风力机专用翼型低雷诺数气动特性实验研究

采用表面压力测量法,在小型回流式低速风洞中开展DU91-W2-250翼型在低雷诺数(Re3×10~5)条件下的气动特性实验研究,获得边界层自由和前缘固定转捩条件下翼型的升力系数、阻力系数和表面压力分布特性。在自由转捩条件下,翼型发生层流分离的临界雷诺数为1.7×10~5,且雷诺数越低,层流分离发生时的攻角越小。层流分离使得翼型升力系数和阻力系数发生跳跃性变化。通过在前缘增加粗糙带,强制边界层发生转捩,可消除前缘层流分离引起的失速,使翼型的气动力系数随攻角稳定变化。     

基于DES方法的变形叶片气动性能数值模拟研究

针对适用于垂直轴风力机的叶片,以NACA0012作为基准翼型,采用DES湍流模型,在来流雷诺数Re=1×106的情况下进行了等厚度翼型中弧线主动变形运动的数值模拟研究。选用弦长c=0.601 m,展向长度B=1 m,攻角α为15°(浅失速攻角)和18°(深失速攻角),变形频率f为0.5,2和5 Hz,变形幅值A〖DD(-*2〗-〖DD)〗为0.1c的参数条件,对比变形翼型与不变形翼型的气动性能。研究表明：在深失速攻角下变形翼型相较于不变形翼型,其升力系数提升52%以上,阻力系数减小64%以上,气动性能可得到有效提升,且变形翼型在特定工况下能有效减小翼型表面分离区及分离涡尺度。     

低雷诺数下NACA64-418翼型的流动分离研究

通过粒子图像测速（PIV）技术，在低速风洞中研究了0°~15°攻角和雷诺数分别为1.54×105、2.57×105和3.59×105下NACA64-418翼型的压力性能，并基于γ-Reθ转捩模型分析了翼型表面的流动分离及涡脱落情况。 研究表明:NACA64-418翼型具有较大的失速攻角,PIV结果的时均流场和瞬时流场表明，NACA64-418翼型具有较大的失速攻角，随着雷诺数的增加，失速攻角变小;从翼型壁面回流区可以看出γ－Reθ转捩模型可以准确评估翼型表面从层流到湍流流动的变化;数值结果与实验结果进行比较，验证了γ－Reθ转捩模型的预测是准确的。     

风力机叶片S832翼型的两种湍流模型数值分析方法及其比较

采用S-A和RNGK-ε湍流模型对风力机专用S832翼型的绕流流动建立了二维不可压缩湍流模型,利用计算流体力学软件Fluent,对两种模型进行数值模拟,得到了雷诺数为3×10^6时该翼型在-16°～30°攻角下的升力系数和阻力系数与来流攻角的关系以及压力分布图,并进一步分析了不同攻角下翼型表面压力分布特性,预测了大攻角（达30°）下翼型分离流动特性。结合NREL的试验数据,对两种湍流模型模拟的精度进行了分析比较,结果表明在小攻角范围内采用RNGK-~模型预测该翼型气动性,其结果更加有效。     

基于两种湍流模型的某风机专用翼型数值研究

针对风力机专用S832翼型绕流流动建立了二维不可压缩湍流模型,利用计算流体力学软件Fluent,分别选用S—A、RNGk-ε两种湍流模型对S832进行数值模拟,对比了两种湍流模型对气动模拟精度的影响,得出了雷诺数为3×10^6时,该翼型在-16°～30°攻角下的升力系数和阻力系数随来流攻角的变化关系及压力分布图,分析了不同攻角下翼型表面压力分布特性并进一步预测了大攻角（达30°）下翼型分离流动特性．并与NREL的试验数据进行比较,研究结果表明：RNGk—ε在预测该翼型小攻角范围气动性方面更加有效。     

导流式翼缝控制多段翼型流动分离的数值研究

为改善叶片失速特性,以具有圆弧形缝道的两段式NACA0021翼型为基础研究模型,设计一种导流式翼缝(Flow-deflecting Gap,FDG),研究在不同的导叶设计参数与不同雷诺数下导流式翼缝在多段翼型被动流动控制中的效果。研究发现:导流式翼缝可在一定攻角范围内抑制甚至消除分离涡的生成及发展;当前翼缝宽度为0.03c,后翼缝宽度为0.01c时,最大升力系数可提升5.33%,失速攻角增大2°,出现较大尺度分离涡的攻角增大2°,升力波动载荷大幅降低;在不同雷诺数下,FDG翼型的最大升力系数均有不同程度提升,失速特性均有不同程度改善,升力波动载荷均大幅降低。     

PREDICTION OF THE AERODYNAMIC CHARACTERISTIC OF WIND TURBINE AIRFOILS THROUGH ±180°ANGLE OF ATTACK

利用经验公式、小攻角下翼型气动特性数据建立了翼型在-180°～180°攻角范围内的气动特性估算模型.以NACA0012翼型、NACA0015翼型为例,对翼型全流向范围的升力系数、阻力系数、力矩系数进行了估算,并对风力机翼型DU96-W-180的升力系数、阻力系数进行了估算,将估算结果与实验结果进行比较,验证了估算方法的合理性.     

