大型立式泵机组电机两种推力轴承比较

介绍了大型立式泵机组电机刚性支撑和弹性支撑两种滑动推力轴承的结构,比较分析了两种推力轴承的性能。结果表明,弹性支撑推力轴承具有推力瓦间受力均匀、瓦面受力均匀、抗冲击性能好、安装维修简便等优点,可以推广应用。     

单级循环气压缩机支推轴承的设计

介绍了可倾瓦支撑轴承和可倾瓦推力轴承的工作原理及主要结构特点。论述了可倾瓦支撑轴承和推力轴承的设计方法、重要参数考核指标、润滑、材料选取等。     

大型地平式望远镜的方位轴系支撑结构

设计了用于2m口径望远镜的方位轴系支撑结构.通过对比大型地平式望远镜方位轴系的典型支撑结构,拟定了由向心球轴承和大接触角推力球轴承集成的一体化轴系支撑方案以及相应的轴承结构参数.依据Hertz接触理论并采用AYSYS有限元软件对60～85°不同原始接触角下的静载荷特性参数进行了理论计算和非线性仿真分析验证,结合加工工艺设计了85°接触角的推力球轴承结构.研制成功了直径为1 500 mm轴承样机,其轴向跳动为0.009 mm,径向跳动为0.006 mm,最大空载启动摩擦力矩为30 N·m,承载能力优于30 t.该项设计为大型望远镜高精度方位轴系的研制提供了可靠的设计依据和技术途径.     

大型重载推力轴承热弹流计算及尺寸效应

针对考虑热弹变形的大型重载推力轴承性能预测和尺寸效应问题,对某大型重载推力轴承进行热弹流计算,研究轴承性能随极端载荷与尺寸的变化规律。介绍可倾瓦推力轴承热弹流模型的基本方程,通过计算得到不同尺寸和比压下的轴承性能数据,讨论大型重载轴承的尺寸效应。结果表明:案例轴承瓦块最高油膜压力应远离瓦尖,靠近瓦块支点,该设计有利于压力分布均匀而提高承载力;对于大尺寸推力轴承,由于变形的影响,当载荷超过某一限制值后,轴承性能会随着载荷的稍微增加而发生剧烈变化,甚至导致烧瓦失效。为了避免该现象出现,推力轴承设计时应该进行最大许用比压校核;对于大型重载,还需进行瓦块弹性支撑或平衡梁等均载结构设计。     

带有挠性弹簧的大型可倾三瓦径向滑动轴承稳定工作点的确定

本文结合一个实际的、具有挠性弹簧的大型可倾三瓦轴承分析了弹簧预紧力对轴承预加负荷及轴承工作点的影响,并说明了如何根据弹簧的特性曲线求轴承的实际工作点。计算结果表明:考虑弹簧预紧力后,轴承的承载能力增加,工作偏心减小;但主承载瓦(二瓦)因摆角增大,最小油膜厚度有所减小;轴承偏位角明显减小;轴心向右偏移(偏向载荷作用线),使侧瓦负荷减轻.     

圆形可倾瓦推力轴承润滑的计算机仿真

针对大型设备中所应用的圆形可倾瓦推力轴承的润滑问题,采用计算机对圆形可倾瓦推力轴承的润滑性能进行了仿真,通过软件程序计算了单个圆形可倾瓦推力轴承瓦面的油膜形状分布情况、油膜压力分布规律及油膜温度分布规律、功率损耗大小、流量多少等参数。结果表明,通过该仿真程序可模拟出不同工况下圆形可倾瓦推力轴承润滑参数,进而提前实现对圆形可倾瓦推力轴承润滑特性的预测,为大型设备中所使用的圆形可倾瓦推力轴承的设计、润滑和实验提供基础数据。     

推力瓦热瞬态变形机理及抑制方法研究

针对核主泵水润滑推力轴承在事故工况下的热瞬态过程,建立了热固耦合瞬态有限元分析模型。基于所建立模型,分析了常见两层和三层结构推力瓦热瞬态过程瓦面变形,重点分析了三层结构推力瓦隔热层厚度对瓦面变形的影响。随后,进一步探索了遏制瓦面凹变形的方法,阐明了热瞬态过程中瓦面温度场分布不均是产生瓦面凹变形的主因。进一步提出一种新型包边式推力瓦,并仿真验证其能够有效降低热瞬态过程瓦面凹变形,为核主泵水润滑推力轴承的推力瓦设计提供了新思路。     

