基于有限元分析的风电机组塔架结构正交试验设计

采用正交试验设计方法设计正交试验模型,利用ANSYS有限元分析软件对正交试验模型进行静强度、疲劳强度、模态和屈曲分析,通过使用极差分析法,分析塔架结构因素对各试验指标的影响。并绘制因素与指标趋势图,直观地显示试验指标随因素水平变化的趋势,为进一步试验指明方向。     

基于正交试验的风电机组塔架结构参数的优化设计

本文采用正交试验设计方法设计正交试验模型,利用ANSYS有限元分析软件对正交试验模型进行静强度、疲劳强度、模态和屈曲分析,运用数据统计分析软件进行多元线性回归分析,建立优化数学模型,再应用MATLAB优化工具箱对模型进行求解,得到了塔架结构优化结果。     

强阵风条件下风电机组钢-混凝土塔架瞬态响应分析

以陆地某5 MW大型风力机钢-混凝土组合塔架为研究对象,参考GL2010风力发电机塔架设计规范,对塔架的瞬态响应进行分析。考虑塔顶机舱风轮质量及钢-混组合结构的影响,建立了塔架有限元分析模型;采用Block Lanczos法对塔架进行了模态分析,得到了塔架前六阶固有频率和振型;通过模态叠加法求解,得到了恒定风速下塔架结构的稳态动响应与主要频率成分;分析了在瞬时强阵风作用下,塔架结构承载的变化规律与瞬态位移动响应时域历程;研究发现,在强阵风的作用下塔架横向振动会产生大幅波动,最大增加188.09%,在塔架结构设计时应给予一定的重视。     

低温环境下风电机组塔架选材研究

我国风能资源富集区有较大部分处于低温环境,低温环境对结构部件最直接的影响是容易使承受动载的结构发生低温脆断,这是一种危害很大的灾害性破坏形式。塔架是风电机组的重要结构部件,为了避免塔架发生低温脆断有必要对低温环境下塔架选材进行研究。在阐述断裂韧性和低温冲击功关系的基础上,本文给出了按国内标准和欧洲标准Eurocode3进行低温环境塔架选材的对比分析,讨论了低温环境下塔架选材存在的问题,为低温环境下塔架选材提供参考。     

风电机组塔架高强度螺栓的质量控制研究

高强度螺栓是风电机组安装和整体连接中至关重要的连接件,其质量是否能达到设计需要,直接影响风电机组结构整体的承载能力、使用寿命与安全性能。本文在对数十个风场的检查和调研基础上,对高强度螺栓从制造到安装过程的质量控制进行了全面、深入的分析,提出了以保证质量为基础,在安装中注重对力矩和安装操作要点的控制来保障风电机组运行的建设性意见。     

风电机组塔架钢板下料尺寸计算

本文提供了风电机组塔架钢板下料尺寸计算方法,风电机组塔架是由数段圆锥筒体依靠法兰连接组成一个锥形圆筒状结构,对每一张钢板的尺寸计算有极高的要求,必须严格控制其误差。本文给出了一个固定的模板,只需输入个别已知数据,模板就会自动算出所有所需尺寸,同时尽可能减少人为因素。     

大型风电机组柔性塔架结构改进研究

针对大型风电机组柔性塔架分段处的动态响应问题,文章利用双向流固耦合法对塔架分段处法兰进行流体与结构动力学分析,得出动力响应曲线。将考虑耦合作用与未考虑耦合作用的塔架法兰的应力、位移进行对比,经过基本应用理论分析,提出塔架结构改进措施。对比结果表明:考虑耦合作用的塔架法兰位移、应力变化幅度均比未考虑耦合作用的小;结构改进后的塔架应力、位移变化幅度相对较小。     

风电机组塔架的振动特性分析

为了研究塔架的振动特性,采用结构动力学的方法,从理论分析和仿真计算两方面,对塔架的振动特性进行了分析和仿真计算,得到了激振力频率和塔架位移、加速度的响应特性。研究表明:在外部激振载荷作用下,塔架的振动频率中同时包含激振力频率和塔架的固有频率,仿真计算的结果与理论分析的结论一致。通过对比实测数据,风机正常运行时,塔架加速度的频谱主要集中在塔架的三倍旋转频率附近。     

