垂直轴风力机的现在和未来

本文主要介绍小型垂直轴风力机的类型,各类小型垂直轴风力机的优缺点、小型垂直轴风力机的设计思想,以及小型垂直轴风力机主要设计参数的关联性和未来垂直轴风力机的发展方向,也简要介绍了磁悬浮在垂直轴风力机中的应用状态。     

直径比对组合型垂直轴风力机气动特性影响仿真计算

与Savonius风轮组合使用是解决直线翼垂直轴风力机启动性不佳的主要手段。Savonius风轮与直线翼垂直轴风力机直径的比值(简称直径比),是影响组合型垂直轴风力机性能的重要因素。为了研究直径比对组合型垂直轴风力机气动特性的影响,对直径比分别为0.25,0.33,0.5的组合型风力机以及直线翼垂直轴风力机进行仿真计算。计算基于二维定常不可压缩流体的方程,采用标准模型,计算风速为12 m/s。计算包括直线翼垂直轴风力机及3种直径比的组合型风力机的动态输出力矩,同时,对动态输出力矩最优的组合型风力机与直线翼垂直轴风力机的静态启动力矩进行计算与分析。结果表明,组合型垂直轴风力机的最佳直径比为0.5,此时组合型风力机的最大风能利用系数相对于直线翼垂直轴风力机提高了7.1%,平均启动力矩提高了约2倍。     

垂直轴风力机技术讲座(六)垂直轴风力机应用及其发展前景

1 垂直轴风力发电机的应用 以发电为目的垂直轴风力机主要有以下几种形式:大型并网垂直轴风力机;大型离网垂直轴风力机;小型并网垂直轴风力机;小型离网垂直轴风力机:互补型垂直轴风力发电机.     

阻力型垂直轴风力机叶型研究现状

阻力型垂直轴风力机因其结构简单、自启动性能好、噪音小、不易磨损等优点而受关注,将其与建筑结合用于节能也得到了越来越多的研究。阻力型垂直轴风力机的叶型是影响其性能的重要因素,合适的叶型不但能提高阻力型垂直轴风力机的功率系数,还能改善其气动特性。详细概述了国内外阻力型垂直轴风力机叶型的相关信息,根据几何参数的不同进行了分类、总结,旨在为阻力型垂直轴风力机叶型的优化设计提供一定的参考。     

垂直轴风力机技术讲座(三) 升力型垂直轴风力机

1 升力型垂直轴风力机概述 近30年来,螺旋桨式水平轴风力机发展迅速,已成为大型商业风力发电的主流.与此同时,以达里厄风力机为代表的升力型垂直轴风力机也受到一些风电发达国家的关注.虽然垂直轴风力机没有像水平轴风力机那样快速发展,但也取得了一定的进展.     

低尖速比下双转子垂直轴风力机气动性能试验研究

虽然水平轴风力发电机的技术已经发展的非常成熟,是世界上的主流风机,但在适应风机大型化、深海化的趋势方面,垂直轴风力发电机因其结构特点表现出一定优势。近年来,对于垂直轴风力机的研究日益增多,将两台相同的垂直轴风力机间隔一定距离置于一起即得到双转子垂直轴风力机。文章利用风机模拟与实际风场较接近的非定常风,通过物理模型试验对比了单转子垂直轴风力机和具有不同双转子间距的双转子垂直轴风力机在不同风速下同一转子的扭矩、转速与轴功率,证实了双转子垂直轴风力机的增益效果,并探讨了风速及两转子间距对风机性能及增益效果的影响。试验结果表明,风速越大、两转子间距越小,双转子垂直轴风力机的增益效果越显著。     

