However, testing seems to indicate that gapless low power DBDs are underpowered to have any substantial flow control authority at higher Reynolds numbers and angles of attack. With improved materials for DBD construction and more testing, DBDs could potentially be an effective form of flow control on UAVs and manned aircraft in the future.

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