Flow induced vibrations in heat exchanger tube arrays

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When a flexible structure is exposed to a high velocity flowing fluid, the stucture is induced to vibrate.  If these vibrations are excessive, structural failure may occur.  A familiar example is spectaclar collapse of the Tacoma Narrows Bridge.  The proposed research examines the vibrations of power or chemical plant heat exchanger tubes caused by liquid, gas or steam flows. The objective is to understand the fluid forces which cause the vibrations and thereby, to develop methods for designing against damaging vibrations.  The particular applications are related to improving performance and reliability of heat exchangers, condensers and steam generators in power (nulcear and fossil) and chemical process plants.    Heat exchanger tubes are often long and flexible and may be induced to vibrate excessively by fluid flowing across them.  In the case of nuclear steam generators, this can cause a leak of heavy water from the core of the reactor.  The proposed research will help in developing an understanding of the conditions which lead to damaging tube vibration.  The results will assist the development of design codes which ensure the reliability of heat exchangers in service or of analysis codes for predicting the reliability of aging equipment.     One of the projects involves heat exchanger tubes with fins used to enhance heat transfer.  The fins appear to enhance flow instability in tube arrays and little information currently exists for design against such problems.