Thursday, 25 November 2010

In the lab, pursuing a more intelligent wind turbine

In the lab, pursuing a more intelligent wind turbine - Smart Planet

University researchers are working hard to improve the design of the wind turbine.

In 2008 and for the first time, new wind turbine power generation capacity topped new coal-fired capacity in the U.S. The growth of the nascent wind power market only promises to drive down costs in the future, but engineers say the design of the wind turbine itself could use an upgrade.

One problem is that the turbine is designed to work best under one wind condition: steady. Mother Nature, of course, rarely lets that happen.

So researchers at Syracuse University are testing intelligent systems-based active flow control methods to allow large turbines to better handle naturally-occurring gusts, turbulence, wakes and shear.

With support from the U.S. Department of Energy and the University of Minnesota Wind Energy Consortium, researchers Guannan Wang,Basman El Hadidi, Jakub Walczak, Mark Glauser and Hiroshi Higuchiare using their technology to estimate the flow conditions over the blade surfaces from surface measurements.

By feeding the information to an intelligent controller, they can implement real-time actuation on the blades to control the airflow and increase the overall efficiency of the wind turbine system.

The result, according to their simulations: allowing a turbine to have a wider operational range with the same rated power output. What’s more, the flow separation may help reduce noise and vibration.

Meanwhile, researchers at the University of Minnesota are investigating how to reduce drag on wind turbine blades.

To reduce the effect, the researchers are implementing tiny grooves — described as triangular “riblets,” just 40 to 225 microns deep — by scoring them into the coating on the blade.

The researchers – Roger Arndt, Leonardo Chamorro and Fotis Sotiropoulos — are testing various groove geometries on the airfoil surfaces of a 2.5-megawatt turbine, in both simulations and the wind tunnel.

The concept of “riblets” is hardly new, but it’s not yet been applied to turbine blades. Conventional thinking grouped wind turbine blades with airplane wings, but it turns out that the peculiarities of the job — turbulence near the ground, a different blade design — means turbine blades require a different approach to drag reduction.

According to the researchers, the riblets will increase wind turbine efficiency by about 3 percent.

Both ideas were presented this week at the 63rd annual American Physical Society Division of Fluid Dynamics meeting in Long Beach, Calif.

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