空气静压导轨静态性能的解析计算及分析

空气静压导轨是空气静压止推轴承的一种，在直线气浮导轨中被广泛采用。本文利用线性气源假设，将气膜中气体的二维流动化为一维流动，使雷诺方程得到简单的解析解，推导出空气静压导轨的解析计算公式，并利用该计算公式分析导轨参数对其静态性能的影响，从而为空气静压导轨找到了一种快捷方便的设计方法。     

三坐标测量机气浮导轨滑块结构设计与仿真

静压气浮导轨采用气体润滑,具有无摩擦、热变形小、寿命长等优点,且气膜的误差均化作用显著提高了其运动精度,满足三坐标测量机高精度、高平稳运动需求。为探究三坐标测量机中静压气浮导轨滑块的承载性能,建立了矩形气浮滑块结构模型,滑块内置小孔节流型气浮垫,运用COMSOL有限元仿真软件对其气浮静态承载特性进行仿真分析,验证了结构设计的合理性。     

高精度平面气浮导轨的误差均化效应研究

气浮导轨具有高运行精度、高平稳性的一个重要因素在于气体具有误差均化作用。为了探究误差均化作用的大小,通过多个不同波长的正弦函数来模拟导轨轮廓误差,建立平面气浮导轨物理模型,采用有限差分的数值计算方法求出动气浮导轨在运动过程中的各个平衡位置参数,进而利用最小包容法求出其运行直线度。结果表明:气体润滑很好地实现了气浮导轨误差均化作用,且效果明显;与无气体润滑状态时相比,气浮导轨在通气状态时的运行直线度提高了约一倍,与静导轨轮廓误差相比提高了约2/3。建立的气体误差均化效应计算方法为探究误差均化的影响因素奠定了理论基础。     

高速运行条件下静压气浮导轨摩擦力分析

以静压气浮导轨为研究对象,对导轨气浮块底部气体压力的二维分布规律及影响摩擦力的因素进行了理论分析。在气浮块气膜受力分析的基础上,推导了单孔和多孔矩形气浮块底部气体压力的二维分布方程、气浮导轨摩擦力方程,获得了速度与摩擦力之间的关系。以三坐标测量机为实例进行仿真,结果表明高速运行条件下静压气浮导轨的摩擦力降低了三坐标测量机的定位精度,且其对系统运动速度的影响不可忽略。     

闭式双排节流孔矩形气浮导轨的计算方法(二)

闭式双排节流孔矩形气浮导轨是气浮导轨中最常见的结构,本文推导了它的计算方法,从而为该导轨的设计找到了一条有效、快捷的途径     

基于ADAMS和ANSYS Workbench的气浮导轨防脱气浮塔优化设计

针对在太阳翼展开过程中,气浮吊挂滑车偏向横导轨单边导致气浮垫脱落甚至横导轨卡死等问题,对气浮导轨的防脱气浮塔应力和变形进行了研究。对气浮导轨的防脱气浮塔进行了分析,提出了一种基于ADAMS和ANSYS Workbench联合仿真的方法,运用Solid Works对气浮导轨进行了三维建模,导入ADAMS建立了其多体动力学分析模型,通过动力学仿真分析分别得出了气浮导轨在载荷偏向单边的加速运动过程中防脱气浮塔所受的最大动载荷,利用ANSYS Workbench建立了其有限元模型,对防脱气浮塔进行静强度分析,计算得出了防脱气浮塔的应力、变形,并运用ANSYS Workbench对防脱气浮塔进行结构优化设计,并对优化前后的防脱气浮塔进行对比分析。研究结果表明:优化后的防脱气浮塔的应力和变形大大减小,证明了优化方案的可行性。     

定位运动平台气浮导轨设计

针对高加速度高精度定位气浮平台对气浮导轨高刚度高承栽能力的要求,采用二维线性插值和有限元法推导平面气浮空气轴承的静态性能公式,利用数学软件MATLAB编写有限元程序计算气浮导轨的静态性能并分析相关参数对静态性能的影响.有限元分析结果表明:当气浮平台中节流孔之问的排距与气浮面宽度的比值为一定值、气浮厚度为另一定值时,气浮平台的角刚度和承栽能力得到较优值.研究结果为气浮导轨的静态性能优化提供了理论参考,为气浮平台的结构优化提供了方向.     

