Abstract:

In addition to blade-to-casing rubbing, drum-to-labyrinth rubbing is another common interaction in aero-engines. In this study, the labyrinth seal is simplified and modeled as an inner ring. First, considering the flexibility of both the drum and inner ring, a novel rubbing force model applicable to drum-inner ring rubbing is proposed, and this model is partially validated with the measured vibration responses. Incorporating both drum-inner ring rubbing faults and bolt joint effects, a dynamic model of the shaft-disk-drum-inner ring-vane-casing system (SDDIRVCS) is established with beam-shell hybrid elements to investigate the nonlinear dynamic responses induced by rubbing at various rotational speeds. The established dynamic model of the SDDIRVCS is validated by the comparison of its modal characteristics with those obtained from the ANSYS simulations. The results indicate that the rotor spectrum is dominated by odd-multiple harmonics, while the stator spectrum exhibits prominent even-multiple harmonics. Moreover, the rubbing location between the drum and the inner ring varies with the dynamic behavior of the rotor system.

Key words: shaft-disk-drum-inner ring-vane-casing system (SDDIRVCS), vibration characteristic, drum-inner ring rubbing fault, bolted joint, finite element method (FEM)