突加不平衡激励碰摩转子反向涡动分析

A modified rotor with blade-casing rubbing and squeeze film damping was established and the criteria for instability of rubbing rotor were derived. The dynamic characteristic of rotor with sudden unbalance was analyzed from nonlinear mode view and the mechanism and existence conditions of backward whirl response were revealed. The sensitive parameters and influence laws on backward whirl were obtained and the response characteristics of the backward whirl rotor were used to analyze an aero-engine sudden unbalance failure. The calculation results show that two conditions should be met for backward whirl rotor. One is that the rotor has modal damping instability region of backward whirl motion; the other is that the excitation of sudden unbalance makes the rotor amplitude reach the modal damping instability point and enter the modal damping instability region. In actual aero-engine rotors, there is a risk of backward whirl due to the sudden unbalance, which will cause damage to the supporting structure and seriously threaten the safety of aero-engine. Reducing the blade stiffness, increasing the damping of the rotor, reducing the rotor-stator friction coefficient and adopting squeeze film damping design are all beneficial to reduce the risk.