McDonald-Mehta Lecture Series #3: Dr. William Devenport
The third and final segment of the 2011-2012 McDonald-Mehta Lecture Series continued with a visit by Dr. William Devenport from Virginia Tech. Dr. Devenport is Professor and Director of the Stability Wind Tunnel in the Department of Aerospace and Ocean Engineering at Virginia Tech, and talked on his research: Wind Tunnel Testing of Wind Turbine Blade Sections.
Dr. Devenport received his Ph.D. from the University of Cambridge (UK) and joined the faculty at Virginia Tech in 1989. Since then, he has built an extensive research program centered on experimental studies of aerodynamics and aeroacoustics.
The performance of large, horizontal axis wind turbines is in large part determined by aerodynamic and acoustic behavior of their blade sections. Wind turbine airfoils are generally much thicker and aerodynamically more aggressive than airfoils used for lifting vehicles, for which most experimental data exists. Measurements of the aeroacoustic characteristics of wind turbine blade sections at realistic conditions are thus a critical part of making these devices quieter and more efficient. Conventional open-jet wind tunnels are not well suited to such measurements. A large lifting surface placed in such a facility deflects the jet, resulting in large aerodynamic errors, problems with the jet catcher and sound contamination from the self-noise of microphones placed near the flow. At Virginia Tech, a new hybrid wind tunnel configuration has been developed which uses a test section flanked by anechoic chambers separated from the flow by walls made from thin Kevlar cloth. The cloth contains the bulk of the flow but permits the transmission of sound with little loss. The containment results in smaller far-field aerodynamic corrections, meaning that larger models can be tested at higher Reynolds numbers. The containment also eliminates the need for a jet catcher and allows for a much longer test section. Model-generated noise is thus more easily separated from facility background using beamforming. This new capability has established the Virginia Tech Stability Wind Tunnel as one of very few where aeroacoustic testing of wind turbine blade sections can be performed at, or close to, full scale conditions. This development has not only provided new research capability and a unique testing venue for wind turbine manufacturers, but has also established wind turbine blade testing as part of the undergraduate educational experience in Aerospace and Ocean Engineering at Virginia Tech.
(Above photo): Dr. William Devenport from Virginia Tech, reports on his research at the third lecture in the 2011-2012 McDonald-Mehta Lecture Series.