压黏效应对螺旋油楔动压滑动轴承特性的影响

对螺旋油楔动压滑动轴承进行了研究,推导出了斜坐标系下雷诺方程、油膜厚度方程和速度方程的有限差分公式.在此基础上,建立了考虑压黏效应的螺旋油楔动压滑动轴承的雷诺方程式.运用有限差分法,计算得出有无考虑黏压效应情况下,轴承的动静特性参数.结果表明:压黏效应使滑动轴承的油膜厚度有所提高,油膜压力、承载力和端泄量有所减小;压黏效应对轴承的刚度系数和阻尼系数、流线分布、摩擦阻力和温升都有不同程度的影响,是分析螺旋油楔动压滑动轴承动静特性的一个不可忽略的因素.     

计入供油压力的螺旋油楔动压滑动轴承动静特性分析

对螺旋油楔动压滑动轴承的动静特性进行了研究、联立求解雷诺方程、油膜厚度方程和速度方程等,运用有限差分法计算得出有无考虑供油压力情况下,轴承的动静特性参数.结果表明:供油压力使滑动轴承的油膜压力总体上有所提高;供油压力对轴承的刚度系数和阻尼系数都有不同程度的影响;供油压力的存在加快了流体质点的运动,这对于改善轴承的润滑性能非常有利.因此,研究螺旋油楔动压滑动轴承的动静特性必须计入供油压力的影响.     

基于两相流三油楔滑动轴承的油膜特性分析

运用CFD模拟软件中的多相流模型、SST湍流模型求解Navier Stokes 方程,研究三油楔滑动轴承的油膜特性。建立三油楔滑动轴承的几何模型,通过合理的网格划分,采用CFD软件计算分析三油楔滑动轴承中3个油楔内润滑油的油膜特性及其气穴分布特点,研究转速、润滑油黏度对润滑油气化的影响,并与未考虑两相流的三油楔轴承的油膜特性进行对比分析。结果表明：两相流模型更能真实反映实际的油膜特征;转速高、润滑油黏度大越容易产生气化现象;黏度对主承载区的影响较大,而转速对非主承载区的影响较大。     

基于MATLAB/GUI的滑动轴承特性研究

以三油楔固定瓦滑动轴承为研究对象,根据定常和非定常雷诺方程,采用有限差分法分别计算了轴承的油膜压力分布和扰动油膜压力分布,进而计算出轴承的静、动特性。采用MATLAB软件自带的图形用户界面的设计功能,实现了轴承特性计算的可视化交互。     

基于CFX的柱面弧形油楔推力滑动轴承仿真分析

柱面弧形油楔推力滑动轴承是一种能够实现双向动载润滑的推力轴承。文中利用Workbench的CFX模块,对柱面弧形油楔推力滑动轴承在动压润滑条件下的油膜特性进行仿真分析。并研究了不同转速和不同黏度对油膜压力的影响,结果表明,转速越高,油膜黏度越大,柱面弧形油楔推力滑动轴承的动压承载能力就越高。     

油膜涡动对三油楔固定瓦滑动轴承性能的影响

以三油楔固定瓦滑动轴承为研究对象,通过数值模拟研究,探讨了油膜涡动角度和涡动半径对轴承静、动特性及稳定性的影响规律,并得出了一系列关于油膜涡动的涡动角度和涡动半径对三油楔滑动轴承静、动特性影响的规律性曲线.结果表明,油膜涡动角度的变化对三油楔固定瓦滑动轴承的静、动特性和稳定性将产生很大的影响,且这种影响随油膜涡动半径增大而增大.     

轴瓦式滑动轴承主轴机构的修理

轴瓦式滑动轴承是一种高精度的滑动轴承,又叫多油楔径向动压滑动轴承;它具有多个相互独立并且均匀分布的收敛油楔表面,当主轴高速回转时,其油楔表面仍维持楔形间隙,因此无论主轴是否承载,各独立油楔均可形成均匀的承载油膜,并使旋转主轴保持在无偏心旋转状态。它回转精度高,刚性好,一般用在磨床主轴上。现以Ｍ7150Ａ型平面磨床使用的结构为例,介绍这种轴承的修理。1　结构特点分析　　(1)主轴前、后轴承均为短三瓦自动调位滑动轴承,主轴直径为100ｍｍ,保持轴承间隙为001～0.02ｍｍ,球面支承螺钉和锁紧螺母装配关系见图1所示。(2)主轴轴向采…     

