Effects of ambient turbulence on the near wake of a wind turbine

Kim, Yusik; Jost, Eva; Bangga, Galih; Weihing, Pascal; Lutz, Thorsten

doi:10.1088/1742-6596/753/3/032047

Cited by 14 publications

(15 citation statements)

References 11 publications

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“…It is shown that the Reynolds stresses magnitudes reduce with increasing streamwise distance. This confirms preceding studies that only the stochastic part of u v /U 2 ∞ enhances the momentum mixing in the wake area [20,27].…”

Section: Wake Characteristicssupporting

confidence: 92%

“…For the streamwise variance profile, strong peaks are observed for the whole rotor area at -1.0 < Y /R < 1.0. This behaviour is in contrast to the wake characteristics for HAWTs where the peaks are strong only near the tip and hub areas [20], inferring that the tip vortices are the main contributors to the turbulence mixing in the wake. In case of VAWTs, the interactions of wake vortices occur very early close to the rotor because of the blade vortex interaction phenomena (BVI) [3].…”

Section: Wake Characteristicscontrasting

confidence: 56%

“…It shall be noted that the pole connector mesh was handled using the degenerate line boundary condition which allows a higher grid skewness on the pole boundary to be used. Several preceding works from the authors were carried out using this approach with good results [18,19,10,20,21]. The total number of grid points employed is of 327,524 divided into 92 different grid blocks.…”

Section: Computational Mesh and Numerical Setupmentioning

confidence: 99%

“…The CFD simulations were carried out using a block-structured solver FLOWer from the German Aerospace Center (DLR) [22]. The code has been developed during the last years for wind turbine applications [18][19][20]10]. The time integration is carried out by an explicit hybrid 5-stage Runge-Kutta scheme.…”

Section: Computational Mesh and Numerical Setupmentioning

confidence: 99%

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Unsteady Navier-Stokes studies on loads, wake, and dynamic stall characteristics of a two-bladed vertical axis wind turbine

Bangga

Lutz

Dessoky

et al. 2017

Journal of Renewable and Sustainable Energy

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Computational fluid dynamics (CFD) studies are carried out on a two-bladed vertical axis wind turbine (VAWT) operating at a wind speed of 8 m/s for the tip speed ratios (λ) of 0.50 -3.0. The blade consists of the NACA 0021 airfoil with the chord length of 0.265 m and a rotor radius of 1 m. Basic sensitivity studies for various time step sizes are carried out. The results are validated against available measurement data from literature. An excellent agreement is obtained for small λ up to optimum condition. For the higher tip speed ratios, the two dimensional CFD computations predict higher results than the wind tunnel experiment, but they are very similar to the field measurement data. Wake characteristics are presented in the present studies, showing that the wake becomes Gaussian at 5 times radius downsteam of the rotor. It is shown that complex flow phenomena occur due to dynamic stall onset especially for the smaller tip speed ratio.

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Section: Wake Characteristicssupporting

confidence: 92%

Section: Wake Characteristicscontrasting

confidence: 56%

Section: Computational Mesh and Numerical Setupmentioning

confidence: 99%

Section: Computational Mesh and Numerical Setupmentioning

confidence: 99%

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Unsteady Navier-Stokes studies on loads, wake, and dynamic stall characteristics of a two-bladed vertical axis wind turbine

Bangga

Lutz

Dessoky

et al. 2017

Journal of Renewable and Sustainable Energy

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“…numerical) model. Numerical simulation might underestimate peak vorticity and radii of wake vortices, especially when the grid size of the simulation is not sufficient (Kim et al, 2016). Another way of studying WEC wakes are wind tunnel experiments that try to recreate wake patterns in a smaller scale (e.g.…”

Section: Introductionmentioning

confidence: 99%

First identification and quantification of detached-tip vortices behind a wind energy converter using fixed-wing unmanned aircraft system

et al. 2019

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Abstract. In the present study, blade-tip vortices have been experimentally identified in the wake of a commercial wind turbine using the Multi-purpose Airborne Sensor Carrier Mark 3 (MASC Mk 3) unmanned aircraft system (UAS) of the University of Tübingen. By evaluation of the wind components, detached blade-tip vortices were identified in the time series. From these measurements, the circulation and core radius of a pair of detached blade-tip vortices is calculated using the Burnham–Hallock (BH) wake vortex model. The presented data were captured under a dominating marine stratification about 2km from the North Sea coastline with northern wind direction. The measured vortices are also compared to the analytical solution of the BH model for two vortices spinning in opposite directions. The model has its origin in aviation, where it describes two aircraft wake vortices spinning in opposite directions. An evaluation method is presented to measure detached-tip vortices with a fixed-wing UAS. The BH model will be used to describe wake vortex properties behind a wind energy converter (WEC). The circulation and core radius of detached blade-tip vortices will be calculated. Also a proposition of the model for WEC wake evaluations will be made to describe two independent co-rotating vortices. Quantifying blade-tip vortices helps to understand the process of vortices detaching from a rotor blade of a wind turbine, their development in the wake until finally dissipating in the far wake and contributing to overall atmospheric turbulence. This is especially interesting for set-ups of numerical simulations when setting the spatial resolution of the simulation grid.

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Turbulent Inflow Models

Ehrich¹

2020

Handbook of Wind Energy Aerodynamics

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Effects of ambient turbulence on the near wake of a wind turbine

Cited by 14 publications

References 11 publications

Unsteady Navier-Stokes studies on loads, wake, and dynamic stall characteristics of a two-bladed vertical axis wind turbine

Unsteady Navier-Stokes studies on loads, wake, and dynamic stall characteristics of a two-bladed vertical axis wind turbine

First identification and quantification of detached-tip vortices behind a wind energy converter using fixed-wing unmanned aircraft system

Turbulent Inflow Models

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