纵向涡发生器对棒状燃料元件温度场的影响分析

Effect of longitudinal vortex generators on temperature field of rod fuel element

运用CFD方法,模拟计算了在反应堆棒状燃料元件包壳表面加装纵向涡产生器(LVG)后,燃料棒、气隙、包壳和冷却剂的温度场和冷却剂的流场。计算时采用分块结构网格对带LVG的计算区域划分网格,使用SSTk-ω模型模拟冷却剂的湍流流动,对于控制方程和湍流方程的离散采用二阶格式以保证计算精度。计算结果表明:加装LVG后,包壳和冷却剂间的换热有所改善,燃料棒、气隙和包壳的最高温度有所降低。在LVG附近,燃料棒、气隙、包壳和冷却剂温度均会出现一个峰值,然后急剧下降。冷却剂流动的湍动能突然增强,有效地增强了冷却剂的横向流动,经过LVG后,湍动能逐渐减弱,横向流动速度也逐渐减小。

The CFD method was used to simulate the temperature field of core, gas gap and cladding of the fuel rod installed with LVGs as well as the temperature and flow field of the coolant. A decomposed structural meshing strategy was adopted to mesh the coolant volume with the LVGs. The 5ST k-ω model was used to simulate the turbulent flow of the coolant, where the control equations and turbulent equations were discretized with the second-order form. It is found that the heat transfer between cladding and coolant is improved with the LVGs which lower the maximum temperature of core, gas gap and cladding. Near the LVGs, the temperature of core, gas gap, cladding and coolant all reach a peak and then decrease rapidly. The transverse flow is enhanced because of the suddenly increased turbulent kinetic energy. Through the LVGs, the turbulent kinetic energy becomes weak and the cross flow slows down.