Vibration localization of cracked impellers of centrifugal compressors

With regard to the mistuning and crack problems of centrifugal impellers operating under complex conditions, the effects of crack and mistuning on the forced response and vibration localization of centrifugal impellers were investigated. 3D finite element models of impellers were established for the dynamic analysis of complex impellers. Several contact pairs were defined on the crack surfaces to simulate the nonlinear crack breathing effects. Then, the hybrid interface component mode synthesis method was employed to reduce the number of degrees of freedom of the system. The method can reply the chanllenges of huge computation requirment and convergence in the dynamic response computation of nonlinear system by using directly 3D finite element models. The Monte Carlo method was employed to statistically study the effects of random mistuning and crack fault on the vibration localization of impellers. The results show that both the crack and mistuning will significantly affect the dynamic response of impellers and will lead to the localization of energy on certain blades.