平顶建筑物顶面风力机安装位置和高度的研究

采用CFD方法,对放置于某风场的长方形平顶建筑物(长×宽×高=12.4 m×2.4 m×3.1 m)顶面的风资源特征进行模拟计算,计算中同时考虑中性大气边界层和地表粗糙度的影响,分析4个不同风向条件下建筑物顶面15个参考位置的风速增大系数和湍流强度随高度的变化规律,确定屋顶风力机的适合安装位置和高度。结果表明:平顶建筑物顶面安装风力机时其安装高度至少要达到1.3H(H为建筑物高度),以避开强湍流区域;在高于建筑物顶面0.5H高度后,建筑物顶面各位置出现风速增大现象,而当高于建筑物顶面2.0H后,风速增大系数趋于定值;当风力机安装高度高于建筑物顶面0.5H~2.0H时,长方形平顶建筑物顶面15个参考位置均可安装风力机。     

建筑密度对建筑物群内风能利用的影响

针对建筑物群内风能应用问题,采用CFD方法,对建筑密度分别为26%、20%、18%、16%、14%的5种建筑物群周围风速和湍流强度特征开展研究,分析建筑密度对建筑物群内风力机合理安装位置的影响方式。结果表明：在低于1.5H高度范围内,建筑物群的建筑密度越大,同一安装高度上适合于安装风力机的区域就越大,即越有利于建筑物群内风能的应用;在高度高于1.5H后,建筑密度对建筑物群内风力机安装位置的影响消失;无论建筑密度大小,在低于1.2H的高度范围内,建筑物群内不适合安装风力机;在高度高于1.45H后,可优先考虑将风力机安装于建筑物群内中间一排建筑物顶面,在建筑物顶面可优先将风力机安装于拐角位置;5种建筑密度的建筑物群内只考虑风速要求即可确定风力机的合理安装位置。     

建筑顶面风力机微观选址数值分析方法的研究

为确定建筑物顶面屋顶风力机微观选址的有效方法,分别采用SKE、RKE、RNG、SST k-ε及LES共5种湍流模型对日本建筑物学会在风洞实验中所用建筑物的顶面及周围流场进行数值模拟,将各湍流模型的预测值与AIJ风洞实验的测量值进行对比分析,并采用3种统计参数对各湍流模型的预测精度进行评估,结果表明:LES模型对建筑物顶面风场湍流特性的预测是最准确的,而SKE、RKE、RNG这3种湍流模型的预测精度均略低于LES模型的,且这3种湍流模型对建筑物顶面三维风速的预测精度基本一致,但对湍动能的预测略有差别,其中SKE湍流模型最差,RKE湍流模型居中,RNG湍流模型最好。考虑到计算成本及实际建筑物的大尺寸,采用数值模拟方法进行建筑物顶面屋顶风力机微观选址时,SKE、RKE、RNG这3种湍流模型的计算精度完全可达到要求,其中RNG湍流模型的预测精度最好。     

长方体建筑长宽比对屋顶风力机微观选址的影响

采用CFD方法,对长宽比分别为0.25、0.30、0.40、0.50、0.60、0.70、0.80、0.90的8种长方体单体高层建筑物顶面的风流场特征进行模拟计算,确定长宽比对长方体建筑物顶面风力机微观选址的影响.结果表明:长宽比越大,建筑顶面低风速区域越大,且风速随高度增长得越慢,而迎风面拐点风速恢复最快;同时由于建...     

集装箱顶风力机的微观选址及功率预测研究

根据国际能源署Task 27项目,针对置于张北风能基地的集装箱替代建筑物进行建模。利用适宜该地风资源的中性平衡大气边界层理论编制更精确的入流条件,从风加速因子、平均湍流厚度及风力机功率增大因子等新的角度分析箱顶垂直方向上的湍流特性及箱顶风力机适宜的安装位置及高度。结果表明:270.0°入流条件,箱顶1.17倍箱高高度范围为非高湍流区,且1.17~1.50倍箱高高度范围为风力机的适宜安装高度、前沿点为适宜安装位置;选定风力机的适宜安装位置为前沿点、安装高度为1.42~1.52倍箱高,且年平均风速、不同水平风向角下风力机功率增大因子最大可达54.5%,可为建筑屋顶风力机的微观选址提供参考。     

