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Blade control.

The Largest wind turbines can be so imposing that it might seem they are impervious to damage. But the Long blades are subject to vibrations that can degrade the material or even make them fail. To combat this, wind turbines have been engineered to shed power in high-wind situations, sometimes feathering the blades to reduce the lift on them.

Miki Amitay, a professor of mechanical engineering at Rensselaer Polytechnic Institute in Troy, N.Y., believes there is another approach. Amitay envisions wind turbine blades that, instead of trying to duck out of the wind, actively work to reduce the vibrations created by turbulent air flowing over their surfaces.


To do this, Amitay and his colleagues are developing a system that would be embedded in the blades of a wind turbine and would change the aerodynamic characteristics of the blade on the fly. Sensors along the blade would monitor vibrations; when the blades started to flap, puffs of air would be shot out from jets along the Length of the blade to change the flow of air. By disrupting the natural air flow, the jets can break up vortices in the air that can form on the blade. This will reduce the stresses on the blade and increase the time between failures, all with an eye toward making Large turbines more cost efficient.

In preliminary studies, Amitay and his colleagues found that in a wind tunnel, blades had their vibrations reduced by a factor of 100 when jets of air were puffed across them.

The jets can also improve the ability of wind turbines to work in relatively light winds by maintaining a flow of air on the blades and thereby reducing the Likelihood of stalling. This may make it possible for Large wind turbines to harvest energy from even low-speed winds.

The New York State Energy Research and Development Authority recently awarded Amitay a $250,000 grant to develop this technology. As part of the research project, Amitay and his students at RPI will study the flow of air around turbine blades and how the airflow interacts with the blade. They will use that data to optimize blade design.

This section was edited by Associate Editor Jeffrey Winters.

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Title Annotation:TECH FOCUS: Instrumentation & Control
Author:Winters, Jeffrey
Publication:Mechanical Engineering-CIME
Geographic Code:1USA
Date:Jun 1, 2011
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