Videometric research on deformation measurement of large-scale wind turbine blades

Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbine blades in mechanics experiments using a videometric method. In view that the blades experience small buckling deformation and large integral deformation simultaneously, we proposed a parallel network measurement(PNM) method including the key techniques such as camera network construction,camera calibration,distortion correction,the semi-automatic high-precision extraction of targets,coordinate systems unification,and bundle adjustment,etc. The relatively convenient construction method of the measuring system can provide an abundant measuring content,a wide measuring range and post processing.The experimental results show that the accuracy of the integral deformation measurement is higher than 0.5 mm and that of the buckling deformation measurement higher than 0.1mm.

Performance Investigation of Three Combined Airfoils Bladed Small Scale Horizontal Axis wind Turbine by BEM and CFD Analysis

The present work is based on the comparative study between “Blade-Element- Momentum” (BEM) analysis and “Computational-Fluid-Dynamics” (CFD) analysis of small-scale horizontal axis wind turbine blade. In this study, the pitch is considered as fixed and rotor speed is variable. Firstly, the aerodynamic characteristics of three different specialized airfoils were analyzed to get optimum design parameters of wind turbine blade. Then BEM was performed with the application of the open source wind turbine design and performance computation software Q-Blade v0.6. After that, CFD simulation was done by Ansys CFX software. Here, k-ω “Shear-Stress-Transport” (SST) model was conducted for three-dimensional visualization of turbine performance. However, the best coefficient of performance was observed at 6o angle of attack. At this angle of attack, in the case of BEM, the highest coefficient of performance was 0.47 whereby CFD analysis, it was 0.43. Both studies showed good performance prediction which was a positive step to accelerate the continuous revolution in wind energy sector.

Experimental study of rotating wind turbine breakdown characteristics in large scale air gaps

When a wind turbine is struck by lightning,its blades are usually rotating.The effect of blade rotation on a turbine＇s ability to trigger a lightning strike is unclear.Therefore,an arching electrode was used in a wind turbine lightning discharge test to investigate the difference in lightning triggering ability when blades are rotating and stationary.A negative polarity switching waveform of 250/2500 μs was applied to the arching electrode and the up-and-down method was used to calculate the 50%discharge voltage.Lightning discharge tests of a 1：30 scale wind turbine model with 2,4,and 6 m air gaps were performed and the discharge process was observed.The experimental results demonstrated that when a 2 m air gap was used,the breakdown voltage increased as the blade speed was increased,but when the gap length was 4 m or longer,the trend was reversed and the breakdown voltage decreased.The analysis revealed that the rotation of the blades changes the charge distribution in the blade-tip region,promotes upward leader development on the blade tip,and decreases the breakdown voltage.Thus,the blade rotation of a wind turbine increases its ability to trigger lightning strikes.

A Very Large Scale Wind Turbine

A very large scale wind turbine can be made as a circular large scale stator frame;the frame,which can reach some kilometers in diameter and some hundred meters in height,contains many circular sail trains.The stator frame can be made using a light-weight tubular design.Wind can almost freely blow through this frame.Train rails are fixed at the outer surface of the frame as horizontal rings.The distance between the rails of one ring can be made to be several meters.As a result,the number of the rings can be ten or more.Each rail ring supports one sail train that is moved with wind power around the frame.The energy of this movement is transformed to electric power and is transmitted to the base of the frame.This design can be realized in a very large scale,which is difficult to achieve using a traditional three-blade turbine.

Shape design and performance test for small wind turbine blade

Based on the 1D-blade element momentum theory (BEM) with the improved tip loss correction introduced, a new aerodynamic model of wind turbine is developed. Using one high aerodynamic performance airfoil with 18% relative thickness, one small wind turbine blade is designed and the distribution of the chord and twist angle of the blade are determined. According to the shape parameters of the blade, a method to set up the 3D model is presented by investigating the coordinate position of each section of the blade. Based on the fiber reinforced polymer (FRP) molding technology, the manufacturing process of wind turbine blade is put forward. Using fiber reinforced polymer, the wind turbine blades are manufactured by the mold making and layer process. A test platform and method of wind turbine output power are carried out, the output powers at different speeds of the wind turbine are obtained and discussed. The comparison between the designed and one existing wind turbine rotor is completed to show the reliability and superiority of the design and test method presented in this paper.

