偏心率对高速动静压轴承动特性影响

本文分析了水润滑,五腔动静压轴承偏心率对轴承静动性能的影响。轴承量在高压力、高转速下使用。计算表明,在中小偏心下,轴承动力系统为常数;而在大偏心率下,由于流体膜空穴和油腔位置的影响,轴承动特性有较大变化。同时考虑了轴承系统稳定性。     

动静压混合气体润滑轴承动态稳定性实验研究

对动静压混合气体润滑轴承进行了动态稳定性试验。通过实验呈现了气体润滑轴承-转子系统中的气膜涡动和混沌振动现象,分析了动态失稳过程中,分叉、混沌等非线性特征与动态稳定性的关联性。结果表明,系统是由周期1的同频涡动开始,气膜涡动导致倍周期分叉,而进入周期2运动形式;随着振动加剧,系统通过时间很短的周期3运动进入混沌;利用混沌振动的"有界"性质,可以有效控制振幅,提高稳定性。     

涡轮泵流体静压轴承设计及性能特性分析

针对流体静压轴承在液体火箭发动机涡轮泵中的设计和应用,以现有的滚动轴承支承的涡轮泵转子为应用对象,提出流体静压轴承的参数设计思路,采用粒子群优化算法设计得到支承刚度最大化的轴承结构参数组合,并计算分析所设计轴承的性能以及轴承-转子系统的动力学特性。分析表明：优化设计得到流体静压轴承的承载力和支承刚度可以满足要求,但轴承总流量达泵流量的21%,这会显著降低涡轮泵的总体效率;仅将滚动轴承改为流体静压轴承,而不改变其他结构或布局,转子的稳定性不能满足要求;涡轮泵流体静压轴承转子系统设计时应尽量将轴承布置在转子位移较大的位置,以充分发挥其阻尼作用。     

浅油腔动静压轴承动特性分析

本文提出了基于有限差分法的浅油腔动静压轴承动特性分析的偏导数法，并利用该法分析了两种在国产磨床中常用的浅油腔动静压轴承的动特性。     

航天飞机主发动机涡轮泵轴承的润滑

航天飞机由安装在尾部的三个助推器和两个固体火箭发动机推动进入轨道。固体火箭发动机脱离后助推器仍然工作。助推器的主要部分是四个提供燃料的涡轮泵。涡轮泵以极高的速度旋转，这对轴承润滑十分不利，涡轮泵包含一根由球轴承和滚子轴承支承的轴。轴两端各有一个泵叶轮和涡轮盘。如果轴承不能承受载荷，没有足够的刚度和耐磨性，涡轮泵内的旋转部件就会产生磨损，后果不堪设想。     

液体动静压轴承润滑机理及计算

在分析动静压轴承润滑机理时必须综合考虑动、静压以及其联合作用时的工作原理及润滑方程求解。利用雷诺方程和流量连续方程建立了润滑机理的基本模型并给出了联立求解方法及计算步骤以指导工程设计,并指出了设计中必须考虑的变形、公差以及润滑油选取等问题。     

动静压轴承的试验研究

本文对一个重型磨床上的大型特殊结构的动静压轴承进行了实验研究。完善了一大型高速动静压轴承试验台,改进了基于频谱分析动静压轴承动特性测试方法。实验中着重考虑了激振频率的影响。得出了一些有实用价值的结论。     

Creep and separation of oil films in reciprocating motion

As a fundamental investigation of gas/liquid two-phase lubrication under reciprocating conditions, the behaviour of oil films between a reciprocating plate and a stationary optical flat was observed. It was found that under reciprocating conditions the dynamic behaviour of oil films with free boundaries was influenced by complicated interfacial phenomena, showing creep, notching and separation of their contours. Analysis of the results clarified the influencing factors and the inherent conditions in the characteristics types of film contours     

Feed pressure flow in plain journal bearings

The purpose of this short technical note is to update the literature on feed pressure flow in plain bearings and to give a summary of suitable equations for predicting such flows. The work is part of a detailed study of feed pressure flow¹.     

Performance of three-lobe pressure-dam bearings

The use of multi-lobe bearings, considered to be more stable than ordinary circular bearings in industry is increasing daily. Studies have shown that performance can be further improved if pressure dams are incorporated into these bearings. Analysis of two-lobe pressure dam bearings has been reported in the literature. The present work was carried out to assess the performance of a three-lobe bearing with pressure dams. The results show that the performance of a three-lobe pressure-dam bearing is far superior to that of an ordinary three-lobe bearing.     

