ERI: Formation Mechanisms and Modeling of Wake Meandering in Wind Farms

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Interactions between stochastic fluctuations in the atmospheric surface layer and turbulent features produced by wind turbines drive major challenges to explain and model turbulence mechanisms in wind farms. Understanding the underlying behaviors can reduce power production variability, which adversely influences the levelized cost of electricity, and enhance wind energy’s competitiveness compared to other forms of power production. Specifically, large atmospheric fluctuations and the small turbine-scale dynamics are separately hypothesized to initiate the wake meandering phenomenon, a coherent oscillation of the far wake of wind turbines. Wake meandering affects the unsteady dynamics of wake recovery, wake interactions, and uncertainty of power production in wind farms. This project will elucidate its underlying formation behavior, which is crucial to enable designs and models to lower the levelized cost of wind energy. The project will also include significant educational activities including outreach programs with Memphis non-profit organizations and increased public science awareness and education through art and its intersection with turbulence. The proposed project advances fundamental insights into dominant instabilities in wind turbines. The project will develop a series of high-fidelity large-eddy simulations to measure the spectra and evolution of kinetic energy and vorticity in the upwind atmospheric boundary layer and wind turbine wake. An approach to investigate and model the transfer and transport of kinetic energy of large coherent structure scales will be developed using data-driven analysis and computational-enabled discovery from the simulated wake flows. The methodology and simulations will be employed to investigate the formation mechanism of meandering of a wind turbine wake and leveraged to develop multi-resolution wind farm models. The project proposes to (1) develop and evaluate wake meandering genesis mechanisms by quantifying the energy transfer between upwind features in the atmospheric surface layer and wake meandering; and (2) develop wind farm models to capture disparate length scales of the wind turbine, wind farm, and atmosphere. Expected outcomes of this research include fundamental understanding of the spatio-temporal evolution of wake meandering and multi-resolution, multi-scale wind farm modeling. By addressing the uncertainty of the formation and persistence of large coherent structures in wind turbine wakes, the uncertainty and model inadequacy of time-accurate wind farm models can be mitigated, and designs to modify the role of wake meandering in power fluctuations can be introduced.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.