Flow-Induced Vibrations in Bellows

Abstract

Flow-induced vibrations have caused fatigue failures in a number of bellows units carrying cooling water flows. The bellows are made from Inconel 600 and have a nominal inside diameter of 20 mm. This paper presents the results of a project undertaken to study these vibrations and to develop a method for vibration alleviation. The experiments were conducted on prototype bellows with vibration amplitudes and frequency spectra being observed as a function of flow velocity. The bellows exhibit flow-induced resonant peaks with successively higher modes being excited by increasing flow velocities. The upstream flow geometry used in service conditions was found to reduce the mean flow velocity required to produce resonance. A fine stainless steel wire mesh was found to be the most effective means of eliminating the vibrations.