Self Adapting Mechanical Step Bearings for Variations in Load

As the application of small-scale and precision technologies increases, the need will grow for bearings which are able to provide precision control of their location. Thus, there is a need for new bearing technologies to reduce friction and wear, and provide precision control of bearing motion. This control can be provided by electronically controlled actuators and sensors, but then the system is dependant on the reliability of the electronics. This work uses numerical methods to research the design and behavior of self adapting step bearings. These step bearings are designed to change their surface profiles to achieve an optimal or controlled behavior, without the use electronics or external control. The bearing changes its profile to control the film height of the bearing to a near constant value for different loads. The result is a self adapting step bearing design that may be applied at multiple scales for use in a wide variety of machine components. The numerical simulation shows that the self adapting step bearing is able to autonomously adapt in real time to dynamic loads and maintain a desired film thickness with a relatively small amount of deviation. The self adapting step bearing also exhibits smaller dynamic responses to transient loads in comparison to a conventional static geometry step bearing. A self adapting step bearing using a linear spring instead of a non-linear spring also appears to show similar improvements in performance.     

高速水润滑动静压轴承环面节流器节流系数研究

采用Fluent建立了用于高速水润滑动静压轴承的环面节流器的有限元模型,计算了环面节流器的流场,研究了小孔直径、油膜厚度、压力差和主轴转速与节流系数的关系,探讨了节流系数的变化规律。结果表明:在油膜厚度较小时,节流器性能主要取决于轴颈线速度和压力差,说明在半径间隙较小的高速水润滑动静压轴承性能计算中,根据运行参数取节流系数是很有必要的。     

Analyses of thermal hydrodynamic lubrication in high-speed rolling. Part I: the effect of the roller's elastic deformation

A study of thermal hydrodynamic lubrication for high-speed strip rolling, which includes the roller's elastic deformation, was developed for a lubricant whose rheological behaviour satisfies the Barus' model. The difference in lubricating performances between an elastic roller and a rigid roller was assessed using parameters such as film thickness and pressure; temperature distributions in the fluid film, roller, and workpiece; separating force and shear torque. The elastic roller was made either of a unique material or its substrate was coated with one layer of a harder material to improve the wear resistance. The elastic deformation of the roller was obtained with the aid of Hitchcock's elastic-deformation theory and the biharmonic equation of Airy's stress function. It was found that the elastic deformation produces a substantial effect on some rolling characteristics.     

Comparative study of four gas-lubricated noncircular journal bearing configurations

Offset-halves, lemon-bore, three-lobe and four-lobe bearing performance has been compared at the same load capacity and speed. Both steady state and stability characteristics have been considered.     

Analysis of hydrodynamic journal bearings lubricated with non-Newtonian fluids

A procedure for solving the Navier-Stokes equations for the steady, three-dimensional flow of a non-Newtonian fluid within a finite-breadth hydrodynamic journal bearing is described. The method uses a finite-difference approach, together with a technique known as SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) which has now become established in the field of computational fluid dynamics. The concept of ‘effective viscosity’ to describe the non-linear dependence of shear stress on shear rate is used to predict the performance of bearings having a single full-width axial inlet groove situated at the position of maximum film thickness. To illustrate the capabilities of the procedure, results are obtained for a range of non-linearity factors, and lead to the conclusion that the pressure distribution, attitude angle, end-leakage rate, shear force and load capacity can all be predicted for a variety of non-Newtonian lubricants using the SIMPLE numerical integration technique.     

Transient Pressure and Temperature Field Measurements in a Lightly Loaded Circumferential Groove Journal Bearing from Startup to Steady-State Thermal Stabilization

The fluid film pressure and temperature fields have been measured simultaneously under laboratory conditions at one land of a circumferential groove journal bearing (CGJB), together with friction torque and oil flow rate, during a time span from stand-still startup to the development of a thermally stabilized steady operating regime.A very fine measurement grid—that is, 216 pressure and 180 temperature points spread across the axial and circumferential directions—has been obtained by joining and synchronizing measurements from separate test runs while rigorously re-creating the test conditions.The study confirmed that the pressure field is established faster than the temperature field, that film rupture occurs both from cavitation nuclei downstream the minimum film thickness and through air ingestion from the environment. Furthermore, the high pressures in the convergent zone stabilize relatively quickly, whereas the low pressures in the divergent zone cavitated region require a longer time to stabilize. The cavitated region reverse flow appearance has been identified thermally through upstream-oriented isotherms. This study is the first to present the transient evolutions of pressure and temperature fields.     

Developments in engine bearing design

Some of the important recent developments in engine bearing design techniques are highlighted. The availability of increased computing power has enabled more realistic assumptions about bearing conditions to be considered; these include oil feed features, oil film history, non-circular bearings, inertia effects due to journal centre movement, improved prediction of main bearing loads, flexible housings and special bearings. References to these advances are made, together with illustrations of how they affect predicted bearing performance. Experimental evidence is also being obtained, which helps to verify and give confidence in the analytical predictions