充液弹性管束流固耦合系统模态分析

作为一种新型换热元件，弹性管束结构与管内流体构成了一个典型的流固耦合系统.考虑流体的可压缩性,用有限元法的位移－压力格式对管束－流体耦合系统进行离散,建立了系统的振动控制方程.在此基础上分别对管束结构、管内流体和管束－流体耦合系统进行了模态计算.结果表明：由于流体与结构的相互作用，不但弹性管束结构和流体本身的固有频率和振型发生改变,而且一个子系统的振动还会迫使另一子系统产生新的振动模式.不同密度的流体对结构频率改变的影响程度不同.因此,在研究管内充液弹性管束的动态响应时必须考虑流体与管束结构的相互作用影响.

Modal Analysis of Liquid-Filled Elastic Tube Bundles

The structure of elastic tube bundles and the fluid inside constitute a typical fluid-structure interaction system.The governing vibration equation of the system is derived from the displacement-pressure format and the finite element models are built by considering the compressibility of the fluid.Natural frequencies and modal shapes of the structure,the fluid inside and the structure-fluid system are calculated separately.The results show that not only the natural frequencies and mode shapes of the original structure and fluid are changed due to the interaction between fluid and structure,but also one subsystem is forced to vibrate in a particular pattern corresponding to the vibration of the other subsystem.The effects of fluids with different densities on the structure are also different.The influence of fluid-structure interaction must be taken into account when the dynamic response of elastic tube bundles is studied.