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Computational Investigation of the Causes of Wind Turbine Blade Damage at Japan’s Wind Farm in Complex Terrain  [PDF]
Takanori Uchida
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2018, DOI: 10.4236/jfcmv.2018.63013
Abstract: During the passage of Typhoon 0918 (Melor) over southern Honshu in Japan on 7 and 8 October 2009, strong winds with extremely high turbulence fluctuations were observed over Shirataki Mountain and the surrounding mountains in Shimonoseki, Yamaguchi Prefecture, Japan. These strong winds caused damage to wind turbine blades at the Shiratakiyama Wind Farm owned by Kinden Corporation. In order to investigate the causes of the blade damage, the airflow characteristics from the time of the incidences are first simulated in detail with the combined use of the WRF-ARW mesoscale meteorological model and the RIAM-COMPACT LES turbulence model (CFD model). Subsequently, in order to evaluate the wind pressure acting on the wind turbine blades, an airflow analysis is separately performed for the vicinity of the blades with the RANS turbulence model. Finally, the stress on the blades is investigated using the FEM with the RANS analysis results as the boundary conditions.
Wind Farm Siting and Protected Areas in Catalonia: Planning Alternatives or Reproducing 'One-Dimensional Thinking'?
Pere Ariza-Montobbio,Katharine N. Farrell
Sustainability , 2012, DOI: 10.3390/su4123180
Abstract: Wind energy is an emblem of sustainability with the potential to promote a qualitative alternative to current energy systems and nuclear options for CO2 reduction. However, wind farm siting often conflicts with aspirations to conserve traditional landscapes and wildlife habitats. In this paper we adopt a Critical Theory perspective, informed by Herbert Marcuse`s work, to study the discourse concerning wind energy siting in Catalonia, Spain. We give particular attention to how tensions between potentially conflicting sustainability objectives are addressed and by whom. Based on a review of this siting discourse and the application of Marcuse’s theory, we find that the Catalan wind energy siting discourse is both influenced by and reproducing what Marcuse referred to as the ‘one-dimensional thinking’ of technology as ideology: erasing the possibility of critical dialectical thought by subsuming the question of “what should be” under the question of “what is”. This has implications both for how these conflicts are investigated and for the sustainability of decisions taken. We conclude that closer attention to the role of ‘one-dimensional thinking’ in wind energy siting discourses could improve not only the understanding of their logic but might also have the potential to help make them more democratic.
Post Evaluation of Wind Resource Assessment and Micro-Siting  [PDF]
Shuang Han, Linyue Gao, Yongqian Liu, Wei Yang
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.24040
Abstract: The design energy productions deviate from the actual situation, which are affected by the accuracy of two significant factors - the wind resource assessment and wind farm micro-siting. A running wind farm in northern China was taken as the object in this investigation. The measured data obtained in operation phase and the relevant information in design phase were integrated and a post evaluation of wind resource assessment, micro-siting and generating capacity reduction factors of the wind farm in design phase was provided. The results indicate that the representative year wind regimes of the wind farm in design phase can basically reflect the wind conditions in the wind farm without the consideration of the trends of long-term changes in wind speed; micro-siting project in design phase is superior to that in practical; generating capacity reduction factors, overall on the high side, should be further optimized considering 20-year operation period.
CO2 payback time for a wind farm on afforested peatland in the UK
J.T. Mitchell,J. Grace,G.P. Harrison
Mires and Peat , 2010,
Abstract: The siting of wind farms on natural and afforested upland peatlands presents an interesting public policy dilemma. Such locations may offer developers attractive wind characteristics amidst sparse human settlement, but the associated disturbance of carbon from soils and vegetation may reduce the carbon benefits that can be derived from wind farm operation. To examine the relative impacts, an estimate was made of the CO2 payback time for a wind farm hypothetically sited on an afforested peatland in north-east England known as Harwood Forest. The location is representative of many potential wind farm sites, and was chosen for this study because its carbon fluxes and stores have been extensively characterised. We adjusted a published LCA for a wind farm in another location to take account of CO2 that would be emitted or not sequestered as a result of site disturbance if it were constructed and operated in Harwood Forest. The results show that the wind farm would compensate for its life cycle CO2 emissions in less than three years of operation in Harwood Forest, whereas the CO2 payback time would be reduced to less than five months if it were placed at an alternative site where CO2 emissions from disturbed soil and vegetation were not an issue.
