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Investigation of critical flow velocity of a triangular U-tube bundle subjected to two-phase flow
Seinosuke Azuma

Last modified: 2018-06-24


Fluid elastic instability is one of the severe vibration phenomena for tube bundle. Recently, the occurrence of in-plane (stream-wise) fluid elastic instability was indicated by observation of tube-to-tube wears in steam generators. Then, many experimental investigations have been conducted with straight tube bundle flow tests. However, the evaluation guideline of the in-plane fluid elastic instability for U-bend tube bundle with triangle arrays has not been established yet. In this paper, the critical flow velocity of fluid elastic instability with two types of test rig for triangle arrays in two-phase flow (SF6 - ethanol) which simulates steam-water two-phase flow was investigated. One test rig consists of 156 rows and 6 columns of straight tube bundles. The influences of the number of flexible tubes, void fraction and vibration directions on fluid elastic instability were investigated. The other test rig consists of 126 rows and 6 column of U-bend tube bundle with 5 anti-vibration bars. Six flow inlets can make various flow velocity distributions in the U-bend tube bundle. The influences of flow velocity and void fraction distributions on fluid elastic instability were investigated.


fluid elastic instability;tube bundles;two-phase flow

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