Flow-Induced Vibrations of Metal Bellows

Abstract

Results are given of an experimental and analytical study of longitudinal vibrations resulting from internal flow in metal bellows. It is shown that vortex shedding from the convolutions is the fluid excitation mechanism responsible for the vibrations. An N-degree-of-freedom spring-mass mechanical model is presented which is useful for predicting the bellows frequencies, and methods for estimating the fluid added mass for use in the model are discussed. Results of experiments designed to determine the vortex shedding forces are presented. An argument is given advocating the use of an effective vortex shedding force coefficient for vortex shedding excitation problems because of inaccuracies in experimentally obtained vortex amplitude and phase angle data.