Mesh‐adaptive simulations of horizontal‐axis turbine arrays using the actuator line method

Deskos, Georgios; Piggott, Matthew D.

doi:10.1002/we.2253

Cited by 10 publications

(2 citation statements)

References 42 publications

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“…Following the previous studies, for example, the one by Ishihara and Qian, the standard Smagorinsky‐Lilly SGS model is applied. The governing equations obtained by filtering the N‐S equations are expressed as:

\frac{∂ρ}{∂t} + \frac{\partial}{\partial x_{i}} ((), normalρ {\overset{false~}{normalu}}_{i}) = 0,

\frac{\partial {\overset{false~}{normalu}}_{i}}{∂t} + \frac{\partial {\overset{false~}{normalu}}_{i} {\overset{false~}{normalu}}_{j}}{\partial x_{j}} = - \frac{1}{ρ} \frac{\partial \overset{p}{true}}{\partial x_{i}} + normalμ \frac{\partial}{\partial x_{j}} ((), \frac{\partial {\overset{u}{true}}_{normali}}{\partial {normalx}_{normali}}) + \frac{\partial {\overset{false~}{normalτ}}_{ij}}{\partial x_{j}} + f_{i},

where, ρ denotes the density,

\overset{p}{true}

is the fitted pressure,

{\overset{false~}{u}}_{i}

represents the fitted velocities (

\overset{u}{true}

\overset{v}{true}

\overset{w}{true}

), μ is the viscosity,

{\overset{false~}{τ}}_{ij}

denotes the SGS stress, and f i is the source term representing the external force because of the effects of the wind turbine, which is determined by ALM . In the present LES, the Gaussian smearing technology…”

Section: Wind Turbine Wake Simulationmentioning

confidence: 99%

Numerical simulations of fatigue loads on wind turbines operating in wakes

Liu

Ishihara

et al. 2020

Wind Energy

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Wake effects increase the fatigue loads on wind turbines in operation. However, the wake flow is considerably different from the traditional boundary layer flow, and poses many challenges in determining the fatigue loads on wind turbines operating in a wake. Therefore, in the present study, the actuator-line model was adopted to numerically simulate the wake flow and an in-house code named AOWT, which is based on a generalized coordinate method, was developed for analyzing the dynamics of wind turbines under an arbitrary distribution of the turbulent flow field varying in time and space. Using the numerically modeled instantaneous wake flow fields and AOWT, the dynamic response of a wind turbine, located at specified positions in both tandem and staggered arrangements in a wake, was examined, and the fatigue loads were determined. Furthermore, to determine the major contributions to the fatigue loads, the loads induced by the spatial variation of the mean flow fields were predicted. To the best of the authors' knowledge, no such analysis has been conducted thus far. Importantly, it was found that in the near-wake region, the mean flow field had a significant influence on the fatigue loads, especially in the staggered layout. However, there is no analytical wake model available in the literature capable of predicting the near-wake mean flow fields. Therefore, in this study, a near-wake model was proposed, which yielded satisfactory predictions of the mean velocities in the near-wake region. K E Y W O R D Sblade element method, dynamic response, fatigue load, LES, wake flow, wake model | INTRODUCTIONWind turbines are usually installed as wind farms, in which the upstream wind turbines disturb the upcoming flow field and increase the downstream turbulence. 1-7 Consequently, the fatigue loads on the downstream wind turbines owing to the wake effects are different from those created by a traditional boundary layer flow. 8,9 A method using the effective turbulence intensity 10,11 has been commonly employed to assess the wake effects on the fatigue loads on wind turbines. However, the flow field in a wake is strongly distorted in terms of both the turbulence intensity and the mean flow. As a result, detailed examinations of the wake effects on the fatigue loads are needed. Whereas, the researches 12-15 considering this issue are not as many as those about the fatigue loads induced by the traditional boundary layer. [16][17][18][19][20] This could be owing to the fact that the wind turbine wake flow is much different with the traditional boundary layer flow, failing the applications of the conventional approaches for the turbulent flow generations, 11,21 posing many challenges in determining the fatigue loads on a wind turbine operating in wakes. In recent years, the engineering models, such as

