STUDY ON TRANSIENT VIBRATION OF MISTUNED BLADED DISK PASSING THROUGH RESONANCE

In a variable speed engine, it is impossible to avoid the resonance during operation. In a constant speed engine, the resonance during start-up or shut-down also cannot be avoided. Therefore, the increase of the acceleration rate in passing through the resonance has been considered as one of the effective methods for reducing the vibratory stress of the blade and increasing the reliability of the turbomachinery. In this study, the transient vibration analysis of the mistuned bladed disk passing through the resonance is carried out, using the conventional modal analysis method and the numerical integration method. First, the mistuned bladed disk is modeled by the equivalent spring-mass model, and the steady frequency response analysis is carried out by the Monte Carlo simulation, in order to obtain the worst mistuning pattern. Second, for the mistuned bladed disk of the worst mistuning pattern, the transient vibration analysis in passing through the resonance is carried out, and the effect of the acceleration rate and the blade damping on the transient vibration response is examined in detail. From these results, it is concluded that the larger the acceleration rate is, the smaller the mistuning effect is.