自然循环蒸汽发生器倒U型管内倒流现象影响因素研究

在某些自然循环工况下，蒸汽发生器部分倒U型管内存在倒流现象。基于一维Oberbeck-Boussinesq方程，建立了蒸汽发生器并联倒U型管内单相水流动传热模型，并以两种尺寸的蒸汽发生器为例进行了计算。计算结果表明，小型蒸汽发生器内短管易发生倒流，大型蒸汽发生器内长管易发生倒流；蒸汽发生器进口水温对倒流现象的发生具有重要的影响。

Investigation on Factors Affecting Reverse Flow in Inverted U-Tubes of Steam Generator Under Natural Circulation

For natural circulation, it is shown that reverse flow occurs in the inverted U-tubes of steam generator (SG) at certain low power levels. A flow model based on one-dimensional Oberbeck-Boussinesq equation was formulated to analyze this phenomenon. Two SGs of different scales were calculated. The results show that the reverse flow phenomenon occurs easily in the shorter U-tubes in small SG, but the phenomenon occurs easily in the longer U-tubes in large SG. The inlet temperature has great influence on the occurrence of reverse flow.