Wind characterization leads to new innovations

Expanding wind energy volume takes an interdisciplinary perspective

Hui Hu, professor of aerospace engineering
Hui Hu, professor of aerospace engineering

Aerospace engineering and atmospheric sciences are joining forces and technology at Iowa State to better understand airflow and wind shear on wind farms.

Using computer models, wind and icing tunnel experiments, and field measurements, the researchers say their work can depict individual turbine dynamics, turbine-to-turbine interaction and ultimately how wind farms impact regional wind profiles.

“The projects we’re leading give insight into how much wind energy is harvested and also the lifetime of turbines, providing an overall sense of how well a wind farm is operating,” said Hui Hu, professor of aerospace engineering. “From there, we want to figure out ways to increase efficiency, keeping cost effectiveness a priority.”

One way the team is working on improving wind farm productivity involves creating a dual-rotor wind turbine. The project, which was recently funded by the National Science Foundation, features a second rotor that fits into the larger, less aerodynamic section of the main rotor. The smaller rotor is designed to extract energy from wind that initially passes by the main rotor.

Anupam Sharma, assistant professor of aerospace engineering and Walter W. Wilson Faculty Fellow
Anupam Sharma, assistant professor of aerospace engineering and Walter W. Wilson Faculty Fellow

“This setup can also help in mixing out the wake, or disturbances that occur in the atmosphere from the wind turbine, replenishing the energy in the wind before it gets to the next turbine on a farm,” explained Anupam Sharma, assistant professor of aerospace engineering and Walter W. Wilson Faculty Fellow.

For this project, Hu runs experiments in the wind tunnel while Sharma develops analytical and numerical models. The combination offers a complementary environment where details can be thoroughly investigated, giving the researchers an exact picture of what would happen in the field.

But at Iowa State, the research goes one step further. Bringing in Gene Takle, professor of agronomy and geological and atmospheric sciences, the aerospace engineers can confirm their data using on-site measurements to come up with optimal solutions.

Gene Takle, professor of agronomy and geological and atmospheric sciences
Gene Takle, professor of agronomy and geological and atmospheric sciences

Takle’s research group has access to power generation data for large wind farms across the state of Iowa. And the group actively measures wind activity on different sites as well. His team looks at several factors, including wind direction, shear and speed, as well as atmospheric stability at different elevations. While his work is primarily investigating how wind turbines affect crops and soil, the information he has can be applied to the research of Hu and Sharma.

Takle says one of the most interesting things the researchers have worked on has been identifying the changes in wind flow as it goes through a large field.

“While Anupam has substantiated our observations of changing wind patterns with numerical models, we have yet to determine the implications,” Takle said. “For example, as warm, moist air is pushed up, there’s potential for it to lead to clouds and eventually rain. We want to know the larger scale impact of this phenomena and if in fact wind farms can influence weather conditions.”

As the researchers explore and expand these and other projects—like turbine blade positioning and de-icing, ideal terrain conditions and turbine alignment on farms, turbine noise signatures, and even wind forecasting—they plan to continue collaborating with one another and add insights from others on campus.

Wake simulation of dual-rotor wind turbine
Wake simulation of dual-rotor wind turbine

“The wind energy field is such that we need input from many disciplines, and the fact that we are able to bring it all together here at Iowa State makes us one of the very few places that can carry out work in such great magnitude,” Sharma said. “We’re tackling the problem the way it’s supposed to be tackled.”

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