矩形空气静压导轨气浮垫的实验性能对比

提出并设计了一种具有弹性薄板可变截面积均压槽的高刚度空气静压导轨气浮垫,用以提高气浮垫的刚度。通过气浮垫性能测试试验台。对新结构气浮垫的承载能力和气膜间隙进行了测定,得到气浮垫的承载力和刚度。通过实验分析,结果表明,在气体压力的作用下,环形弹性薄板产生弹性变形,引起节流面积和均压槽深度的变化,使得新结构气浮垫的刚度较之传统已有气浮垫得到明显提高。新结构矩形空气静压导轨气浮垫具有较广的应用推广空间。     

气浮导轨性能测试实验台设计与分析

在超精密气浮定位平台研究工作中,对静压空气轴承的安装位置对系统影响的研究相对较少,文中介绍了一种新型机械结构的气浮导轨性能测试实验台,实验台导轨滑架采用焊接框架组合结构,实现不同类型气浮轴承的更换及不同数量的气浮轴承的安装,形成不同结构布局的气浮导轨,能够满足多种气浮导轨的实验研究,提高了气浮导轨实验台的利用率和使用范围。此实验台具有机械精度高、系统刚度大、结构稳定性好,安装使用方便等特点。     

静压气浮导轨承载能力的解析法和有限元法对比分析

承载能力是静压气浮导轨的一个重要的静态性能指标.采用解析法和有限元分析法2种方法计算了闭式矩形静压气浮导轨的承载能力.结果表明:闭式矩形静压气浮导轨的承载能力随供气压力的增大而增大;2种方法计算结果具有较好的一致性,其中有限元法实现了对气体流场的三维仿真,不仅考虑了扩散效应的影响,而且把求解域从传统的薄膜区扩展到节流孔上游,可考虑更多因素的影响,结果更符合实际情况.     

星轮减速器转臂轴承组件的有限元分析

本文应用ANSYS软件,对星轮减速器的转臂轴承组件进行有限元分析。介绍了基于ANSYS的网格划分和接触对建立的方法,阐述了其对有限元分析结果的影响。经分析结果验证,转臂轴承满足承载要求,其应力集中在滚子与内外圈的接触面上,为进一步分析星轮减速器的性能奠定了基础。     

Non-contact position control via fluid shear force

Non-contact position control of components is beneficial to avoid wear, damage, and nonlinearities associated with friction. Air bearings, in particular, offer non-contact, high stiffness guidance, but no means of controlling the position of the supported component. In this work, we investigate the use of shear force resulting from the air bearing fluid flow as a means of actuation. Shear force actuation is tested in an air bearing slumping system, where a flat, horizontally placed glass substrate is supported on both sides by top and bottom air bearings. We investigate the use of two methods of substrate position sensing: a fiber-optic sensor and a machine vision sensor. We show that the glass substrate position can be successfully controlled by using fluid shear force. The magnitude of the fluid shear force is measured. System identification is performed, and the results are shown to agree with a second-order model.     

复合节流的静压导轨设计及其稳定性分析

就表面复合节流方式的静压导轨建立一维流动数学模型,从理论上推导出其承载能力与刚度的计算方法。根据气体质量变化连续性特点,建立了表面复合节流方式的静压导轨动态方程,由此对表面复合节流方式的静压导轨进行了稳定性分析,为表面复合节流方式的静压导轨的设计提供了一种理论计算方法。     

Large Bearing Number Stability Analysis for Tango Class Gas Bearing Sliders

Air bearing sliders in the Tango class use load bearing pads with inlet-throttled leading edges to control the mass flux and lift. The influence of leakage or diffusion effects is always present in real sliders. In some designs such as railed taper flat designs leakage is dominant. The behavior of such sliders must be determined with numerical methods that obscure deeper understanding. Many aspects of the behavior of Tango class sliders can be understood with the vast simplification allowed by inlet throttling. In this paper such a simplified analysis is applied to describe a complete air bearing slider composed of two pads. The conditions for static level flight are determined, as well as the linear stability of heaving and pitching oscillations. Both stable and unstable modes are identified. Either damping or amplification can result from convective effects in the absence of mechanical damping. In real implementations of Tango class sliders instability has not been observed thanks to diffusion. The present analysis can serve as a guide to select initial choices for the operating parameters that correspond to maximum convective damping.     

