双向均压槽节流静压气体轴承静态特性分析

为进一步优化径向静压气体轴承的静态性能,提出在传统小孔节流的基础上配合开设轴向和周向均压槽的复合节流式静压气体径向轴承。利用Fluent软件对比分析传统孔式节流与不同形式复合节流静压气体轴承的静态特〖JP2〗性,探究均压槽截面形状及供气压力对轴承静态特性的影响规律;利用正交试验探究节流器各结构参数对承载特性的影响。结果表明：复合节流式静压气体轴承在一定程度上提升了轴承的静态性能,其中均压槽以“口”字形布置以及截面形状为矩形时效果最优;供气压力的增大也可提升轴承静态特性;节流孔直径和均压槽深度对轴承静态特性的影响要大于节流孔深度和均压槽宽度,节流孔直径以及均压槽深度的增大均使得承载力与刚度呈现出先增大后减小的趋势。     

具有鸟翼轮廓仿生槽的动静压气体轴承静态特性分析

基于仿生学原理和几何重构法,在动静压气体轴承上设计具有鸟翼轮廓仿生槽,以提高其承载能力及刚度。运用变分法求解雷诺方程并使用FLUENT软件,对鸟翼轮廓仿生槽动静压气体轴承进行静态特性仿真分析,研究轴颈转速、供气压力、偏心率、槽深以及槽偏角对轴承静态特性的影响。结果表明：在偏心率相同时,随着轴颈转速的增加,轴承承载能力和刚度随之增大,随着供气压力的增加,轴承承载能力逐渐增加、刚度逐渐减小;当气膜厚度一定时,随着槽深的增加,轴承承载能力和刚度呈现先增加后减小的趋势,随着槽偏角的增加,轴承承载能力和刚度呈现先增加后减小的趋势。     

带轴向微通槽静压气体轴承承载特性研究

以开设轴向微通槽的径向静压气体轴承为研究对象,通过Fluent软件对轴承的承载力和刚度进行仿真分析;针对矩形、三角形和椭圆形3种截面微通槽,分析气膜厚度对轴承的承载力和刚度的影响,得出微通槽的最佳截面形状设置;针对最佳截面形状的微通槽,分析不同槽宽和槽深对承载力的影响。研究发现:轴向微通槽可以明显提高径向静压气体轴承的承载力和刚度,偏心率越大,提升效果越明显;气膜厚度较小时,矩形微通槽气体轴承的承载能力和刚度最佳,且气膜厚度越小,微通槽形状的影响越大;气膜厚度较大时,3种微通槽轴承的承载力及刚度相近;承载力随微通槽槽宽和槽深的增大而先升高后趋于稳定。     

带人字槽和轴向微通槽的动静压气体轴承静态特性

设计带人字槽和轴向微通槽的动静压气体轴承,运用FLUENT对其静态特性进行仿真分析,通过改变轴向微通槽深度、偏心率、气膜厚度、供气压力等参数,研究其对轴承刚度和承载能力的影响。结果表明：其他条件不变,偏心率越大,轴承刚度越小、承载能力越大;人字槽可以提升气体轴承的承载能力和刚度,主轴转速越快,动压效应越强,轴承刚度和承载能力越大;随微通槽深度增加,轴承刚度先增大后保持稳定,轴承承载能力先增大后减小,因此当微通槽深度过大时,轴承刚度变化不大,但轴承承载能力会减小。     

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。     

复合节流式静压气体轴承静态特性分析

为进一步提升静压气体轴承的静态性能,以普通孔式节流为基础,配合表面周向和径向槽节流,提出复合节流式静压气体轴承,以充分发挥2种节流方式的优点,使静压气体轴承具有更好的承载能力和刚度。利用Fluent计算轴承内流场参数并分析流场特性,比较复合节流式与普通孔式节流静压气体轴承的承载能力和刚度,并研究孔式参数和表面槽参数对复合节流式静压气体轴承静态特性的影响。结果表明：在一定气膜厚度范围内,复合节流式静压气体轴承对于提升承载力、增强刚度有着显著的效果;复合式节流因为有表面槽二次节流的存在,均压效果更好。增加节流孔数、节流孔直径、节流孔分布圆半径,以及在气膜厚度较小时增加表面槽长、槽宽、槽深,均有利于增加轴承承载力;在气膜厚度较小时,增加节流孔数、减小节流孔直径,以及增加表面槽长和槽宽、降低槽深,均有利于增加轴承刚度。     

