Experimental investigation of wind farm effects using model wind turbines

Wind farms are complex systems, entailing challenges for scientists and engineers: The turbines are subjected to atmospheric turbulence throughout their life time, whereas the interactions of turbulent wind conditions with the rotors are yet to be fully understood and need investigation. Next, the individual turbines in a wind farm arrangement interact through their wakes, which feature an increased turbulence level and a decreased mean wind velocity. The former is connected to loads and therewith to a turbine's life time, while the latter is directly linked to the energy yield. Thus, the so-called wake effects become a very important aspect in wind energy research. In recent years, concepts of active wake control strategies have been discussed throughout the research community, whereas a lateral wake deflection by intentional yaw misalignment gained great attention. In order to successfully apply this concept to future wind farms, a detailed understanding of wind turbine wakes, the effect of yaw misalignment and the impact on downstream turbines is needed. This work aims to contribute to the mentioned discussions by wind tunnel experiments using controllable model wind turbines, which were conducted in three different wind tunnels in Oldenburg, Germany and Trondheim, Norway.