极端运行阵风对15 MW风力机叶片结构性能影响的分析

基于CFD方法,对极端运行阵风条件下IEA Wind 15 MW水平轴风力机气动性能进行分析。采用ANSYS APDL软件定义复合材料铺层方案建立15 MW风力机叶片有限元模型,并基于Workbench平台对风力机叶片进行模态分析和静力学分析,研究极端运行阵风对风力机叶片结构性能的影响。结果显示:极端运行阵风对风力机气动性能和叶片结构性能影响较大,风轮推力与转矩极值出现的时间点均迟于风速极值点,沿叶片展向叶片流动分离区域与风速呈正相关;在极端运行阵风期间,叶片位移均是从叶根至叶尖逐渐增大,叶片最大应力出现在叶片主梁并且距叶根0.6 R处,同时,由于叶片的叶尖位移和最大应力在短时间内大幅度变化,会使叶片破坏的概率增加。

基于BLADED软件的大型风力机叶片气动分析

基于BLADED软件,根据德国GL2003国际标准,对应用于GL3A风场的某款1.50 MW大型风力机叶片的气动额定功率、风能利用系数、疲劳载荷、极限载荷等进行分析。研究结果表明:在与某款1.65 MW风力发电机组匹配时,该叶片在风速为11.0 m/s时的额定功率能达到1.65 MW;在叶尖速比为7.8～11.4时,其风能利用系数均在0.460以上,在叶尖速比为9.5时,其最大风能利用系数可达0.486,表明该叶片具有较好的气动性能和较宽的风速适应范围;其叶根等效疲劳载荷为2.107 7 MN.m,叶根极限挥舞载荷为4.614 6 MN.m,均比该叶片载荷的原设计值小,说明其应用是安全的。

陆上风电碳足迹动态变化的国际比较研究

碳中和目标下国际风电产业将继续扩大规模,碳市场、碳关税等国际气候减排政策工具也在不断完善,未来可再生能源碳足迹对相关产业成本与发展将产生重要影响。本文以中国、欧洲、美国等风电产业优势国家和地区作为研究对象,构建陆上风电系统生命周期评价过程、生命周期清单,完成相关地区陆上风电碳足迹的参数比较并总结变化趋势,进一步分析趋势成因并阐明影响因素。结果表明,在风力机大型化加速、发电效率提高、工业生产清洁化的态势下,2011—2022年世界优势地区的陆上风电碳足迹均呈下降趋势,中国、欧洲、美国的平均降幅分别为49.2%、46.2%、20.8%,相应下降量均集中在设备生产阶段;中国已将碳足迹下降至与欧洲接近的水平,与美国的差距缩减到3.63 g/kW·h,其中工业生产清洁化水平不高、风机容量因子偏低分别是中国陆上风电碳足迹高于欧洲、美国的主要原因。中国在推进风电产业发展的过程中,需着重提高风电系统发电效率、加快改善产业清洁化生产水平、支持风电系统退役回收产业发展,以稳步降低陆上风电系统生命周期内的碳足迹。

多变气热参数下大尺度槽深叶顶的流动换热特性

为了研究具有渐缩型面凹槽在不同深度下叶顶间隙的流动换热特性,针对某一级高压涡轮,在发动机五种典型工况下通过改变其凹槽深度,采用k-ω湍流模型以及自适应湍流模拟方法(SATES)分别进行定常和非定常的数值仿真分析。研究结果表明,凹槽深度是影响间隙泄漏流动和叶顶换热特性的重要因素,同时该影响趋势也受涡轮工作状态的限制。相比于深凹槽,浅凹槽方案的间隙泄漏量明显降低,对应的涡轮动叶出口总压损失系数也有所降低,这在涡轮小流量状态时尤为明显。然而,深凹槽设计在降低叶顶热负荷方面表现更好,其中槽深0.8H方案比槽深0.1H方案的叶顶平均努塞尔数降低38.3%~95.3%。定常和非定常两种计算方法主要影响了间隙内局部泄漏量和叶顶前部热负荷的预测值,并未改变流动换热特性的分布趋势。

