防振条间隙对蒸汽发生器U形管固有频率影响敏感性分析

为满足安装与制造的要求，在蒸汽发生器U形管部位防振条与换热管之间存在一定量的间隙，从而导致了防振条约束强度的不确定性，因此对其间隙进行敏感性分析十分必要。通过数值模拟中的模态分析，采用弹簧刚度表征防振条间隙对支撑强度的影响。结果显示，当防振条全部完全失效时，对1阶固有频率的影响较大，可使其减小88.15%；单点约束失效对固有频率影响较小，最大仅可使1阶固有频率减小2.65%；各个支撑位置中，临近直管段且连续的2点约束失效时影响最大，可使1阶固有频率减小23.58%。 

Sensitivity Analysis of Effect of Anti-Vibration Bar Gap on Natural Frequency of U Tube in Steam Generators

In order to meet the requirements of installation and manufacturing, there is a certain gap between the anti-vibration bar and the tube in the part of the U tube of the steam generator. This gap?leads to the uncertainty of the restraining strength of the anti-vibration bar, so it is necessary to carry out the sensitivity analysis of the gap.?Through the modal analysis in numerical simulation, the spring stiffness is used to characterize the effect of the anti-vibration bar gap on the restraining strength.?The results show that when the anti-vibration bar is completely failed, it has great?effect on the first natural frequency , which can reduce it by 88.15%.?The single point constraint failure has little effect on the natural frequency, and it can only reduce the first natural frequency by 2.65% to the maximum.?In each supporting position, the continuous two point constraint near the straight tube has the greatest effect, and the first natural frequency can be reduced by 23.58%.