Analysis of a hydrodynamic thrust bearing with elastic deformation using a recurrent neural network

A theoretical analysis on the general behaviour of a thrust bearing is presented in this paper. The model programme using a method adaptation of finite differences was developed to solve the Reynolds equation for lubrication. The model in the theoretical analysis uses a single one-dimensional grid. The altering of total lubrication load obtained in the result of under-cutting in the thrust bearing have been determined together with the parameters such as oil film thickness and pressure. Parameters such as the pressure and thickness of the oil film were determined. The hydrodynamic behaviour of thrust bearing was analysed by considering of different dimensionless system pressure, speed and geometry of the bearing. The effect of the elastic load due to elastic deflection is taken into account as on the load-bearing characteristics is included. Also, a proposed neural network predictor is utilised to analyse of the general behaviour of thrust bearing. The results of the proposed neural network predictor gives superior performance for analysing of the behaviour of a thrust bearing undergoing in elastic deformation.     

3D Two-way coupled TEHD analysis on the lubricating characteristics of thrust bearings in pump-turbine units by combining CFD and FEA

The thermal elastic hydro dynamic(TEHD) lubrication analysis for the thrust bearing is usually conducted by combining Reynolds equation with finite element analysis(FEA). But it is still a problem to conduct the computation by combining computational fluid dynamics(CFD) and FEA which can simulate the TEHD more accurately. In this paper, by using both direct and separate coupled solutions together, steady TEHD lubrication considering the viscosity-temperature effect for a bidirectional thrust bearing in a pump-turbine unit is simulated combining a 3D CFD model for the oil film with a 3D FEA model for the pad and mirror plate. Cyclic symmetry condition is used in the oil film flow as more reasonable boundary conditions which avoids the oil temperature assumption at the leading and trailing edge. Deformations of the pad and mirror plate are predicted and discussed as well as the distributions of oil film thickness, pressure, temperature. The predicted temperature shows good agreement with measurements, while the pressure shows a reasonable distribution comparing with previous studies. Further analysis of the three-coupled-field reveals the reason of the high pressure and high temperature generated in the film. Finally, the influence of rotational speed of the mirror plate on the lubrication characteristics is illustrated which shows the thrust load should be balanced against the oil film temperature and pressure in optimized designs. This research proposes a thrust bearing computation method by combining CFD and FEA which can do the TEHD analysis more accurately.     

可倾瓦推力轴承系统的稳定性研究

在可倾瓦推力轴承系统中,利用薄膜压力和薄膜厚度的Taylor级数展开式,对瞬态雷诺方程进行了求解,求出了薄膜力和瓦块所受力矩的Taylor级数展开式,建立了镜板和可倾瓦自由振动时的微分方程及其特征方程,以出口处与入口处薄膜厚度的比值,外载荷、瓦块倾角、镜板速度和薄膜动力粘度等为变量,经判断霍尔维茨行列式的值大于零时,表明可倾瓦推力轴承系统具有稳定性。一旦瓦块的支点确定后,出口处入口处薄膜厚度的比值即可确定,而与其它参数无关。镜板和瓦块的运动微分方程可进行解耦合求解。     

Nanosys-1000机床静压止推轴承流场分布规律及承载特性

为了提高Nanosys-1000非球面曲面光学零件超精密加工机床加工精度,研究了机床核心部件静压止推轴承内流场分布规律,进而揭示其承载特性。利用ANSYS/Fluent软件建立对称结构静压止推轴承扇形油垫的仿真模型,采用层流模式对进油压力为1.3~1.9 MPa、油膜厚度为20~36 μm的油垫流场分布规律与承载特性进行分析。研究结果表明：油垫内压力在油腔区域比较均匀,沿封油边呈线性下降;油膜承载力随油腔压力线性增长,且在同一进油压力下,油膜厚度越小,油膜承载力越大,进油压力为1.5 MPa时,油膜厚度从36 μm减小到20 μm,油腔压力从3.05×10⁵ Pa增加到8.02×10⁵ Pa,油膜承载力相应地从880 N增加到2 109 N;同一负载即油膜承载力下,进油压力越高,油膜厚度越大,油膜承载力为1 320 N时,进油压力从1.3 MPa增加到1.9 MPa,油膜厚度从26 μm增加到30 μm;同一油膜厚度下,进油压力越高,润滑油流量越大,油膜厚度为28 μm时,进油压力从1.3 MPa增加到1.9 MPa,润滑油流量从0.179 L/min增加到0.231 L/min。相关研究结果在研制的Nanosys-1000非球面曲面超精密加工机床静压止推轴承上得到了验证。     

银盘水电站推力轴承支撑性能及镜板泵外循环技术研究

为了评估银盘水电站推力轴承支撑性能对机组运行的稳定性以及验证镜板泵外循环技术在设计工况下的冷却效果,通过对不同结构特点推力轴承支撑性能进行分析,阐述了银盘水电站推力轴承弹性油箱支撑结构在轴流转桨式水轮发电机组中自动调整各轴瓦受力平衡的优点;同时,利用流体力学计算公式,对银盘水电站镜板泵外循环系统工作压头和流量进行了计算分析,结合现场机组运行工况进行了试验验证。研究结果表明:采用弹性油箱支撑结构的推力轴承,能使推力轴承轴瓦间受力不均匀的问题得到根本改善,大大提高了机组运行的稳定性;通过计算分析,结合机组运行监测数据,得出了银盘水电站镜板泵实际压头系数和流量系数,证明镜板泵外循环系统能够在设计工况点附近工作,从检测数据来看系统冷却效果较好。     