First discovery of fossil Diplothrix (Muridae, Rodentia) outside the Ryukyu Islands, Japan
Yuan Wang,ChangZhu Jin,GuangBiao Wei
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-009-0541-4
Abstract: The first Diplothrix (Muridae, Rodentia) fossils of the early Early Pleistocene are described as D. yangziensis sp. nov., which were collected from the Renzidong Cave deposits in Anhui Province, Eastern China. Diplothrix was previously represented by a single species, D. legata, whose geographical distribution during the Late Pleistocene is restricted to the Ryukyu Islands, Japan. With straight chevrons on M1, distinct t3 and t9 on upper molars, primitive M3, mlc on m1, and developed a-lab on m2 and m3, the new species is morphologically distinct from other large murids in East Asia, and should belong to the genus Diplothrix. There are also differences in molar morphology between the new species and D. legata, the type species of Diplothrix, as well as other known fossils. For example, D. yangziensis sp. nov. has a smaller size, a more elongated crown, developed precingulum and pc on M1, more primitive M3, weaker mlc and more primitive pc on m1, and stronger plc and pc on m3. In short, Diplothrix yangziensis sp. nov. is evidently more primitive than D. legata, suggesting that the former is likely the ancestor of the latter. Diplothrix yangziensis sp. nov. is the first discovery of the genus outside the Ryukyu Islands, Japan and is also the earliest and most primitive species of the genus in Eurasia. Its discovery has significant implications for reconstructing the evolution and dispersal pattern of Diplothrix, as well as for discussing its palaeoecological variation.
Latest Developments in Numerical Wind Synopsis Prediction Using the RIAM-COMPACT? CFD Model—Design Wind Speed Evaluation and Wind Risk (Terrain-Induced Turbulence) Diagnostics in Japan  [PDF]
Takanori Uchida,Yuji Ohya
Energies , 2011, DOI: 10.3390/en4030458
Abstract: Because a significant portion of the topography in Japan is characterized by steep, complex terrain, which results in a complex spatial distribution of wind speed, great care is necessary for selecting a site for the construction of Wind Turbine Generators (WTGs). We have developed a CFD model for unsteady flow called Research Institute for Applied Mechanics, Kyushu University, COMputational Prediction of Airflow over Complex Terrain (RIAM-COMPACT ?). The RIAM-COMPACT ? CFD model is based on Large-Eddy Simulation (LES) technique. The computational domain of RIAM-COMPACT ? can extend from several meters to several kilometers, and RIAM-COMPACT ? can predict airflow and gas diffusion over complex terrains with high accuracy. First, the present paper proposes a technique for evaluating the deployment location of WTGs. Next, wind simulation of an actual wind farm was executed using the high resolution elevation data. As a result, an appropriate point and an inappropriate point for locating WTGs were shown based on the numerical results obtained. This cause was found to be a topographical irregularity in front of WTGs.
Four Methods for LIDAR Retrieval of Microscale Wind Fields  [PDF]
Allen Q. Howard,Thomas Naini
Remote Sensing , 2012, DOI: 10.3390/rs4082329
Abstract: This paper evaluates four wind retrieval methods for micro-scale meteorology applications with volume and time resolution in the order of 30m3 and 5 s. Wind field vectors are estimated using sequential time-lapse volume images of aerosol density fluctuations. Suitably designed mono-static scanning backscatter LIDAR systems, which are sensitive to atmospheric density aerosol fluctuations, are expected to be ideal for this purpose. An important application is wind farm siting and evaluation. In this case, it is necessary to look at the complicated region between the earth’s surface and the boundary layer, where wind can be turbulent and fractal scaling from millimeter to kilometer. The methods are demonstrated using first a simple randomized moving hard target, and then with a physics based stochastic space-time dynamic turbulence model. In the latter case the actual vector wind field is known, allowing complete space-time error analysis. Two of the methods, the semblance method and the spatio-temporal method, are found to be most suitable for wind field estimation.
