基于CFD的蒸汽发生器U型管内回流现象数值分析

反应堆一回路系统在自然循环条件下，蒸汽发生器（SG）部分U型管内可能会出现回流现象，利用计算流体动力学（CFD）方法，对某非能动三代反应堆蒸汽发生器U型管内流体的流动传热特性进行数值模拟分析。选取6组不同管长的U型管，对比分析U型管内单相流体的流动传热特性。基于数值仿真结果，得出6组U型管质量流量-进出口压降曲线，并?T分析了U型管长度和一次侧进口流体温度与二次侧壁面温度温差（?T）对流体回流的影响。研究结果表明，当?T一定时，随着进出口压降的降低，长管内更容易发生回流。当U型管长度一定时，?T越小越容易发生回流。 

Simulation of Reflux in U-Tube of Steam Generator Based on CFD Method

Under the condition of natural circulation in reactor systems,?reflux may occur at U-tubes of steam generator(SG). Taken a SG of a Generation III Pressurized Water Reactor (PWR) with passive safety systems as the prototype, the thermal-hydraulic characteristics of the SG reflux are investigated. In this paper, the SG U-tubes are divided into six groups according to their lengths, and the flow and heat transfer characteristics of single-phase fluid in the U-tubes are analyzed with (CFD)?methodology. The trends of total pressure drop against mass flow rate are derived based on the simulation results. The effect?of the U-tube length and the temperature difference between the primary side fluid and the secondary side wall(?T)?on the reflux?are discussed. It is shown that when ?T?is constant, the reflux occurs more often in the longer U-tubes. When the U-tubes length is constant, the smaller ?T?is, the more often reflux occurs.