Mode and transient response localization occurred in rotating multi-packet blade systems due to random mistuning

In a multi-packet blade system, random mistuning always exists among blades due to several reasons such as manufacturing tolerance, material irregularity and operation wear. It is well known that mistuning in a periodic structure often results in vibration phenomena such as mode and transient response localization. In this paper, a structural dynamic model of a randomly mistuned rotating multi-packet blade system subjected to cyclic nozzle forces is proposed. The accuracy of the proposed model is first validated by comparing its numerical results to those obtained with a finite element model. Then, using the proposed model, the relation between mode and transient response localization is investigated and a design guideline for multi-packet blade systems subjected to cyclic nozzle forces is suggested.