Investigation on friction-excited vibration of flexibly supported shafting system

Abstract

Self-excited vibration of a flexibly supported shafting system in a gravity water tunnel was investigated by experiment and numerical simulation. Vibration of the flexibly supported shafting system, such as the acceleration responses of the shaft and the dynamic reaction forces at the propeller support, were measured at different shaft speeds. Experimental results demonstrated that the self-excited vibration, characterized by a single-mode vibration modulated by the shaft speed, emerges as the shaft speed decreases in a speed range. To reveal the mechanism of the self-excited vibration, a fluid-structure coupling model was established. Simulation results show that the instable modes are associated with the rotational vibration modes of the flexible support, which can be easily excited by the circumferential friction, and the coupling between the vibration of the flexible support and the friction of the water-lubricated rubber bearing is the main factor leading to the vibration instability in the flexibly supported shafting system.