管阵动力响应的模态分析

Modal Analysis of Dynamical Response of Beam Bundle

核反应堆堆心、热交换器之类的重要结构是由浸没在流体中的有着规则排列的大量管梁组成,流固耦合作用是影响管束动力响应的重要现象。很多研究者为了提出一个可以预测管束全局行为的数学模型作了不少努力。本文基于张提出的三维耦合模型,在流体域采用流体速度势而非压力作为基本未知量,从而避免了采用压力格式而导致的系数矩阵非对称性的弊端,得到了易于求解的陀螺系统,通过计算系统特征值,利用模态展开法,求得了地震激励下系统的动力响应。

Important structures like nuclear reactor cores, heat exchangers, are schematically composed of a great number of beams immersed in fluid. The fluid - structure interaction is an important phenomenon influencing the dynamical response of the bundle. Much effort has been made upon the development of a mathematical model capable of predicting the global behavior of the beam bundle. Based on the 3 - D homogenization model derived by Zhang, using the fluid velocity potential rather than pressure as the fundamental unknown in the fluid region, the principal disadvantage of the pressure formulation resulting in non - symmetric coefficient matrices is removed. It gives rise to the gyroscopic system, which makes it relatively easy to calculate the eigenvalues of the fluid - structure system. Through modal expansions, the dynamical responses of the system under seismic exciation are presented.