Modeling Coriolis and stability effects on wake dynamics for wind farm flow control

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Wind turbines operating within wind farms interact aerodynamically. By extracting power from the wind, wind turbines produce wake regions downwind that are characterized by low wind speed and high turbulence. Wake interactions can significantly reduce the efficiency of wind farms but they can be alleviated by controlling the wind flow in the farm. Given the continuing expansion of wind energy generation, there is a growing need to improve the fluid dynamics knowledge of the interactions between wind turbines and the atmospheric flow and to leverage this knowledge to improve farm efficiency. This research project will characterize and model the impacts of atmospheric flow on wind turbine wakes. The working hypothesis of this research is that the incorporation of the atmospheric effects from Earth’s rotation, buoyancy, and temperature variations will improve the predictive accuracy of wind farm flow models and will increase farm efficiency when using model-based flow control. This research will characterize the impacts of these atmospheric effects on wakes using computer simulations under a wide range of atmospheric conditions. A new flow model which captures these effects will be developed and validated, and the model will be used for case studies of flow control. The climate change mitigation impacts of this project will be integrated into engagements with K-12 schools, courses and mentoring for Massachusetts Institute of Technology students about careers in the physics of energy systems, and workshops with energy industry about wake losses, modeling, and flow control.This research will characterize and model the impacts of Coriolis forces from Earth's rotation and atmospheric stability effects from buoyancy and temperature gradients on wake dynamics, which will lead to improved flow control strategies to maximize farm efficiency. First, the impacts of Coriolis and stability effects on wakes will be characterized using controlled, large eddy simulation (LES) numerical experiments. Coriolis effects influence wake deflection, deformation, and recovery both through direct forcing and through modification of the wind speed and direction shear in the atmospheric boundary layer (ABL) wind profiles incident to turbines. Novel controlled numerical experiments will be developed to isolate each of these effects as independent flow parameters and to characterize their impacts on wakes. The influence of stability on wakes will be characterized and quantified using LES of turbines in stratified ABLs, simulated over a range of non-dimensional flow parameters. Second, a new, computationally-efficient flow model which captures these effects from first-principles will be developed. Third, validation and uncertainty quantification of the model will be performed, and the model will be used for wind farm flow control case studies using LES.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.