Calculated Performance of Non-Newtonian Lubricants in Finite Width Journal Bearings

A numerical procedure has been developed for the calculation of the performance of non-Newtonian, polymer-thickened lubricants in finite width journal bearings. Such oils were found to act as if they had averaged “anisotropic viscosities,” i.e., different viscosities in the circumferential and side leakage directions, even though the viscosity was taken to have one definite value, a function of the resultant shear stress, at each point in the oil film. Overall, polymer oils carried less load at a given eccentricity, gave less friction and a flatter pressure distribution than mineral oils of the same low shear viscosities. By analogy with the previously calculated infinite width case, which gave similar results, it is expected that the flatter viscosity temperature slope of the polymer oils will compensate for their apparent viscosity decrease. The program has also been adapted to “natural” boundary conditions, which improve upon the delineation of the cavitation region on the inlet side of the bearing.     

Performance of Large Steam Turbine Journal Bearings

Behavior of 16 and 20-inch diameter bearings of elliptical and pad types are examined for speeds ranging up to 5000 rpm and loads up to 1200 psi. The higher power loss, greater oil film thickness, and oil feed requirements are evaluated for the turbulent oil film conditions existing at the upper test speeds. The laminar-turbulent transition speed is found to be strongly related to bearing loading.     

汽轮发电机径向滑动轴承性能研究

基于流体动压润滑理论,计入温粘关系和紊流效应,对汽轮发电机滑动轴承性能进行了理论研究。针对汽轮发电机滑动轴承结构,开发了适于工程应用的多种汽轮发电机用轴承性能计算程序。对汽轮发电机径向滑动轴承进行了计算,分析了轴承静动特性和稳定性参数,并验证了计算结果的可靠性。     

薄膜节流器动静混合径向气体轴承性能

对薄膜节流器动静混合径向气体轴承进行理论研究与数值仿真,建立薄膜节流器内气体流动模型并进行简化,采用流体阻抗法将薄膜节流器的流量表达式并与气体轴承小孔节流流量表达式联立,使用牛顿迭代法对非线性气体雷诺方程进行处理,采用有限差分法对上述方程进行离散化进而求解含有薄膜节流器小孔节流气体轴承的雷诺方程,得到薄膜节流器的气体流量分配规律,进而获得有转速和零转速下轴承承载力。数值仿真结果表明,节流器气腔高度和节流器出口直径是薄膜节流器设计的关键参数,气腔高度越小,节流器出口直径越小,承载能力越大;使用薄膜节流器后,各节流孔的入气压力均有所降低,但是各孔之间的入气压力差增大,进而显著提高气体轴承承载能力。     

On Performance Characteristics of Three-Lobe Porous Hydrodynamic Journal Bearings

This paper presents an analysis of a three-lobe porous hydrodynamic journal bearing for its static and dynamic performance characteristics. The performance characteristics of the bearing have been computed and presented in graphical form for a wide range of permeability parameter to investigate the effect of porosity on bearing performance. The stability margin of the three-lobe journal bearing system, in terms of crtical mass of journal, has been established using Routh's criteria. The nature of transient motion of the journal has been analyzed using the complex eigen values of characteristic equation and motion trajectories obtained by numerical integration of equations of motion.     

Properties and Performance of Gas-Expanded Lubricants in Tilting Pad Journal Bearings

Lubricants enable proper function and reduce friction in rotating machinery, but they can also contribute to power loss and heat buildup. Gas-expanded lubricants (GELs) have been proposed as tunable mixtures of lubricant and CO₂ under pressure with properties such as viscosity that can be controlled directly in response to changing environmental or rotordynamic conditions. In this work, experimental results of GEL viscosity, gas diffusivity, and thermal conductivity were combined with high-pressure phase equilibrium data to understand how these mixtures will behave in tilting pad journal bearings under a range of industry-relevant high-speed conditions. Simulations were carried out using the experimental data as inputs to a thermoelastohydrodynamic model of tilting pad journal bearing performance. Viscosity could be easily tuned by controlling the composition of the GEL and the effect on bearing efficiency was appreciable, with 14–46% improvements in power loss. This trend held for a range of lubricant chemistries with polyalkylene glycols, polyalpha olefins, and a polyol ester tested in this work. Diffusivity, which drives how readily CO₂ and lubricants form homogenous mixtures, was found to be a function of the viscosity of the synthetic lubricant, with more viscous lubricants having a lower diffusivity than less viscous formulations. Model results for a bearing in a pressurized housing suggested that cavitation would be minimal for a range of speed conditions. Other bearing parameters, such as eccentricity, temperature, and minimum film thickness were relatively unchanged between conventionally lubricated and GEL-lubricated bearings, suggesting that the efficiency improvements could be achieved with few performance tradeoffs.     