基于模态叠加法的风电机组塔架实时状态研究

振动模态是机械结构在某一自振频率下的振动型态,是多自由度系统的固有属性。在模态分析的基础之上,提出一种基于模态叠加法的风电机组塔架振动状态与应力状态计算模型。该模型首先通过有限元法得到塔架的模态,然后通过模态叠加法根据塔架各监测点处的振动值计算得到整个塔架的振动状态及应力状态。以某风电场2.0 MW风电机组为例,通过有限元法数值模拟验证该模型计算结果的准确性。研究结果表明,该模型具有精度高和速度快的特点,能够满足实时在线计算要求。     

预应力风电机组基础与风电机组塔架连接分析

风电机组塔架与预应力基础混凝土之间的连接包括T型法兰和L型法兰。国内外相关资料中只有T型法兰的相关计算公式,而有关L型法兰是否适用于风电机组塔架与预应力基础混凝土之间的连接并没有相关文献及规范说明。针对这个问题,参照T型法兰连接,推导出L型法兰连接的理论公式,并对其承载性能进行有限元校核分析,得到如下结论:风电机组塔架与基础混凝土(或高强灌浆)间不能直接采用L法兰连接,最有效的解决办法为将L法兰改为T法兰。     

A comprehensive approach to cooling tower design

In this paper, a mathematical model for a counterflow wet cooling tower is derived, which is based on one-dimensional heat and mass balance equations using the measured heat transfer coefficient. The balance equations are solved numerically to predict the temperature change of air and water, as well as the humidity as a function of the cooling tower high. Experimental measurements on two pilot-scale cooling towers were carried out in order to analyze the performance of different cooling tower filling materials. Also, the performance of other cooling tower elements, such as droplet separators and water spray nozzles, was investigated in the pilot experiments. The flow distribution, i.e. the velocity field, upstream to the filling material was predicted using the three-dimensional version of the computational fluid dynamics (CFD) code Fluent/uns, version 4.2. The calculated flow fields are presented for different distances between the inlet of the air and the filling material. In addition, the two-dimensional version of the CFD code Fluent/uns, version 4.2, was applied to predict the external airflow around the cooling tower and the backflow in different weather conditions in summer and winter. The research project was carried out in connection to an industrial cooling tower installation.     

闭式冷却塔冷却盘管的优化设计

以冷却盘管的优化设计为例,介绍一个完整的优化过程:建立数学模型,确定约束条件,选取优化变量,编制计算机程序分析其结构参数对投资费用和运行费用的影响。优化结果可以为闭式冷却塔中冷却盘管的设计提供参考。     

塔式熔盐吸热器热效率计算数值研究

本文论述了拟建的100MW塔式光热电站熔盐吸热器热损失主要组成项:辐射热损失、对流热损失及导热热损失,其中辐射热损失可由公式直接算出,由于本项目计算的雷诺数大,对流热损失关联式已不适用,故采用数值模拟方法进行对流热损失计算.分析了吸热器外壁温、环境风速、环境温度对换热系数的影响,计算出本项目的吸热器热效率.     

Thermodynamic study of wet cooling tower performance

An analytical model was developed to describe thermodynamically the water evaporation process inside a counter‐flow wet cooling tower, where the air stream is in direct contact with the falling water, based on the implementation of the energy and mass balance between air and water stream describing thus, the rate of change of air temperature, humidity ratio, water temperature and evaporated water mass along tower height. The reliability of model predictions was ensured by comparisons made with pertinent experimental data, which were obtained from the literature. The paper elaborated the effect of atmospheric conditions, water mass flow rate and water inlet temperature on the variation of the thermodynamic properties of moist air inside the cooling tower and on its thermal performance characteristics. The analysis of the theoretical results revealed that the thermal performance of the cooling tower is sensitive to the degree of saturation of inlet air. Hence, the cooling capacity of the cooling tower increases with decreasing inlet air wet bulb temperature whereas the overall water temperature fall is curtailed with increasing water to air mass ratio. The change of inlet water temperature does not affect seriously the thermal behaviour of the cooling tower. Copyright © 2005 John Wiley & Sons, Ltd.     

