微小型气体轴承高速透平机械研究进展

阐述了国内外微小型气体轴承高速透平机械的发展概况.介绍了空间制冷机及微小型燃气透平中,以通常机加工方法制作的微型三可倾瓦动压气体轴承、箔片动压气体轴承、微型静压气体轴承的国内外研制发展现况.     

国内首个现代箔片气体动压轴承技术培训班在长沙成功举办

正为了提高透平机械行业技术人员对现代箔片气体动压轴承技术的全面深入了解,拓展气体轴承在透平机械及更多领域内的应用,加快国内箔片气体动压轴承的产业化进程,2021年6月19-20日,由中国国际透平机械产业联盟、沈阳鼓风机研究所和风机技术杂志社主办的国内"现代箔片气体动压轴承技术培训班"在长沙召开,本次培训得到了业内广泛的关注和热烈反响,来自于99家单位的187名学员参加了培训。     

高速透平箔片动压气体轴承固体润滑涂层研究进展

箔片动压气体轴承广泛应用于高速透平膨胀机、微小型燃气轮机、涡轮增压机等高速透平机械中。固体润滑涂层可为箔片动压气体轴承提供启停阶段的润滑保护,对保证箔片动压气体轴承稳定性与使用寿命至关重要。本文回顾了国内外箔片动压气体轴承固体润滑涂层的研究历史与现状;结合文献资料着重分析了PS系列、Korolon系列和DLC系列的固体润滑涂层特性,并对其应用场合和优缺点进行了探讨。     

高速动压气体轴承箔片材料表面处理的探讨

针对高速透平机械动压气体轴承——箔片式气体轴承金属箔片材料的表面处理问题进行了一定的探讨。对箔片式气体轴承箔片材料的选择、材料的表面处理方法以及该轴承的启停性能和稳定性进行了实验研究。分析表明：通过对箔片材料及表面处理方法的合理选择，可以显著改善箔片式动压气体轴承的启停性能。     

弹性支承箔片动压气体径向轴承的实验研究

对新型结构弹性支承箔片动压气体径向轴承进行试验研究,在高速透平膨胀机(主轴轴径D=25.0mm、转子总长l=250.5mm、转子质量Gm=891g、额定工作转速10.64×104r/min)上达到了转子转速14.8×104r/min、超速40%的良好试验效果。对这种弹性支承箔片动压气体径向轴承的振动特性和稳定性进行试验研究。结果表明,该轴承具有优良的动态特性与稳定性,能有效抑制高速自激涡动的发展,在正确选择结构参数和表面处理方法后,有望替代目前在高速透平机械中广泛应用的静压气体轴承。     

箔片式动压空气轴承试验研究

箔片式动压空气轴承是一种以箔片为弹性支承的自作用式动压气体轴承,因其优越的动力学性能广泛应用于高速透平机械、高精密机床以及航空、航天、国防等高端装备领域.箔片式动压空气轴承采用空气为润滑介质,根据动压润滑原理,轴颈与轴承间需要达到一定的相对速度,所形成的动压气膜才能克服转子径向力,使轴颈与轴承脱离机械接触,即转速要达到...     

弹性箔片轴承的研究进展*

近年来,弹性箔片轴承在高速透平机械的应用中展现出巨大的潜力。为获取轴承高承载力、减少轴承启停过程的摩擦与磨损、提高轴承的高速稳定性,研究人员开展了大量的理论、实验与应用研究。从弹性箔片轴承的结构特性、涂层特性和建模方法3个方面对气体弹性箔片轴承的研究进展进行综述。首先从轴承结构优化的角度,介绍箔片轴承结构改进的发展历程,以及具有新颖结构设计的多叶搭接式弹性动压箔片轴承及其优点;然后从减少轴承启、停阶段摩擦力,提高弹性箔片轴承使用寿命的角度出发,比较分析了应用广泛的多种涂层,总结国内外新型润滑剂的适用条件及减摩效果;最后从轴承建模角度,介绍经典的简单弹性模型、考虑箔间摩擦力与分离等影响因素的系列复杂模型,为后续模型构建与性能分析提供依据。展望弹性箔片轴承在高精尖等领域的前景,并对弹性箔片轴承的研究方向提出了建议。     

