Nontechnical Description
Over the past decade, the size of wind turbine blades used for the conversion of wind energy to electricity has grown rapidly. New designs for wind turbines are often tested using scale models in a wind tunnel, similar to testing of new airplane designs. However, the behavior of scale models of wind turbines within a wind tunnel often does not represent the behavior of actual wind turbines deployed in the field because of issues relating to the scaling of the air flow around the turbine blades for long turbine blades. The goal of this research is develop a new approach for designing wind tunnel tests for wind turbines. This will be accomplished by using a wind tunnel which uses highly compressed air at over 200 times atmospheric pressure to proportionally scale the effects of flow inertia relative to blade rotation for a scaled down model wind turbine. Aerodynamic models will be used to scale the behavior back up to a real wind turbine operating at atmospheric pressure. This approach has the potential to improve the reliability of wind tunnel data for the design of new wind turbines, leading to improved performance models and wind turbine designs. As the part of the project activities, the principal investigator will serve as a mentor for National Wind Resource Center Summer Research Institute Program, organized at TexasTech University, and work with undergraduate students, high school students, and high school teachers to provide training in wind energy topics and recruit students from under-represented groups for future graduate study.
The overall goal of this project is to develop a new approach for scaling wind turbine scale model tests within wind tunnels to Reynolds numbers that are representative of full scale wind turbines in field operation. Wind turbine aerodynamics is mainly governed by two dimensionless parameters, the Reynolds number and the Strouhal number, also known as the tip-speed-ratio. Over the past decade, the size of wind turbines has grown rapidly, and has moved their operation to higher Reynolds numbers. In order for wind tunnel tests to give an exact representation of the aerodynamics, both the Reynolds and the Strouhal number must simultaneously be matched to what is experienced by the full scale turbine. However, studies on scaled down models in conventional wind tunnels can only match one of these parameters, and not both simultaneously. This project will investigate the effect of the parametric mismatch and give new insight into the effect of rotation on the aerodynamics by developing a new experimental approach that will allow for simultaneous matching of both parameters. This will be accomplished using a unique high-pressure flow facility where both the Reynolds number and tip-speed-ratio will be matched to a modern large scale wind turbine. Since the working air pressure can easily be changed from 1 to 220 atm, a wide range of Reynolds numbers can be tested, and can potentially provide new insight on scalability of wind tunnel studies. A miniature wind turbine will be built and installed in the existing High Reynolds Number Test Facility. Experiments will be conducted at full dynamic similarity, which will address fundamental questions about how Reynolds number and rotational effects determine the aerodynamic behavior and power output of wind turbines. As the part of the project activities, the principal investigator will serve as a mentor for National Wind Resource Center Summer Research Institute Program, organized at TexasTech University, and work with undergraduate students, high school students, and high school teachers to provide training in wind energy topics and recruit students from under-represented groups for future graduate study.
