绕丝定位的燃料棒流致振动机理研究

Investigation on Flow-Induced Vibration Mechanism of Fuel Rods Fixed by Wrapped Wire

通过实验和数值模拟的方式对泄漏流影响下绕丝定位的燃料棒流致振动机理进行研究。数值模拟及实验结果表明:由于绕丝的存在,使得流体在棒束通道内的流动存在着较强烈的搅混效应,在流速较小时,相比于通道内流体横向流动对燃料棒的扰动,泄漏流动对燃料棒振动的影响很小;随着流量的增加,泄漏流动对燃料棒振动的影响逐渐增强。影响分为2点:改变了振动能量在频域内的分布,使得高频段的振动能量增加;使得燃料棒振动的位移有效值(均方根值)增大。

The flow-induced vibration mechanism of the fuel rod fixed by wrapped wire under the influence of leakage flow is investigated by the way of experiment and numerical simulation. According to the CFD and experimental results, it is found that the wrapped wire would play a role of increasing the cross flow mixing effect in the flow channel, which would have a significant influence on the stability of fuel rod. Based on experimental and numerical results, it is found that when flow rate is low, the vibration of rods is mainly caused by the turbulence, but as flow rate increases, the effects of leakage flow become obvious. Effect of vibration leakage flow of the fuel rods are divided into two kinds： changing the vibration energy distribution in the frequency domain, so that the high frequency energy of vibration is increased; increasing the RMS value of vibration displacement of fuel rod.