直线翼垂直轴风力机起动性的实验研究

为探明直线翼垂直轴风力机的叶片个数对其起动性的影响,设计制作了可更换叶片个数(1～5枚)的风力机模型,通过风洞实验获得了起动力矩与转角的关系曲线,并与用单叶片力矩模拟的结果进行了对比。接着又制作了1台3叶片小型风力机模型,进行了烟线法可视化实验,获得了不同转角下的风力机周围流场迹线图。两项实验结果表明:增加叶片个数可使风力机平均起动性提高,但叶片间相互影响也增加,不同角度下各叶片周围流场受影响程度不同,对叶片受力和风力机起动力矩的影响程度和趋势也不同。     

直线翼垂直轴风力机静态叶片结冰的观测与分析

设计制作了采用NACA0015翼型的直线翼垂直轴风力机叶片,安装于寒冷地区的室外.冬季,对雨雪等在静止叶片表面的附着情况进行了现场观测.将获得到的叶片表面结霜和结冰(霜状冰和瘤状冰)的观测结果与温度、湿度、风速和风向等气象条件进行了对比分析,研究了静止叶片表面结霜和结冰的产生机理与气象条件的影响关系.针对翼型表面瘤状结冰情况下翼型改变前后的静态升阻力系数进行了数值模拟计算,分析了翼型改变对升阻力特性和静态特性的影响.     

叶片附着物对直线翼垂直轴风力机性能影响的风洞试验

直线翼垂直轴风力机是一种升力型风力机,多被作为离网型风能利用装置。在寒冷地区的冬季,风力机叶片表面结冰、积雪以及附着其他物质会影响风力机的性能。文章介绍了采用粘土作为附着物模拟叶片表面前缘结冰的风洞试验,研究了叶表附着物对风力机的转速和输出功率性能的影响。     

叶片附着物对直线翼垂直轴风力机性能的影响

采用黏土作为附着物模拟了直线翼垂直轴风力机叶片表面前缘的结冰情况,并通过风洞试验测试分析了附着物对自行设计制作的直线翼垂直轴风力机模型转速和功率特性的影响.结果表明:附着物的存在降低了风力机的稳定转数、减少了输出功率,且随着附着质量的增加和风速的增大,影响效果越明显.通过将同等质量的黏土附着在叶表和嵌入叶片内的对比试验表明:在本试验条件下,附着物质量轻时,附着质量与翼型变化对风力机性能的影响基本为同等程度;随着附着物质量的增加,附着质量对风力机性能的影响占居主导地位.     

导流式翼缝对直线翼垂直轴风力机气动性能的影响

为减小流体从吸力面流至压力面的速度损失,基于小间距翼缝有助于减小气动损失的设计原理,针对NA-CA0021翼型,提出双侧导流式、内导流式和外导流式3种新型翼缝形式.通过数值模拟方法,分析不同翼缝对垂直轴风力机气动性能和流场结构的影响,并将其性能参数与原始翼型和非圆弧翼缝翼型进行对比.结果表明:内导流式翼缝风力机气动性能...     

垂直轴风力机动态流场及其气动性能分析

垂直轴风力机气动性能研究是风力机设计、实验的重要部分,对其运动状态下的流场进行分析是观测垂直轴风力机性能重要环节.基于NACA0012对称翼型,建立二维几何模型并进行模拟计算.采用k-ωSST湍流模型及滑移网格技术,通过CFD软件数值计算得到达里厄型直叶片垂直轴风力机运行时周边流场分布情况.通过比较不同方位角下流场涡量以及升、阻力系数得出:在方位角为105°附近时,翼型下表面产生流动分离,并导致失速;下风区翼型运行的流场由于受到上风区尾流的影响,翼型周围没有产生明显的流动分离.     

弯曲翼缝对垂直轴风力机气动性能的影响

通过改变椭圆长短轴比来构造不同曲率的翼缝,并研究了翼缝开口宽度和不同曲率对垂直轴风力机功率系数和启动特性的影响.结果表明:在低尖速比、大攻角下弯曲翼缝翼型使流体重新附着于吸力面,有效延缓了流动分离,使扭矩波动减小,且扭矩系数较原始翼型显著提高;与原始翼型相比,弯曲翼缝翼型的最佳尖速比较低,风力机运行环境更加稳定.     