考虑混合润滑的飞机燃油泵径向滑动轴承静特性分析

针对飞机燃油泵径向滑动轴承润滑油黏度极低、润滑油膜形成难、表面易磨损等问题,通过综合考虑紊流、热效应、质量守恒、温黏效应及混合润滑边界等因素,建立轴承的热流体动力学润滑分析模型,采用有限元方法联立求解雷诺方程、能量方程、接触方程得到轴承的静态特性,研究轴承间隙比、宽径比、转速、载荷、进油温度等对轴承静态润滑性能如油膜厚度和油膜压力的影响规律。结果表明：由于航空煤油动力黏度低,造成轴承的浮起转速高（大于5 500 r/min）,极限承载力低（小于37 N）、油膜厚度过低;降低进油温度、适当减小间隙,增加轴瓦宽度有利于增加油膜厚度,提高轴承可靠性。研究结果对飞机燃油泵径向滑动轴承设计与运行维护具有一定的工程借鉴价值。     

多油楔浮动滑动轴承磨损实验研究

实验研究了三种不同结构的多油楔浮动滑动轴承,它们可用于不同载荷下的旋转机械,兼有普通径向滑动轴承和多油楔滑动轴承的优点.实验研究表明,这种轴承既可以提高运行过程中轴承的稳定性,又能够减少轴承的磨损,提高轴承的寿命.磨损试验研究发现,轴承间隙是影响轴承磨损量的重要因素之一.当外间隙一定,内间隙值在规定范围内时,多油楔浮动滑动轴承磨损量最小;内间隙值过大或过小,均会加剧轴承的磨损.实验研究工作为进一步设计研究此类轴承提供了一定的实验依据.     

液体动静压混合轴承

液体动静压混合轴承是一种既综合了液体动压轴承和液体静压轴承的优点,同时又克服了两者缺点的新型多油楔油膜滑动轴承。由于利用小孔和浅腔二次节流形成的静压承载力将主轴悬浮在高压油膜中间,从而提高了主轴刚度和抗过载能力;同时由于高压油膜本身具有很好的均化作用,使主轴获得了很高的回转精度。主要技术指标:主轴端部锥面径向跳动<0.001mm;主轴轴     

惯性和滑移对弹性金属塑料轴承的影响研究

从连续性方程和Navier-Stokes方程出发,推导出在圆柱坐标系中考虑了界面滑移和流体惯性影响的雷诺方程。通过数值计算,考察了界面滑移和流体惯性对弹性金属塑料径向滑动轴承水膜压力和承载能力的影响程度。计算结果表明：界面滑移将降低水膜压力和承载能力,流体惯性力的存在略微增大了水膜压力和承载能力;随偏心率的增大,界面滑移对水膜压力和承载能力的影响程度增大。
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A Theoretical Study of the Effect of Offset Loads on the Performance of a 120° Partial Journal Bearing

Reynolds' equation for a 120° partial journal bearing of the clearance type having an L/D ratio of 1 is solved numerically to determine the effect of positioning circumferentially the line of action of the load at various points along the bearing arc. The influence of the load position (α/β) on film thickness, eccentricity, journal position, friction, flow, temperature rise, and maximum film pressure is investigated and performance curves given. It is shown that the position of the load has a significant effect on bearing performance.     

热效应对粗糙表面倾斜轴颈轴承润滑性能的影响

联立基于平均流量模型的广义Reynolds方程、三维能量方程和固体热传导方程等,计算了计及热效应时,不同表面形貌和轴颈倾斜角下的轴承油膜压力、油膜温度、油膜反力、端泄流量、摩擦系数和保持轴承稳定工作的力矩.考虑和不考虑热效应的轴承润滑特性计算结果表明,计入热效应时,表面形貌和润滑油粘压效应对偏心率较大的轴颈倾斜轴承润滑性能影响较大.     

轴变形产生的轴颈倾斜对滑动轴承润滑影响的试验研究

针对各种机械装置使用最普遍、最基本的轴-滑动轴承摩擦副系统,设计研制了专用试验装置,对轴受载荷作用产生弯曲变形,导致轴颈在轴承孔中倾斜时滑动轴承的润滑性能进行了试验研究。结果表明,在轴-滑动轴承摩擦副系统中,轴受载荷作用产生变形将导致轴颈在轴承孔中倾斜;轴变形导致轴颈倾斜时,滑动轴承的油膜压力、油膜厚度和温度的分布状况及数值发生了明显变化。轴受载越大,其变形产生的轴颈倾斜越严重,对滑动轴承润滑性能的影响越明显;轴承半径间隙与轴承宽度比值越小,轴变形产生的轴颈倾斜对轴承油膜压力、油膜厚度和温度的数值及分布的影响越大。因此,滑动轴承设计中应该考虑轴受载荷作用产生的变形导致轴颈倾斜的影响,对于重要的机械设备,尤其应当考虑这种影响。     

Squeeze films in full porous metal bearings

The behaviour of squeeze films in porous journal bearings under a steady load is analysed. A full journal bearing with a non-rotating journal is considered. The Reynolds equation governing the pressure in the film region is modified to take account of the mass exchange of the lubricant between the film and the bearing matrix. In the case of thin-walled bearing (H?R), the modified Reynolds equation takes a simpler form. However, since this equation cannot be solved directly as applied to a finite bearing, solutions in a closed form are found both for the long bearing and narrow bearing approximations. It is found that the permeability of the bearing matrix and the wall thickness of the bearing adversely affect the load capacity and greatly reduce the time needed for the journal to attain a given eccentricity. With a permeable bearing, there is the possibility of the journal coming into contact with the bearing (ε=l) in a finite time. Generally the performance of a long bearing is better than that of a narrow bearing.     

