Characteristics of dry friction backward whirl—A self-excited oscillation in rotor-to-stator contact systems

In this paper,the response characteristics of dry friction backward whirl of a general rotor/stator model,which accounts for both the dynamics of the rotor and the stator as well as the friction and the deformation at the contact surfaces,are investigated.The existence boundaries and the whirl frequencies of the dry friction backward whirl are determined analytically.It is found that there are two or three existence boundaries of the dry friction backward whirl that usually form two existence regions,either standing completely separately,or overlapping each other partly,or one containing the other completely,depending upon the system parameters.The whirl frequencies in the two existence regions are quite different and may jump between the lower and the higher values with the variation of the rotating speed.The results have been found to have good correspondence in the related rotor/stator rubbing experiments.

转子/定子碰摩系统的非线性模态及其在干摩擦反向涡动响应预测中的应用

为了分析转子/定子碰摩系统中的非线性模态,确定交叉耦合效应对非线性模态的影响以及非线性模态在预测系统干摩擦反向涡动响应中的作用,针对一个考虑了定子运动学特性以及转子和定子间交叉耦合效应的四自由度转子/定子碰摩系统,用解析方法求解了其线性和非线性模态,分析了系统干摩擦反向涡动响应的涡动频率,确定了激发干摩擦反向涡动的临界速度与系统模态之间的关系。分析结果表明:系统存在2个负的线性模态频率;随着碰摩面摩擦系数的增大,其负的非线性模态频率由1个增加到3个;系统的2个负线性模态频率不但是相应非线性模态的边界,也是干摩擦反向涡动频率的上边界;非线性模态存在的最小摩擦系数就是发生干摩擦反向涡动失稳的最小摩擦系数。此项研究可为转子/定子碰摩系统的响应预测提供新的思路。