日本压缩机、鼓风机和通风机的发展趋势

本文阐述了日本压缩机、鼓风机和通风机等气体透平机械的最新发展趋势;介绍了透平机械与能源的关系、透平机械的技术发展动向及有关的实例。     

电磁轴承在透平膨胀机中的应用研究进展

电磁轴承是目前发展迅速的新一代支承部件 ,在国外已有许多应用实例 ,透平机械是其主要应用领域之一。介绍此项技术的主要特点及在国内透平机械应用领域中的研究进展情况 ,结合我们的获得的试验结果 ,分析讨论试验过程中出现的部分现象及产生的主要原因     

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。     

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.     

环形节流孔径向静压气体轴承的数值仿真

以环形节流孔径向静压气体轴承为研究对象,介绍了静压气体轴承的结构形式和工作原理,对气体润滑理论基础Reynolds方程进行了分析,利用计算流体动力学软件FLUENT对气体轴承的流场进行仿真分析,求解出了轴承气膜的压力分布.在轴承几何参数不变的情况下,分析了承载力与空气质量流量随不同供气压力和偏心率变化关系,并研究了静压气体轴承在高速工作下,动压效应对承载力的影响.     

高速精密角接触球轴承结构及性能

以高速精密角接触球轴承为对象 ,介绍了它的基本结构和结构参数 ,定性分析了它们对轴承高速性能和刚性性能的影响 ,给出了用于高速旋转和超高速旋转应用场合轴承结构及结构参数的确定原则。这些确定原则对其他高速精密轴承也有一定的借鉴作用。附图 1幅 ,参考文献 11篇     

On the Fluid Flow and Thermal Analysis of a Compliant Surface Foil Bearing and Seal

Foil gas bearings have been applied successfully to a wide range of high-speed rotating machinery such as air cycle machines (ACMs) and auxiliary power units (APUs). The performance of these bearings are based on the high pressure gas in a very thin layer between the journal and the bearing governed by the Reynolds equations. Generation of heat in these bearings especially at high journal rotating speed and high loads or at high ambient temperature directly affect their performance. Thermal and fluid flow analysis of an advanced compliant foil journal bearing/seal are presented. The side flow (known as leakage) and the approximate temperatures are the results of this analysis. The result of preliminary analysis shows that the major portion of the heat is carried through conduction and using the modified Couette flow approximation for the present working fluid, air, helped in analysis of the temperature magnitude, which can be related to the gas viscosity behavior and thin gas film thicknesses.     

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.     

A Method to Calculate Frictional Effects in Oil-Lubricated Ball Bearings

Friction and heat generation in oil-lubricated ball bearings is mainly the result of sliding in the ball-raceway contacts and agitation of the lubricant in the free space between the balls, cage. and bearing rings. Endurance of a ball bearing is highly dependent on the thicknesses of the oil films which serve to separate the balls from the raceways in a well-lubricated bearing. The film thicknesses, in turn, are dependent upon the lubricant's viscous properties. These are functions of bearing temperatures and are determined by the balance between the rates of frictional heat generation and heat dissipation. Therefore, in the design of a ball bearing application such as the high speed rotor and low speed rotor support bearings in an aircraft gas turbine, it is important to be able to predict the bearing frictional heat generation rates with reasonable accuracy. This paper presents a method to perform the required calculations considering hearing loading and speeds, realistic lubricant rheological properties, and a relatively simple heat transfer system between the hearing rings, halls. And lubricant. The results of the analysis are shown to compare favorably with experimental data.     

