Engineers at Iowa State University (ISU) are studying how hills and nearby wind turbines affect wind energy production. The researchers are using wind-tunnel tests to quantify the characteristics of surface winds over hilly terrains, determine the best placement of wind turbines on these terrains and find the best design for large wind farms in these types of locations.
According to ISU, the research aims to boost total energy capture and lengthen wind turbine lifetimes by making them more efficient.
Experiments for the project include the following: Mini generators mounted inside the mini turbine nacelles measure power production; sensors mounted at the base of the mini turbines measure the wind loads placed on turbines and turbine towers; and advanced flow measurements, such as particle image velocimetry to measure wind flow fields, the wind vortices created by the tips of turbine blades and the total wind energy captured by the blades.
Preliminary results of the studies indicate that wind turbines on hilly terrain are hit with much higher wind loads than turbines on flat terrain. The experiments also show that, compared with turbines on flat ground, wind flowing over hilly terrain recovers its power potential more rapidly as it moves from turbine to turbine.
Data from the wind tunnel indicates that a turbine on flat ground in the wake of another turbine at a distance equal to six times the diameter of the turbines loses 13% of its power production, and a turbine in the wake of another with the same downstream distance on hilly ground loses 3% of its power production.
The project's next steps include building a nine-turbine array in ISU's big wind tunnel to study power production and wind flows through a mini wind farm.
The studies are supported by a three-year, $300,000 grant from the National Science Foundation and a two-year, $100,000 grant from the Iowa Alliance for Wind Innovation and Novel Development.
