Flow induced vibrations in heat exchanger tube arrays

当柔性结构暴露在高速流动的流体中时，结构会被诱导振动。如果这些振动过大，可能会发生结构故障。一个熟悉的例子是塔科马窄桥的壮观坍塌。此外，拟议的研究考察了电力或化工厂热交换器管由液体、气体或蒸汽流动引起的振动。其目的是了解引起振动的流体作用力，从而开发防止破坏性振动的设计方法。这些特殊应用与提高动力(核桃和化石)和化学加工厂中的热交换器、冷凝器和蒸汽发生器的性能和可靠性有关。热交换器的管子往往又长又灵活，可能会因流体流过管子而引起过度振动。例如，在核蒸汽发生器的情况下，这可能会导致反应堆核心的重水泄漏。建议的研究将有助于了解导致管子振动破坏的条件。研究结果将有助于制定设计规范，以确保在役换热器的可靠性，或制定用于预测老化设备可靠性的分析规范。他说，其中一个项目涉及带有翅片的换热器管，这些翅片用于强化传热。这些翅片似乎会增强管子阵列中的流动不稳定性，目前针对此类问题的设计信息很少。

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.