Effect of asymmetric shroud gap and shroud friction coefficient on vibration response of shrouded blades

Abstract

Based on the problem of shroud gap and shroud friction having impact on the blade collision vibration, a three-blade dynamic analysis model considering shroud friction and asymmetric gap is established in the present work. In order to study the effect of asymmetric gap and shroud friction coefficient on the vibration of the twisted shrouded blade in practice. The differential equations of shroud oblique collision between the twisted shrouded blade and adjacent blades were established, and a nonlinear Hertz contact force and an exponentially decaying friction model were used to describe the shroud contact collision force and friction, respectively. Numerical simulation and experiment are used to verify the vibration response of the blade under different gaps. The results show that the shroud movement under the asymmetric gap is more complicated than symmetric gap. The presence of shroud friction causes the passive blades to enter a cyclic motion. And shroud friction coefficient increases will decrease the amplitude of the blade.