垂直轴风力机叶片变桨距运转模式研究

针对垂直轴风力机自启动性能差和风能利用率低的问题,提出一种新型自动变桨距垂直轴风力机方案。结合垂直轴风力机叶片攻角变化及翼型气动力特性,制定了一种最优叶片桨距角变化模式。根据叶素理论,计算得到了采用该变桨距模式在低叶尖速比和高叶尖速比时的叶轮扭矩系数,结果表明,采用该变桨距模式可有效增大垂直轴风力机的启动力矩以及提高其风能利用系数,为进一步开发自动变桨距垂直轴风力机奠定了研究基础。     

垂直轴风力机叶尖速比分析研究

分析了垂直轴风力机叶尖速比选择的特点和影响因素;给出了垂直轴风力机叶片攻角与旋转位置的关系式;计算并分析了各种叶尖速比下的攻角分布情况;得出了垂直轴风力机最佳叶尖速比和相应的叶片设计要求。如果只考虑提高风能利用系数,垂直轴达里厄型风力机叶尖速比值应选择4。     

新型随动变桨垂直轴风力机气动性能的数值分析

文中研究目的是开发一种使垂直轴风力机自启动能力强、风能利用率高的随动变桨技术,此变桨技术的原理是在不需添加任何外加动力的情况下,利用风力机主轴旋转的同时带动风力机叶片的旋转,且保持主轴的旋转角速度是叶片旋转角速度的2倍。通过运用数值模拟的方法,得到了该新型随动变桨垂直轴风力机的气动参数值及特点;并分别将其与传统垂直轴风力机、理想直叶片垂直轴风力机的气动参数进行了对比分析,分析结果表明:新型随动变桨垂直轴风力机的气动性能优于其它两种类型风力机。     

阻力型垂直轴风力机聚风装置研究现状

阻力型垂直轴风力机具有结构简单、噪声小、不受来流风向影响等优点,但其功率系数较低。聚风装置不仅能有效提高阻力型垂直轴风力机的功率系数,还能改善其气动特性,故国内外学者对风力机外围的聚风装置做了大量的研究。文章详细描述了国内外阻力型垂直轴风力机聚风装置的研究现状,对其进行了分类整理和总结,旨在对阻力型垂直轴风力机的研究提供有价值的参考。     

Environmental activism and vertical‐axis wind turbine preferences in California

Wind energy is widely recognized as a key element of the worldwide effort to limit greenhouse gas emissions. As compared with the general population, environmental activists have a much higher level of knowledge, interest, and capacity to affect the final outcome of a proposed wind turbine facility. To explore how their opinions on wind energy, particularly on vertical‐axis wind turbines, differ from the general public, we administered the same online experimental survey to a general population sample of adult Californians and to a self‐selected sample of online energy and environmental activists. We find that support for wind energy increases with the degree of environmental activism and engagement. The general public prefers vertical‐axis wind turbines in open spaces, away from one's residence. Location and price sensitivity, however, are weaker among activists. Among activists, attitudes about specific vertical‐axis wind turbine technologies are more crystalized and less susceptible to the information effects except on the topic of minimizing bird deaths.     

垂直轴风力机三维效应的数值模拟研究

文章针对二维和三维垂直轴风力机的数值模拟的差异,提出了风力机的三维效应是造成模拟差异的主要原因。运用计算流体力学方法对某直线翼垂直轴风力机模型进行了二维和三维的数值模研究。通过比对实验得到的风力机功率系数,发现三维模拟结果与实验值吻合。观察尖速比为1.5时二维和三维垂直轴风力机的速度型分布曲线、流向速度云图和涡量云图,研究了阻塞效应、叶梢涡、支撑结构和塔架对数值模拟结果的影响。研究发现:在二维的数值模拟中,风力机没有受阻塞效应影响,功率系数被严重高估;三维的数值模拟能够模拟出全部的流畅细节,受叶梢涡和支撑结构的影响,风力机的功率系数明显降低。     

Modelling the aerodynamics of vertical‐axis wind turbines in unsteady wind conditions