基于CFD的篱笆下游风力机安装位置及高度的研究

利用CFD方法,考虑不同入流角、风剖面和地表粗糙度的影响,对篱笆下游的流场特征进行模拟计算。分析:3种入流角时,篱笆下游湍动能分布情况;2种入流角时,42个参考位置处的风加速因子和湍流强度随高度的变化规律,得到风力机安装的合适位置和高度,最后通过实验验证了模拟结果的正确性。结果表明:避开湍流区,篱笆下游风力机的安装高度至少要高于篱笆0.5 H(H为篱笆高度);篱笆下游水平方向上(1~2.6)H的区间内和垂直方向上高于篱笆(0.5~2)H区间内均可安装风力机且输出功率会增加。     

风电场山坡地形的数值模拟研究

以典型复杂地形山坡的三维模型为研究对象,采用CFD数值模拟方法并选用SST湍流模型研究均匀来流条件下,坡度为15°、30°和45°时山坡周围流体绕流特点。对比分析不同时刻坡度不同时山坡附近不同位置处的速度分布,讨论不同坡度的山坡坡顶边缘、平台和山坡后涡运动情况和湍动能变化。研究结果表明,15°和30°的山坡坡顶风速品质较好,可考虑安装风力机;为了避免山坡后流体的强湍流流动,导致的风力机和塔架的振动,应将风力机安装在距山坡10H(H为山坡高度)后;山坡一侧可获得较好的风能,若在此处安装风力机可适当降低风力机的高度。     

建筑物尾流区风资源利用的数值模拟

基于Fluent软件,利用标准的湍流模型,针对不等高的相邻建筑物建模,下游建筑物完全处于上游建筑物尾流区内,分析了上下游建筑物高度差对上游建筑物尾流区的影响:同一下游建筑高度下,越远离建筑物前沿,风速比越小;在上游建筑物尾流区内,随着下游建筑物高度的升高,风速比的峰值会相应升高。假定进口风速为5 m/s,结合1 000 W的小型风机,比较了下游建筑物不同高度下风机的输出功率,可知:当下游建筑物较低时,风机安装位置风速低于启动风速;随着下游建筑高度的升高,输出功率提升。     

基于激光雷达扫描数据的湍流强度影响下风力机尾流特性研究

以张家口市某风电场作为实验场地,利用激光多普勒雷达(WindMast WP350和Wind 3D6000分别扫描风力机的来流和尾流)对风力机的尾流以及风场风况进行测量,并分析湍流强度变化以及探究湍流强度对风力机尾流特性的影响。研究发现,随时间改变的大气环境对湍流强度的影响较为明显,而高度对湍流强度的影响较小;湍流强度对风力机尾流有较大影响,湍流强度越大,则尾流恢复越快且尾流宽度和深度越小;随着沿轮毂中心轴向距离的增加,尾流速度衰减在尾流发展4D～6D(D表示风力机直径长度)后加速下降。     

基于PIV测试的天然气流量特性研究

管道内天然气流场的脉动特征是影响计量的重要指标,结构性汇管内天然气流动规律及管内流场湍流强度是引起脉动不稳定的关键。以3种结构性天然气汇管为研究对象,采用PIV流场测试方法,分析不同流量时天然气流场的流速与湍流强度。研究表明:在不同工况下,速度分布均匀,靠近中心区域速度大,靠近边壁速度小,表现为相对充分发展的流动;速度越小,湍流强度越大,管道中间湍流强度相对小,越靠近边壁湍流强度逐渐变大,在距管道中心剖面位置30～50 mm范围湍流强度呈明显上升趋势;相比理想状态,其他工况在距离管道中心的0.04～0.39倍管径处的流场脉动均出现了不同程度的汇管结构性不稳定区;安装整流器的汇管的脉动区域明显小于未安装整流器汇管流场脉动的区域;流量为100和500 m~3/h时整体扰动小,较为适合不同的安装条件。     

Performance and safety of rooftop wind turbines: Use of CFD to gain insight into inflow conditions

The installation of small and medium-size wind turbines on the rooftops of high buildings has been often suggested by architects and project developers as a potential solution for achieving sustainable energy in building design. In such locations, however, because of the presence of buildings and other adjacent obstructions, wind is normally turbulent, unstable and weak, in terms of direction and speed. The use of wind turbines in the built environment poses challenges to overcome, including energy yield reduction due to lower mean wind speeds in urban areas, and environmental impacts because of their close vicinity to people and property.There is a need to understand the inflow wind conditions for a small wind turbine in the built-environment. A resource assessment of the potential wind turbine site in the built environment can determine the wind characteristics including zones of wind acceleration, recirculation, blocking and channelling. This knowledge is crucial for input into the design process of a small wind turbine to accurately predict blade fatigue loads and ensure that it operates safely, and performs optimally in the environment.Computational Fluid Dynamics (CFD) is a useful method to model wind flows in order to perform a resource assessment for the application of small wind turbines in a manner that requires less time and investment than a measurement campaign. This paper presents the results of research using a CFD code to model wind flows over the roof of a building and assesses the possibility of combining a CFD package with wind atlas software to form a wind energy resource assessment tool for the application of small wind turbines on the roof of a building. Experimentation with the model shows that the results are particularly sensitive to building height and shape, roof shape, wind direction, and turbine installation height and location. The results will be used to help develop a recommended practice of wind resource assessment in the built environment, in an international collaborative effort via the International Energy Agency Task 27.     

