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首页> 外文学位 >Tilt pad bearing effects on rotordynamic stability and improvements in global system dynamic analysis.
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Tilt pad bearing effects on rotordynamic stability and improvements in global system dynamic analysis.

机译：倾斜垫轴承对转子动力学稳定性的影响以及整体系统动力学分析的改进。

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摘要

A general method of incorporating pad flexibility effects into isothermal tilting pad bearing analysis is developed. The pad assembly approach is extended using two-dimensional finite elements to determine pad deformations of a single pad. The pad deformations are represented by a single degree of freedom, the change in the pad radius of curvature, thus the current method is an approximate approach. The equations to calculate frequency reduced coefficients for a single pad are developed. Synchronously reduced coefficients for a single pad are in agreement with previous curved beam approximate methods and a more rigorous iterative approach. The finite element pad model provides more versatility in modeling nonuniform pad dimensions and the skewed boundary conditions which occur at the spherical pivot-pad socket interface. Pad and pivot flexibility effects are studied in an actual bearing. Pad flexibility is shown to decrease the predicted instability onset speed of the rotor-bearing system. The use of complex eigenvalue-dependent bearing coefficients as compared with synchronously reduced coefficients is seen to produce a more significant decrease in the instability onset speed. Further reductions in the instability onset speed are obtained by including pivot stiffness in the complex eigenvalue-dependent bearing coefficients.;Relative and absolute shaft vibration data have revealed that the commonly made assumption of rigidly supported bearings may be grossly inaccurate, especially for fans, generator sets, and natural gas transmission compressors. This research also provides a systematic method for modeling flexibly mounted rotating machinery utilizing eight node isoparametric three-dimensional finite elements for the foundation and four node isoparametric "patch" type boundary elements for the soil. The rotor is modeled utilizing Euler-Bernoulli beam elements and includes disk gyroscopics and cross coupled bearing coefficients. The large number of degrees of freedom included in the model is reduced utilizing a nested superelement scheme and Guyan reduction.
机译：开发了将垫块柔韧性效应纳入等温可倾瓦块轴承分析的一般方法。使用二维有限元扩展了垫组装方法，以确定单个垫的垫变形。垫变形由单个自由度，垫曲率半径的变化表示，因此当前方法是一种近似方法。开发了用于计算单个焊盘的降频系数的方程式。单个焊盘的同步减小系数与以前的弯曲梁近似方法和更严格的迭代方法一致。有限元垫模型在建模不均匀的垫尺寸和在球形枢轴-垫插座接口处出现的偏斜边界条件时提供了更多的功能。在实际的轴承中研究了垫和枢轴的柔韧性影响。垫的柔韧性显示出降低了转子轴承系统预计的不稳定性开始速度。与同步减小的系数相比，使用与特征值相关的复杂轴承系数，可以看到不稳定性起步速度的明显降低。通过将枢轴刚度包括在与特征值相关的复杂轴承系数中，可以进一步降低不稳定性开始速度。相对和绝对轴振动数据表明，通常对刚性支撑轴承的假设可能非常不准确，特别是对于风扇，发电机套和天然气传输压缩机。该研究还提供了一种系统化的方法来建模柔性安装的旋转机械，该方法使用八个节点等参三维有限元作为基础，并使用四个节点等参“面片”型边界元素作为土壤。转子是利用Euler-Bernoulli梁单元建模的，包括圆盘陀螺仪和交叉耦合的轴承系数。利用嵌套的超元素方案和Guyan缩减来减少模型中包含的大量自由度。

著录项

  • 作者

    Earles, Larry Lee.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Applied Mechanics.;Engineering Mechanical.;Engineering Civil.
  • 学位 Ph.D.
  • 年度 1989
  • 页码 320 p.
  • 总页数 320
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 应用力学;建筑科学;机械、仪表工业;
  • 关键词

  • 入库时间 2022-08-17 11:50:43

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