A tall tower study of Missouri winds

This paper summarizes the results of a study of wind speeds observed at heights up to 150 m above ground level around Missouri. This is an amalgamation of four projects that allowed a total of eleven tall communication towers to be instrumented with wind observation equipment across the State of Missouri. This provided an assessment of the wind resource and the characteristics of the seasonal and diurnal cycles of wind in different areas of Missouri at the heights of utility scale wind turbines. Comparisons were also made to wind speeds predicted at these levels from a previously published wind map.The main finding was that the observed winds at each tower were smaller than those presented in the wind map. The discrepancy is most likely to be due to underestimation of the surface roughness and turbulence leading to an overestimation of near-surface wind shear. However, the wind shear, as expressed by the shear parameter was consistently greater than the ‘standard’ value of 1.4. The reconciliation of these two apparently contradictory findings is that the shear varies with the height at which it is measured. In wind resource assessment, wind shear is usually observed below 50 m and is tacitly assumed to be constant with height when used to extrapolate winds to higher levels. The author advocates the use of the friction velocity as a measure of shear in wind power applications in preference to the shear parameter that is usually used. This is because the shear parameter has a velocity bias that can also manifest as a bias with height or season. As wind power resource assessment is starting to use taller towers than the standard 50 m, intercomparison of site resources and extrapolation to turbine heights can be compromised if the shear parameter is used.     

冷却塔外复杂流场的数值模拟与实验研究

对某能源中心楼顶的冷却塔组、烟囱、通风孔等散热设备及整个楼顶空间的流场与温度场进行了整体数值模拟,探讨了高温烟囱帽引起的排烟方向改变对冷却塔组进风处空气温度场及流场的影响,并进行了实验测试。结果表明,烟囱帽使排烟向下折转,导致冷却塔进风处下部位置空气温度显著升高;较低的烟囱烟气直排时,高温烟气会先抬升一段距离,然后受冷却塔进风处负压区吸引进入冷却塔内。     

基于散堆填料的空气湿化塔性能实验研究

搭建了内径约600mm的空气湿化塔性能实验台,以塑料阶梯环散装填料塔为研究对象,实验并分析了气速、水气比、填料总高度对湿化塔的压力损失、加湿效果和传质单元高度的影响,以及进水温度对后两者的影响,同时获得了空气湿化填料塔精细设计数据,并对结果进行了拟合,得到填料的传质单元高度经验关联式。     

Numerical simulation of a closed wet cooling tower with novel design

A closed wet cooling tower with novel design was proposed and numerically investigated. The studied cooling tower consists of two main parts: one heat and mass transfer unit (HMTU) and one heat transfer unit (HTU). In the HMTU, copper tubes are arranged as heat transfer tubes while plastic tubes are collocated to enlarge the mass transfer area between the spray water and the airflow. In the HTU, only copper tubes are adopted as heat transfer tubes. Heat and mass transfer process takes place among the process water, airflow and spray water in the HMTU, while in the HTU only heat transfer between the process water and the spray water is observed. A transient one dimensional distributed-parameter model was adopted to evaluate the cooling tower performance under different operating conditions. Determination of heat and mass transfer coefficients, as well as the influence of Lewis number on the cooling tower performance, was presented.     

降低活性炭脱硫塔阻力的实验研究

针对实际运行中的活性炭脱硫塔阻力大、能耗高、效率低的问题,采用不同结构的支承装置,模拟实际运行工况,对其阻力特性进行了实验研究。结果表明,在平板支承装置上加装“T”型和倒“L”型导气管,使液相速度场与气相速度场达到了一定的协同效应,有效降低了床层阻力,提高了脱硫塔脱硫效率。     

湿式冷却塔进风口加装导风板的优化设计

基于两相流传热传质理论,利用Fluent软件模拟300 MW机组冷却塔填料区使用多孔介质时的通风率,采用离散相模型（DPM）在配水区上表面加入热水,模拟研究新型旋流型叶片导风板的优化能力,给定不同弧度及安装角,分别在0、3和7 m·s^-1风速下计算冷却塔出塔水温,并分析侧风对冷却塔冷却性能的影响。研究结果表明：加装导风板可以降低侧风引起的不利影响,导风板数量为50块时效果最好,旋流型叶片导风板的最佳安装角为20°,此时旋流型叶片的最佳弧度为15°,最大温降可达0.787 4 K。研究结果为火电厂选择导风板提供了依据。