Effects of Twist Angle on Rubbing Induced Vibration Responses of Blade

In rotating machinery, such as axial-flow compressor, gas turbine and aero-engine, the small clearance between the rotational blade and casing can increase the system efficiency, but may also lead to the rubbing between the blade and casing. The severe rubbing can bring about damages of the blade or casing. In this paper, two mathematical models of blade: a uniform-thickness-shell (UTS) model and a uniform-thickness-twisted-shell (UTTS) model, are established to compare the effects of the blade twist angle on the rubbing-induced vibration responses. The natural characteristics obtained from the two models are compared. Dynamic behaviors obtained from two models considering the combined effects of centrifugal force and aerodynamic force are also compared. Moreover, considering the effects of the misalignment angle and radial misalignment, the transient responses caused by rubbing using the two models are discussed. The results exhibit that the resonance in the radial direction cannot be observed when the blade twist angle is ignored (using UTS model). However, this resonance can be observed using the UTTS model, i.e., taking the influences of twist angle into account.