有限体积法与正交试验法相结合的动静压轴承结构优化设计

针对小孔节流深浅腔动静压轴承的性能优化问题,基于平行平板扩散流动计算模型及流量守恒原理,推导了微元控制体边界压力的插值函数,提出了分析小孔节流深浅腔动静压轴承的油腔压力、承载力、静刚度、进油流量及温升等承载特性的有限体积计算方法。使用该方法研究了供油压力、主轴转速、进油孔径、浅腔深度、初始油膜厚度等参数对小孔节流深浅腔动静压轴承承载特性的影响规律,从而得到了以上相关参数的优化区间。在此基础上,采用四因素三水平的正交试验法,在满足多目标性能最优的前提下,得到了小孔节流深浅腔动静压轴承结构参数与工作参数的最优组合。以该组参数试制了小孔节流深浅腔动静压轴承并建立了试验平台,测量了不同转速及供油压力下油腔的压力值。试验结果表明,轴承油腔压力试验数据及理论计算值随主轴转速的变化趋势一致;误差在11%以内。验证了有限体积法与正交试验法相结合的动静压轴承结构优化设计方法的正确性。     

A new basis for the optimization of hybrid journal bearings

A design strategy is presented for hybrid hydrodynamic/hydrostatic journal bearings which maximizes the hybrid load for minimum total power dissipation. It is shown that the detailed design of hybrid bearings is quite different from the design of recessed hydrostatic bearings. It is found that design for hybrid operation may lead to substantial increases in load support with significantly less total power dissipation than would be required if the designs were developed from hydrostatic bearing procedures.A new technique for optimizing hybrid journal bearings is presented. The method involves the comparison of the bearings to be optimized with a reference bearing on the basis of load/total power, load/pumping power and load/flow.     

椭圆度对椭圆滑动轴承稳定性的影响

建立了椭圆滑动轴承的油膜力力学模型,并采用基于Sommerfeld数的滑动轴承转子系统稳定性分析方法分析了该模型。利用量纲一运行参数up得到不同椭圆度误差的滑动轴承的稳定性临界曲线。结果表明：滑动轴承轴颈的椭圆度误差对滑动轴承转子系统有显著影响。     

Testing of a Large Adjustable Hydrodynamic Journal Bearing

The design and testing of two novel adjustable hydrodynamic journal bearings are outlined. Each was designed to replace a conventional bearing in a large marine gearbox. They were tested in a land based rig and their performances compared with that of the conventional bearing.

The novel bearings demonstrated the ability to suppress journal centre orbits, to reposition the journal centre in any direction, and to operate with significantly reduced temperature rise. One of the bearings also demonstrated the ability to translate the journal centre in a controlled manner by an amount exceeding double the clearance of the conventional bearing. Implications of such characteristics are considered as potential benefits in various bearing applications.     

基于遗传算法的液体动压轴承优化设计

根据液体动压轴承的承载能力、轴承发热情况和温升建立数学模型,选择遗传算法对液体动压轴承进行优化设计。实例计算的结果表明,此方法符合轴承实际工作性能,能够获得最优化轴承结构参数。     

考虑不同加速工况的滑动轴承的启停性能分析*

滑动轴承的摩擦磨损主要发生在启停阶段。为了研究启停工况下的滑动轴承的摩擦学性能,建立一种面向径向滑动轴承的混合润滑数值分析模型。采用质量守恒边界条件的雷诺方程求解流体压力,采用Greenwood和Tripp接触模型预测固体表面接触,而通过Johnson载荷分配概念将润滑模型和接触模型联系起来,从而实现对滑动轴承在启停工况下从混合润滑过渡到动压润滑的摩擦学行为分析。利用该模型,研究轴承系统在启停阶段从边界润滑、混合润滑到动压润滑演化过程中的摩擦学性能;以径向滑动轴承系统为例,结合不同的轴承转速变化函数,分析轴承加速对轴承启停性能的影响;同时研究工作工况、润滑油温度、轴承的结构参数对轴承启停性能的影响。结果表明：轴承启动加速度在合理范围内越大越好,能使轴承更快进入动压润滑;较高的转速、较低的润滑油温度和较大的径向轴承间隙能使轴承拥有更好的启停性能。     

