固定偏角垂直轴潮流能水轮机叶片安装位置试验研究

叶片安装位置是影响固定偏角垂直轴潮流能水轮机水动力性能的关键参数之一,为了研究其对水轮机性能影响的基本规律,建立了垂直轴水轮机水槽模型试验系统,设计了垂直轴水轮机性能和载荷测试方法。通过试验结果的分析,得到了叶片安装位置对水轮机能量利用率、推力系数、侧向力系数和合力系数的影响规律,为水轮机设计提供了试验依据。     

基于滑移网格的垂直轴潮流水轮机的三维数值模拟

为了探究翼型对垂直轴水轮机水力效率的影响,基于叶素理论分析建立了垂直轴潮流水轮机在水槽中的物理模型,采用滑移网格技术在Fluent软件中对模型的流场进行了三维数值模拟。在保持转速一定、更改来流速度即改变叶尖速比的条件下,分析了两种不同NACA翼型直叶片的潮流水轮机内部流场以及水力性能。结果表明,翼型以及叶片安装角对垂直轴潮流水轮机的利用效率影响很大,其流动特性与来流速度、叶片布置形式有重要联系,为新型潮流水轮机的设计和翼型的选择应用提供了依据。     

一种新型垂直轴潮流能水轮机性能的初步研究

针对普通潮流能垂直轴3叶片水轮机难以自行启动的缺点,文章提出了一种新型6叶片水轮机。通过数值模拟和模型试验两种方法,分别研究了新型6叶片水轮机与普通3叶片水轮机的自启动性能和能量捕获性能,并将两者进行了比较分析。研究结果表明,新型6叶片水轮机的总体性能优于普通3叶片水轮机,是一种很有发展潜力的结构形式。     

基于正反装叶片的垂直轴潮流水轮机水动力性能分析

为了解不对称翼型叶片的正反安装对垂直轴潮流水轮机水动力性能的影响,运用CFD软件技术,建立了不对称叶片正反安装的潮流水轮机模型,分析了不对称叶片在正反两种安装方式下,叶片压力面和吸力面压力系数随叶片相位角不同而发生的变化,同时利用效率公式计算得到了效率。结果表明,叶片的正反安装对水轮机的水动力性能影响较大,当叶片正装即不对称翼型叶片凸向朝外时,垂直轴潮流水轮机效率优于叶片反装时,叶片在相位角为0°~120°区间转动时,转轮扭矩先增大后减小,在60°、180°、300°时得到最大扭矩。     

叶片端板对垂直轴水轮机水动力性能影响的研究

为了减小叶片端部涡流的影响,提高叶片效率,在垂直轴潮流能水轮机叶片端部加装端板。使用Fluent软件对不同流速下加装端板前后的水轮机流场进行三维数值模拟,比较其水动力性能的变化,并通过拖曳水池进行物理模型实验验证。结果表明,为垂直轴水轮机叶片末端加装端板可抑制叶片端部涡流,提高水轮机输出功率。     

垂直轴水轮机CFD数值模拟有效性验证

CFD方法作为垂直轴水轮机水动力性能预报和分析的一种重要手段,得到了广泛的应用,但是目前,对于垂直轴水轮机CFD数值模拟的精度和可信度缺乏系统的研究,因此针对这一问题,展开了垂直轴水轮机CFD数值模拟有效性研究,探讨了湍流模型、时间步长和网格尺度对计算结果的影响,并通过与试验结果的对比,验证了CFD方法的有效性,为以后CFD方法在垂直轴水轮机性能预报方面的应用奠定了基础.     

导流涵道对垂直轴水轮机性能影响的研究

垂直轴水轮机作为重要的潮流能捕获装置,相比于水平轴水轮机,它具有结构简单、适应任意水流等优点,但获能效率较低。为了增大垂直轴水轮机的获能效率,文章提出了一种导流涵道装置。采用CFD方法研究了其增速性能,并探究了水轮机在导流涵道下的输出扭矩特性,最后讨论了水轮机与导流涵道之间的间距对获能效率和转矩的影响。研究表明:导流涵道在一定程度上增大了来流的速度,涵道中心处速度可增大至原来的2倍。在导流涵道作用下,水轮机转矩脉动系数减小了0.474。水轮机与导流涵道的间距对效率与转矩产生了显著的影响,当间距为0.175倍水轮机直径时,其能源利用率达到最大,同时转矩系数在0.1倍直径时降至最小。     

非对称翼垂直轴水轮机水动力性能研究

为了研究非对称翼垂直轴水轮机的水动力性能,利用Fluent软件建立水轮机的二维模型,分析采用不同拱度非对称翼的垂直轴水轮机在不同叶尖速比下的水动力性能、能量提取性能以及非对称翼的安装位置对水轮机性能的影响,并与对称翼垂直轴水轮机的性能进行对比。研究结果表明:与对称翼垂直轴水轮机相比,非对称翼垂直轴水轮机在较低和较高叶尖速比区间具有更高的能量提取效率,但在中等叶尖速比区间,即水轮机最佳工作区间,采用非对称翼会导致能量提取性能下降;增大水翼的拱度,能有效减小水翼受力波动幅度,有利于提高水轮机的疲劳寿命;非对称翼的安装位置为0.7c时,非对称翼垂直轴水轮机的能量提取性能最佳。     

