Development of wake meandering detection algorithms and their application to large eddy simulations of an isolated wind turbine and a wind farm

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.

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The Aerodynamics of the Curled Wake: A Simplified Model in View of Flow Control

10.5194/wes-2018-57 ◽

2018 ◽

Cited By ~ 2

Author(s):

Luis A. Martínez-Tossas ◽

Jennifer Annoni ◽

Paul A. Fleming ◽

Matthew J. Churchfield

Keyword(s):

Boundary Layer ◽

Steady State ◽

Wind Farm ◽

Stokes Equations ◽

Large Eddy Simulations ◽

Simplified Model ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Actuator Disk ◽

Large Eddy

Abstract. When a wind turbine is yawed, the shape of the wake changes and a curled wake profile is generated. The curled wake has drawn a lot of interest because of its aerodynamic complexity and applicability to wind farm controls. The main mechanism for the creation of the curled wake has been identified in the literature as a collection of vortices that are shed from the rotor plane when the turbine is yawed. This work extends that idea by using aerodynamic concepts to develop a control-oriented model for the curled wake based on approximations to the Navier-Stokes equations. The model is tested and compared to large-eddy simulations using actuator disk and line models. The model is able to capture the curling mechanism for a turbine under uniform inflow and in the case of a neutral atmospheric boundary layer. The model is then tested inside the FLOw Redirection and Induction in Steady State framework and provides excellent agreement with power predictions for cases with two and three turbines in a row.

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Numerical Reproducibility of Terrain-induced Turbulence in Complex Terrain by Large-eddy Simulation (LES) Technique

10.20944/preprints201807.0077.v1 ◽

2018 ◽

Author(s):

Takanori UCHIDA

Keyword(s):

Wind Turbine ◽

Turbine Blade ◽

Wind Farm ◽

Simulated Data ◽

Wind Turbine Blade ◽

Eddy Simulation ◽

Minute Period ◽

Large Eddy ◽

Horizontal Grid ◽

Simulated Time

In the present study, field observation wind data from the time of the wind turbine blade damage accident on Shiratakiyama Wind Farm were analyzed in detail. In parallel, high-resolution LES turbulence simulations were performed in order to examine the model’s ability to numerically reproduce terrain-induced turbulence. The comparison of the observed and simulated time series (1 second average values) from a 10 minute period from the time of the accident led to the conclusion that the settings of the horizontal grid resolution and time increment are important to numerically reproduce the terrain-induced turbulence that caused the wind turbine blade damage accident on Shiratakiyama Wind Farm. A spectral analysis of the same set of observed and simulated data revealed that the simulated data reproduced the energy cascade of the actual terrain-induced turbulence well.

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

Energies ◽

10.3390/en15010282 ◽

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.

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Wind Turbine Control Based on Computational Fluid Dynamics (CFD) and Its Economic Effects

10.20944/preprints201805.0362.v1 ◽

2018 ◽

Author(s):

Takanori Uchida

Keyword(s):

Wind Turbine ◽

Wind Farm ◽

Economic Effects ◽

Easterly Wind ◽

Wind Turbine Control ◽

Eddy Simulation ◽

Repair Costs ◽

Large Eddy ◽

Computational Fluid Dynamics Cfd ◽

Natural Terrain

At the Atsumi Wind Farm in Aichi Prefecture, Japan, damage to wind turbines occurred frequently due to terrain-induced turbulence. In the present study, numerical analyses of terrain-induced turbulence were conducted by reproducing the topography in the vicinity of the wind turbine sites in high resolution and using RIAM-COMPACT natural terrain version, which is based on large eddy simulation (LES). The results of the diagnoses indicated that, in the case of south-easterly wind, terrain-induced turbulence is generated at a small terrain feature located upstream of Wind Turbine (WT) #2, which serves as the origin of the turbulence. At the Atsumi Wind Farm, a combination of the series of wind diagnoses and on-site operation experience led to a decision to adopt an "automatic shutdown program" for WTs #1 and #2. Here, "automatic shutdown program" refers to the automatic suspension of wind turbine operation upon the wind speed and direction meeting the conditions associated with significant effects of terrain-induced turbulence at a wind turbine site. The adoption of the "automatic shutdown program" has successfully resulted in a large reduction in the number of occurrences of wind turbine damage, thus, creating major positive economic effects. 1) a reduction in the repair costs by 9.322 million yen per year per wind turbine, 2) an increase in the availability factor by 8.05%, and 3) an increase in the capacity factor by 1.7%.

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