The possibility of evaluating turbo-set bearing misalignment defects on the basis of bearing trajectory features

This paper presents the results of computer simulation of bearing misalignment defects in a power turbogenerator. This malfunction is typical for great multi-rotor and multi-bearing rotating machines and very common in power turbo-sets. Necessary calculations were carried out by the computer code system MESWIR, developed and used at the IFFM in Gdansk for calculating dynamics of rotors supported on oil bearings. The results are presented in the form of a set of journal and bush trajectories of all turbo-set bearings. Our analysis focuses on the vibrational effects of displacing the two most vulnerable machine bearings in horizontal and vertical directions by the maximum acceptable range calculated with regard to bearing vibration criterion. This assumption required preliminary assessment of the maximum values for the permissible bearing dislocations. We show the relations between the attributes of the particular bearing trajectories and the bearing displacements in relation to their base design position. The shape and dimensions of bearing trajectories are interpreted based on the theory of hydrodynamic lubrication of oil bearings. It was shown that the relative journal trajectories and absolute bush trajectories carry much important information about the dynamic state of the machine, indicating also the way in which bearings are loaded. Therefore, trajectories can be a source of information about the position and direction of bearing misalignments. This article indicates the potential of using trajectory patterns for diagnosing misalignment defects in rotating machines and suggests including sets of trajectory patterns to the knowledge base of a machine diagnostic system.     

CFD analysis of journal bearing hydrodynamic lubrication by Bingham lubricant

Design of smart journal-bearing systems is an important issue that opens up the possibility for semi-active dynamic control of bearing behavior. Recent studies show that there is an increasing interest in designing hydrodynamically lubricated bearings using electro-rheological fluids (ERFs) or magneto-rheological fluids (MRFs). Both smart fluids behave like Bingham fluids, and thus the Bingham plastic model is used to describe the grease and the electro-rheological (ER) and magneto-rheological (MR) fluids behavior of the non-Newtonian fluid flow. The performance characteristics of a hydrodynamic journal bearing lubricated with a Bingham fluid are derived by means of three-dimensional computational fluid dynamics (3-D CFD) analysis. The FLUENT software package is used to calculate the hydrodynamic balance of the journal using the so-called “dynamic mesh” technique. The results obtained from the developed 3-D CFD model are found to be in very good agreement with experimental and analytical data from previous investigations on Bingham fluids.Journal-bearing performance characteristics, such as relative eccentricity, attitude angle, pressure distribution, friction coefficient, lubricant flow rate, and the angle of maximum pressure, are derived and presented for several length over diameter (L/D) bearing ratios and dimensionless shear numbers T₀ of the Bingham fluid. The above diagrams are presented in the form of Raimondi and Boyd charts, and can easily be used in the design and analysis of journal bearings lubricated with Bingham fluids. The core profile formed in the bearing is also calculated and presented for various bearing eccentricities, L/D ratios, and shear numbers T₀, and found to be in very good agreement with previous experimental and theoretical investigations. The analysis presented here leads to charts that could be used by the designer engineer to design smart journal bearings.     

Effect of textured area on the performances of a hydrodynamic journal bearing

A growing interest is given to the textured hydrodynamic lubricated contacts. The use of textured surfaces with different shapes of microcavities (textures) and at different locations of the texture zone can be an effective approach to improve the performance of bearings. The present study examines the texture location influence on the hydrodynamic journal bearing performance. A numerical modelling is used to analyze the cylindrical texture shape effect on the characteristics of a hydrodynamic journal bearing. The theoretical results show that the most important characteristics can be improved through an appropriate arrangement of the textured area on the contact surface.     

