Explanation of the snubbing mechanism on vibration reduction by means of chaos metrics

Abstract

Snubbing has been proposed as a possible mechanism to reduce blade vibration of turbo machinery in resonant condition. It consists in physically limiting the vibration amplitude on the blade tip, leaving a small gap between the shrouds of adjacent blades. When the relative displacement between adjacent blades exceeds the gap, a contact occurs between the shrouds, the relative motion is restricted and energy is dissipated by friction and impact during the contact. Whilst effectiveness of snubbing has been proven in the practice on test benches and theoretical models have been developed to simulate bladed disk response in presence of snubbing, the explanation of its actual effectiveness is by intuition. In this paper, the authors propose an explanation of snubbing effectiveness to reduce blade vibrations in resonant condition, by investigating the relationship between vibration reduction and chaos onset using a suitable chaos metrics.