新型径向槽结构静压气体轴承静态特性研究

设计一种新型径向槽结构静压气体轴承,其周向和径向截面分别呈椭圆弧形和扇形。建立该径向槽结构静压气体轴承CFD模型,分析径向槽结构参数如深度、半径、数目、角度和试验参数供气压力,对静压气体轴承承载能力和刚度的影响。研究结果表明:静压气体轴承承载能力随槽结构深度、数目、角度和供气压力增加逐渐增大,随槽结构半径增加先增大后减小;槽结构数目和供气压力对其承载能力影响尤为显著;静压气体轴承径向槽结构参数和供气压力影响其刚度及最佳刚度对应的气膜厚度,其中槽结构半径、数目和供气压力对刚度值影响显著,槽结构角度和半径对最佳刚度对应的气膜厚度影响显著。由此可见,径向槽结构参数显著影响静压气体轴承的承载能力和刚度。     

均压槽气体静压轴承数值计算与静态性能分析

针对气体静压导轨承载力和刚度较低的问题,在导轨的工作面上设计横截面为矩形的直线形均压槽,分别研究均压槽的尺寸、节流孔的尺寸和个数以及供气压力对轴承静态性能的影响;建立轴承气膜的CFD(Computational Fluid Dynamics)模型,通过仿真计算得到轴承的质量流量,利用差膜计算方法得到轴承的承载力和刚度,分析不同结构参数下轴承承载力、刚度和质量流量的变化规律。分析结果表明:增加均压槽可以有效提高气体静压轴承的承载力和刚度,但轴承的耗气量也会增加;随着轴承偏心率的增大,轴承的承载力逐渐增大,轴承的刚度则先增大后减小,轴承的耗气量逐渐减小;均压槽的深度、节流孔的直径和个数以及供气压力对轴承承载性能的影响较大,而均压槽宽度和节流孔高度的影响则较小。     

节流孔轴向布置方式对气浮主轴轴承特性的影响

气浮主轴承载能力和刚度作为衡量气浮主轴性能的关键指标,受到节流方式的直接影响,而目前节流孔轴向布置方式对孔式节流静压气体轴承支承性能的影响尚缺乏深入研究.为研究节流孔轴向布置方式对静压气体轴承特性的影响,设计两排孔、中部排气式四排孔、中部不排气式四排孔3种典型的节流孔轴向布置方式,基于雷诺方程建立静压气体轴颈轴承气膜力...     

带气腔结构的平面静压气体轴承特性分析

采用小孔节流的平面静压气浮运动平台由于其精度高、成本低等特点被广泛应用于精密设备当中,但相对于传统轴承存在承载力和刚度低的问题,很难将其应用到高速重载的设备中.针对以小孔节流的平面静压气体轴承承载力和刚度低的问题,通常采用开设气腔和均压槽来实现高的承载力,但是气腔的结构也会对气体静压轴承产生不同影.响.文中采用Flue...     

The Performance of Externally Pressurized Bearings Using Simple Orifice Restrictors

The load capacity and vibration characteristics of externally pressurized thrust and journal bearings have been investigated. The bearings used orifices sufficiently recessed back from the bearing surface to ensure that the area of the orifice is the minimum presented to the gas flow. The journal bearings consist of plain cylinders with one or two rows of eight orifices, and the thrust plates of plain discs with six orifices drilled in equispaced circumferential grooves.

The load capacity of the thrust plates agrees with that calculated but the vibrations are greater than predicted. The load capacity of journal bearings is about half that calculated assuming axial flow conditions in the bearing, but circumferential flow can account for the difference. Synchronous and half-speed vibrations of a shaft rotating within these bearings have been measured and found to agree with those calculated on the assumption that the gas films behave as linear springs.     

带有圆周方向均压槽的静压气体止推轴承的气锤自激

通过开设均压槽,可以增加静压气体轴承的承载能力和刚度,但是如果气体轴承的均压槽等参数设计不合理,会出现一种振动现象——气锤自激振动,尤其是设计高压重载气体止推轴承时。针对常用的圆盘止推气体轴承,建立轴承活动件的动力学方程,再运用小扰动方法和流量连续性方程得到了气锤自激振动的稳定性判别方程。通过求解稳定性判别方程,发现供气压力越大,自激振动的倾向性越强;气膜间隙在一定范围内容易引起自激振动;节流孔直径越大,自激振动的倾向性越强;当止推轴承的外径和内径的比值比较小时,容易发生气锤自激。通过计算得到了不发生气锤自激振动的轴承设计参数,可用于高压重载气体止推轴承的设计。     