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\frac{∂ρ}{∂t} + \frac{\partial}{\partial x_{i}} ((), normalρ {\overset{false~}{normalu}}_{i}) = 0,

\frac{\partial {\overset{false~}{normalu}}_{i}}{∂t} + \frac{\partial {\overset{false~}{normalu}}_{i} {\overset{false~}{normalu}}_{j}}{\partial x_{j}} = - \frac{1}{ρ} \frac{\partial \overset{p}{true}}{\partial x_{i}} + normalμ \frac{\partial}{\partial x_{j}} ((), \frac{\partial {\overset{u}{true}}_{normali}}{\partial {normalx}_{normali}}) + \frac{\partial {\overset{false~}{normalτ}}_{ij}}{\partial x_{j}} + f_{i},

where, ρ denotes the density,

\overset{p}{true}

is the fitted pressure,

{\overset{false~}{u}}_{i}

represents the fitted velocities (

\overset{u}{true}

\overset{v}{true}

\overset{w}{true}

), μ is the viscosity,

{\overset{false~}{τ}}_{ij}

Section: Wind Turbine Wake Simulationmentioning

confidence: 99%

Numerical simulations of fatigue loads on wind turbines operating in wakes

Liu

Ishihara

et al. 2020

Wind Energy

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show abstract

“…The numerical domain used to simulate the wind farm contains about 315 million cells. In [29] the ALM is implemented in a mesh-adaptative fluid dynamic solver, under an unsteady Reynolds-averaged Navier-Stokes-based turbulence modeling approach, where the Lillgrund wind farm was also simulated. For model validation, the focus was made on predicting the power losses along different rows of wind turbines by again comparing the results with ten minutes of power averages obtained from SCADA data.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of an Onshore Wind Farm with the Actuator Line Model Including Wind Turbine’s Control below and above Rated Wind Speed

Guggeri

Draper

2019

Energies

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As the size of wind turbines increases and their hub heights become higher, which partially explains the vertiginous increase of wind power worldwide in the last decade, the interaction of wind turbines with the atmospheric boundary layer (ABL) and between each other is becoming more complex. There are different approaches to model and compute the aerodynamic loads, and hence the power production, on wind turbines subject to ABL inflow conditions ranging from the classical Blade Element Momentum (BEM) method to Computational Fluid Dynamic (CFD) approaches. Also, modern multi-MW wind turbines have a torque controller and a collective pitch controller to manage power output, particularly in maximizing power production or when it is required to down-regulate their production. In this work the results of a validated numerical method, based on a Large Eddy Simulation-Actuator Line Model framework, was applied to simulate a real 7.7 MNW onshore wind farm on Uruguay under different wind conditions, and hence operational situations are shown with the aim to assess the capability of this approach to model actual wind farm dynamics. A description of the implementation of these controllers in the CFD solver Caffa3d, presenting the methodology applied to obtain the controller parameters, is included. For validation, the simulation results were compared with 1 Hz data obtained from the Supervisory Control and Data Acquisition System of the wind farm, focusing on the temporal evolution of the following variables: Wind velocity, rotor angular speed, pitch angle, and electric power. In addition to this, simulations applying active power control at the wind turbine level are presented under different de-rate signals, both constant and time-varying, and were subject to different wind speed profiles and wind directions where there was interaction between wind turbines and their wakes.

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End-to-end wind turbine wake modelling with deep graph representation learning

Zhang

Piggott

2023

Applied Energy

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Mesh‐adaptive simulations of horizontal‐axis turbine arrays using the actuator line method

Cited by 10 publications

References 42 publications

Numerical simulations of fatigue loads on wind turbines operating in wakes

Numerical simulations of fatigue loads on wind turbines operating in wakes

Large Eddy Simulation of an Onshore Wind Farm with the Actuator Line Model Including Wind Turbine’s Control below and above Rated Wind Speed

End-to-end wind turbine wake modelling with deep graph representation learning

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