推力球轴承接触问题有限元分析

推力球轴承是被广泛应用的支承机械,用于承受转速较低的轴向载荷.它是由上下座圈、保持架和球体组成的可分离结构,分为单向推力球轴承和双向推力球轴承两种.着重分析了不同尺寸、形状的球形滚动体和橄榄球形滚动体对接触情况下的应力和变形量的影响.使用Pro/E建立实体模型,导入ANSYS进行数值模拟和计算.通过对获得的数值模拟结果和赫兹理论解进行对比,结果表明有限元分析是比较准确而且可靠的.最大接触应力和弹性趋近量取决于滚动体与滚道接触处的主曲率和、主曲率差,与滚动体形状、体积没有直接联系.     

Performance of synthetic oils in the hydrodynamic regime ‐ II. Generalisation

In Parti I the results of an extensive experimental investigation of the performance of environmentally adapted oils in the hydrodynamic regime were reported. Four oils were tested in a tilting‐pad thrust bearing for different combinations of load, shaft speed, and supply oil temperature. In this second part, details of a generalisation procedure are described. A number of parameters representing the physical properties of an oil, such as viscosity and viscosity‐temperature coefficient, are adopted. The influence of each of these parameters on minimum oil film thickness, maximum temperature rise, and bearing power loss is then analysed. It is shown that viscosity measured at the supply oil temperature is the most important parameter. The effects of the viscosity‐temperature coefficient and oil thermal conductivity are less pronounced and yet significant. It is also shown that it is not possible to select an optimum oil that yields maximised oil film thickness, minimised temperature rise, and minimised power loss at the same time.     

Dynamic stability experiments of compliant foil thrust bearing with viscoelastic support

In order to reduce the complexity of machine construction and improve the mechanical efficiency, high speed rotation machineries usually implement self-acting gas bearings to substitute the traditional oil-lubricated bearings. This paper presents test results of a gas thrust bearing with viscoelastic support which is designed for high speed turbo-machinery. The gas bearing, which belongs to compliant foil bearings, consists of a top thin metal foil and a bottom thin rubber foil. Static and stability experiments are conducted on a high speed gas turbine test rig. The static results indicate that the structural stiffness of test bearing generally increases with the increase in axial load and the decrease in thickness of bottom foil. In the rotation tests, rotor runs stably with small vibration amplitude, which is dominant in waterfall plot during whole speed up procedure. It shows that test bearing has preferable stability characteristics for high speed gas turbines.     

万向铰节点推力关节轴承的力学性能分析

针对推力关节轴承复合受载情况下的安全性能问题,根据某场馆所采用的万向铰节点结构特点与承载特点,利用有限元法对结构中的推力关节轴承进行了两种不同载荷工况下的力学性能分析。利用大型有限元前处理软件ANSA对三维模型进行了网格划分,再通过ANSA与ANSYS软件的接口,准确建立了万向铰节点结构有限元计算模型,并计算出两种工况下推力关节轴承内、外圈的应力分布规律。研究结果表明,压剪工况下,除盖板外,各部件最大应力均比拉剪工况大;且两种工况下,万向铰节点的最大VonMises应力值发生的位置一样,均发生在下部轴承外圈内上边缘,因此该部位有可能会是轴承外圈开裂的起始源处。分析结果为万向铰节点推力关节轴承的设计与改进提供了有益的参考。     

Experiments on thermal effects in a hydrodynamic thrust bearing

The objective of this work is to analyse the characteristics of a fixed-geometry thrust bearing in typical operating conditions and to give experimental results in order to validate future thermohydrodynamic models. The influence of the applied load, the rotational speed and the feeding temperature on the thrust bearing performance is presented and discussed.     

基于热流固耦合的离心压缩机推力轴承温度场预测

针对离心压缩机推力轴承的温度场预测,采用热-流-固多场耦合分析方法,利用专业轴承计算软件THRUST开展有限元仿真分析,在考虑推力盘和瓦块的受力、受热形变的前提下,首先计算得出了推力瓦块的温度分布云图,在此基础上,以转速、轴承载荷、进油温度为主要指标,计算得出不同参数对推力轴承最高瓦温的影响规律。结果表明:提高转速或增加进油温度,轴瓦最高温度会升高,加大轴向载荷最高瓦温同样升高,但趋势变缓。研究结果可为离心压缩机推力轴承的设计、选型、故障诊断提供理论依据。     

