双金属复合翅片管振动特性的研究

双金属复合翅片管是一种高效传热元件，容易发生流体诱导振动破坏，对其进行振动模态理论分析具有重要的工程指导意义。针对双金属复合翅片管的结构特征，将其简化为串、并联刚度系统，采用组合截面等效弯曲刚度、等效扭转刚度和等效抗拉压刚度，并结合等效质量和等效转动惯量的方法，对其弯曲、扭转和轴向振动模态进行理论解析。为了验证理论分析方法的准确性，对双金属复合翅片管的振动模态进行了实验测试和有限元分析。研究了翅片几何参数对双金属复合翅片管振动频率的影响规律。结果表明，对于矩形翅片形式的钢铝双金属翅片管，其弯曲、扭转和轴向振动频率均随翅片高度和翅片厚度的增大而减小，随翅片间距的增大而增大。

Study on vibration characteristics of bimetallic finned tubes

Bimetal finned tubes are the highly efficient heat transfer components, and prone to occur flow-induced vibration damage. The modal analysis of bimetal finned tube has important engineering significance. Bimetal finned tube was reduced to series and parallel stiffness system according to its structural characteristics. The bending, torsion and axial vibration modal of a bimetal finned tube was analyzed theoretically, by using the methods of equivalent cross-sectional bending stiffness, torsion stiffness and tension-compression stiffness, combined with the equivalent mass and equivalent moment of inertia. The experimental tests and finite element analysis on vibration modal of bimetallic composite finned tubes were conducted in order to verify the accuracy of the theoretical methods. The effect of fin geometry on the natural frequencies of steel- Aluminum bimetal finned tubes with rectangular fins was investigated. The results show that its natural frequencies decrease with the fin height and fin thickness increases, and increase with the fin pitch increases.