19th Asia-Pacific Vibration Conference (APVC2021)

Labyrinth seal is an effective and long-life gas sealing structure widely used in aero engines. As the rotor moves inside the seal chamber with offset relative to the shaft center position, the rotor blade will form a seal excitation force with nonlinear characteristics when moving inside the seal chamber. In this paper, the interaction between the time-varying stiffness of the rolling bearing and the nonlinear dynamic characteristics of the rotor under the labyrinth seal condition is investigated. A finite element model of the bearing-friction-sealed rotor system with rolling bearing time-varying stiffness under maneuvering flight condition is developed. The Newmark-β integration method is used to solve the dynamic equations of the system, and the phase diagram, Poincaré cross section, time domain diagram, bifurcation diagram and three-dimensional spectral diagram of the system response are obtained. The nonlinear dynamic characteristics of the bearing-rotor system with bumper-friction are also analyzed. The results show that: for the sealed rotor system, the time-varying law of the bearing support stiffness becomes more complicated with the increase of the rotational speed, and the overall variation of the stiffness shows an increasing trend; the frequency component of the system is mainly subharmonic resonance, and the amplitude of subharmonic resonance increases with the increase of the rotational speed; the motorized load has a significant influence on the motion state of the system at low and medium speeds, and the stability of the system can be improved when the motorized load takes a specific value.

Time-varying stiffness,Labyrinth Seal,Maneuvering flight,Bearing-rotor systems,Nonlinear dynamics