核电厂蒸汽管道中高速运动水团冲击研究

High Velocity Water Slug Impact in Steam Pipelines of NPP

高压蒸汽作用下,核电站管道系统中凝结产生的水团可以对系统中的非连续部位造成强烈的冲击,使之损坏或者丧失功能,从而给核电站的安全运行带来较大威胁。针对高速运动水团对管端弯头的冲击问题,考虑水团在弯头处的高维动力学特性,建立了单个水团的冲击动力学模型,分别运用欧拉方法和四阶龙格-库塔方法对模型进行了数值求解。为了验证模型的有效性,特别是弯头反作用力的计算方法,模拟了不同工况下的高速水团冲击问题,并将模拟结果与文献中的实验结果以及其他模型数值结果进行了对比。对比结果表明,不论是冲击力幅值,还是冲击压力时程曲线,本文模型所得结果都与实验结果高度吻合,并且优于已有模型结果,这也证明了所提出的弯头反作用力计算方法的合理性。另外,当时间步长较小时,数值积分算法对结果没有显著的影响。

Under high driving pressure of gas or steam in nuclear power plants(NPP),condensed water slug in steam piping system can attain a high velocity and induce damageable dynamic forces to various obstacles,posing a potential threat to safe operation of NPP.Based on high-dimensional feature of the water slug at bend,an improved one-dimensional model for slug impact is proposed and validated against experimental and numerical results in literature.It is shown that both the amplitude of the impact and the overall pressure trend obtained using the current model have better agreements with the experiments than those given by existing models.Different time integration algorithms(Euler method and fourth-order Runge-Kutta method)are also tested,and it is found that when time step is small,no obvious differences can be observed.