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

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.

scholarly journals Numerical Investigation of Terrain-Induced Turbulence in Complex Terrain by Large-Eddy Simulation (LES) Technique

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2638 ◽  
Author(s):  
Takanori Uchida
Keyword(s):  
Wind Speed ◽  
Large Eddy Simulation ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Turbulence Intensity ◽  
Field Observation ◽  
Wind Farm ◽  
Wind Turbine Blade ◽  
Eddy Simulation ◽  
Large Eddy

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 large-eddy simulation (LES) turbulence simulations were performed in order to examine the model’s ability to numerically reproduce terrain-induced turbulence (turbulence intensity) under strong wind conditions (8.0–9.0 m/s at wind turbine hub height). Since the wind velocity and time acquired from the numerical simulation are dimensionless, they are converted to full scale. As a consequence, both the standard deviation of the horizontal wind speed (m/s) and turbulence intensity evaluated from the field observation and simulated wind data are successfully in close agreement. To investigate the cause of the wind turbine blade damage accident on Shiratakiyama Wind Farm, a power spectral analysis was performed on the fluctuating components of the observed time series data of wind speed (1 s average values) for a 10 min period (total of 600 data) by using a fast Fourier transform (FFT). It was suggested that the terrain-induced turbulence which caused the wind turbine blade damage accident on Shiratakiyama Wind Farm was attributable to rapid wind speed and direction fluctuations which were caused by vortex shedding from Tenjogadake (elevation: 691.1 m) located upstream of the wind farm.

Wind Turbine Blade Tip Flow and Noise Prediction by Large-eddy Simulation

2004 ◽  
Vol 126 (4) ◽  
pp. 1017-1024 ◽  
Author(s):  
Oliver Fleig ◽  
Makoto Iida ◽  
Chuichi Arakawa
Keyword(s):  
Large Eddy Simulation ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Acoustic Emissions ◽  
Wind Turbine Blade ◽  
Tip Vortex ◽  
Aerodynamic Noise ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Blade Tip

The purpose of this research is to investigate the physical mechanisms associated with broadband tip vortex noise caused by rotating wind turbines. The flow and acoustic field around a wind turbine blade is simulated using compressible large-eddy simulation and direct noise simulation, with emphasis on the blade tip region. The far field aerodynamic noise is modeled using acoustic analogy. Aerodynamic performance and acoustic emissions are predicted for the actual tip shape and an ogee type tip shape. For the ogee type tip shape the sound pressure level decreases by 5 dB for frequencies above 4 kHz.

Research on Wind Turbine Blade Surface Damage Fault On-Line Monitoring and Diagnosis System

2013 ◽  
Author(s):  
Yongxin Feng ◽  
Tao Yang ◽  
Xiaowen Deng ◽  
Qingshui Gao ◽  
Chu Zhang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Farm ◽  
Turbine Blades ◽  
Surface Damage ◽  
Wind Turbine Blade ◽  
Offshore Wind ◽  
Blade Surface ◽  
Diagnosis System ◽  
On Line

The basic fault types of wind turbine blades are introduced, a novel blade surface damage detection method based on machine vision is being suggested. The network of wind turbine blade surface damage fault on-line monitoring and fault diagnosis system has already been developed. The system architecture, software modules and functions are described, and given application example illustrates the usefulness and effectiveness of this system. The result shows that this system can monitor the surface damage failure of the blade in real time, and can effectively reduce the blade’s maintenance costs for wind farms, especially offshore wind farm.

Aeroacoustics response of wind turbine blade profiles in normal and icing conditions

2018 ◽  
Vol 42 (3) ◽  
pp. 243-251 ◽  
Author(s):  
Edison H Caicedo ◽  
Muhammad S Virk
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Numerical Study ◽  
Turbulence Models ◽  
Wind Turbine Blade ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

This article describes a multiphase computational fluid dynamics–based numerical study of the aeroacoustics response of symmetric and asymmetric wind turbine blade profiles in both normal and icing conditions. Three different turbulence models (Reynolds-averaged Navier–Stokes, detached eddy simulation, and large eddy simulation) have been used to make a comparison of numerical results with the experimental data, where a good agreement is found between numerical and experimental results. Detached eddy simulation turbulence model is found suitable for this study. Later, an extended computational fluid dynamics–based aeroacoustics parametric study is carried out for both normal (clean) and iced airfoils, where the results indicate a significant change in sound levels for iced profiles as compared to clean.

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

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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