基于改进融合的大型风力发电机组运行状态检测研究

为解决传统的大型风力发电机设备运行状态检测方法效果不佳的问题,设计了基于多特征融合的大型风力发电机设备运行状态检测方法。通过计算提取出的运行状态数据集的多个数据特征,并计算不同特征的权重值,实现数据的多特征融合,并对其进行特征分类。通过计算运行状态数据的偏离阈值和检测阈值,完成对设备运行状态的检测。实验结果表明,和以往的大型风力发电机设备运行状态检测方法相比,设计的基于多特征融合的大型风力发电机设备运行状态检测方法在实际应用中ROC曲线面积较大,检测效果较好。

考虑大变形的柔性风电叶片气弹性分析

针对超长柔性风电叶片在传统线性(小变形)条件下发生动力学分析失效的问题,提出考虑大变形结构的柔性叶片模型并进行气动弹性分析。首先将叶片简化成非均匀悬臂梁,利用大变形Euler-Bernoulli梁模型进行离散化建模;后结合叶素动量理论,建立叶片的非线性结构动力学方程,并运用Newton-Raphson和逐步积分相结合的方式进行时域仿真。整个过程重点考虑大变形结构的刚度变化、以及柔性叶片截面扭转运动和外形变化。以DTU 10 MW风力机为算例,比较叶片在大变形和小变形结构下的动态气动特性,结果表明:动态响应中,大变形结构的刚度变化导致挥舞方向的叶尖位移明显增加,略微减小摆振方向的位移,同时叶尖扭角也会显著减小。此外,叶根面外载荷在大变形条件下会显著下降,但叶根面内载荷则会略微增加。这与传统线性条件下的气弹现象具有明显差异。该文的叶片模型能有效预测长柔叶片的动态气动特性。

基于GUM法的风电叶片结构试验方法不确定度研究

针对风电叶片全尺寸结构试验方法,首先分析试验过程中所需测量物理量的不确定度因素来源;其次利用GUM法建立不确定度数学模型,然后评定各部分输入量的标准不确定度;最后分析得到叶片结构试验各测试物理量的合成标准不确定度和扩展不确定度,从而建立风电叶片试验不确定度的系统评价方法。

基于光纤传感器的大型风电机组叶片荷载在线监测方法

现阶段,风电机组得到深层次开发和运用,向低成本、高功率方向发展,机组风轮直径、扫琼面积不断增加,有效加快电力输送效率,满足社会的用电需求,但也提高运行隐患,极易出现叶片荷载不均匀的现象,影响大型风电机组的发电效果。该文以提高风电机组的发电稳定性为研究目标,着重阐述光纤传感器下大型风电机组叶片荷载在线监测系统,并简单论述叶片结构和受力分析,以及常见故障类型等内容,希望对相关研究工作有所参考。

大型风电叶片模具绿色制造与服役关键技术

从绿色设计、绿色工艺、绿色服役3个方面系统探讨了大型风电叶片模具绿色制造的关键技术,重点研究了模具轻量化设计、环保材料应用、智能化加工、表面强化处理、再制造等方面的新理念、新技术、新方法,为风电产业的健康可持续发展提供有力的装备技术支撑。

大型风电叶片模具电加热系统设计

随着风电行业不断向大型化发展,叶片模具逐步由传统的水循环加热方式转变为电阻丝加热。在风电叶片制造过程中,固化时的温度控制是一个关键环节。固化过程要求叶片模具型腔表面的温度具有精确性和均匀性。文章将详细介绍大型风电叶片模具的电加热控制系统的硬件架构与软件算法,以更好地满足叶片生产过程中的控温要求。