Load Capacity Estimation of Foil Air Journal Bearings for Oil-Free Turbomachinery Applications

This paper introduces a simple “Rule of Thumb” (ROT) method to estimate the load capacity of foil air journal bearings, which are self-acting compliant-surface hydrodynamic bearings being considered for Oil-Free turbomachinery applications such as gas turbine engines. The ROT is based on first principles and data available in the literature and it relates bearing load capacity to the bearing size and speed through an empirically based load capacity coefficient, D. It is shown that load capacity is a linear function of bearing surface velocity and bearing projected area. Furthermore, it was found that the load capacity coefficient, D, is related to the design features of the bearing compliant members and operating conditions (speed and ambient temperature). Early bearing designs with basic or “first generation” compliant support elements have relatively low load capacity. More advanced bearings, in which the compliance of the support structure is tailored, have load capacities up to five times those of simpler designs. The ROT enables simplified load capacity estimation for foil air journal bearings and can guide development of new Oil-Free turbomachinery systems.     

Hydro-Roll: A Novel Bearing Design with Superior Thermal Characteristics

A novel journal bearing design, called hydro-roll, which combines a hydrodynamic journal bearing with a rolling-element bearing in series, is presented. The hydro-roll principally operates as a rolling-element bearing at low speeds and as a hydrodynamic bearing at high speed. When properly designed, the hydro-roll can offer superior performance over the conventional hydrodynamic bearing in terms of both wear and thermal characteristics. The hydro-roll prevents the severe wear which occurs during the start-up of hydrodynamic journal bearings since it operates as a rolling-element bearing whenever the sliding friction is too high. This characteristic has the important advantage of reducing the risk of catastrophic failure by bearing seizure.

At a steady high speed, the hydro-roll operates as a hydrodynamic journal bearing while the sleeve together with the inner race of the rolling-element bearing turn at a low speed. This study focuses on the thermal analysis of a journal bearing with a rotating sleeve in comparison to an identical stationary sleeve. The results indicate that the sleeve rotation reduces the risk of bearing failure due to local overheating of the sleeve. The minimum sleeve speed required for this effect is evaluated.     

Novel approach to solve the dynamical porous journal bearing problem

Analytical pressure solutions are a simple and robust way to model plain journal bearings in rotordynamics, but cannot be extended to porous journal bearings. Using the method of weighted residuals—viz. Galerkin's method with global shape functions—a novel and fast approach to solve the dynamical porous journal bearing problem is proposed. This approach allows for the influence of rough surfaces on the hydrodynamic pressure implemented through flow-factors, journal misalignment and calculation of stiffness and damping coefficients for finite bearings. The proposed method will be verified using analytical expressions and new results will be shown for porous journal bearings including the influence of rough surfaces.     

计及轴颈轴向运动的径向滑动轴承润滑分析

以轴-径向滑动轴承系统为研究对象,综合考虑轴颈轴向运动和倾斜,建立了倾斜轴颈的轴承的流体动力润滑模型,采用有限差分法求解Reynolds方程,分析了不同的轴颈倾角、转速、偏心率和轴承间隙下的轴颈轴向运动对倾斜轴颈的轴承润滑性能的影响规律。结果表明：轴颈轴向运动对倾斜轴颈滑动轴承润滑特性影响显著,且影响程度与轴颈倾角和转速有直接的关系,倾角越大,对轴承润滑性能的影响越大,转速越低,对轴承润滑性能的影响越显著;轴承间隙越小,对轴承润滑性能的影响越大。     