两种非对称翼风力机性能的试验研究

在低速风洞中对两种非对称翼型(3734和GOE382)小型垂直轴风力机的自启动性能和功率输出性能进行了测试,研究了叶片数和来流风速对两种翼型的风力机性能的影响。结果显示,非对称翼3734风力机的静态自启动性能劣于GOE382,但功率输出性能优于GOE382风力机。     

基于垂直轴风力机的盘式永磁电机的试验研究

随着永磁材料的发展,盘式永磁发电机的技术突破,基于盘式发电机的小型垂直轴风力发电机重新得到重视。设计出双外转子中间定子的盘式永磁发电机,安装在Φ型风力机下端,利用风洞实验室进行不同风速下的试验研究,试验得到无负载与蓄电池负载下的2组数据。数据表明,盘式发电机应用在Φ型垂直轴风力机中,启动性能不理想,但在风力机启动后功率可以很快达到额定功率,故在启动性能好组合式垂直轴风力发电机具有良好适用性。     

垂直轴风力机搅拌阻尼致热装置的试验研究

提出了一种搅拌和阻尼联合作用的风能致热方式,将液体搅拌和液体阻尼两种致热方式集合在一起,搭建一套试验装置,进行搅拌阻尼致热的试验研究;采用对比分析的方法对试验数据——包括搅拌介质温度、搅拌速度、搅拌叶片尺寸等进行分析,根据试验数据绘出搅拌介质温度和搅拌叶片转速随时间变化曲线,总结出试验装置致热效果的一般规律,证实了采用搅拌和阻尼联合作用的致热方式具有一定的实用价值。     

Study on power performance for straight-bladed vertical axis wind turbine by field and wind tunnel test

In this paper, the power performance of straight-bladed VAWT is experimentally investigated by wind tunnel experiment and field test. The test rotor is two-bladed with NACA0021 airfoil profile. A survey of varying unsteady wind parameters is conducted to examine the effects of blade pitch angle, Reynolds number and wind velocity on the power performance of VAWT. Moreover, the flow field characteristics are obtained through measuring the wind velocity by Laser Doppler Velocimeter (LDV) system in the wind tunnel experiment and three-cup type anemometers in field test. Power and torque performance are obtained through a torque meter installed in rotor shaft of the wind turbine. Experimental results estimated from the measured values from field test and wind tunnel experiment are compared. In this research, power performance and flow field characteristics are discussed and the relationship between operating conditions and wind velocity are verified. These results provided a theoretical guiding significance to the development of VAWT simplified.     

Performance evaluation of a downwind diffuser on vertical axis wind turbine

Research has proven that the performance of a horizontal axis wind turbine (HAWTs) can be increased significantly by the application of a diffuser. It serves as a power augmented feature to draw higher wind flow toward the HAWT. However, research on integrating a diffuser onto vertical axis wind turbines (VAWTs) is scant, where most of the available power augmentation devices used for VAWTs are the convergent duct, deflector plate, shroud, and guide vanes which are placed in a proper configuration at the upwind. In this paper, laboratory tests and computational simulations have been carried out to study the impacts of a downwind diffuser on the performance of a VAWT. The diffuser is designed with the absence of a concentrator or flange and is placed downwind of the VAWT. Parametric computational fluid dynamics (CFD) studies were carried out for the downwind diffuser length and semi-opening angle. A five-bladed H-rotor was selected as the testing wind turbine, whereas the diffuser used was made up of flat plates. Both simulations and experiment results are consistent. From the experiments, it was found that a downwind diffuser increases the VAWT performance remarkably. The diffuser-augmented VAWT produced an increment in the maximum coefficient of power of 31.42% at the TSR 0.65 to 0.75. Moreover, the diffuser induced a better self-start ability on the VAWT. The simulation showed that the flow field at the diffuser promotes a flow expansion which created a lower-pressure region at downstream that accelerates the wind toward the VAWT, hence increasing the turbine performance significantly.     