Analysis of Thermoelastohydrodynamic Performance of Journal Misaligned Engine Main Bearings

To understand the engine maln bearings’ working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine maln bearings ar...     

静压径向气体轴承静态特性数值分析

对静压径向气体轴承的静态特性进行了详细的理论研究,采用二阶有限差分方法数值求解无量纲雷诺方程,编制Matlab迭代程序计算轴承的气膜压力分布。仿真分析了各种轴承结构参数和工作参数下静压气体轴承的承载、刚度和质量流量等静态性能的变化规律。仿真结果表明轴颈的转速对静压气体轴承的承载、刚度和质量流量等静态特性施加着重要影响,在分析轴承性能时必须考虑轴颈的旋转效应。当轴颈的转速不断增大时,轴承的气膜压力、承载能力和稳态刚度等静态性能能够得到显著提升。     

湍流润滑动静压气体径向滑动轴承性能研究

以动静压气体径向滑动轴承为研究对象,考虑湍流润滑,基于有限差分方法求解引入湍流因子改良的可压缩雷诺润滑方程,计算湍流润滑动静压气体径向滑动轴承的压力分布,获得轴承承载力、静态刚度、交叉刚度、主刚度、交叉阻尼和主阻尼等表征动静压轴承静动态特性的基本参数,并分析偏心率、槽深、槽数、长径比等结构参数及轴颈转速和供气压力等工况对轴承静动态性能的影响规律。结果表明：连续性狭缝湍流润滑动静压气体径向滑动轴承的静态特性优于非连续性狭缝;轴承承载力随着偏心率、长期径比的增大而增大,随着槽区长度、槽深的增大而减小,槽数对承载力影响不大;轴承静态刚度随着偏心率的增大先增大后减小,随着长径比、槽深、槽数的增大而增大,随着槽区长度的增大而减小;较大的转速和供气压力有助于提升轴承的承载力和静态刚度;随着偏心率的增大,交叉刚度逐渐增大,主刚度先增大而减小,而交叉阻尼和主阻尼均增大。     

非对称结构表面织构对滑动轴承摩擦性能的影响

为揭示织构凹坑方式对径向滑动轴承摩擦性能的影响,基于气液两相流理论,建立径向滑动轴承腔内油气两相流数值计算模型.将传统普通织构改进为出入口呈阶梯状的非对称织构,定义出入口壁面高度比值H为非对称因数,采用SIMPLEC算法进行求解,分析非对称因数对凹槽织构单元流体域内流场的影响,探讨径向滑动轴承不同位置织构、不同转速下非...     

The Effects of Lubricant Rheology on the Performance of Journal Bearings

Experiments have been carried out on a relatively simple journal bearing rig to test the theory that extra load-carrying capacity is generated the elasticity of viscoelastic lubricants. Model lubricants were used. The viscoelastic lubricants were solutions of high-molecular-weight polyisobutene in low-molecular-weight polyisobutene while the inelastic lubricant was low-molecular-weight polyisobutene.

The extra load-carrying capacity has been established. An analysis of the detailed results strongly indicates that the extra benefit of elasticity is much greater than that predicted by existing theory.     

新型牙轮钻头浮动套轴承工作机理试验研究

针对石油钻井用新型浮动套轴承理论模型和仿真软件,设计了浮动套轴承工作机理理论模型和仿真软件的试验验证方案,试验不同参数、不同工况下,被测件的摩擦力矩、温升、摩擦损耗等性能,验证了新型浮动套轴承理论模型和仿真软件的正确性,为进一步完善新型浮动套轴承的理论模型,合理设计新型浮动套轴承奠定试验基础.     

倾斜轴颈重载轴承润滑性能分析及试验

针对重载及安装导致的轴颈倾斜问题,推导径向滑动轴承油膜厚度方程,建立计入轴颈倾斜的流体润滑模型。以某重载轴承为例分析倾斜轴颈轴承的润滑性能。结果表明,轴颈倾斜会导致油膜压力发生轴向偏布,峰值偏离轴向中分面,且倾角越大偏离越严重;近轴端面油膜厚度远小于远轴端面,倾角较大时两端面油膜厚度差值大于最小油膜厚度值,可能导致轴颈与轴承碰磨甚至烧瓦,因此在轴承设计时必须予以考虑。动平衡机上进行的现场试验验证了理论分析的正确性。     

滚动轴承润滑脂耐高温性能的试验及评价

比较了润滑脂耐高温性能的静态和动态试验方法,说明润滑脂的耐高温性能应该采用动态试验方法,以试验后润滑脂润滑功能的劣化程度即轴承摩擦力矩的升高程度或手感的加重程度来评价,强调试验后润滑脂色变与否及色变程度与其润滑功能没有必然联系,不宜作为润滑脂耐高温性能的评价依据.     