动压径向滑动轴承有限元优化设计

本文介绍液体动压润滑径向滑动轴承的自动优化设计方法。它以有限元素法解雷诺方程作为数学模型,优化则使用共轭方向的极小化罚函数法。以摩擦功耗小或稳定性高为目标函数,在给定负荷条件下,求得槽台轴承的最优设计参数组合。构造了表征稳定性的目标函数。编制的程序具有通用性和灵活性。采取偏位角作为设计变量、免去解雷诺方程中的重复积分运算、以及优化过程中的近似分析法等有效措施,获得经济机时,以致不用传统的拟合法,而直接进行动压轴承的优化设计成为切实可行。     

Investigations on a permanent magnetic–hydrodynamic hybrid journal bearing

In the present work, a permanent magnetic–hydrodynamic hybrid journal bearing is developed. The force of the journal bearing comes from the hydrodynamic film and the permanent magnetic field. When a hydrodynamic film does not form, such as during starting and stopping a machine, the journal bearing relies on the magnetic force to support the rotor system. This paper studies a model of the permanent magnetic force and develops an experimental rig of the journal bearing. Experiments show that the hydrodynamic film force uncouples with the magnetic force in the journal bearing. Predictions from the model are compared with experimental data.     

滑动轴承的应力分析

本对发动机的滑动轴承进行了计算,求解了滑动轴承的雷诺方程,粘度方程,密度方程与载荷方程,得到了压力分布与油膜厚度分布,进而通过接触力学分析得到轴承衬内的应力分布。应力分布是影响材料的塑性变形,并对分析滑动轴承的胶合失效有实际意义,因此建议用最大Mises应力来指导滑动轴承的设计。     

微沟槽表面的滑动轴承性能分析

分析了微沟槽表面滑动轴承的润滑性能 ,计算结果表明 ,微沟槽表面轴承的压力分布与光滑表面轴承有着显著不同。轴承表面油槽中的油在油润滑时能防止轴承表面的胶合失效 ,而且这种轴承衬表面层的应力分布与光滑表面轴承也有显著不同。     

Feasibility Study of Hydrodynamic Lubrication in Supporting of Rotating Elements of Galvanizing Hardware Submerged in Molten Zinc

Severe wear of sink roll supports in continuous galvanizing lines has been a cause for concern for some years. This wear, which affects the quality of the coating and downtime costs, is a result of a corrosive environment and highly loaded surface contact.

This paper presents results from a feasibility study to use journal bearings lubricated with molten zinc to separate the interacting surfaces. Analytical and experimental investigations were aimed at identifying the load capacity of sink roll bearings when operating in the hydrodynamic regime, as well as the effect of the molten zinc bath environment on bearing performance. This environment includes chemical zinc attack and the presence of inter-metallic particles in the bath.

The study indicates that it is difficult to achieve hydrodynamic bearing operation for the entire range of operating conditions. It also shows that, when selecting materials for journal bearings support to the rotating elements submerged in molten zinc baths, possible contact of the bearing surfaces as well as chemical inertness and resistance to the hard intermetallic particles do need to be addressed.     

基于ANSYS的轴承保护环的设计

矿山机械中转子-轴承系统采用传统的设计方法很容易发生故障,基于一种新的设计方法,给转子-轴承系统增加了一个轴承保护环,并通过ANSYS有限元分析软件对其形状进行了优化,最后在试验室柔性转子动平衡系统上进行弹性振动试验可知,转轴运动轨迹中的高次谐波信号得到了很好的抑制,轴承保护环使得轴承基本上不与系统发生共振,大大增加了轴承的使用寿命.     

评价箔片径向空气轴承载荷性能的一种经验方法

介绍一种简单的“经验法则”来评价箔片空气轴承的载荷性能,它是一种可挠面的动压气体轴承,正在研究其在无油透平机械中的应用。经验法则是基于基本原理和文献中报道的可靠实验数据得出的,通过一个经验值——载荷系数D,将轴承的载荷性能和轴承的尺寸、速度联系起来。在经验法则中,轴承承载力是轴承转速和轴承设计面积的线性函数。轴承载荷系数D和轴承弹性支承结构的设计特点和轴承运行工况(温度、速度)有关。