基于环量场影响的Magnus风力机组合旋转圆型翼设计与研究

提出一种新型的面向Magnus风力机的组合旋转圆型(combined rotating cylinder,CRC)翼型设计思想,理论分析该翼型提高升力的作用机理;采用数值模拟计算方法研究该翼型的气动性能,将该翼型的数值模拟结果与传统翼型的试验结果作对比分析。结果表明:由于圆柱翼旋转产生的环量使得整个新型风力机翼型的环量得到较大提高,导致CRC翼型在马格努斯效应下产生的升力得到较大提高。表现为在整个攻角范围内的CRC翼型升力系数均远大于传统翼型,尤其是在低攻角范围内其升力系数约为传统翼型最大值的3倍,表明该翼型具有良好的价值。     

襟翼相对长度对翼型气动性能的影响

以NACA0018为基准翼型,采用Fluent数值模拟方法对比研究了襟翼相对长度(分别取0.2、0.3和0.4)和翼缝相对宽度(分别取1.0%、1.5%和2.0%)对翼型流场结构及升、阻力特性的影响,并着重分析襟翼相对长度对翼型气动性能的影响.结果表明:由于襟翼对翼型周围主涡发展和变化的影响,不仅改善了翼型的失速特性,同时也提高了翼型的气动性能;襟翼翼型的失速攻角在研究范围内均大于基准翼型;在攻角小于失速攻角时,襟翼翼型的升力系数均小于基准翼型,阻力系数均大于基准翼型,但升力系数的最大值均大于基准翼型;随着襟翼相对长度的增大,翼型失速攻角逐渐减小;当攻角接近翼型失速攻角时,升力系数先增大后减小;襟翼相对长度相同时,随着翼缝相对宽度的增大,升力系数逐渐减小.     

风力机二元翼型大攻角实验研究

本文报道了二元翼型在0—180°时的大攻角实验和采用简易壁压法对二元翼型测力实验的修正。实验结果表明,利用相对应的四点壁压对二元翼型大攻角测力进行修正是完全可行的。修正后的实验结果与文献[1]基本吻合。     

风速廓线在风电场功率预报中的应用

过分析我国内陆河北省张北县和吉林地区风电场内的风速廓线变化特性发现,各高度间风速的差异分布大体相同：各高度间风速差异由夜间到白天逐渐缩小,在中午达到最小,由白天到夜间逐渐增大,并且在各个阶段又相对稳定,即在日出后由地面向上的热量输送逐渐增强,湍流加强,各层间的风速差异减少,并迅速趋于稳定,直至日落湍流减弱。各层间的风速差异迅速增大,并趋于稳定。这一规律的发现对解释涡轮高度不同时间、相同风速条件下风机出力不同及风电功率建模有重要意义。     

陕西省金润河北镇风电场风能资源开发评估

对陕西省宝鸡市陇县金润河北镇风电场气象条件、风功率密度、平均风速、主导风向等风能参数进行分析评价。结果表明,测风塔100 m高度月平均风速、月平均风功率密度最大均出现在4月,最小均出现在8月;测风塔100 m高度主导风向为SSW(南西南),主要风能方向为SSW(南西南),风电场风功率密度等级为1级。风电场安装20台2500 kW的风电机组,装机容量50 MW,年设计发电量1.33485×108 kW·h,年出厂电量9.5426×107 kW·h。结果可为其他风电场选址和发电量估算提供参考。     

酒泉地区风电场风电功率预报研究

利用NOAA天气预报模式Weather Research andForecasting Model(WRF)结合统计订正方法对酒泉地区短期风电功率预报进行了预报实验。与实际出力比较24 h短期风电功率预报精度较高。并在此基础上利用风电场附近测风塔观测数据通过时间序列发进行了0~4 h超短期预报实验,预报结果显示0~2 h预报结果有利于运行调度。     

