Abstract
This paper describes the phenomenon of the flow-induced vibration in a shell&tube type heat exchanger. This type heat exchanger has often been used in the LPG gas carrier ship and has sometimes caused a fretting and finally comes to a fatigue failure. In flow-induced vibration, there are a vortex-induced vibration, a fluid elastic instability and a buffeting. Experiments are carried out by use of an actual heat exchanger in order to clarify the cause of tube vibration. The vibration of a lot of tubes is measured for various flow rates and the natural frequency and its damping ratio are also measured. As a result, the cause of the vibration of tubes is not the fluid elastic instability and the vortex-induced vibration but the buffeting due to the turbulence of upstream flow. The main reason is that these tubes are supported by many baffle plates with clearance and then the vibration system becomes the nonlinear.