翼型型线改变的三叶片H型垂直轴风力机气动特性研究

为改善H型垂直轴风力机(VAWT)的气动特性,文章研究了6种翼型型线改变后的翼型对H型VAWT气动特性的影响,并进行了数值模拟计算和风洞试验。风洞试验验证了模拟计算的结果,证明了型线改变后的风力机对提高气动性有积极的作用。试验结果表明:1波浪型风机和Dimple型风机均可在一定叶尖速比(λ)范围内提高风力机的风能利用率,其中1波浪型风力机在低λ下最高可提高风能利用率13.76%,其单叶片切向力在下游区明显增大;Dimple型风力机在高λ下最高可提高风能利用率14.6%,其单叶片切向力在上游区明显增大。两种改型后的翼型均可改善流动分离,并提高VAWT的气动性能。     

Starting torque improvement using J-shaped straight-bladed Darrieus vertical axis wind turbine by means of numerical simulation

In this study a 3 kW straight–bladed Darrieus type Vertical Axis Wind Turbine (VAWT) is investigated numerically using OpenFOAM computational fluid dynamic package. The newly proposed J-Shaped profile is used as the blade airfoil in the simulation. The J-Shaped profile is designed by means of eliminating a fraction of pressure side of Du 06-W-200 airfoil. The main purpose of this investigation is the improvement of the VAWT starting torque using J-shaped profile. The power curves for both conventional and J-shaped profiles are calculated and the torque variation is obtained at different azimuth angles. In addition, the vorticity and pressure field surrounding the wind turbine is presented. The results indicate that the performance of turbine is optimized for J-shaped profile which eliminates the pressure side of airfoil from the maximum thickness toward the trailing edge. Moreover, by employing this J-Shaped profile, the wind turbine performance is intensified TSRs and self-starting of turbine is improved.     

一种升阻复合型垂直轴风力机

提出了一种基于活固叶片的新型升阻复合型垂直轴风力机。分析了这种风力机的空气动力学原理,阐述了其整体结构,设计并制造了一台扫风面积为0.49 m2的样机。在7 m/s的风速下,对其进行了性能测试:当负载扭矩为3.6 Nm时,风力机仍能可靠自启动,其功率系数曲线具有阻力型垂直轴风力机和升力型垂直轴风力机的双重特点;当负载扭矩为1.5 Nm时,其功率系数接近30%。     

驱动热泵的垂直轴风力机风轮气动特性数值分析

根据风能热泵系统的工作环境及匹配特性,针对给定供热面积的系统各参数选取方法以及垂直轴风力机风轮设计进行了探讨,在此基础上初步完成了额定功率为300 W的风轮设计,并利用二维数值模拟方法对不同叶尖速比下的性能曲线进行计算,分析得到了额定风速9.00 m/s时,驱动压缩机的最佳风轮转速为350~375r/min。结果表明,300 W垂直轴风力机的输出特性可满足风能热泵机组的工作要求,该数值分析结果可为风能供热技术的应用示范提供理论支撑。     

有弯度翼型垂直轴风力机的数值模拟研究

应用计算流体动力学有限体积法SIMPLE算法,配合SST k-ω湍流模型和滑动网格技术模拟分析了有弯度翼型4叶片垂直轴风力机的气动特性,以其作为有弯度翼型垂直轴风力机设计的参考依据。研究结果发现,在入口流速为10 m/s,尖速比为1.6时,该种风力机单个叶片的瞬时力矩系数为-0.03～0.18,并且在一个转动周期内正的瞬时力矩系数历时较长;整个风轮的的力矩系数在尖速比为1.6左右时达到最大值,功率系数在尖速比为1.7左右时达到最大值。     

Simulation and wake analysis of a single vertical axis wind turbine

Because of several design advantages and operational characteristics, particularly in offshore farms, vertical axis wind turbines (VAWTs) are being reconsidered as a complementary technology to horizontal axial turbines. However, considerable gaps remain in our understanding of VAWT performance since cross‐flow rotor configurations have been significantly less studied than axial turbines. This study examines the wakes of VAWTs and how their evolution is influenced by turbine design parameters. An actuator line model is implemented in an atmospheric boundary layer large eddy simulation code, with offline coupling to a high‐resolution blade‐scale unsteady Reynolds‐averaged Navier–Stokes model. The large eddy simulation captures the turbine‐to‐farm scale dynamics, while the unsteady Reynolds‐averaged Navier–Stokes captures the blade‐to‐turbine scale flow. The simulation results are found to be in good agreement with three existing experimental datasets. Subsequently, a parametric study of the flow over an isolated VAWT, carried out by varying solidities, height‐to‐diameter aspect ratios and tip speed ratios, is conducted. The analyses of the wake area and velocity and power deficits yield an improved understanding of the downstream evolution of VAWT wakes, which in turn enables a more informed selection of turbine designs for wind farms. Copyright © 2016 John Wiley & Sons, Ltd.     

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。