Most numerical and experimental studies of the performance of vertical‐axis wind turbines have been conducted with the rotors in steady, and thus somewhat artificial, wind conditions—with the result that turbine aerodynamics, under varying wind conditions, are still poorly understood. The vorticity transport model has been used to investigate the aerodynamic performance and wake dynamics, both in steady and unsteady wind conditions, of three different vertical‐axis wind turbines: one with a straight‐bladed configuration, another with a curved‐bladed configuration and another with a helically twisted configuration. The turbines with non‐twisted blades are shown to be somewhat less efficient than the turbine with helically twisted blades when the rotors are operated at constant rotational speed in unsteady wind conditions. In steady wind conditions, the power coefficients that are produced by both the straight‐bladed and curved‐bladed turbines vary considerably within one rotor revolution because of the continuously varying angle of attack on the blades and, thus, the inherent unsteadiness in the blade aerodynamic loading. These variations are much larger, and thus far more significant, than those that are induced by the unsteadiness in the wind conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

垂直轴风力机两种翼型气动性能比较研究

叶片是风力机最重要的组成部分,在不同的风能资源情况下,翼型的选择对垂直轴风力机气动特性有着重要的影响。文章分别以NACA0018翼型(对称翼型)和NACA4418翼型(非对称翼型)建立3叶片H型垂直轴风力机二维仿真模型。应用数值模拟的研究方法,从功率系数、单个叶片切向力系数等方面比较两种风力机模型在不同叶尖速比下的气动特性,并采用风洞实验数据验证了流场计算的准确性。CFD计算结果表明:在低叶尖速比下,NACA4418翼型风力机气动特性优于NACA0018翼型风力机,适用于低风速区域;在高叶尖速比下,NACA0018翼型风力机气动特性较好,适用于高风速地区。而且在高叶尖速比时,NACA0018翼型在上风区时,切向力系数平均值要高于NACA4418翼型,在下风区时,NACA418翼型切向力系数平均值高。该研究可为小型垂直轴风力机翼型的选择提供参考。     

基于复合形法的垂直轴风力机翼型优化设计

针对低速航空翼型不完全适合垂直轴风力机的问题,采用复合形法对小型垂直轴风力机常用的NACA0015翼型进行了优化设计。在复合形法优化设计过程中,选取翼型的弯度和厚度作为设计变量,以翼型最大切向力系数Ctmax和失速攻角αs的加权和作为目标函数。将XFOIL程序与Viterna-Corrignan失速后模型相结合,计算出优化前后翼型气动性能参数。结果表明,与NACAOO15翼型相比,新翼型的气动性能有了较大提高,最大升力系数增大了33.5%,失速攻角提高了3°,最大切向力系数增大了43.5%。     

基于CFD的二维垂直轴风力机性能计算

采用计算流体力学方法(CFD)针对垂直轴风力发电机,开展简化的二维绕流特性研究。首先,基于开放型转子和增强型转子,研究网格节点数和壁面y+、计算时间步长和湍流模型等的变化对计算结果的影响,对计算模型和方法进行确认。随后,计算分析增强型垂直轴风力机与开放型垂直轴风力机的特性。结果表明,与开放性垂直轴风力发电机相比,增强型垂直轴风力发电机的功率系数和转矩系数有明显增加,且达到最大值的位置向叶尖速比增大的方向移动。然后对增强型垂直轴风力机发电机在不同来流风速下进行计算,发现增强型垂直轴风力发电机的转子转矩随来流风速增加,而转矩系数和功率系数与来流风速无关。最后,针对定子叶片在不同的方向开展计算研究。结果表明,定子叶片在不同方向时,增强型垂直轴风力机的转子转矩不同,且转矩到达峰值的位置也不同;在当前3个方向角中,叶片处于0°方向角时风力机具有最高的转矩系数,即具有最佳的功率系数。     

