双弹性管流固耦合振动的数值模拟

为研究反应堆结构中诸如燃料棒、蒸汽发生器和其他换热器等管束类结构的流固耦合振动问题，利用有限体积法离散大涡模拟的流体控制方程及有限元方法离散结构动力学方程，结合动网格技术，建立了三维流体诱发弹性管束振动的数值模型，实现了计算结构动力学与计算流体力学之间的双向耦合。得到横流作用下单管的振动响应，并与已有的实验数据比较，证明了本文模型的合理性；对横流作用下的两串列管、两并列管的流固耦合振动进行了数值模拟，着重研究了节径比为1.2、1.6、2、3、4的两弹性管在不同流速作用下的动力学响应及流场特性；得到串列管、并列管的临界间距与临界流速。

Numerical Simulation of Fluid Structure Interaction in Two Flexible Tubes

In order to further investigate fluid structure interaction problems, occurring in the nuclear field such as the behavior of PWR fuel rods, steam generator and other heat exchanger tubes, a numerical model was presented. It is a three-dimensional fully coupled approach with solving the fluid flow and the structure vibration simultaneously, for the tube bundles in cross flow. The unsteady three-dimensional Navier-Stokes equation and LES turbulence model were solved with finite volume approach on structured grids combined with the technique of dynamic mesh. The dynamic equilibrium equation was discretized according to the finite element theory. The vibration response of a single tube in cross flow was calculated by the numerical model. Both the amplitude and frequency were compared with experimental data and existing models in the literature. It is shown that the present model is reasonable. The flow induced vibration characteristics, for both inline and parallel sets in cross flow, were investigated by the numerical model. The dynamic response and flow characteristics, for both inline tubes and parallel tubes with pitch ratio of 1.2, 1.6, 2, 3 and 4 under different incident velocities, were studied. Critical pitch and critical velocity were obtained.