Large-eddy simulation and experimental study on the turbulent wake flow characteristics of a two-bladed wind turbine

Large-eddy simulation(LES) with fully resolved rotor method(FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunnel experiments have been done based on time resolved particle image velocimetry(TRPIV) technique. The simulation results are validated by the experimental data and they are in good agreement. The axial average velocity, turbulent kinetic energy, shear Reynolds stress, and vortex structure of the wind turbine wake are analyzed based on the comparison of LES results and experimental data. It is observed that the wake diameter of wind turbine enlarges with the increase of tip speed ratio(TSR). Turbulent kinetic energy meets its minimum value when x/R=2.0. Shear Reynolds stress appears a positive peak in the near wake when x/R<2.0, and the value of shear Reynolds stress decreases along the axial direction. The blade tip vortex dissipates more quickly than the central vortex in the wind turbine wake, and the gradient of the relationship curve between the blade tip vortex core position and the vortex age decreases as the TSR increases. With the increase of TSR, the thrust coefficient increases, and the power coefficient increases first and then decreases.The present work proves that LES with FRM could calculate wind turbine turbulent wake flow with a high accuracy.

弧形锯齿尾缘对叶片气动噪声影响及机理的研究

以弧形锯齿尾缘叶片为研究对象,同时设置三角形锯齿尾缘和直尾缘叶片作为参照组,采用大涡模拟结合声类比方程的方法,对比分析不同攻角下3种叶片的声压级指向性、噪声频谱特性。通过分析3种叶片周围涡结构,进一步对弧形锯齿尾缘所特有的声学机理进行研究。结果表明:同三角形锯齿一样,弧形锯齿结构并未改变叶片声压级指向性呈偶极子分布的规律;弧形锯齿尾缘有效降低中高频段的噪声,低频段降噪效果不明显;锯齿结构影响尾缘处展向涡的发展,进而对叶片气动噪声产生影响,且弧形锯齿尾缘对尾部涡结构的影响程度大于三角形锯齿尾缘。

中国海上风电发展现状及展望

海上风电是中国加快能源转型进程,助力“双碳”目标早日实现的重要战略支撑。2022年中国海上风电正式进入平价时期,但在补贴取消、需求透支等因素影响下,海上风电市场经历短期低谷。在梳理后补贴时代中国海上风电发展现状的基础上,分析了新增装机容量、招标数量、技术创新、风机价格等方面的新变化。最后,结合行业发展现状与能源发展“十四五”规划要求,预测未来几年中国海上风电建设成本将进一步下降、行业将迎来新一波的建设高峰。

碳纤维在风电领域的应用现状及发展趋势

近年来全球风电产业迅猛发展,中国风电更是“一枝独秀”,保持全球领先地位,为中国乃至全球的新能源应用做出了巨大贡献。风机大型化是未来发展趋势,越来越大的风电叶片,让碳纤维有了用武之地。在满足同等刚度和强度的前提下,与玻璃纤维材质的叶片相比,碳纤维材质要轻30%以上,而且还能提高风电叶片的耐候性。预计未来5~10年,中国风电将继续引领全球风电的增长,这将是拉动碳纤维需求增长的主要引擎。

风电叶片全尺寸静力测试的形变分析

针对风电叶片静力测试过程中叶片大挠度变形和叶根连接法兰变形对截面弯矩与形变测量精度的影响,本文分别基于柔度法和逐段刚化法得到叶片挠度以及变形后叶片承受弯矩的计算公式,进一步修正法兰变形带来的影响,并建立风电叶片多点静力加载的仿真模型,对比理论计算结果和有限元仿真数据。结果表明设计加载方案时考虑大挠度变形,可以降低靠近叶根区域截面的弯矩误差至1.07%;修正法兰变形带来的叶片挠度后,5.7 m处叶片挠度计算误差减小0.1%,从而可以确保全尺寸叶片静力加载的测试精度。