磁动压混合推力轴承的研究

提出了一种利用磁场力辅助流体动压轴承工作的磁动压混合推力轴承。这种轴承在机器起动和停车阶段，依靠磁场力支承转子系统，当机器达到一定转速后，主要由动压油膜承受轴上载荷，从而克服了流体动压轴承在此阶段出现混合摩擦的问题。研究了这种混合推力轴承承载能力的数学模型，计算了磁轴承的承载能力。设计制造了试验装置并对这种轴承在不同气隙和转速下的性能进行了试验测试。结果表明这种磁动压混合的工作原理是可行的，可以改善流体动压轴承的工作性能。     

Improving the performance of spring-supported thrust bearing by controlling its deformations

The performance of the spring-supported thrust bearing is studied with three-dimensional thermo-elastic hydrodynamic lubrication theory. The generalized Reynolds equation, the energy equation, the heat conduction equation, and the thermo-elastic deformation equation are solved simultaneously using the combination of the finite difference method and finite element method. Thermo-elastic deformation plays an important role in the performance of the spring-supported thrust bearing. Several factors such as spring pattern, pad thickness and initial pad geometry are analyzed. The results show that the above factors influence the performance of the bearing significantly. Suggestions based on the results are put forward to assist design considerations.     

Design of annular recess hydrostatic thrust bearing under dynamic loading

Design charts are presented of a dynamically loaded thrust bearing with as annular recess. The effect of non-parallelism between the bearing and the runner surfaces is also considered, since this is a common problem in hydrostatic thrust bearings. Based on pre-assigned dynamic excitations the pressure equation is solved numerically by finite difference methods to render the bearing performance characteristics namely: load capacity; bearing stiffness; damping coefficient; and lubricant flow rate. Results concluded that the bearing performance chareacteristics are dependent on the bearing radii ratios, the squeeze number, the bearing number and the tilt parameter.     

Hydrodynamic calculation of a thrust plain bearing that operates with viscoelastic lubricant under turbulent friction conditions

An accurate self-similar solution of the problem on hydrodynamic calculation of the thrust plain bearing that operates at viscoelastic lubricant under turbulent friction conditions has been found. Two fluid states are examined separately: 1) the lubricant is fed into the bearing under total relaxation of an elastic component of deformation, and 2) the lubricant should be under an unstressed state outside the bearing and subjected to sudden shear with a certain speed at the moment of its entering into the bearing. Analysis of the obtained analytical expressions for the bearing’s basic operating performances, including bearing capacity and friction force, makes it possible to design thrust plain bearings with turbulent viscoelastic lubricant, which operate with less power loss than similar bearings with laminar viscoelastic lubricant.     

轮缘推进电机推力轴承水润滑性能分析

轮缘推进电机采用海水润滑,由于海水黏度低,难以建立有效的动压润滑效应。同时随着轮缘推进器的推进功率不断提升,其传递的推力也显著升高。这些问题以及需求对轮缘推进器推力轴承的润滑性能提出了新的挑战。提出一种满足轮缘推进电机推进需求的推力轴承设计方案,结合流体动力润滑理论,建立水润滑推力轴承流体动力学模型,基于有限单元法计算了推力轴承的压力分布和最大温度分布,以及雷诺数和摩擦功耗的变化规律。结果表明：该轮缘推进电机推力轴承的压力集中分布在轴瓦中间部分,并随轴瓦倾角和膜厚而变化;温度分布随转速基本保持不变;高速情况下雷诺数大幅降低;摩擦功耗随转速持续增加。     

袋式阶梯瓦气体止推轴承的分析计算

利用有限元法求解可压缩流体雷诺方程，计算了袋式阶梯瓦气体止推轴承的工作性能，分析了不同结构参数对轴承承载能力的影响，通过计算实例说明，该种轴承具有与螺旋槽气体止推轴承接近的较高承载能力，值得推广应用。     

Design of an offset hydrostatic thrust bearing under dynamic loading conditions

An offset hydrostatic thrust bearing is analysed to determine the effect of vibration of the rotating plate on the performance characteristics. The flow developed is asymmetric because the surface rotation axis is offset from the bearing axis. The governing Reynolds equation is solved using semianalytical methods. The average load capacity, frictional force and lubricant flow rate are strong functions of the bearing offset L, bearing number λ, film thickness profile H, film thickness variation ? and the ratio between the frequency of vibration of the rotating plate and the angular speed of rotation.     

电磁推力轴承的磁场分析及磁路概念设计

用有限元法对同向和反向偏流输入情况下,各种结构布置形式的电磁推力轴承系统,按整体模型进行磁场和承载力的计算分析,较清楚地揭示了它们的变化规律和影响因素。尝试将电磁推力轴承系统的磁路模拟为等效的电路网络,通过串、并联电路分析,对有限元分析结果进行了解释和归纳。据以提出若干指导电磁推力轴承系统磁路设计优化的原则建议。     

A tolerancing procedure for inherently compensated, rectangular aerostatic thrust bearings

Manufacturing errors on aerostatic bearing surfaces and orifice geometry are known to impair performance. Theoretical analyses were carried out on a rectangular thrust bearing for the most common form of gap non-uniformities — tilt, concavity, convexity and waviness at various spatial wavelengths, as well as changes in orifice diameter and position from the bearing edge. The results illustrate the sensitivity of both static load and stiffness to various forms of manufacturing error. A tolerancing procedure is recommended to limit changes in static load and stiffness to 10%.