风电场风切变指数研究

根据山东某风电场实测资料,对风电场逐月、逐时、不同风速下的风切变指数进行研究并探究风切变指数不同取值对风电场轮毂高度处风资源的影响。在分析轮毂高度风资源时,建议采用高差较小的高度处风速根据综合风切变指数进行推导。     

计及随机波动风速、风向的风电场建模方法研究

提出风电场建模方法建立风电场随机模型,对风电场运行特性进行仿真,为实现大规模风力发电的可预测、可控制目标服务。通过对风电场等值模型与详细模型的仿真比较,验证建模方法的合理性,并得出在研究风电场动态特性及其对电网影响时应考虑风速、风向的随机波动建立风电场模型。     

A review of wind energy activities in Japan

By 2012, Japan must cut down on its annual emissions of greenhouse gases by 6% from 1990 levels. However, greenhouse emissions increased by 6.4% in 2006. More effective responses to reduce greenhouse gases are required. Attention is currently focused on increasing the use of renewable energy, and wind energy has received a lot of attention. The national target for wind power capacity in the year 2010 is 3000 MW; however, there are many barriers to the development of wind energy. Japan's climate differs from that of the European Union countries. It often experiences typhoons and lightning strikes because of its meteorological characteristics. Wind has a stronger turbulence level due to the complex terrain. Furthermore, power fluctuation of wind causes power system problems because of issues related to the grid connection. Many endeavours have been made to find the best solutions for these problems. This paper reviews the wind energy activities in Japan, including wind resources, market trends, environment, prospects and research and development. Copyright © 2009 John Wiley & Sons, Ltd.     

Investigation of wind energy potentials in Brunei Darussalam

Conventional power generation mainly depends on natural gas and diesel oil in Brunei Darussalam. The power utility company is now thinking of power generation using natural wind. In this paper, wind energy, being one of the most readily available renewable energy sources, was studied. The wind characteristic, velocity and directions were studied using Weibull distribution based on the measurement of wind speed at two different locations in Brunei Darussalam. These wind speed distributions were modeled using the Wind Power program. The wind rose graph was obtained for the wind direction to analyze the wind power density onshore and offshore. Based on this analysis, it has been found that the wind speed of 3 to 5 m/s has a probability of occurrence of 40%. Besides, the annual energy production at a wind speed of 5 m/s has been found to be in the range between 1000 and 1500 kWh for both the locations in Brunei Darussalam.     

风切变对大直径风力机风轮输出功率影响的初探

以风切变幂指数为0．14的风廓线模型进行了风轮输出功率计算,并与以风轮中心风速计算风轮功率进行了对比分析,指出风切变对风轮输出功率的影响不容忽视。     

Correlation and statistical characteristics of aggregate wind power in large transcontinental systems

Studies have shown that the unpredictability and variability of wind power is reduced in systems with large numbers of geographically diverse wind plants. These effects are caused by the decreased correlation of power output between wind plants as their separation and diversity in terrain increases. One way that system operators have increased geographic diversity is by enlarging balancing areas through the physical or administrative connection of adjacent systems. This strategy can be extended from the regional level to the transcontinental level. As such, it is important to study the correlation and statistical characteristics of aggregate wind power between large, distant systems. This paper analyzes multi‐year historical data from four North American system operators—Bonneville Power Administration, Electric Reliability Council of Texas, Midwest Independent Transmission System Operator and PJM—to see how effective transcontinental interconnection of systems is at enabling wind plant integration. The effects of separation and timescale on correlations of instantaneous and hourly variations are analyzed. The analysis is complemented by a study of a hypothetical transcontinental connection of the systems across yearly, monthly, daily and hourly timescales. The results show that correlations between large systems exhibit similar characteristics as the correlations between individual wind plants, but are somewhat larger in magnitude. The transcontinental system exhibits a close to normal distribution of power output and decreased variability, but there is still appreciable and statistically significant correlation at the longer timescales driven by seasonal and diurnal forcing, as well as synoptic weather systems. Copyright © 2013 John Wiley & Sons, Ltd.     

Wind energy resources on Phuquoc Island,Vietnam

This study analyzes the wind energy resources on Phuquoc Island, Vietnam. Daily wind data are collected from 2005 to 2011 in this study. The annual mean speed and power density are 6 m/s and 355 W/m², respectively. Results show that more than 35% of the wind energy comes from the northwest. In this study, a 75 MW wind farm with 25 wind turbines is simulated by using the WAsP 10 program. The wind farm can produce over 189.636 GWh annually. In addition, the effects of wind disturbance and three-phase short circuit of the grid are analyzed using the ETAP 7.0 program.