scholarly journals Simulation of wind turbine wakes using the actuator line technique

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140071 ◽  
Author(s):  
Jens N. Sørensen ◽  
Robert F. Mikkelsen ◽  
Dan S. Henningson ◽  
Stefan Ivanell ◽  
Sasan Sarmast ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Analytical Formula ◽  
Decomposition Analysis ◽  
Wind Farms ◽  
Near Wake ◽  
Performance Predictions ◽  
Wake Interaction ◽  
Large Eddy ◽  
Basic Features ◽  
Proper Orthogonal

The actuator line technique was introduced as a numerical tool to be employed in combination with large eddy simulations to enable the study of wakes and wake interaction in wind farms. The technique is today largely used for studying basic features of wakes as well as for making performance predictions of wind farms. In this paper, we give a short introduction to the wake problem and the actuator line methodology and present a study in which the technique is employed to determine the near-wake properties of wind turbines. The presented results include a comparison of experimental results of the wake characteristics of the flow around a three-bladed model wind turbine, the development of a simple analytical formula for determining the near-wake length behind a wind turbine and a detailed investigation of wake structures based on proper orthogonal decomposition analysis of numerically generated snapshots of the wake.

scholarly journals Wake behavior and control: comparison of LES simulations and wind tunnel measurements

2019 ◽  
Vol 4 (1) ◽  
pp. 71-88 ◽  
Author(s):  
Jiangang Wang ◽  
Chengyu Wang ◽  
Filippo Campagnolo ◽  
Carlo L. Bottasso
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Farm ◽  
Operating Conditions ◽  
Test Cases ◽  
Near Wake ◽  
Large Eddy ◽  
Control Comparison ◽  
High Turbulence ◽  
And Control

Abstract. This paper applies a large-eddy actuator line approach to the simulation of wind turbine wakes. In addition to normal operating conditions, a specific focus of the paper is on wake manipulation, which is performed here by derating, yaw misalignment and cyclic pitching of the blades. With the purpose of clarifying the ability of LES methods to represent conditions that are relevant for wind farm control, numerical simulations are compared to experimental observations obtained in a boundary layer wind tunnel with scaled wind turbine models. Results indicate a good overall matching of simulations with experiments. Low-turbulence test cases appear to be more challenging than moderate- and high-turbulence ones due to the need for denser grids to limit numerical diffusion and accurately resolve tip-shed vortices in the near-wake region.

scholarly journals Research on the Power Capture and Wake Characteristics of a Wind Turbine Based on a Modified Actuator Line Model

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 282
Author(s):  
Feifei Xue ◽  
Heping Duan ◽  
Chang Xu ◽  
Xingxing Han ◽  
Yanqing Shangguan ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Output Power ◽  
Wind Turbines ◽  
Wind Farm ◽  
Three Dimensional ◽  
Wind Farms ◽  
Line Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Actuator Line Model

On a wind farm, the wake has an important impact on the performance of the wind turbines. For example, the wake of an upstream wind turbine affects the blade load and output power of the downstream wind turbine. In this paper, a modified actuator line model with blade tips, root loss, and an airfoil three-dimensional delayed stall was revised. This full-scale modified actuator line model with blades, nacelles, and towers, was combined with a Large Eddy Simulation, and then applied and validated based on an analysis of wind turbine wakes in wind farms. The modified actuator line model was verified using an experimental wind turbine. Subsequently, numerical simulations were conducted on two NREL 5 MW wind turbines with different staggered spacing to study the effect of the staggered spacing on the characteristics of wind turbines. The results show that the output power of the upstream turbine stabilized at 5.9 MW, and the output power of the downstream turbine increased. When the staggered spacing is R and 1.5R, both the power and thrust of the downstream turbine are severely reduced. However, the length of the peaks was significantly longer, which resulted in a long-term unstable power output. As the staggered spacing increased, the velocity in the central near wake of the downstream turbine also increased, and the recovery speed at the threshold of the wake slowed down. The modified actuator line model described herein can be used for the numerical simulation of wakes in wind farms.

scholarly journals Optimized Placement of Onshore Wind Farms Considering Topography

