箔片气体轴承流场及平箔变形对轴承性能影响的分析

发布时间：2018-02-14 19:30

本文关键词： 波箔式箔片气体轴承端部泄露平箔变形承载力姿态角稳定性　出处：《中国科学院研究生院（工程热物理研究所）》2011年硕士论文　论文类型：学位论文

【摘要】：波箔式箔片气体轴承被广泛应用于各种高速透平机械,但承载力较低仍然是限制其应用的主要原因,为了提升箔片轴承的承载力,学者们不断对箔片气体轴承的结构进行优化与改进。至今为止,波箔式箔片气体轴承已经发展到第四代,承载力也已经得到较大提升。通过对箔片轴承的结构进行优化从而提升承载力是在对箔片轴承静态特性、动态特性的准确预测基础上进行的。对箔片轴承静态特性的分析离不开箔片轴承内部气膜的三维流场分析。本文的研究工作就是在此基础上展开的,主要内容与结论如下： (1)建立了考虑平箔变形和气体可压缩性的耦合求解静态特性的物理模型,利用有限差分法,通过Matlab自编程,完善了箔片轴承的静态特性求解,模拟结果与NASA的实验结果符合较好。并在此基础上研究了箔片轴承参数对轴承承载力及稳定性的影响。 (2)建立了具有压力远场边界的三维网格模型,并用Fluent模拟了轴承内部气膜的三维流场,模拟结果与文献结果符合很好。此外,得到了端部的流场分布、压力分布以及泄露情况,与之前的文献将端部压力设定为环境压力不一样。在流场分析的基础上,初步地分析了不同轴承参数下的流场,分析参数对承载力影响的内部机理。 (3)分别建立了不考虑平箔变形和考虑平箔变形的静态特性耦合求解的物理模型,并将结果进行对比,研究平箔变形对箔片轴承承载力和稳定性的影响,结果显示：平箔变形使得承载力降低,高转速时稳定性降低。通过用Fluent分别模拟了平箔不变形时和平箔变形时的三维流场,研究了平箔变形使承载力降低的流场内部机理：平箔变形使得箔片轴承承载力下降的原因在于平箔变形形成的槽道使得轴承内部的气体的切向流阻增大,从而导致气体切向运动减弱,整个端部的轴向运动增强,泄露增大,而不是因为平箔变形形成的槽道为气体泄露提供了通道,也不是因为平箔变形使得气膜厚度增大从而导致承载力降低。 (4)研究了平箔参数(厚度、弹性模量、泊松比)对平箔变形和轴承性能的影响；鉴于第二代波箔式箔片气体轴承的结构形式,研究了端部波箔刚度对轴承性能的影响。此外,在对箔片轴承端部泄露分析的基础上,研究了端部供气压力对箔片轴承性能的影响。 (5)在平箔参数、端部波箔刚度、端部供气压力分析的基础上,对箔片轴承的平箔参数、端部波箔刚度、端部供气压力进行优化,提升了承载力和稳定性。
[Abstract]:Foil foil gas bearing is widely used in various high speed turbine machinery, but its low bearing capacity is still the main reason to limit its application, in order to enhance the bearing capacity of foil bearings, Scholars continue to optimize and improve the structure of foil gas bearings. So far, foil foil gas bearings have been developed to 4th generations, The bearing capacity has also been greatly improved. By optimizing the structure of foil bearings, the lifting capacity is based on the static characteristics of foil bearings. Based on the accurate prediction of the dynamic characteristics, the analysis of the static characteristics of foil bearing is inseparable from the three-dimensional flow field analysis of the inner film of foil bearing. The main contents and conclusions are as follows:. In this paper, a physical model considering the deformation of foil and the compressibility of gas is established to solve the static characteristics of foil bearings. The finite difference method is used to solve the static characteristics of foil bearings by Matlab self-programming. The simulation results are in good agreement with the experimental results of NASA, and the influence of foil bearing parameters on bearing bearing capacity and stability is studied. (2) A three-dimensional mesh model with a pressure far field boundary is established, and the three-dimensional flow field of the gas film inside the bearing is simulated by Fluent. The simulation results are in good agreement with the literature results. In addition, the distribution of the flow field, the pressure distribution and the leakage at the end of the bearing are obtained. On the basis of the flow field analysis, the flow field under different bearing parameters is preliminarily analyzed, and the internal mechanism of the influence of the parameters on the bearing capacity is analyzed. (3) physical models of coupling solution of static characteristics without and without foil deformation are established, and the effect of foil deformation on bearing capacity and stability is studied by comparing the results. The results show that the deformation of flat foil reduces the bearing capacity and the stability of flat foil at high speed. The three-dimensional flow field of flat foil without deformation is simulated by Fluent. The internal mechanism of the flow field in which the bearing capacity is reduced by the deformation of flat foil is studied. The reason that the bearing capacity of foil is reduced by the deformation of flat foil is that the groove formed by the deformation of flat foil increases the tangential flow resistance of the gas inside the bearing. As a result, the tangential movement of the gas weakens, the axial motion of the entire end increases, and the leakage increases, rather than because the groove formed by the deformation of the flat foil provides the passage for the gas leak. It is not due to the deformation of flat foil that the film thickness increases and the bearing capacity decreases. (4) the effects of foil parameters (thickness, modulus of elasticity, Poisson's ratio) on the deformation of flat foil and bearing performance are studied. In view of the structure form of the second generation foil foil gas bearing, the effect of end wave foil stiffness on bearing performance is studied. Based on the analysis of the tip leakage of foil bearing, the effect of end gas supply pressure on the performance of foil bearing is studied. 5) based on the analysis of foil parameters, end wave foil stiffness and end gas supply pressure, the foil parameters, end wave foil stiffness and end gas supply pressure of foil bearing are optimized, and the bearing capacity and stability are improved.
【学位授予单位】：中国科学院研究生院（工程热物理研究所）
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH133.3

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