基于弹性壳体模型的波箔型动压气体径向轴承动特性分析

Hydrodynamic Characteristics Analysis of Bump Foil Aerodynamic Journal Bearings Based on Elastic Shell Model

波箔型气体轴承的动态纲度和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。用摄动法建立波箔型气体轴承动特性系数计算分析的数学模型,应用弹性板壳模型计算波箔及平箔的变形,应用有限差分法及有限元法耦合对模型进行求解,获得波箔型气体轴承的动特性系数。将所得结果与已公布的实验数据对比,证明该模型的合理性和精确性。分析偏心率和轴颈转速对动特性系数的影响,结果表明,刚度系数随偏心率和轴颈转速的增加而递增,阻尼系数随偏心率和轴颈转速的增加而递减。

The dynamic characteristics of a gas foil bearing can be represented by a set of spring and damping coefficients which are functions of eccentricity ratio, rotating speed and whirl frequency of the journal. In addition, these coefficients which can be used directly in a critical speed calculation or an unbalance response calculation and in a stability in- vestigation are the essential parameters. A perturbation method was used to develop a mathematic model which can be used for gas foil bearings dynamic coefficients calculation. An elastic shell model was used to calculate the deformation of the bump foil and the top foil. The finite difference method and the finite element method were coupled to solve the model. The dynamic characteristics of the gas foil bearings were obtained. With the results compared to the published experimental data, the model was proved to be correct and accurate. The effects of eccentricity ratio and shaft speed on the dynamic coefficients were discussed. The results show that the stiffness coefficients increase with the increase of eccentricity ratio and shaft speed, while the damping coefficients decrease with the increase of eccentricity ratio and shaft speed.