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2944 ◽  
Author(s):  
Xiawei Wu ◽  
Weihao Hu ◽  
Qi Huang ◽  
Cong Chen ◽  
Zhe Chen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Production Cost ◽  
Wind Farms ◽  
Power Production ◽  
Optimization Method ◽  
Wake Effect ◽  
Onshore Wind ◽  
Wake Interaction ◽  
Height Change

As the scale of onshore wind farms are increasing, the influence of wake behavior on power production becomes increasingly significant. Wind turbines sittings in onshore wind farms should take terrain into consideration including height change and slope curvature. However, optimized wind turbine (WT) placement for onshore wind farms considering both topographic amplitude and wake interaction is realistic. In this paper, an approach for optimized placement of onshore wind farms considering the topography as well as the wake effect is proposed. Based on minimizing the levelized production cost (LPC), the placement of WTs was optimized considering topography and the effect of this on WTs interactions. The results indicated that the proposed method was effective for finding the optimized layout for uneven onshore wind farms. The optimization method is applicable for optimized placement of onshore wind farms and can be extended to different topographic conditions.

scholarly journals Investigating wind turbine impacts on near-wake flow using profiling lidar data and large-eddy simulations with an actuator disk model

2015 ◽  
Vol 7 (4) ◽  
pp. 043143 ◽  
Author(s):  
Jeffrey D. Mirocha ◽  
Daniel A. Rajewski ◽  
Nikola Marjanovic ◽  
Julie K. Lundquist ◽  
Branko Kosović ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Large Eddy Simulations ◽  
Wake Flow ◽  
Lidar Data ◽  
Near Wake ◽  
Disk Model ◽  
Actuator Disk ◽  
Large Eddy

scholarly journals Large-Eddy Simulation of Yawed Wind-Turbine Wakes: Comparisons with Wind Tunnel Measurements and Analytical Wake Models

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4574 ◽  
Author(s):  
Mou Lin ◽  
Fernando Porté-Agel
Keyword(s):  
Wind Tunnel ◽  
Large Eddy Simulation ◽  
Wind Turbine ◽  
Wind Farms ◽  
Disk Model ◽  
Actuator Disk ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Wind Tunnel Measurements ◽  
Tangential Forces

In this study, we validated a wind-turbine parameterisation for large-eddy simulation (LES) of yawed wind-turbine wakes. The presented parameterisation is modified from the rotational actuator disk model (ADMR), which takes account of both thrust and tangential forces induced by a wind turbine based on the blade-element theory. LES results using the yawed ADMR were validated with wind-tunnel measurements of the wakes behind a stand-alone miniature wind turbine model with different yaw angles. Comparisons were also made with the predictions of analytical wake models. In general, LES results using the yawed ADMR are in good agreement with both wind-tunnel measurements and analytical wake models regarding wake deflections and spanwise profiles of the mean velocity deficit and the turbulence intensity. Moreover, the power output of the yawed wind turbine is directly computed from the tangential forces resolved by the yawed ADMR, in contrast with the indirect power estimation used in the standard actuator disk model. We found significant improvement in the power prediction from LES using the yawed ADMR over the simulations using the standard actuator disk without rotation, suggesting a good potential of the yawed ADMR to be applied in LES studies of active yaw control in wind farms.

scholarly journals Turbulence and entrainment length scales in large wind farms

2017 ◽  
Vol 375 (2091) ◽  
pp. 20160107 ◽  
Author(s):  
Søren J. Andersen ◽  
Jens N. Sørensen ◽  
Robert F. Mikkelsen
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Turbulent Structures ◽  
Length Scales ◽  
Self Organized ◽  
Reference Simulation ◽  
Large Eddy ◽  
Entrainment Process ◽  
Proper Orthogonal ◽  
Large Wind

A number of large wind farms are modelled using large eddy simulations to elucidate the entrainment process. A reference simulation without turbines and three farm simulations with different degrees of imposed atmospheric turbulence are presented. The entrainment process is assessed using proper orthogonal decomposition, which is employed to detect the largest and most energetic coherent turbulent structures. The dominant length scales responsible for the entrainment process are shown to grow further into the wind farm, but to be limited in extent by the streamwise turbine spacing, which could be taken into account when developing farm layouts. The self-organized motion or large coherent structures also yield high correlations between the power productions of consecutive turbines, which can be exploited through dynamic farm control. This article is part of the themed issue ‘Wind energy in complex terrains’.

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