Vibrations of a dual-rotor system in aero-engine induced by the support misalignment

In this paper, an analytical model of a rotor-bearing-rotor coupling system is established for aero-engine from the Lagrange equation, based on the dynamics theory of the dual-rotor system and combined with its stiffness, damping, and misalignment characteristics. In the model, the misalignment fault simulation method is introduced. The coupling effect between the low-pressure rotor and high-pressure rotor and the influence of misalignment of the support on low-pressure coupling are considered. The vibration characteristics of the dual-rotor system with the misalignment fault of the low-pressure turbine rear support are studied. The time-domain responses, the frequency spectra, and the shaft-center trajectory of the dual-rotor system with different misalignments are obtained. The influence of unbalance on the vibration characteristics of the low-pressure rotor and the high-pressure rotor with misalignment fault is analyzed. Finally, test verification is carried out by the designed dual-rotor test rig. The experimental results are consistent with the analytical results, confirming the established model's feasibility and simulation method in this paper. The results may provide a theoretical basis for research on the misalignment fault in aero-engine dual-rotor systems.