空穴效应对倾斜轴颈轴承润滑性能影响的研究

为更准确地分析倾斜轴颈轴承的润滑性能,基于控制体积质量守恒原理,综合考虑宏观空穴和微凸体间空穴的影响,建立包括空穴区域在内的统一润滑控制方程,分析了宏观空穴和微凸体间空穴对润滑性能的影响。研究结果表明,空穴现象对最大油膜压力影响不大;宏观空穴现象使得轴承润滑油进口低压区域面积增大,形成较大的空穴区域,同时油膜出口边界滞后;微凸体间空穴使进口空穴边界和出口空穴边界均略微提前;在空穴区域,润滑介质密度低,空穴程度较大;微凸体间空穴对全润滑区域的润滑介质密度分布影响较大,特别是在空穴边界附近;宏观空穴对端泄流量、油膜力矩和油膜承载力有较大的影响,微凸体间空穴的影响可以忽略。     

水润滑赛龙轴承

指出了传统水润滑轴承材料的不足，详细介绍了水润滑赛龙轴承的材料分类、轴承结构、特性和优点以及设计使用原则，并指出水润滑赛龙轴承具有广阔的应用发展前景。     

THD Effects of Static Performance Characteristics of Infinitely Wide Turbulent Journal Bearings

Formulas for static parameters were found for infinitely wide turbulent full journal bearings that correlate either load capacity or friction coefficient for thermohydrodynamics (THD) effects in terms of a single THD parameter. The database was built by numerical simulation of turbulent liquid lubricant flows with various eccentricity ratios in a wide range of the Reynolds number for both isoviscous and THD cases. The least-squares method was applied to the groups of parameters yielding the formulas of load capacity, friction coefficient, and attitude angle. The isoviscous attitude angle was fitted as a function of the maximum-to-minimum film thickness ratio, and the variation of attitude angle due to THD is linearly dependent on the THD-to-isoviscous load capacity ratio. With the formulas provided in this study, designers can quickly determine static parameters of turbulent journal bearings without the burden of labor-intensive numerical computation of the governing differential equations.     

汽车发动机系滚动轴承润滑脂动态可靠性测试及评价

介绍了汽车发动机系滚动轴承润滑脂动态可靠性的测试及评价方法,包括SKF Emcor润滑脂动态抗腐蚀测试,FAG FE8润滑脂动态抗极压和磨损性能测试以及FAG FE9润滑脂动态润滑寿命测试,对正确选用润滑脂以及汽车发动机系滚动轴承可靠度设计等提供参考.     

混合轴承动特性简化计算方法

用一维流计算原理分析了多腔混合轴承的动态特性；计算了典型的毛细管节流四腔轴承在各种设计参数下的线性化刚度系数和阻尼系数，得到了轴承相应的刚度和稳定性速度阈值；比较了简化计算方法得到的数据与传统的雷诺方程数值解法得到的数据，且讨论了前者的误差影响。在常用工况条件下，其计算结果满足工程需要。     

The Effects of Viscosity and Clearance on the Performance of Hydrodynamic Journal Bearings

In the present work, the effects of viscosity and clearance ratios have been analyzed on the reliable performance and design of a steady-loaded, pressure-fed, hydrodynamic cylindrical bearing. The technique for bearing performance evaluation has been developed based on the maximum oil temperature in the region of load carrying oil film, and variation of oil viscosity with temperature.

In this paper viscosity coefficients have been determined using iterative procedures for different oils. And also, a viscosity integral has been evaluated by method of splines as a function of inlet oil temperature to the load carrying oil film and exit oil temperature from the oil film. The viscosity integral has also been evaluated for a bearing operating under different conditions. Thus, by comparison of the viscosity integrals, exit oil temperature from the load carrying oil film and safe load carrying capacity of a bearing with different clearance ratio and using different oils have been examined. Nomographs have also been plotted for easy assessment of bearing performance.

The developed technique gives a more realistic approach for design and performance evaluation of a bearing as compared to conventional procedures. This may have potential as an effective tool to assess performance of a hydrodynamic journal bearing.