A Study of Dynamic Phenomena Caused by Impulse Mistuning in Case of Self-Excitation

Further reduction of vibratory stresses of blades and vanes using an appropriate damping system is required whenever the total damping of the stage is insufficient to avoid High Cycle Fatigue during the life of the blades. An alternative to standard friction based damping systems are impulse mistuning systems — a kind of vibration impact induced non-linear energy sink. Previous publications introduced impulse mistuning systems for avoidance of HCF caused by forced synchronous vibrations of blades and vanes. This included the development of the system, analytical predictions of the effectiveness as well as experimental validation. The effectiveness of the impulse mistuning systems in the case of self-excitation (e.g. flutter) has not been investigated yet to the knowledge of the authors. In this paper, a numerical study of the dynamic phenomena taking place in lumped-parameter models with negative damping and different impulse mistuning systems is presented. One of the results shown is that energy transfer takes place, whereby the vibration initiates at one mode and after some time gets transferred into higher vibration at another mode.