Effects of Terrain-Induced Turbulence on Wind Turbine Blade Fatigue Loads  [PDF]
Yasushi Kawashima, Takanori Uchida
Energy and Power Engineering (EPE) , 2017, DOI: 10.4236/epe.2017.913053
Abstract: Recently, the issue has surfaced that the availability factors for wind farms built on complex terrain are lower than the originally projected values. In other words, problems have occurred such as extreme decreases in generation output, failures of components inside and outside wind turbines including yaw motors and yaw gears, and cracking on wind turbine blades. As one of the causes of such issues, the effects of wind turbulence (terrain-induced turbulence) have been pointed out. In this study, we investigated the effects of terrain-induced turbulence on the structural strength of wind turbines through the measurement of strains in wind turbine blades and the analysis of wind data in order to establish a method for optimal wind turbine deployment that uses numerically simulated wind data and takes the structural strength of wind turbines into consideration. The investigation was conducted on Wind Turbine #10 of the Kushikino Reimei Wind Farm (in operation since Nov. 2012) in cooperation with Kyudenko New Energy Co., Ltd. Subsequently, we conducted numerical wind simulations (diagnoses of terrain-induced turbulence) to study the effects of the properties of airflow on the structural strength of wind turbines. For these simulations, the natural terrain version of the RIAM-COMPACT software package, which is based on large eddy simulation (LES), was used. The numerical simulations successfully reproduced the characteristics of the wind conditions and the structure of the three-dimensional airflow. These results enabled us to determine the threshold value for a turbulence index to be used for optimal wind turbine deployment planning that utilizes quantitative data from simulations with the natural terrain version of the RIAM-COMPACT software package.
Turbulent Flow Inside and Above a Wind Farm: A Wind-Tunnel Study  [PDF]
Leonardo P. Chamorro,Fernando Porté-Agel
Energies , 2011, DOI: 10.3390/en4111916
Abstract: Wind-tunnel experiments were carried out to better understand boundary layer effects on the flow pattern inside and above a model wind farm under thermally neutral conditions. Cross-wire anemometry was used to characterize the turbulent flow structure at different locations around a 10 by 3 array of model wind turbines aligned with the mean flow and arranged in two different layouts (inter-turbine separation of 5 and 7 rotor diameters in the direction of the mean flow by 4 rotor diameters in its span). Results suggest that the turbulent flow can be characterized in two broad regions. The first, located below the turbine top tip height, has a direct effect on the performance of the turbines. In that region, the turbulent flow statistics appear to reach equilibrium as close as the third to fourth row of wind turbines for both layouts. In the second region, located right above the first one, the flow adjusts slowly. There, two layers can be identified: an internal boundary layer where the flow is affected by both the incoming wind and the wind turbines, and an equilibrium layer, where the flow is fully adjusted to the wind farm. An adjusted logarithmic velocity distribution is observed in the equilibrium layer starting from the sixth row of wind turbines. The effective surface roughness length induced by the wind farm is found to be higher than that predicted by some existing models. Momentum recovery and turbulence intensity are shown to be affected by the wind farm layout. Power spectra show that the signature of the tip vortices, in both streamwise and vertical velocity components, is highly affected by both the relative location in the wind farm and the wind farm layout.
Analysis of wind field and wake characteristics of wind farm in Northwest China based on measured data

- , 2018, DOI: 10.3969/j.issn.1001-0505.2018.04.016
Abstract: 基于西北地区某风电场2015―2016年的风速风向实测数据,分析了风电场风塔的尾流特性,并与现有风力机尾流模型进行了对比分析.在此基础上,对在远尾流场作用下的风速风向、湍流强度、湍流积分尺度、概率密度分布等风场特性进行了详细分析.研究结果表明:现有的Jensen模型、Park-Gauss模型与实际工程中多个尾流作用下的风电场尾流特性存在差异.在多风向多尾流叠加作用下,当风速大于10 m/s时,各风塔湍流强度随着平均风速的增长呈增大趋势,风电场内部风塔湍流强度在低湍流段更加集中,外围风塔湍流强度随平均风速的增大速率略快于内部风塔,而湍流积分尺度随平均风速的增大程度总体慢于内部风塔,且外围风塔实测风速更加接近高斯分布.
The wake characteristics of wind tower and the existing wind turbine wake model were analyzed based on the wind speed and wind direction measurement data of a wind farm in northwest China during 2015―2016. The wind field characteristics under the effect of far wake flow field, such as wind speed, turbulence intensity, turbulence integral scale, and probability density distributions, were studied in detail. The results show that the existing Jensen model and Park-Gauss model are different from the wake characteristics of the wind farm under the action of multiple wakes in practical engineering. Under the action of multi-wake superposition, when the wind speed is greater than 10 m/s,the turbulence intensity of each wind tower increases with the increase of the mean wind speed, and the turbulence intensity of the internal wind tower is more concentrated in the lower turbulence section. With the increase of the mean wind speed, the turbulence intensity of the external wind tower increases faster than that of the internal wind tower; the turbulence integral scale of the external wind tower increases slower than that of the internal wind tower, and the measured wind speed of the peripheral wind tower is more in line with the Gaussian distribution
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