小孔节流静压气体轴颈轴承主轴系统的动态特性分析

通过对小孔节流静压气体轴颈轴承的雷诺方程与描述主轴系统的动力学数学模型联立直接进行数值求解,分析了轴承系统的动力学特性,研究了在不平衡质量作用下轴承主轴系统的响应。结果表明,由于精密离心机小孔节流静压气体轴承的支承刚度大,承载能力高,旋转主轴的运动是稳定的。但在一定条件下,旋转主轴有可能出现不稳定现象,这取决于主轴绕固联坐标系各轴之转动惯量间的关系、轴承支承刚度、主轴旋转速度和不平衡质量控制等因素。该方法用于精密离心机静压气体轴承主轴系统动力学的数值计算,提高了计算精度和可靠性。     

Analysis and Design of Externally Pressurized Gas Bearings

Equations for flow rate, pressure, load, and stiffness of externally pressurized thrust and journal bearings are given for purely viscous, isothermal gas films with longitudinal or radial flow and no relative surface motion. Charts are presented by means of which the bearing characteristics can be evaluated in terms of the bearing parameter, the bearing configuration, and the ratio of supply to ambient pressure. Sample characteristics of thrust and journal bearings are established using the curves and experimental confirmation shown. A method of treating bearing films with two inlet-restricting orifices in series is described.     

气体静压小孔节流与多孔质节流性能的比较

本文给出了传统的小孔节流和多孔质节流轴承的理论分析，分析了外部供压气体轴承的进气形式对轴承性能的影响，对于不同类型的小孔节流和多孔质节流的轴承，本文给出了实验结果，并对轴承的性能参数即承载能力，刚度等进行了比较，作者分析了小孔节流和多孔节流止推轴承的承载能力和刚度，结果表明多孔质止推轴承同小孔节流轴承相比，具有高的承载能力。     

Static characteristics of externally pressurized gas journal bearings with circular slot restrictors

The static characteristics of an externally pressurized gas journal bearing with a circular slot restrictor are described. The slot configuration is circumferentially continuous and is simpler than that of the journal bearing with discrete slots proposed by Dee and Shires¹. Here, the optimum design conditions for the load capacity are theoretically determined and it is shown that gas journal bearings with a circular slot restrictor possess a load capacity comparable to designs which have discrete slots.     

Design procedures for orifice compensated gas journal bearings based on experimental data

This paper presents a method for designing externally pressurized gas journal bearings with orifice compensation. The design procedures include a basis for prediction of bearing stiffness, load, and flow rate for a range of typical bearing configurations, and allow an interactive procedure whereby the designer can visually interpret the effects of various design changes. Guidance is given on bearing geometry to maximise load carrying capacity. Recommendations are also given to enable the designer to select the number of orifices to achieve the predicted load carrying capacity, as well as guidance concerning pocket geometry to minimise the possibility of pneumatic hammer instabilities. The effects on design performance due to variations of bearing clearance and orifice diameter are included and provides a basis for the tolerancing procedure which is proposed     

Analysis of externally pressurized gas bearings with journal rotation

Theoretical studies of rotating externally pressurized gas bearings with multiple pressure sources have been made. The solution is obtained for finite bearings by using pressure perturbation theory. Theoretical results are compared with experimental data. The theory allows good prediction of bearing load capacity, stiffness and attitude angle.     

Stability of the rotor supported in gas journal bearings with a chamber feeding system

This paper describes the results of numerical investigations of the stability problem of the rigid symmetrical rotor supported in two externally pressurized gas journal bearings. The bushes of the bearings are mounted on a system of linear springs and viscous dampers. When the stiffness and damping coefficients of these springs and dampers are chosen correctly, it is possible to avoid the self-excited vibrations of the rotor. Such vibrations, which are caused by the phenomenon of a half-synchronic whirl, are the major obstacle to the widespread application of gas bearings. The results of authors numerical experiments have shown that the elastic support of the bearing bushes can be designed as an additional externally pressurized air ring, surrounding the bush. The set of parameters of such a ring is optimal when the bearing has a chamber feeding system.     

Load and flow characteristics of a capillary-compensated hydrostatic journal bearing

A theoretical analysis of load and flow characteristics of a capillary compensated oil-lubricated externally pressurized journal bearing having four rectangular recesses is presented. The analysis is based on an exact solution of the pressure distribution over the bearing sill area and has been made for two configurations of loading, through the centre of any recess and through the centre of the circumferential sill between any two recesses. The influence of circumferential sill length and intensity of compensation on the load carrying capacity and the flow requirement is shown. Theoretical analysis and experimental results are compared.