摘要
目的研究某水轮发电机组推力轴承的润滑特性,分析润滑油水污染对其物性参数的影响,探究基本工况下油膜特性与瓦块变形,并优化运行参数以提升轴承可靠性和效率。方法通过实验测定不同含水量润滑油的黏度、密度、比热容和导热系数。基于COMSOL Multiphysics建立双向流固耦合的弹流润滑(EHL)模型,模拟基本工况下油膜压力、厚度及瓦块变形。采用正交试验设计,分析转速、载荷、倾角和含水量对润滑性能的影响,通过极差与方差分析确定参数显著性及最优工况组合。结果温度低于308 K时,低含水量(5 g/L)润滑油黏度较纯油降低14.4%,高含水量(100 g/L)时接近纯油,高温可弱化含水量对黏度的影响。基本工况下油膜压力与变形呈“中心高、四周低”环状分布,最大油膜压力为8.4608 MPa,最大变形量为2.69μm,最小油膜厚度为98.716μm。正交优化得到最佳工况为转速135 r/min、载荷1450 kN、倾角0.003°及含水量5 g/L,此时最大油膜压力降至7.4306 MPa,最小油膜厚度增至133.22μm。结论基本工况满足技术规范,材料与结构设计合理。载荷是影响油膜压力与变形的主因,转速主导最小油膜厚度。轻微水污染对润滑性能无显著影响,优化参数可显著提升轴承性能,为实际运维提供了理论依据。
The work aims to investigate the lubrication characteristics of the thrust bearing in a hydroelectric generator unit,exploring the impact of water contamination in lubricating oil on its fundamental physical properties.The oil film characteristics and pad deformation under basic operational parameters were analyzed and the key operating parameters were optimized to enhance the reliability and operational efficiency of the bearing.Through experimental testing of physical properties,the viscosity,density,specific heat capacity,and thermal conductivity of the lubricating oil with varying water contents were measured.A numerical model of elastohydrodynamic lubrication(EHL)incorporating bidirectional fluid-structure interaction was established through COMSOL Multiphysics to simulate the oil film pressure distribution,thickness,and pad elastic deformation under basic operational conditions.Orthogonal experimental design was employed to analyze the effect of rotational speed,load,tilt angle,and water content on the lubrication performance.Range analysis and variance analysis were conducted to determine the significance of each parameter and identify the optimal operational combination.The results of the physical property tests revealed that water incorporation significantly affected the properties of the lubricating oil.For density and thermal conductivity,the values were the lowest for pure oil and increased with the increasing water content.For dynamic viscosity,at temperatures below 308 K,the viscosity of low-water-content oil(5 g/L)decreased by 14.4%compared to that of pure oil,while high-water-content oil(100 g/L)exhibited viscosity approaching that of pure oil.At temperatures above 308 K,the viscosity-temperature sensitivity of all water-content systems converged,indicating that elevated temperatures could markedly mitigate the impact of water content differences on viscosity.For specific heat capacity,increasing water content generally raised the value,but an anomalous trend was observed in the 5 g/L system.Numerical simulations under basic operational conditions demonstrated that the oil film pressure exhibited a ring-shaped distribution characterized by"high center,low periphery"with a maximum pressure of 8.4608 MPa concentrated near the outer diameter of the trailing edge of the pad.The minimum oil film thickness was 98.716μm,primarily distributed along the trailing edge.The thrust pad displayed a concave deformation pattern at the center,with a maximum elastic deformation of 2.69μm,accounting for only 2.72%of the minimum oil film thickness,thus exerting a negligible effect on lubrication performance.Range analysis of the orthogonal experiments indicated that load was the dominant factor affecting the maximum oil film pressure and the maximum elastic deformation,while rotational speed played a primary role in determining the minimum oil film thickness.Trends in the mean values of the maximum oil film pressure,the minimum oil film thickness,and the maximum elastic deformation with respect to each factor level were examined.The results showed that higher rotational speeds or lower loads and tilt angles significantly reduced oil film pressure and elastic deformation while increasing the minimum oil film thickness.Water content exhibited a nonlinear effect,with oil film pressure and deformation minimized at 5 g/L,while oil film thickness peaked at this level.Variance analysis corroborated the range analysis results,further validating the reliability of the significance conclusions.The orthogonal optimization yielded an optimal operational combination of 135 rpm rotational speed,1450 kN load,0.003°tilt angle,and 5 g/L water content,under which the maximum oil film pressure decreased to 7.4306 MPa and the minimum oil film thickness increased to 133.22μm.Slight water contamination showed no significant impact on thrust bearing lubrication performance,and the optimized parameter combination markedly enhanced lubrication performance.This study aims to provide a theoretical foundation for improving the operational reliability of thrust bearings and holds practical engineering value for ensuring the safe and efficient operation of hydroelectric units.
作者
杨子毅
薛炳
徐波
李湧博
张智
向艾军
王优强
YANG Ziyi;XUE Bing;XU Bo;LI Yongbo;ZHANG Zhi;XIANG Aijun;WANG Youqiang(School of Mechanical and Automotive Engineering,Qingdao University of Technology,Shandong Qingdao 266520,China;China Yangtze Power Co.,Ltd.,Hubei Yichang 443000,China;Hubei Innovation Center for Smart Hydropower,Wuhan 430010,China;Key Laboratory of Industrial Fluid Energy Conservation and Pollution Control(Ministry of Education),Qingdao University of Technology,Shandong Qingdao 266520,China)
出处
《表面技术》
北大核心
2025年第23期141-155,共15页
Surface Technology
基金
中国长江电力股份有限公司科研项目资助(Z152402042)
国家自然科学基金(51575289)。
关键词
推力轴承
弹性流体动力润滑
润滑特性
水污染
有限元分析
正交试验
thrust bearing
elastohydrodynamic lubrication
lubrication characteristics
water contamination
finite element analysis
orthogonal experiment
