This article reviews the state-of-the-art numerical calculation of wind turbine wake aerodynamics. Different computational fluid dynamics techniques for modeling the rotor and the wake are discussed. Regarding rotor modeling, recent advances in the generalized actuator approach and the direct model are discussed, as far as it attributes to the wake description. For the wake, the focus is on the different turbulence models that are employed to study wake effects on downstream turbines.

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Review of computational fluid dynamics for wind turbine wake aerodynamics

Wind energy, together with other renewable energy sources, are expected to grow substantially in the coming decades and play a key role in mitigating climate change and achieving energy sustainability. One of the main challenges in optimizing the design, operation, control, and grid integration of wind farms is the prediction of their performance, owing to the complex multiscale two-way interactions between wind farms and the turbulent atmospheric boundary layer (ABL). From a fluid mechanical perspective, these interactions are complicated by the high Reynolds number of the ABL flow, its inherent unsteadiness due to the diurnal cycle and synoptic-forcing variability, the ubiquitous nature of thermal effects, and the heterogeneity of the terrain. Particularly important is the effect of ABL turbulence on wind-turbine wake flows and their superposition, as they are responsible for considerable turbine power losses and fatigue loads in wind farms. These flow interactions affect, in turn, the structure of the ABL and the turbulent fluxes of momentum and scalars. This review summarizes recent experimental, computational, and theoretical research efforts that have contributed to improving our understanding and ability to predict the interactions of ABL flow with wind turbines and wind farms.

https://link.springer.com/content/pdf/10.1007/s10546-019-00473-0.pdf

Wind-Turbine and Wind-Farm Flows: A Review

Wind turbine wakes are one of the most important aspects in wind power meteorology because they decrease the power production and increase the loading of downstream wind turbines. Therefore, there is a continuous need to find a ‘good’ wake model to properly plan wind power plant-level control strategies, predict the performance and understand the fatigue loads of turbines. In this paper, six widely used approaches of wake modelling (Jensen, Larsen, Dynamic Wake Meandering, Fuga and, Ellipsys3D LES and RANS together with their interpretations) that were developed at Technical University of Denmark, are described and the model subcomponents are analysed. The models are evaluated using data from the Sexbierum (onshore) and the Lillgrund (offshore) wind farms to understand how to best utilize them. The paper provides a comprehensive conceptual background to wake modelling combined with the overview of the state-of-the-art models including their implementations on operating wind farms.

/pdf/wind-turbine-wake-models-developed-at-the-technical-1zlwn75lft.pdf

Wind turbine wake models developed at the technical university of Denmark: A review

Air flow behind wind turbines

https://orbit.dtu.dk/files/104615592/Developmentandvalidation.pdf

Development and validation of a new two-dimensional wake model for wind turbine wakes

In the framework of the JOULE-0064 'Full-scale Measurements in Wind Turbine Arrays' in the period between June-November 1992 measurements have been performed in the Sexbierum Wind Farm The aim of the measurements is to provide data for the validation of wake and wind farm models, which are being developed simultaneously, and to provide input data for wind turbine load calculation programmes The campaign concerned measurement of the wind speed, turbulence and shear stress behind a single wind turbine at distances of 25,55 and 8 rotor diarneters, respectively Besides detailed measurements of the wind field, the power of the turbine was measured A database has been compiled containing 1-minute averaged values of the measured quantities The database was analysed using a two-dimensional bin analysis with respect to the undisturbed wind direction and wind speed The analysis contains horizontal and vertical profiles of the: - U-,V-, and W-component of the wind in the wake; - turbulence intensities in three directions and turbulent kinetic energy in the wake; - shear stresses u'v', u'w' and v'w' in the wake These quantities are presented both in dimensional as in non-dimensionalized form With the data base a useful set of data is created for the validation of wake and wind farm models

J.W. Cleijne

Papers

Results of Sexbierum Wind Farm: double wake measurements