Thermal Management Techniques for Oil-Free Turbomachinery Systems

Tests were performed to evaluate three different methods of utilizing air to provide thermal management control for compliant journal foil air bearings. The effectiveness of the methods was based on bearing bulk temperature and axial thermal gradient reductions during air delivery. The first method utilized direct impingement of air on the inner surface of a hollow test journal during operation. The second, less indirect method achieved heat removal by blowing air inside the test journal parallel to the shaft axis to simulate air flowing axially through a hollow shaft. The third method emulated the most common approach to removing heat by forcing air axially through the bearing's support structure. Internal bearing temperatures were measured with three type K thermocouples embedded in the bearing that measured general internal temperatures and axial thermal gradients. Testing was performed in a 1 atm, 260°C ambient environment with the bearing operating at 60 krpm, and supporting a load of 222 N. Air volumetric flows of 0.06, 0.11, and 0.17 m³/min at approximately 150 to 200°C were used.

The tests indicate that all three methods provide thermal management but at different levels of effectiveness. Axial cooling of the bearing support structure had a greater effect on the bulk temperature for each air flow and demonstrated that the thermal gradients could be influenced by the directionality of the air flow. Direct air impingement on the journal's inside surface provided uniform reductions in both bulk temperature and thermal gradients. Similar to the direct method, indirect journal cooling had a uniform cooling effect on both bulk temperatures and thermal gradients but was the least effective of the three methods.     

Air Vortices and Nano-Vibration of Aerostatic Bearings

Small vibration on the order of nanometers poses challenges for the application of aerostatic bearings in ultra-precision machine tools and metrology equipments. In this article, the flow field in aerostatic bearings is numerically investigated and air vortices in the recess are analyzed. Vibration of the aerostatic bearing is also experimentally measured. Design and functioning parameters are varied to study their effects on the air vortices and nano-vibration of aerostatic bearings, and a direct relationship is established between the gas vortices and nano-vibration in aerostatic bearings. It is demonstrated that vibration energy of the aerostatic bearing increases with the strength of air vortices.     

透平膨胀机气体轴承的数值模拟

应用ANSYS有限元软件对透平膨胀机的核心部件——气体轴承进行模态分析和谐响应分析,求解转子的振型、应力分布、固有频率和失稳转速。并对不同轴承半径间隙时的转子动力学分析,根据失稳转速的变化规律,得出所设计的双排径向静压气体轴承的最佳轴承半径间隙:Cr=0.02 mm。     

轴承腔中均匀流体/壁面油膜分层流动分析

航空发动机轴承腔精确的润滑与换热设计依赖于对其内油气两相润滑介质流动与换热本质的认识。针对轴承腔内复杂的油气两相润滑介质流动状态,建立轴承腔均匀流体/壁面油膜分层流动分析模型,开展腔内油气两相润滑介质流动特性研究,探讨转子转速和润滑油供油量对均匀流体和壁面油膜两相介质压力、速度以及温度分布的影响。分析模型中,气相介质(含油滴)的等效物理特征参数通过离散油滴和气相介质的组分比例关系确定,各固体壁面与流体介质的对流换热系数根据其各自的传热特性确定。研究结果表明,均匀流体与壁面油膜两相介质的压力随着润滑油供油量的增加而增大,受转子转速的影响较为复杂;均匀流体与壁面油膜两相介质的速度随着转子转速的增高而增大,受润滑油供油量影响较小;均匀流体的温度随着润滑油供油量的增加而减小,受转子转速的影响较小;与均匀流体温度不同,壁面油膜的温度随着转子转速的增加而增大,随着润滑油供油量的增加而减小。建立了轴承腔试验台系统,开展了轴承腔油气两相流动状态下的压力和温度测试,压力和温度试验结果与理论计算结果均具有较好的吻合性,验证了提出的理论分析方法的可靠性。     

基于降噪研究的导流罩设计

针对铁路提速后高速列车集电部气动噪声过大的问题,在集电部引入导流罩,根据前倾角、引导面长度、前倾面与引导面的导圆半径这三个参数设计导流罩,应用Fluent对不同导流罩的外流场和气动噪声进行数值模拟和分析。计算结果表明,当导流罩的前倾角越小、引导面的长度越长、前倾面与引导面的导圆半径越大时,导流罩的表面总声功率与阻力系数越小。