Focused Airflow Enhances Wind Turbine Efficiency: Wind Energy: Eco20/20

Focused Airflow Enhances Wind Turbine Efficiency

As the overall design of wind turbines is improved, producing energy by using wind turbines is becoming less expensive. That cost reduction is attracting investors, which in turn is encouraging design engineers to more aggressively develop their ideas for designs, treatments or accessories that will boost turbine output. These efforts are raising the wind-energy industry to the status of a fast growing market. Which may explain why, in the year 2008, the U.S. added more power-production capacity from new wind-turbines than it added from coal-fire processes.

Performance Improvement Designs

* A wind turbine performs best when there is a constant steady wind flow. Efficiency suffers when wind gusts, turbulence or shear play havoc with the flow. Customers are looking primarily at efficiency; so researchers are testing methods of boosting efficiency.

o At Syracuse University researchers have been testing active flow control systems that will collect measurements of the airflow over turbine blades, and then send them to an intelligent controller that will adjust the surfaces of the blades to improve how the turbine gathers wind under various circumstances.

o Simulations suggest that properly applied flow control could either improve the operational range of a wind turbine while retaining its power level or increase the output power while retaining an operational range. The effects of flow control on the noise levels of a wind turbine are also being measured and assessed at Syracuse, as are issues of drag.

o At the University of Minnesota other scientists have been scrutinizing active controls just as intensely. And, meanwhile, trying to determine if putting tiny grooves on turbine blades will reduce drag. The grooves are actually shapes scored into a coating on the surfaces of the blades. An assortment of grooves and various positions for the blades are being tested in wind tunnels and by computer simulation.

Ice Reduction Treatment

o Another ongoing project at the University of Minnesota seeks to reduce turbine down time by reducing ice formations. That project is testing blade coatings and films that will aid in de-icing turbines

Accessories

o The one accessory every horizontal-axis wind turbine needs is a method for pointing it into the wind. Small turbines use the historical method of attaching a wind vane. Larger turbines have a wind sensor and a motor. (On vertical-axis wind turbines there is always a sail facing windward.)

o Another already existing accessory is a funnel-like device that encircles the turbine and redirects the surrounding wind flow to the critical area of the blades. Passive structures of this sort are adaptable to any wind turbine.

o The concept of a funneling device, sometimes called a vortex, has received mixed reviews. Opponents feel the structures are bulky and inconvenient. They suggest that the bother of erecting funnels outweighs any benefit. Proponents feel any performance improvement is worthy of further testing and consideration.

Regardless of method, active or passive, focusing the airflow is the primary concern of wind turbine research.

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