Transient Analysis for a Twin Spool Rotor with Squeeze-Film Dampers Considering Blade Loss

Abstract

The transient, nonlinear vibration of a twin spool rotor assembly in the situation of blade loss should be accurately examined. To relate the macroscopic vibration of the rotor with blade damage, a power-function based model is proposed to express the mass unbalance force to the rotor during the blade loss, which is different from the traditional loading using the step function. With this function the characteristics of damage growth with time is exhibited for both foreign object damage and high fatigues of engine blades. The governing equation of transient rotordynamics considering nonlinear squeeze-film damping force is derived and solved numerically in fault operations using different blade loss parameters. Various cases of different blade loss durations have been simulated with the proposed function. It is demonstrated through results that the present model of loading is suitable for transient analysis for the damaged rotor due to blade losses by foreign object impact and high-cycle fatigues.