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。     

Wind environment at a roof-mounted wind turbine on a peaked roof building

Knowledge of the wind resource above peaked roofs is necessary to determine whether installing small wind turbines on low-rise peaked roof buildings is feasible. The wind characteristics at a representative peaked roof barn in southern Ontario, Canada were investigated using a boundary layer wind tunnel and computational fluid dynamics. Field measurements at the barn were collected using sonic anemometers and compared with the simulation results. Wind speed amplification was confined to a region immediately above the roof and was relatively low for wind energy purposes. The presence of nearby trees or buildings adversely impacted wind speed amplification. Considering only wind-related factors, the placing of micro-wind turbines on roof peaks may be warranted. However, if sufficient space is available, it is recommended to place small turbines on a tower rather than on the peaked roof of a low-rise building.     

极限环境载荷诱导风力机结构振动影响分析

风力机桩基、塔架及连接部件构成的支撑结构属顶部承担较大质量的力学结构,地震对其造成的影响远大于常规建筑.针对上述问题,基于NREL开发计算平台,联合TurbSim、AeroDyn、FAST及Seismic,对变风载荷、变地震载荷(波形、强度)下的风力机动力学响应进行研究.发现:地震横波对风力机结构响应造成剧烈影响,纵波...     

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...     

水平轴风力机气动性能计算模型

基于片条理论建立了水平轴风力机气动性能计算模型,考虑叶尖损失、轮毂损失、叶栅理论及失速状态下动量理论的失效对片条理论进行了修正,并且考虑了风剪切、偏航、风轮的结构参数和风力机安装参数对计算模型的影响,使得理论模型更接近于实际工况中的风力机。应用所设计的气动性能计算程序对一台1．3MW的失速调节风力机进行了气动性能计算,与国外大型商业软件的计算结果取得了良好的一致性,从而验证了模型的正确性和实用性。     

Low‐cost mounting arrangements for building‐integrated wind turbines

Micro‐generation is being widely promoted as a way for householders in the UK and elsewhere to take part in ‘the Green Revolution’. Building‐integrated wind turbines (BIWTs) provide a way to do this, enabling people to reduce their contribution to the problems of both climate change and decreasing fossil fuel availability. Although energy yields from BIWTs for many householders have been shown to be low, there are still situations where such turbines can make a useful contribution to electricity generation, e.g. in windier areas and for isolated detached buildings. The standards for the installation of BIWTs are still being developed including those for the safe mounting of turbines on domestic buildings. This paper investigates the current trend for mounting small wind turbines on the walls of domestic premises and compares this with an approach which uses roof timbers. It identifies the main characteristics of building construction which affect the integrity of such installations. European and British standards have been used to calculate wind and gravitational loads. Finite element models are used to derive working stresses and, hence, some basic principles of good design. The likely costs of wall and roof mounting are then compared. Installation and health and safety issues are also examined briefly. Copyright © 2010 John Wiley & Sons, Ltd.     

Optimal placement of wind turbines within a wind farm considering multi-directional wind speed using two-stage genetic algorithm

Most wind turbines within wind farms are set up to face a pre-determined wind direction. However, wind directions are intermittent in nature, leading to less electricity production capacity. This paper proposes an algorithm to solve the wind farm layout optimization problem considering multi-angular (MA) wind direction with the aim of maximizing the total power generated on wind farms and minimizing the cost of installation. A two-stage genetic algorithm (GA) equipped with complementary sampling and uniform crossover is used to evolve a MA layout that will yield optimal output regardless of the wind direction. In the first stage, the optimal wind turbine layouts for 8 different major wind directions were determined while the second stage allows each of the previously determined layouts to compete and inter-breed so as to evolve an optimal MA wind farm layout. The proposed MA wind farm layout is thereafter compared to other layouts whose turbines have focused site specific wind turbine orientation. The results reveal that the proposed wind farm layout improves wind power production capacity with minimum cost of installation compared to the layouts with site specific wind turbine layouts. This paper will find application at the planning stage of wind farm.