并列式垂直轴水轮机尾流场的干扰特性研究

为研究并列式垂直轴水轮机的水动力性能及尾流干扰特性,进而指导阵列式水轮机的排列,文章对并列式垂直轴水轮机的水动力性能进行数值分析。首先针对单个垂直轴水轮机的水动力性能进行分析,基于数值分析结果与实验数据的对比,验证了所采用数值分析方法的准确性,继而对并列式垂直轴水轮机的性能进行了分析。分析结果表明:垂直轴水轮机的尾流具有明显的非对称现象,且尾流之间的干扰对尾流场的速度影响较大;由于水轮机尾流压力分布不均,两个水轮机尾流之间会产生压力差,进而导致尾涡向低压力区域偏移,整体表现为向迎流侧偏移;尾流继续传播扩散,最后与流场混合;在并列排布垂直轴水轮机时,应尽量使相邻水轮机处于顺流侧并反向旋转,当水轮机处于相邻水轮机的迎流侧时,应注意加大水轮机之间的间距。     

导流涵道安装角度对垂直轴水轮机性能影响研究

垂直轴水轮机转子增加增速装置能够有效提高能源利用率,但相关导流涵道安装角度对垂直轴水轮机水力学性能影响的研究较少。文章针对一种导流涵道装置,采用CFD数值模拟研究方法,研究导流涵道安装角度不同时,对垂直轴水轮机的输出功率和能源利用率的影响,以及垂直轴水轮机叶片和导流涵道的受力情况。研究结果表明:当导流涵道安装角α为0°时,水轮机的能源利用率最大,最大可达0.658,导流涵道受力情况更好;当安装角α为0～10°时,随着安装角度的增大,水轮机的能源利用率逐渐减小,最大减少13.6%,水轮机叶片受到的平均侧力会增加,平均推力和平均扭矩会减小,下导流涵道受力和力矩增大。     

A conceptual study of floating axis water current turbine for low-cost energy capturing from river,tide and ocean currents

The cost of utilizing kinetic energy of river stream, tidal and ocean current is considered to be higher than that of wind power generation because of difficulties in construction and maintenance of devices installed in seawater. As a solution to the problem, the authors propose a new concept of water stream turbine. The main idea is in the manner of supporting turbine. Although it is similar to a vertical axis turbine, the direction of turbine axis is not firmly fixed and its tilt angle is passively adjustable to the stream velocity. Since it does not have to keep the turbine axis in upright position, required structural strength and weight of the device will be reduced significantly. This paper describes the application ranging from the small hydro power in river streams to large application of tidal and ocean current turbine. In the large capacity plant for tidal stream and ocean current, the main mechanism of turbine axis support is the same as that of the wind turbine authors proposed in the previous paper. It leads to the further opportunity of cost reduction. The sample design of a multi-megawatt ocean current turbine shows the possibility of high economic performance of the concept. The results show that the cost of energy in the concept can be comparable to a land based wind turbine.     

安装于跨海桥梁下部结构的竖轴潮流能水轮机水动力性能研究

文章采用物理模型实验和基于Fluent的二维数值模拟方法研究了竖轴水轮机安装在典型桥梁下部结构(单圆桩、圆端形墩台、四圆桩)且相对尺寸发生变化时,水轮机水动力性能的变化情况。研究结果表明:与桥梁下部结构组合后,竖轴水轮机的能量输出显著提升,单圆桩提升幅度最大,圆端形墩台次之,四圆桩最小;单圆桩和圆端形墩台相对水轮机尺寸增大时,水轮机的能量输出随之增大,四圆桩相对水轮机尺寸增大时,水轮机的能量输出随之减小;竖轴水轮机与桥梁下部结构结合后,下部结构附近的高流速区增加了水轮机的能量输入,扩大了竖轴水轮机的获能范围并提高了能量获取幅值。     

Numerical analysis of the characteristics of vertical axis tidal current turbines

Tidal current is considered to be one of the promising alternative green energy resources. Tidal current turbines are devices used for harnessing tidal current energy. The development of a standard for tidal current turbine design is a very important step in the commercialization of tidal current energy as the tidal current industry is growing rapidly, but no standard for tidal current turbines has been developed yet. In this paper, we present our recent efforts in the numerical simulation of the characteristics (e.g., power output, torque fluctuation, induced velocity, and acoustic emission) of tidal current turbines related to the development of the standard. The relationship between the characteristics and the parameters of an example turbine are extensively discussed and quantified. The findings of this paper are expected to be helpful in developing the standards for tidal current turbines in the near future.     