Texture shape effects on hydrodynamic journal bearing performances using mass-conserving numerical approach

ABSTRACT

It is a known fact that incorporating textures in the contact surfaces can significantly enhance bearing performances. The purpose of this paper is to outline the effects of texture bottom profiles and contour geometries on the performances of hydrodynamic textured journal bearings. The analysis was conducted using computational approach to test eight texture shapes: rectangular, cylindrical, spherical, triangular (TR, T1, T2, T3) and chevron. The steady-state Reynolds equation for modelling the hydrodynamic behaviour of thin viscous film was solved using finite difference technique and mass conservation algorithm (JFO boundary conditions), taking into account the presence of textures on both full film and cavitation regions. The comparison with the benchmark data shows good consistency and an enhancement in bearing performances (load carrying capacity and friction). The results clearly show that the mechanisms of wedge effect and micro-step bearing for the full/partial texturing feature are the main crucial parameters, where the convergent wedge effect present in T2 triangular texture shape can significantly enhance the load-carrying capacity, while the divergent wedge action causes a net load loss. Considering the right arrangement of textures on the contact surface, their surface contours can have a significant impact on the performance of hydrodynamic journal bearings at high eccentricity ratios.     

Dynamically loaded micropolar fluid lubricated journal bearings with special reference to squeeze films under fluctuating loads

The Reynolds equation is derived for the general case of a dynamically loaded journal bearing, where both wedge and squeeze films are active and the load and speed of rotation vary with time in magnitude and direction. The bearing characteristics for an infinitely long journal bearing are obtained. The dynamic behaviour of squeeze films in a half journal bearing under a fluctuating load with no journal rotation is considered in detail.     

弹性变形对径向轴承弹流润滑性能的影响

本文以上具有不同弹性模量、泊松系数的两种轴承材料为例分析了弹性变形对有限长径向滑动轴承的弹流润滑性能的影响。流体动力润滑方程采用雷诺方程,应用力学问题的通用有限元软件ＭＡＲＣ产生柔度矩阵计算弹性变形。对比分析了二种轴承的油膜压力分布、油膜厚度分布、最小油膜厚度以及承载能力。     

内燃机曲轴-轴承系统曲轴变形引起的轴承润滑状态变化对曲轴强度的影响

在计及曲轴变形的轴承润滑分析的基础上,应用得到的轴承油膜压力分布作为载荷边界条件计算曲轴应力和强度,以分析目前曲轴强度计算中作用在轴颈上的载荷普遍采用假设的轴承油膜压力分布形式对结果精度的影响。计算中采用整体曲轴梁单元法计算曲轴变形和轴承负荷,采用动力学法进行曲轴轴承的润滑分析,应用有限元法计算曲轴应力。结果表明,计及曲轴受载变形的影响时,轴承油膜压力产生偏布且最大油膜压力明显增加,导致曲轴轴颈过渡圆角表面局部区域的应力数值明显增大,曲轴安全系数减小。因此为使曲轴设计更加合理、更接近实际,曲轴强度计算时应取曲轴—轴承系统为研究对象,根据轴承润滑分析实际计算结果,确定作用在曲轴轴颈上的载荷分布。     

Calculation of a Safety Margin for Hydrogenerator Thrust Bearings

The purpose of this paper is to present the two-dimensional linear stability analysis considering the fluid flow in both full film and cavitation regions for a plain cylindrical journal bearing. The Lund's infinitesimal perturbation procedure is applied to Elrod's universal equation for evaluation of unsteady pressure gradients. Based on JFO theory, the pressure distribution, film rupture, and reformation boundaries can be obtained using Elrod's universal equation, for a given operating position of the journal. In this work, it is assumed that for infinitesimal perturbation of a journal about the equilibrium position, the film rupture and film reformation boundaries are the same as those obtained for steady state. However, the unsteady pressure gradients in the full film region are evaluated taking into consideration the perturbed flow parameters in the cavitation region, i.e., at both rupture and reformation boundaries. The linearized stiffness and damping coefficients, whirl frequency ratio, and threshold speed for various values of eccentricity and L/D ratios are obtained for a plain cylindrical journal bearing with an axial groove along the load line. Measured data of dynamic coefficients for a 120° partial arc bearing are chosen for comparison with this work. Results show good agreement between the theoretical and experimental results.