抗振条面内接触刚度对蒸汽发生器传热管流致振动的影响

流弹性失稳是引起蒸汽发生器传热管管束失效的一种主要原因。在相同流场条件下，传热管是否出现流弹性失稳与其模态频率直接相关。在实际结构中，抗振条对U型传热管弯管段面内支撑机理与面外的方向上不同，是通过摩擦约束实现的。这使得在模态分析计算中，传热管弯管段支撑处的边界条件设置非常重要。本文将传热管与抗振条接触点处的面外边界条件假设为简支，而在面内方向上用弹簧来模拟抗振条对传热管的摩擦约束。同时，通过改变弹簧刚度，讨论了不同强弱的面内支撑对传热管流致振动的影响。分析结果表明，当抗振条与传热管面内接触刚度较弱时，面内流弹性失稳可能较面外流弹性失稳出现得更早。

Influence of In-plane Contact Stiffness of Anti-vibration Bar on Flow-induced Vibration of Heat-transfer Tube in Steam Generator

The fluid-elastic instability of heat-transfer tubes is a significant reason that causes tube failures in steam generators. Whether the fluid-elastic instability of a heat-transfer tube occurs depends on its modal frequencies. In the actual structure, the in-plane supporting is supplied for the U-band region of the heat transfer tubes by the anti-vibration bars (AVBs) subjected to friction, and is different from the out-of-plane one in supporting mechanism and direction. This makes the setting of boundary condition at supporting points very important in the modal analysis. In this paper, the out-of-plane boundary conditions were set as simply supported, however, springs were used to simulate the in plane supporting subjected to the friction between the tubes and AVBs. By changing the stiffness of the springs, the effect of in-plane supporting magnitude on the flow-induced vibration of heat-transfer tubes was discussed. It is indicated that the in-plane fluid-elastic instability may occur earlier than the out-of-plane instability when the contact stiffness  between the tube and AVBs is loose.