巨型机组下导轴承安装偏差对油膜特性的影响

水电机组在“碳达峰、碳中和”中发挥着非常重要的作用。下导轴承是水电机组轴系的重要组件,用于径向支撑和约束主轴,在水轮发电机运行过程中发挥重要作用。本文建立了考虑喷淋系统的下导轴承整体三维模型,对其油膜润滑性能以及安装偏差对轴承负荷的影响开展研究。分析发现,喷淋系统减少了油箱内的油搅,但瓦块间的润滑油流动是混乱的,损失主要是由瓦块之间的混乱流动所造成。对瓦块均沿径向偏移的偏差模型,随着瓦块沿径向向内偏移,其油膜压力与温度均逐渐升高;对瓦块均向一侧偏移的偏差模型,随着瓦块均向x轴正向偏移,压力与温度呈不对称分布,瓦面的最大压力与最高温度随偏差的增加而增加,不平衡径向力随偏差的增加而增加。因此,在下导轴承的安装过程中,必须注意瓦块均布圆周与主轴的同轴度。本研究对提高水轮发电机运行质量、降低运行成本和提高水电站效益具有重要意义,为保障百万千瓦水电机组的稳定安全运行提供参考依据。

带流量调节系统的往复式压缩机连杆轴瓦润滑特性分析

往复式压缩机采用进气流量调节系统后,会导致其连杆轴瓦磨损、烧瓦故障率上升。针对这一问题,以一台2D20的压缩机为例,对流量调节状态下的往复式压缩机连杆轴瓦润滑特性进行了研究。首先,分析了压缩机活塞运动过程中传动机构的作用力,并基于压缩机热力循环过程,构建了含连杆轴瓦润滑油膜的压缩机动力学模型;然后,利用RecurDyn软件对传动机构进行了运动学和动力学仿真分析,并研究了不同流量负荷对活塞杆受力特性的影响;最后,量化分析了10%~100%流量调节负荷对于连杆轴瓦油膜润滑特性的影响。研究结果表明:相比于作用力的换向,十字头销与轴瓦水平相对位置的换向具有明显的滞后性,且在15%~40%的低流量负荷段内,十字头销和衬套组件的两侧润滑效果均有较为明显的恶化;在设备的实际运行过程中,应避免使其长期处于低调节负荷段内运行;该结果可以为设备人员进行压缩机流量优化调节提供实际的参考。

船舶可倾瓦推力轴承工况参数对润滑特性的影响

为研究船舶工况参数对可倾瓦推力轴承稳态和瞬态润滑特性的影响,利用Matlab建立船舶可倾瓦推力轴承热弹流体动压润滑计算模型,考虑轴瓦的热弹性变形,联立黏温方程、能量方程、油膜刚度和阻尼系数方程求解模型,研究热弹性变形以及不同载荷和转速情况下船舶可倾瓦推力轴承的润滑特性。结果表明:考虑热弹性变形时,最小油膜厚度增大,最大油膜压力和最高油膜温度降低;在正常运行工况条件下,轴瓦的热弹性变形有利于改善推力轴承的润滑性能,轴承设计时应考虑材料的抗压性和耐热性;在转速不变时随着载荷的增大,最小油膜厚度降低,最大油膜压力、温度、油膜刚度和阻尼均增加,需要特别注意重载工况下轴承的动压润滑状况;在载荷相同的情况下,随着转速的提高,油膜厚度和油膜温度增大,油膜压力变化不明显,油膜刚度和阻尼随转速增大而降低,在转速较低时下降较为明显。研究结果为优化轴承设计、提高轴承运行的可靠性和稳定性提供参考。

基于润滑机理的智能液压元件本体性能预测方法

以液压泵为例,以其最为薄弱的环节——滑靴副为研究对象,并以滑靴磨损作为性能退化原因,结合滑靴磨损数学描述方程、泄漏流量公式和柱塞腔压力瞬时变化模型,建立了滑靴磨损过程的油膜润滑特性方程组;揭示了液压泵性能失稳失效机理,计算了失稳和失效临界点;对液压泵性能退化状态进行区域划分,分析液压泵不同状态下滑靴磨损量与油膜润滑特性参数及性能退化参数的变化规律,建立了性能预测模型;通过仿真分析验证理论模型的正确性,通过液压泵性能测试试验验证预测模型的有效性和预测精度,结果表明,所构建的模型能够精确预测液压泵性能。

Analysis of lubrication performance for internal meshing gear pair considering vibration

The thermal elasto-hydrodynamic lubrication characteristics of the internal meshing gears in a planetary gear train under vibrations were examined considering the influence of the modification coefficient and time-varying meshing stiffness.Based on dynamic theory of the gear system,a dynamic model of the planetary gear train was established.The lubrication performances of modified gear systems under vibrations and static loads were analyzed.Compared with other transmission types,the best lubrication effect could be produced by the positive transmission.A thicker lubricating oil film could be formed,and the friction coefficient and oil film flash temperature are the smallest.Increasing modification coefficient improves the lubrication performance continuously but intensifies the engage-in and tooth-change impact.For the planetary and inner gears,the increase in the modification coefficient also leads a decrease in the oil film stiffness.

Thermal elastohydrodynamic lubrication of modified gear system considering vibration

The thermal elastohydrodynamic lubrication characteristics of a modified gear system under a dynamic load were investigated,including the influence of the modification coefficient and vibrations.Based on the dynamic theory of gear systems,a six-degree-of-freedom tribo-dynamics model was established.Thermal elastohydrodynamic lubrication characteristics of a modified gear system under vibrations and a static load were analyzed.The results showed that the positive transmission gear system exhibited the better lubrication effect compared with other transmission types.A thick lubricating oil film could be formed,and the friction coefficient between the teeth and the oil film flash temperature were the smallest.As the modification coefficient increased,the lubrication condition was continuously improved,and the scuffing load capacity was enhanced.The increment of the modification coefficient increased the meshing stiffness of the gear system but reduced the stiffness of the oil film.