Turbulence of Wakes

Neunaber, Ingrid

doi:10.1007/978-3-030-05455-7_45-1

Cited by 2 publications

(1 citation statement)

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“…For this reason, wind turbine wakes have been subject of many numerical and experimental studies both in the laboratory under controlled conditions and in the field for several decades (see, e.g., [2][3][4][5] for reviews). It has been shown that the turbulence in the wind turbine wake is highly complex: Directly downstream of the rotor, in the near wake, the wake is characterized by the tower wake and tip and root vortices that are shed from the blades and are transported downstream on a helical path that forms a vortex sheet which blocks the entrainment of flow to the wake (e.g., [6]).…”

Section: Introductionmentioning

confidence: 99%

Wind Tunnel Study on the Tip Speed Ratio’s Impact on a Wind Turbine Wake Development

2022

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We propose an experimental study on the influence of the tip speed ratio on the spatial development of a wind turbine wake. To accomplish this, a scaled wind turbine is tested in a wind tunnel, and its turbulent wake measured for streamwise distances between 1 and 30 diameters. Two different tip speed ratios (5.3 and 4.5) are tested by varying the pitch angle of the rotor blades between the optimal setting and one with an offset of +6∘. In addition, we test two Reynolds numbers for the optimal tip speed ratio, ReD=1.9×105 and ReD=2.9×105 (based on the turbine diameter and the freestream velocity). For all cases, the mean streamwise velocity deficit at the centerline evolves close to a power law in the far wake, and we check the validity of the Jensen and Bastankhah-Porté-Agel engineering wind turbine wake models and the Townsend-George wake model for free shear flows for this region. Lastly, we present radial profiles of the mean streamwise velocity and test different radial models. Our results show that the lateral profile of the wake is properly fitted by a super-Gaussian curve close to the rotor, while Gaussian-like profiles adapt better in the far wake.

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Section: Introductionmentioning

confidence: 99%

Wind Tunnel Study on the Tip Speed Ratio’s Impact on a Wind Turbine Wake Development

2022

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Distinct Turbulent Regions in the Wake of a Wind Turbine and Their Inflow-Dependent Locations: The Creation of a Wake Map

et al. 2020

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Wind turbines are usually clustered in wind farms which causes the downstream turbines to operate in the turbulent wakes of upstream turbines. As turbulence is directly related to increased fatigue loads, knowledge of the turbulence in the wake and its evolution are important. Therefore, the main objective of this study is a comprehensive exploration of the turbulence evolution in the wind turbine’s wake to identify characteristic turbulence regions. For this, we present an experimental study of three model wind turbine wake scenarios that were scanned with hot-wire anemometry with a very high downstream resolution. The model wind turbine was exposed to three inflows: laminar inflow as a reference case, a central wind turbine wake, and half of the wake of an upstream turbine. A detailed turbulence analysis reveals four downstream turbulence regions by means of the mean velocity, variance, turbulence intensity, energy spectra, integral and Taylor length scales, and the Castaing parameter that indicates the intermittency, or gustiness, of turbulence. In addition, a wake core with features of homogeneous isotropic turbulence and a ring of high intermittency surrounding the wake can be identified. The results are important for turbulence modeling in wakes and optimization of wind farm wake control.

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Turbulence of Wakes

Cited by 2 publications

References 50 publications

Wind Tunnel Study on the Tip Speed Ratio’s Impact on a Wind Turbine Wake Development

Wind Tunnel Study on the Tip Speed Ratio’s Impact on a Wind Turbine Wake Development

Distinct Turbulent Regions in the Wake of a Wind Turbine and Their Inflow-Dependent Locations: The Creation of a Wake Map

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