scholarly journals AD/RANS Simulations of Wind Turbine Wake Flow Employing the RSM Turbulence Model: Impact of Isotropic and Anisotropic Inflow Conditions

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4026 ◽  
Author(s):  
Tian ◽  
Song ◽  
Zhao ◽  
Shen ◽  
Wang
Keyword(s):  
Wind Turbine ◽  
Turbulence Intensity ◽  
Isotropic Turbulence ◽  
Sensitivity Study ◽  
Wake Flow ◽  
Wake Region ◽  
Anisotropic Turbulence ◽  
Wide Range ◽  
Turbine Wake ◽  
Wind Turbine Wake

The Reynolds-averaged Navier–Stokes (RANS)-based generalized actuator disc method along with the Reynolds stress model (AD/RANS_RSM) is assessed for wind turbine wake simulation. The evaluation is based on validations with four sets of experiments for four horizontal-axis wind turbines with different geometrical characteristics operating in a wide range of wind conditions. Additionally, sensitivity studies on inflow profiles (representing isotropic and anisotropic turbulence) for predicting wake effects are carried out. The focus is on the prediction of the evolution of wake flow in terms of wind velocity and turbulence intensity. Comparisons between the computational results and the measurements demonstrate that in the near and transition wake region with strong anisotropic turbulence, the AD/RANS_RSM methodology exhibits a reasonably good match with all the experimental data sets; however, in the far wake region that is characterized by isotropic turbulence, the AD/RANS_RSM predicts the wake velocity quite accurately but appears to over-estimate the wake turbulence level. While the introduction of the overall turbulence intensity is found to give an improved agreement with the experiments. The performed sensitivity study proves that the anisotropic inflow condition is recommended as the profile of choice to represent the incoming wind flow.

Investigation and Validation of Wind Turbine Wake Models

2008 ◽  
Vol 32 (5) ◽  
pp. 459-475 ◽  
Author(s):  
A. Duckworth ◽  
R.J. Barthelmie
Keyword(s):  
Wind Turbine ◽  
Turbulence Intensity ◽  
State Of The Art ◽  
Turbulence Models ◽  
Measured Data ◽  
Subsequent Work ◽  
Velocity Deficit ◽  
The Individual ◽  
Turbine Wake ◽  
Wind Turbine Wake

This article discusses the application of widely used, state of the art, wake models, focusing on the Ainslie [1], Katic [2] and Larsen [3] models, breaking these down and explaining the individual, integral components. Models used to predict the turbulence intensity within the wake are also explained. Measured data are subsequently used to validate these wake and turbulence models, showing acceptable results for the prediction of velocity deficit within the wake, wake width and wake shape. Results also highlight the validity of the analysed turbulence models. The paper describes the problems encountered when using measured data to validate wake models and concludes by outlining subsequent work which could be carried out to further validate these models.

scholarly journals Volumetric Lidar Scanning of Wind Turbine Wakes under Convective and Neutral Atmospheric Stability Regimes

2014 ◽  
Vol 31 (10) ◽  
pp. 2035-2048 ◽  
Author(s):  
Giacomo Valerio Iungo ◽  
Fernando Porté-Agel
Keyword(s):  
Thermal Stability ◽  
Wind Turbine ◽  
Wind Power ◽  
Wind Velocity ◽  
Turbulence Intensity ◽  
Atmospheric Stability ◽  
Power Harvesting ◽  
Turbine Wake ◽  
Wind Turbine Wake