水平轴潮流能水轮机复合材料叶片自适应性研究

叶片是水轮机中潮流能向机械能转化的核心部件,直接影响水轮机的水动力性能和结构性能。以水平轴潮流能水轮机复合材料叶片为例,基于复合材料弯扭耦合理论,采用双向流固耦合方法研究了叶片的自适应性。结果表明,采用对称铺层方式的复合材料叶片,可提高水轮机的能量利用率,并在较大的速比范围内使水轮机保持较高的效率;降低叶片上的应力集中,可改善结构性能;对称铺层可利用叶片的弯扭耦合特性,使叶片具备自适应性,从而提高水轮机的水动力性能和结构性能。     

水平轴潮流水轮机转轮尾流特性数值分析

针对潮流水轮机转轮尾流对机组之间水力性能的干扰问题,利用CFD分析软件Fluent对单个水平轴潮流水轮机转轮模型和10倍转轮直径间距下的两台机组模型在额定流速条件下进行三维流场的数值模拟。结果表明,在水轮机转轮旋转平面内不同半径位置处的尾流流速恢复情况明显不同,离旋转轴线越远,尾流流速恢复越快,其流速亏损也越少;当水轮机组之间串列布置,且来流方向与旋转平面垂直情况下,下游机组运行受上游机组转轮的尾流影响较大,应尽量避免该布置方式。     

潮流发电技术的发展现状及趋势

介绍了潮流发电的基本原理和关键技术,对国内外潮流发电的关键设备水轮机的发展和成果进行了评述,分析了今后潮流发电技术的发展趋势。潮流发电作为一种最新的可再生新能源利用技术,具有很好的发展前景。     

Performance analysis of a HAT tidal current turbine and wake flow characteristics

Having very strong current on the west coast with up to 10 m tidal range, there are many suitable sites for the application of tidal current power (TCP) in Korea. The turbine, which initially converts the tidal energy, is an important component because it affects the efficiency of the entire system. To design a turbine that can extract the maximum power on the site, the depth and duration of current velocity with respect to direction should be considered. To extract a significant quantity of power, a tidal current farm with a multi-arrangement is necessary in the ocean. The interactions between devices contribute significantly to the total power capacity. Thus, the study of wake propagation is necessary to understand the evolution of the wake behind a turbine. This paper introduces configuration design of horizontal axis tidal current turbine based on the blade element theory, and evaluating its performance with CFD. The maximum efficiency of the designed turbine was calculated as 40% at a tip speed ratio (TSR) of 5. The target capacity of 300 kW was generated at the design velocity, and the performance was stable over a wide range of rotating speeds. To investigate the wakes behind the turbine, unsteady simulation was carried out. The wake velocity distribution was obtained, and velocity deficit was calculated. A large and rapid recovery was observed from 2D to 8D downstream, followed by a much slower recovery beyond. The velocity was recovered up to 86% at 18D downstream.     

潮流能水平轴水轮机振动位移时间序列的自相似性研究

为了研究潮流能水平轴水轮机振动位移时间序列的自相似性,文章在不同的波流共同作用下对20kW潮流能水平轴水轮机进行数值模拟和波浪水槽试验,并将数值模拟与试验结果利用分形维数的方法计算得到Hurst指数,再由Hurst指数判断上述位移时间序列是否具有自相似性。数值模拟和试验结果表明:潮流能水轮机振动位移时间序列具有自相似特征,为采用自相似理论研究潮流能水轮机的动态特性奠定了数学基础,所揭示的时间序列整体与局部之间的关系及其自相似性为潮流能水轮机的故障诊断提供了技术支撑。     

Numerical investigations of the effects of different arrays on power extractions of horizontal axis tidal current turbines

As the tidal current industry grows, power extraction from tidal sites has received widespread attention. In this paper, a blade element actuator disk model that is coupled with the blade element method and a three-dimensional Navier–Stokes code is developed to analyse the relationship between power extraction and the layout of turbine arrays. First, a numerical model is constructed to simulate an isolated turbine and the model is validated using experimental data. Then, using this validated model, the power extraction of horizontal axis tidal current turbines using different tidal turbine arrays and rotation directions is predicted. The results of this study demonstrate that staggered grid array turbines can absorb more power from tidal flows than can rectilinear grid array turbines and that staggered grid array turbines are less affected by the rotation of upstream turbines. In addition, for staggered gird arrays, the relationships between power coefficients, lateral distance and longitudinal distance are discussed. The appropriate lateral distance is approximately 2.5 turbine diameters, whereas for the longitudinal distance, the largest value possible should be used. The relative power coefficient can achieve 3.74 when the longitudinal distance is 6 times the turbine diameter. To further increase the power extraction, this study suggests an improved staggered grid array layout. The relative power coefficient of the improved four-row turbine arrays is approximately 3–4% higher than that of the original arrays and will increase as the distance between the second-row and third-row increases. Considering only the first two rows of turbines, the total power extraction can be 11% higher than for an equivalent number of isolated turbines.