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A LES study of interactions between wind turbine wakes and the atmospheric boundary layer

Event Type: 
Date and Time: 
Friday, January 8, 2016 - 16:00
CTR Conference Room 103
Event Sponsor: 
Parviz Moin, Director of Center for Turbulence Research
Shengbai Xie, Graduate Research Assistant, University of Delaware

It is critical to understand how wind turbine wakes interact with the atmospheric boundary layer (ABL) in order to better estimate the wake loss in a wind farm. The ABL is a complex system affected by various forces, e.g., pressure gradient force (PGF), Coriolis force, buoyancy force due to thermal stability, and shear force imposed by the ground, etc. The wind shear and turbulence level in the ABL is strongly influenced by the thermal stability conditions, which in turn affects the properties of wind turbine wakes [1]. Meanwhile, the Coriolis force interacts with the wind shear and the PGF to induce changes of wind directions at different heights, known as wind veering. The wind veering is potentially able to alter some properties of wind turbine wakes, which has not been fully understood before. Here, a large-eddy-simulation based study will be presented to show how the wind turbine wakes evolve according to various thermal stability conditions with consideration of the Coriolis’ effect.

Second, a new approach of the vertically staggered wind farm is proposed, which involves both large-scale horizontal axis wind turbines (HAWT) and small-scale vertical axis wind turbines (VAWT). From our LES study, this vertically staggered wind farm is shown to have improved performance compared to the traditional wind farm, as a result of the enhanced wake recovery due to stronger ambient turbulence. A theoretical top-down model [2] is also developed to further analyze the potential of this new type of wind farm.


 [1] Abkar, M., Porté-Agel, F., 2010. Influence of atmospheric stability on wind-turbine wakes: A large-eddy simulation study. Phys. Fluids 27, 035104.

 [2] Calaf, M., Meneveau, C., Meyers, J., 2010. Large eddy simulation study of fully developed wind turbine array boundary layers. Phys. Fluids 22, 015110.

Shengbai Xie received his PhD from University of Delaware in 2015. His PhD work was mainly focused on numerical simulations of wind turbine wakes and the atmospheric turbulence. He also has a master degree from Johns Hopkins University, where he used LES to study wind-wave-structure interactions.