Electronic Theses and Dissertations

Date of Award

2011

Document Type

Dissertation

Degree Name

M.S. in Physics

First Advisor

Nathan E. Murray

Second Advisor

James P. Chambers

Third Advisor

Jeffrey Roux

Abstract

Recent work has shown that spatial correlation of surface pressure fluctuations in a fully turbulent atmospheric boundary layer (ABL) can give information about the velocity field and turbulence. This is of particular importance to the future of wind energy to predict the incoming velocity flow field of wind turbines so as to actively control them for peak operating efficiency and damage reduction. All of the environmental effects on the surface pressure fluctuations need to be fully understood before a suitable flow prediction algorithm can be constructed. One such environmental effect which has not been previously studied is the effect of surface heating on the surface pressure fluctuations. The current study aims to create a situation in a low speed wind tunnel that is roughly analogous to that of a ground heated turbulent ABL and to study the effects on the surface pressure fluctuations. The intent was not to perfectly scale the ABL but to create a situation in the wind tunnel that mimics some of the same physical processes associated with the ABL. Experimental data was collected in the 2'x2' square test section low speed wind tunnel at the University of Mississippi's National Center for Physical Acoustics. A 3" tall backward facing step was placed at the entrance of the test section to create a sufficiently thick, fully developed turbulent boundary layer further down the test section where surface pressure fluctuations were measured. The bottom floor of the tunnel was also retrofitted with electric heater blankets so as to study the effect of surface heating on the surface pressure fluctuations. The effect of heating on surface pressure fluctuations was studied for a variety of flow speeds and surface temperatures and it was shown that the surface heating had little to no effect on any of the measurements of the sound pressure level beneath the boundary layer. It was also shown from the cross-correlation coefficient functions that the surface heating had little to no effect on the calculated turbulent convection speeds.

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