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Accueil > Evénements Scientifiques > Conf’luences > Conf’luences 2012 > Conf’luence Jens N. Sørensen 19 décembre

Conf’luence Jens N. Sørensen 19 décembre

30 novembre 2012

Simulation and Modeling of Wakes behind
Wind Turbine Rotors and in Wind Farms

Mercredi 19 décembre à 14h30 - Amphithéâtre Nougaro

Jens N. Sørensen

Department of Wind Energy - Technical University of Denmark

Abstract :

Keywords : Wind turbines, Wakes, Wind Farms, Large Eddy Simulation, Instability
The wake behind a rotor consists essentially of a number of helical vortices that owing to roll-up effects mainly concentrates in tip and root vortices. Near wake features are related to the genesis of the vortex system where the presence of the rotor is felt directly. The far wake is usually the downstream position where the wake dynamics no longer depends on the rotor characteristics. In the past decade we have been studying wakes behind wind turbine blades using analytical tools as well as numerical simulations based on LES methodology and various versions of the immersed boundary technique, such as the actuator line. In the presentation we show that helical wakes are inherent unstable and demonstrate how the ambient turbulence influences the stability properties. Furthermore, we identify one of the main instability mechanisms to be related to vortex pairing. Another part of the work is focused on the interaction of wakes originating from two or more rotors placed close to each other. This is in particular of importance for wind turbines located in wind farms. In the presentation, we show some basic results from the stability analysis as well as numerical simulations of single wakes and interacting wakes, including comparisons to experimental results.