大型水泵机组故障特点与原因分析

大型水泵机组的故障直接影响机组安全、可靠运行,影响泵站功能的发挥.分析了大型水泵机组故障的特点:影响大、原因复杂、隐蔽性强和故障率确定难;确定了主要故障形式:电机推力瓦烧损,电机线圈绝缘失效,水泵导轴承及轴颈磨损,叶片调节机构失效,水泵汽蚀;从设计、结构、安装和运行等方面研究了主要故障的原因.成果对改进大型水泵机组的设计选型,减少故障发生,及时准确诊断和排除故障,缩短维修时间,降低维修费用,确保维修质量有重大意义.     

平衡梁结构对水润滑可倾瓦推力轴承启停过程的影响

建立了带平衡梁结构的水润滑可倾瓦推力轴承启停过程瞬态模型,在该模型中考虑了界面滑移、挤压作用和支点变形的影响。采用该模型分析了相同运行条件下平衡梁结构与非平衡梁结构的可倾瓦推力轴承的启停过程。分析结果表明:随着瓦面高度误差的增加,轴承的启停转速增加。设计了一套水润滑可倾瓦推力轴承机理研究试验系统,包括平衡梁与非平衡梁结构的可倾瓦推力轴承,并对两种轴承的启停过程进行试验。试验结果表明:非平衡梁结构可倾瓦推力轴承各瓦之间的载荷误差达到90%,而平衡梁结构可倾瓦推力轴承各瓦之间的载荷误差小于4.6%。平衡梁结构可以降低轴承的启停转速,同时提高轴承加工及安装误差的最大许可范围。试验结果与理论分析结果取得较好的一致性。     

组合剪切桥式两可倾瓦轴承负荷传感器研究

为在线监测大型汽轮发电机组两可倾瓦轴承负荷，本文研究了一种组合剪切桥式两可倾瓦轴承负荷传感器，分析了该传感器弹性元件的结构地征，测试结果表明该负荷传感器原理正确，结构合理，可用于大型汽轮发电机组两可倾瓦轴承负荷的在线监测。     

Some Mechanical Considerations in the Design of Large Thrust Bearings

The modern thrust bearing is a very important part of the waterwheel generator, for it must support the weight of the rotating parts of the turbine and generator and the hydraulic thrust load. With the continuous increase in size of hydroelectric generating units, machines now are built with thrust loads well above 1000 tons and requiring bearings ten feet in diameter or larger. Continuous trouble-free operation for periods of twenty years or more are desired for the bearings of large hydroelectric units.

Except during the starting period, the pivoted pad thrust bearing operates according to the well-known hydrodynamic theory of lubrication which permits the predetermination of its performance with reasonable accuracy. Alternating slipping between the thrust bearing runner and the supporting structure can result in excessive wear which destroy the accuracy of the bearing surfaces. Such wear can cause undesirable vibrations or damage to the bearing surface which prevents the formation of an adequate oil film. As a result of laboratory tests and experience in the field, it is now possible to make large thrust bearings with a supporting structure which will permit them to operate continuously for long periods of time with practically no wear or loss of adequacy.     

两种电机轴承润滑系统简述

首先分析了卧式水轮发电机润滑系统的特点,同时分析了系统中带推力座式轴承的重要作用,其次指出其设计的关键所在,最后给出两个成功的实例.     

接触角对风电轴承疲劳寿命的影响

风力发电机偏航轴承结构参数复杂,工作条件特殊,笔者通过仿真确定偏航轴承优化的结构参数,使此种轴承的疲劳寿命长,减少轴承在风场中的维修次数;采用有限元分析方法,建立了风电偏航轴承的三维有限元仿真模型,应用典型的联合载荷和边界条件,对各种不同接触角的轴承模型进行疲劳寿命分析,得出了轴承承载过程中的疲劳安全因子、疲劳寿命的相...     

Micropolar fluid lubricated squeeze films and thrust bearings

A theoretical study of squeeze films between two infinitely long rectangular plates, between two circular plates and a thrust bearing assuming the lubricant a micropolar fluid is reported. The effects of the material constants of the fluid on the bearing characteristics are discussed. It is shown that the squeeze with a micropolar fluid is slower than that with a Newtonian fluid. With a given flow rate a thrust bearing can sustain more load, while a given load can be supported with less pump work when the lubricant is micropolar than when it is Newtonian.     

