基于复模态的空间锥螺旋管管内流固耦合振动特性的有限元分析

摘要

空间锥螺旋管束作为一种新型流体诱导弹性传热元件,由于其锥型螺旋结构,管内流动产生的非比例阻尼对其固有振动特性影响明显.基于此,采用有限元法研究螺旋管束管内流固耦合振动特性,通过螺旋升角变换、螺旋单元坐标变换以及对连接体的简化处理,建立了管束振动状态方程,依据复模态理论分析了科氏力所致阻尼对空间锥螺旋管的频率的影响.结果表明:管内流动对锥螺旋管束基频影响很大;由于科氏力所致阻尼阵的存在,螺旋管束在管内流固耦合作用下呈现复模态;随着螺旋节距及流速的变化,管束的基频及阻尼比发生变化.%Heat transfer enhancement was achieved due to flow-induced vibration in elastic tube bundle heat exchangers.To a further study on heat transfer enhancement mechanism and tube structural optimization, it was of importance to study vibration characteristics of fluid-structure interaction in heat transfer element.A helical tube bundle was a new type elastic heat transfer element.Because of its helical structure, the inside flow of the helical tube has a deep influence on its vibration characteristics due to Coriolis force damping.The FEM was used here to study the vibration characteristics of the helical tube with inside flow.The element matrix and the tube vibration equation were established with the regulation of different spiral angle , coordinate transformation and the simplification of the connector between two pipes.The influence of Coriolis force damping on the tube vibration characteristics was analyzed.The results showed that the 1st modal frequency decreases acutely because of inside flow of helical pipe; the spiral pipe reveals complex modal shapes due to Coriolis force damping; the 1st modal frequency and the damping ratio change with varying of the helical pitch and the speed of the inside flow.