Hybrid journal bearings with particular reference to hole-entry configurations

There is a spectrum of pressure-fed journal bearings ranging from the purely hydrostatic bearing characteristics, ie zero speed operation, to the purely hydrodynamic bearing characteristics which depend completely on speed. Between these two extremes, hybrid bearing characteristics rely on mixed modes of external pressurisation and speed-dependent pressurisation. Large high speed hydrodynamic bearings require the lubricant to be pumped under pressure for temperature control. It is therefore attractive to use this external source of pressure to enhance the start-up performance by reducing wear and improving stability. Hybrid bearings offer the possibility of improving on both the zero-speed characteristics of hydrostatic bearings and on the whole range of speed characteristics of hydrodynamic bearings. It is concluded that hole-entry bearings may be particularly effective when compared with other bearing configurations for good load support and low energy consumption, when used in any of the four modes of operation including: zero-speed hydrostatic mode; high-speed hydrodynamic mode; zero and high-speed hybrid mode; and jacking mode where areas are pressurised for start-up. A modification to the procedure for solving the Reynolds equation is introduced to cope with cavitated regions. The technique presented for solving the bearing pressures and cavitation boundaries is efficient and has relevance to any type of liquid film bearing     

钢制和陶瓷圆柱滚子轴承高速性能的有限元分析

在高速圆柱滚子轴承理论研究的基础上,对普通钢制轴承和陶瓷轴承进行有限元分析,研究了转速对接触应力和等效应力的影响.结果表明,高速轴承的疲劳寿命主要取决于滚动体作用于外圈的离心力,减小滚动体离心力是提高此类轴承寿命的最有效途径;在中、低速时,钢轴承的寿命和可靠性均好于陶瓷轴承.但当转速达到高速时,陶瓷轴承在寿命方面显示出更大的优势.为陶瓷轴承的设计与应用提供参考.     

Measurements of Compressibility Effects in Stepped Thrust Gas Film Bearings

Hydrodynamic gas film bearings are used for supporting high-speed, lightly loaded rotating machinery. Stepped-type gas film bearings are often used for such machinery because of theïr simple structure, high stability and load carrying capacity. This paper describes the measurements of compressibility effects on the static and dynamic characteristics of stepped thrust gas film bearings. In the experiments, the minimum film thickness, friction torque on the bearing surface and stiffness and damping coefficients of gas films are measured for a range of rotational speed from 10,000 rpm to 20,000 rpm under a constant stator mass and a fixed step height. The measured data are compared with the theoretical results and the gas film compressibility effects on the static and dynamic characteristics of the bearings are discussed. The experimental results agree well with the predicted results based on the compressible lubrication theory.     

Wave Journal Bearing with Compressible Lubricant—Part II: A Comparison of the Wave Bearing with a Wave-Groove Bearing and a Lobe Bearing

To identify the potential advantages of the wave journal bearing, a three-wave journal bearing was compared to both a three-wave-groove bearing (a wave bearing with axial grooves that isolate each wave) and a three-lobe bearing. The lobe bearing's profile was selected to approximate the wave journal bearing's profile. The lubricant was assumed to be compressible (gas). The bearing number, A, was parameterized from 0.01 to 100, and the eccentricity ratio, ε, was varied from 0 to 0.4. Data at bearing numbers 0.1, 1, and 50, and eccentricity ratios of 0.1 and 0.4, were selected as representative of the bearing performance. The calculated load capacity and the critical mass are presented for the three bearings. The wave bearing shows a better load capacity than the other bearings at any applied load and running regime. However, at high bearing numbers the lubricant compressibility effect is predominant and all three analyzed bearings show similar load capacity. The critical masses of the wave-groove and lobe bearing are greater than the critical mass of the wave bearing if the applied load is small. For low and intermediate bearing numbers the wave-groove bearing is more stable than the other bearings especially at low wave's amplitude ratio. The lobe bearing is more stable than the other analyzed bearings at high bearing numbers or at large preload ratios. If the applied load increases, the wave bearing dynamic performance is competitive with both wave-groove and lobe bearings. In addition, at high bearing numbers, the wave bearing could run stably for any allocated rotor mass over a wide range of wave position angle. Three wave bearings are more sensitive to the direction of the applied load than the other bearings especially at low and intermediate bearing numbers. Therefore, a careful selection of the waves position angle has to be done to maximize the wave bearing performance.