A revised design of circular hydrostatic bearings for optimal pumping power

A modification of the circular flat externally pressurized thrust bearing is presented in this paper. This involves the addition of a central step in the bottom of the rotating pad for the purpose of restricting the lubricant flow and minimizing the pumping power required for continuous operation. The performance of such a bearing configuration under static loads is analysed and the key design parameters are discussed, grouped and presented in a design chart. In addition to the minimization of pumping power, the proposed configuration provides higher thrust loads and enables the bearing to withstand radial loads, an advantage which could not be achieved in other hydrostatic thrust bearing configurations. The bearing is also able to restore concentricity due to the lateral damping provided by the squeezed lubricant film in the clearance between the step and the recess.     

The rotordynamic analysis of the vibration considering the hydro-electric force supported by rolling elements in 500 kW Francis turbine

A Francis turbine which is one of the reaction water turbine types is mainly used in the multipurpose dam. The purpose of this research is to explain the vibration characteristics due to the various causes generated in Francis-turbines generator system. The hydrodynamic force was determined to use the fluid dynamics analysis considering the exciting force that is transmitted to the shaft from the runner part. Besides, in the generator parts electromagnetic forces can have a severe influence on the rotor dynamics in some situations. Because, the hydro turbine-generator system supported by various types of bearing, mechanical vibration analysis is also necessary. Based on a real small-scale Francis-turbine generators parameter, several analysis were performed the stability at the operating speed of the rotor such as natural frequency analysis and forced response analysis. Through this analysis, aside from the mechanical factor, electromagnetic and hydrodynamic factors have also been found to affect vibration.     

Clarifications of the mechanism of nano-fluctuation of aerostatic thrust bearing with surface restriction

Fluctuations of objects supported by aerostatic bearings are a severe problem for ultraprecise positioning technology. The cause of small fluctuations, called nano-fluctuations of objects supported by the thrust bearing was investigated. An aerostatic thrust bearing with surface restriction by T-shaped grooves was the focus of this study. A computational fluid analysis of the airflow around the bearing was conducted and compared with experimental photographs. In addition, the amount of nano-fluctuations was measured by changing the bearing clearance and inlet pressure of the bearing. The nano-fluctuation was induced by the fluctuation of atmospheric pressure due to the unsteady airflow around the bearing edge, and the amount of the fluctuation depended on the Reynolds number corresponding to the flow velocity.     

刚性和弹性支撑可倾瓦推力轴承稳态特性分析

建立刚性球头支撑和弹性橡胶垫支撑可倾瓦推力轴承热弹流耦合模型；在弹性橡胶垫支撑可倾瓦推力轴承橡胶垫的弹性变形分析中采用了变形协调矩阵方法，以协调匹配橡胶垫变形和水膜厚度分布，同时在搜索稳态解的过程中引入模拟退火算法；基于变分原理求解Reynolds方程，得到了轴承水膜压力分布，并比较2种推力轴承在转子存在角不对中时的静特性。结果表明：理想工况下，刚、弹支可倾瓦推力轴承稳态特性没有明显区别；当转子存在不对中时，刚性球头支撑可倾瓦轴承在不同瓦块之间受力偏载严重，进而导致瓦面最小水膜厚度过小，瓦块容易出现磨损，而弹性支撑瓦不同瓦块之间水膜力分布更均匀，利于轴承的长期可靠运行。     

浅析混流式水电机组推力轴承瓦的研刮

水力发电机组在盘车过程中高压顶起转动部分时,推力轴承瓦与镜板之间的间隙值达不到设计规定要求,造成盘车困难,经过对高压顶起液压系统的分析及结合液压理论进行探讨,并根据液压理论计算得出的结果,对推力瓦研刮的油室加以扩展,问题得到了解决,盘车顺利进行。     

推力轴承支承方式及间隙影响研究

研究了推力轴承支承方式及油膜间隙对推力轴承性能的影响,利用Newton-Raphson法编制差分计算程序,求得了推力轴承Reynolds方程和二维能量方程的数值解,得到了不同支撑方式下瓦块的油膜厚度、压力分布和温度分布。计算结果表明,点支承扇形瓦推力轴承的热力学性能要好于线支承扇形瓦推力轴承,同时支承处的油膜厚度对瓦块的承载能力影响很大。可以通过控制每个瓦块支承处的油膜厚度,避免推力轴承内部偏载的发生,降低推力瓦块的最大温升。