Worldwide First Validation of Aerodynamics of Large Wind Turbines
For the very first time in the world, Fraunhofer IWES is measuring the aerodynamics of wind turbines with a rated power of more than five megawatts (MW). The aerodynamic properties of the AD 8 wind turbine, with rated power of 8 MW and rotor diameter of 180 m, are being measured at the site in Bremerhaven and compared against complex models in the scope of the “HighRe” research and development project. The project is funded by the Federal Ministry for Economic Affairs and Energy (BMWi) with a budget of € 4 million. This way it shall be assessed whether the model calculations used to date are also valid for large wind turbines, which will primarily be built offshore in the future.
The “HighRe” project (aerodynamics with high Reynolds numbers for the large offshore wind turbines of the future) conducts complex measurements of the wind field and the aerodynamic reaction of the wind turbine in the near future. With these detailed findings of real wind conditions both in front of and on a wind turbine, it will become possible to analyze and understand the precise aerodynamic effect on rotor blades at such large dimensions. The wind field is scanned using three overlapping LiDAR laser scanners in front of the wind turbine and complemented with additional wind measurements in front of and behind the turbine. At the same time, sensors are installed on the turbine and rotor blades to record these conditions precisely.
Already before the start of the HighRe project, Fraunhofer IWES was able to demonstrate that there are significant deviations in the models of yawing large wind turbines.The model used for such cases was developed almost 20 years ago on considerably smaller turbines. The picture is similar for a large number of wind turbine aerodynamics models. The model calculations are based on small turbines. To compensate for this, computational fluid dynamics (CFD) methods are being used increasingly. However, to date, it has only been possible to check the accuracy of CFD methods on small model turbines. The HighRe project changes this deficit in wind energy aerodynamics completely. “The HighRe project is a great opportunity for wind energy research and the wind energy industry. With this project, the safety and accuracy of wind energy aerodynamics can be adapted to real turbine development. This represents a huge potential for the wind energy industry”, explained project manager Dr. Bernhard Stoevesandt, summarizing the prospects of this project.
Fraunhofer IWES secures investments in technological developments through validation, shortens innovation cycles, accelerates certification procedures, and increases planning accuracy by means of innovative measurement methods in the wind energy sector.