2-PHASE CROSS-FLOW INDUCED VIBRATION OF TUBE ARRAYS - (BRIEF REVIEW OF PREVIOUS STUDIES AND SUMMARY OF DESIGN METHODS)

Many heat-exchange tubes in a shell-and-tube-type heat exchanger are o scillated by means of the flow of fluid through the heat exchanger. Th is flow is often cross flow and gas-liquid two-phase flow. Here, a bri ef review of studies on two-phase cross-flow-induced vibration is pres ented, and a summary of our work in this area provides a design method ology. Three types of vibration have been studied for tubes in two-pha se cross-flow conditions: First, resonance of a tube due to vortex she dding is important primarily in single-phase flow, but also has been o bserved in homogeneous flow and even in two-phase flow. However, this vibration disappears in the slug flow or froth flow regions, which are important in numerous heat exchangers. Therefore, the vortex shedding phenomenon is not considered in this paper. Secondly, turbulent buffe ting vibration is considered as the dominant phenomenon in the slug fl ow and froth flow regions. A method for estimating this type of random vibration is explained in this paper. Thirdly, an unstable form of vi bration, so-called fluid elastic vibration, is also considered. The co mmon method for estimating the instability boundary is similar to that used for single-phase flow; however, new insights on the method for t wo-phase flow are given in this paper.