Abstract Optimization of a wind farm’s layout is a strategic task to reduce wake effects on downstream turbines, thus maximizing wind power harvesting. However, downstream evolution and recovery of each wind turbine wake are strongly affected by the characteristics of the incoming atmospheric boundary layer (ABL) flow, such as the vertical profiles of the mean wind velocity and the turbulence intensity, which are in turn affected by the ABL thermal stability. Therefore, the characterization of the variability of wind turbine wakes under different ABL stability regimes becomes fundamental to better predict wind power harvesting and to improve wind farm efficiency. To this aim, wind velocity measurements of the wake produced by a 2-MW Enercon E-70 wind turbine were performed with three scanning Doppler wind lidars. One lidar was devoted to the characterization of the incoming wind—in particular, wind velocity, shear, and turbulence intensity at the height of the rotor disc. The other two lidars performed volumetric scans of the wind turbine wake under different atmospheric conditions. Through the evaluation of the minimum wake velocity deficit as a function of the downstream distance, it is shown that the ABL stability regime has a significant effect on the wake evolution; in particular, the wake recovers faster under convective conditions. This result suggests that atmospheric inflow conditions, and particularly thermal stability, should be considered for improved wake models and predictions of wind power harvesting.

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

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5392
Author(s):  
Ingrid Neunaber ◽  
Michael Hölling ◽  
Richard J. A. M. Stevens ◽  
Gerard Schepers ◽  
Joachim Peinke
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Isotropic Turbulence ◽  
Turbulence Modeling ◽  
Wind Farms ◽  
Reference Case ◽  
Mean Velocity ◽  
Turbulence Analysis ◽  
Turbine Wake ◽  
Wind Turbine Wake

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.

Wind tunnel study on wind and turbulence intensity profiles in wind turbine wake

2011 ◽  
Vol 20 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Takao Maeda ◽  
Yasunari Kamada ◽  
Junsuke Murata ◽  
Sayaka Yonekura ◽  
Takafumi Ito ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Turbulence Intensity ◽  
Wind Tunnel Study ◽  
Turbine Wake ◽  
Wind Turbine Wake

Wind Resource Assessment in Cold Regions - A Numerical Case Study

2018 ◽  
Vol 875 ◽  
pp. 94-99
Author(s):  
Jia Yi Jin ◽  
Pavlo Sokolov ◽  
Muhammad S. Virk
Keyword(s):  
Numerical Simulations ◽  
Wind Turbine ◽  
Energy Production ◽  
Resource Assessment ◽  
Wake Flow ◽  
Wind Resource Assessment ◽  
Flow Effects ◽  
Wind Resource ◽  
Turbine Wake ◽  
Wind Turbine Wake

This paper describes a case study of wind resource assessment in cold climate region. One-year SCADA data from a wind park has been used to make a comparison with the Computational Fluid Dynamics (CFD) based numerical simulations of wind resource assessment and Annual Energy Production (AEP). To better understand the wind turbine wake flow effects on the energy production, ‘Jessen wake model ‘is used for the numerical simulations. Results show wind resource maps at different elevations, where wind turbine wake flow effects the wind turbine performance and resultant power production. CFD simulations provided a good insight of the flow behavior across each wind turbine, which helped to better understand the wind turbine wake flow effects on wind turbine performance and annual energy production. A good agreement is found between numerical simulations and field SCADA data analysis in this study.

Numerical Simulation for Wind Turbine Wake and Effects From Different Atmospheric Boundary Conditions

2016 ◽  
Author(s):  
Peng Zhou ◽  
Xiuling Wang
Keyword(s):  
Boundary Conditions ◽  
Wind Turbine ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Wake Flow ◽  
Dynamics Simulation ◽  
Experiment Data ◽  
Eddy Simulation ◽  
Turbine Wake ◽  
Wind Turbine Wake

This research focuses on the computational fluid dynamics simulation of near wind turbine wake. Three dimensional wind turbine model is built based on S809 airfoil data [1]. Three different turbulence models are used and compared. They are Realizable k-ε model, SST k-ω model, and Large Eddy Simulation (LES) model. The simulation results from different turbulence models are compared with the NREL Phase VI experiment data. Different boundary conditions, including neutral and unstable conditions, were adopted in the simulation to analyze their influence on wake flow. Updraft and downdraft are considered in this part. Overall numerical results match well with the experiment data. The discussion also compares wind turbine wake under different atmospheric boundary conditions.

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