椭圆轴承－转子耦合系统动力学特性研究

摘要

In order to study lubrication characteristics of an elliptical bearing and the nonlinear dynamic behaviors of a rotor-bearing system,an unsteady flow field was calculated by employing a new dynamic mesh approach based on structured grid.A weak-coupling calculation between oil film in a journal bearing and rotor dynamic behaviors was realized by transferring data between two domains.An analysis was performed to study the transient operation process of journal bearings with different structures using their inner lubrication flow field.Through discussion and calculation for influences of rotating speed,amount of unbalance and structural parameters on the bearing-rotor system's working performance,it was shown that the effects of the tip clearance on the stability is larger than those of the side clearance;the whirling center of the journal is related to not only rotating speed but also dynamic load;with increase in amount of unbalance,the whirling center is close to the coordinate origin to cause a decrease in the stability margin.The results provided a theoretical basis for studying dynamic characteristics of elliptical bearings and stability of a rotor-bearing system.%为研究椭圆轴承的润滑特性及转子－轴承系统的非线性动力学特性，采用适用于椭圆轴承的变流域动网格方法实现了润滑流场的非稳态计算，通过在润滑流场与转子系统间进行数据传递，形成了椭圆轴承润滑流场与转子动力学之间的弱耦合计算。从滑动轴承润滑流场内部分析了圆柱和椭圆轴承的瞬态工作过程，比较了上轴瓦的油膜压力分布及承载力的变化情况。分别就轴承结构参数、转速和不平衡量对轴承－转子系统工作特性的影响展开讨论，数值计算表明，椭圆轴承在 x，y 方向的支撑刚度不一样，对稳定性起主要作用为顶隙；轴颈的涡动中心不仅决定于转速，而且随动载荷的变化而变化，随着不平衡量的增加，涡动中心逐渐向坐标原点靠近，使转子－轴承系统稳定裕度降低。该方法为椭圆轴承动力特性及转子－轴承系统稳定性的研究提供了理论支持。