Abstract
High-resolution field-scale experiments using flow visualization with natural snowfall and high-fidelity large eddy simulations are combined to investigate the effect of dynamic turbine operation and atmospheric conditions on wind turbine wake mixing and recovery in the wake of a 2.5 MW wind turbine. Instantaneous near-wake expansion and deflection in response to changes in blade pitch and wind direction, termed dynamic wake modulation, is quantified using both techniques, demonstrating excellent agreement. The simulations are used to extend these results by calculating the energy flux into the wake 7 rotor diameters downstream, showing that dynamic turbine-atmospheric interactions enhance mixing in the far-wake. This finding is exhibited under both uniform and turbulent inflow conditions. Under turbulent flow, a synergistic relationship is also observed between dynamic wake modulation and wake meandering, as wake recovery can be further accelerated when the two phenomena occur together. The results of this study have implications for the development of more realistic far-wake models that include the significant impact of dynamic wake modulation on wake mixing and development. Additionally, the findings from the current study can be used to develop advanced control algorithms to speed up wake breakdown and recovery, further improving wind farm efficiency.
Highlights
Improved understanding of wind turbine wake development is required to mitigate the undesirable wake effects of power loss and increased fatigue loading on downwind turbines
The current study further investigates the impact of dynamic wake modulation on wake mixing and recovery by combining highresolution field data with high-fidelity large eddy simulations (LES)
High-fidelity LES was combined with field scale experiments to investigate the effect of dynamic turbine operation and atmospheric conditions on mixing and recovery in the wake of a 2.5 MW wind turbine
Summary
Improved understanding of wind turbine wake development is required to mitigate the undesirable wake effects of power loss and increased fatigue loading on downwind turbines. Two studies by Meyers and colleagues [8, 9] modelled in-line turbines with timevarying thrust coefficients to find the optimal time sequence for inducing wake breakdown before it reaches the downwind turbine. Another method of wake control is yaw steering, where a misalignment between the rotor and wind direction is applied to deflect the wake in the spanwise direction [10].
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