考虑动态失速与风轮支架损失的H型垂直轴风力机自由尾迹模型构建

采用基于升力线理论的自由尾迹模拟模型,耦合了Leishman-Beddoes（LB）动态失速模型和模拟支架损失的半经验公式,编制H型垂直轴风轮计算程序,对不同直径、不同实度的风轮进行气动性能模拟。为了检测模型对H型风轮输出计算的准确性,选取2种不同实度（分别为0.13和0.48）的H型风力机进行了对比分析。结果表明,当尖速比小于4时,动态失速影响较为明显。考虑支架损失的计算结果明显优于未考虑支架损失的计算结果,支架损失总体上随尖速比的增大而增大,2台风力机对应的最大支架损失分别高达60%和35.5%。考虑动态失速效应和支架损失的计算模型能较为准确地估算风轮实度较小的H型风轮的输出,但对于实度较大的H型风轮,其计算准确度有待进一步提高。     

A comparative study on dynamic responses of spar‐type floating horizontal and vertical axis wind turbines

Interest in the exploitation of offshore wind resources using floating wind turbines has increased. Commercial development of floating horizontal axis wind turbines (FHAWTs) is emerging because of their commercial success in onshore and near‐shore areas. Floating vertical axis wind turbines (FVAWTs) are also promising because of their low installation and maintenance costs. Therefore, a comparative study on the dynamic responses of FHAWTs and FVAWTs is of great interest. In the present study, a FHAWT employing the 5MW wind turbine developed by the National Renewable Energy Laboratory (NREL) and a FVAWT employing a Darrieus rotor, both mounted on the OC3 spar buoy, were considered. An improved control strategy was introduced for FVAWTs to achieve an approximately constant mean generator power for the above rated wind speeds. Fully coupled time domain simulations were carried out using identical, directional aligned and correlated wind and wave conditions. Because of different aerodynamic load characteristics and control strategies, the FVAWT results in larger mean tower base bending moments and mooring line tensions above the rated wind speed. Because significant two‐per‐revolution aerodynamic loads act on the FVAWT, the generator power, tower base bending moments and delta line tensions show prominent two‐per‐revolution variation. Consequently, the FVAWT suffers from severe fatigue damage at the tower bottom. However, the dynamic performance of the FVAWT could be improved by increasing the number of blades, using helical blades or employing a more advanced control strategy, which requires additional research. Copyright © 2016 John Wiley & Sons, Ltd.     

格尼襟翼垂直轴风力机风场研究

为研究垂直轴风力机风场中机组气动性能受格尼襟翼的影响,采用TSST湍流模型对直线翼垂直轴风力机进行数值模拟研究.结果表明:风场上游风力机组尖速比越大,机组间流体加速效果越显著,使风力机组气动性能高于单风力机;在中低尖速比时,格尼襟翼可有效提升单个风力机气动效率,在尖速比较高时,提升效果并不明显;在风力机组中安装格尼襟翼...     

Benefits of collocating vertical‐axis and horizontal‐axis wind turbines in large wind farms

In this study, we address the benefits of a vertically staggered (VS) wind farm, in which vertical‐axis and horizontal‐axis wind turbines are collocated in a large wind farm. The case study consists of 20 small vertical‐axis turbines added around each large horizontal‐axis turbine. Large‐eddy simulation is used to compare power extraction and flow properties of the VS wind farm versus a traditional wind farm with only large turbines. The VS wind farm produces up to 32% more power than the traditional one, and the power extracted by the large turbines alone is increased by 10%, caused by faster wake recovery from enhanced turbulence due to the presence of the small turbines. A theoretical analysis based on a top‐down model is performed and compared with the large‐eddy simulation. The analysis suggests a nonlinear increase of total power extraction with increase of the loading of smaller turbines, with weak sensitivity to various parameters, such as size, and type aspect ratio, and thrust coefficient of the vertical‐axis turbines. We conclude that vertical staggering can be an effective way to increase energy production in existing wind farms. Copyright © 2016 John Wiley & Sons, Ltd.