自然循环蒸汽发生器并联倒U型管流量分配计算

针对自然循环工况下蒸汽发生器部分倒U型管内存在倒流现象，通过对倒U型管内流动传热特性进行分析，获得了倒流发生的判断依据，从而编制了流量分配计算程序。采用该程序对某型蒸汽发生器并联倒U型管流量分配进行了计算，通过将结果与实验值进行对比分析，对程序可信度进行了验证，并采用该程序对蒸汽发生器并联倒U型管主要热工参数随进出口压降变化情况进行了计算分析。结果表明，倒流现象发生在短管内，倒流的发生使得蒸汽发生器一次侧净流量和单位时间输热呈阶梯下降，对反应堆安全产生较大的影响。

Flow Distribution Calculation of Parallel Inverted U-tubes in Steam Generator Under Natural Circulation

For natural circulation, it is shown that reverse flow occurs in inverted U-tubes of steam generator (SG). The flow and heat transfer characteristics in inverted U-tubes were analyzed, the principle of the reverse flow was gotten, and the flow distribution program was established. The flow distribution of the parallel inverted U-tubes in one type of SG was calculated using the program, the calculation results were compared with experimental data, and the validity of the program was verified. The change of the parallel U-tubes’ parameters with the pressure drop was also calculated and studied by using the program. The results show that reverse flow occurs in the short tubes and the net mass flow rate and the heat transfer rate in the primary side are lowered down step by step, which has great influence on the reactor safety.