弹性波箔型动压气体径向轴承的动特性研究-机械设计及理论专业论文.docxVIP

南京航空航天大学硕士学位论文 摘 要 波箔型动压气体轴承以气体为润滑剂，采用弹性箔片为支承元件，依靠柔性箔片与轴颈表 面之间的相对运动所产生的气膜压力来支承转子，实现无接触悬浮。平箔和波箔、波箔和轴承 壳体之间的相互摩擦作用提供较大的结构阻尼，能抑制轴承转子系统的自激涡动和低频涡动的 发展，从而提高了轴承转子系统的稳定性。 建立多自由度弹簧模型,分析柔性箔片的弹性变形,与箔片的壳体模型结果进行比较,耦合 求解气膜厚度方程和 Reynolds 方程，分析轴承的静特性。波箔型气体轴承的动态刚度和动态阻 尼系数是轴颈偏心率、旋转速度及轴心涡动速度的函数，是进行转子临界转速、不平衡响应计 算及稳定性分析不可或缺的基本参数。用两种数值摄动法各自建立了波箔型气体轴承动态特性 系数计算分析的数学模型，应用弹性板壳模型和多自由度弹簧模型分别计算了波箔及平箔的变 形，应用有限差分法及有限元法对模型进行求解，从而获得了波箔型气体轴承的动态特性系数。 将所得结果与已公布的试验数据对比，证明该模型的合理性和精确性，分析偏心率、轴颈转速 和轴颈扰动频率对动态特性系数的影响。 试验方面，设计了轴承性能测试试验台和波箔轴承，计算了转子的临界转速，所做的基础 工作可为波箔型气体轴承的设计提供参考。 关键词：波箔，动压，气体轴承，动态特性系数，摄动法，Reynolds 方程 I 弹性波箔型动压气体径向轴承的动特性研究 弹性波箔型动压气体径向轴承的动特性研究 II II ABSTRACT Gas foil bearings are constructed with corrugated bump foil as an elastic foundation and a smooth top foil. The air is used as a lubricant of the bearings. And the rotor is supported by the film pressure which generated in the clearance between the top foil and the rotor once the rotor achieves a certain speed. Therefore, the bearing could achieve a non-contact suspension. A large structural damping is generated due to the relative motion between the bumps and the top foil, and between the bumps and the housing. The damping could inhibit the development of the self-excited and low-frequency whirl of the bearing-rotor system, in order to enhance the stability of the system. A spring model of multi-degree of freedom has been used to analyze the elastic deformation of the foil, and compare the results with the shell model. Then, the film thickness equation and the Reynolds equation have been coupled to get the steady state performance of gas foil bearings. The dynamic characteristics of a gas foil bearing has been represented by a set of spring and damping coefficients which are functions of the eccentricity ratio, the rotating speed and the whirl frequency of the journal. In addition, these coefficients are the essential parameters, which could be used to determine the critical rotational speed or an unbalance response and investigate the stab