耦合一、二次侧换热的蒸汽发生器二次侧流场分析

Secondary Side Flow Field of Steam Generator With Coupled Heat Transfer From Primary to Secondary Side Fluid

蒸汽发生器(SG)内三维两相流场可为流致振动分析提供输入条件。本文基于FLUENT采用多孔介质模型对SG二次侧流场进行求解。在动量方程中添加管束附加阻力,分别计算横流和顺流管束阻力,同时考虑了下降段、支承板和汽水分离器阻力。在能量方程中,将一、二次侧换热量三维分布作为二次侧流场的能量源项,在计算中采用耦合迭代求解。计算结果与总体设计值符合较好。计算结果同时显示,二次侧流场分布极不均匀;进入第一级汽水分离器的工质最大、最小流动含汽率分别为0.75和0.07;一、二次侧平均换热系数分别为15 856.5和63 623.0 W/(m2·K),二次侧最大换热系数为122 862.9W/(m2·K),U型管外壁面平均热流密度为149.9kW/m2;U型管弯管段最大横流速度约为4.06m/s;冷侧冲刷U型管的横流能量(ρu2)大于热侧,其值为1 145J/m3。

The 3D flow characteristics in SG can provide input for the analysis of flow induced vibration （FIV ） . The secondary side flow field was simulated based on the porous media model with FLUENT solver .The flow resistances of flow along and cross tubes as well as flow resistances of downcomer ,support plates and separators were added to the momentum equation .T he 3D heat transfer from primary to secondary side fluid was calculated during iteration and set as the energy source of secondary side fluid , and the calculation results agree well with the design values .Meanwhile ,the results show that the resultant localized thermal-hydraulic characteristics were unevenly distrib-uted .The maximum and minimum flow vapor qualities flowing into the primary separa-tors are 0.75 and 0.07 ,respectively .The average heat transfer coefficients of primary and secondary sides are 15 856.5 and 63 623.0 W/（m2 ＆#183; K） ,respectively .The maxi-mum heat transfer coefficient of secondary side is 122 862.9 W/（m2 ＆#183; K ） .T he average heat flux of U-tube is 149.9 kW/m2 .T he maximum cross flow velocity and cross flow energy （ρu2 ） through the U-bend region are 4.06 m/s and 1 145 J/m3 ,respectively .