球床式高温气冷堆旁流三维数值模拟

3D Numerical Simulation on Bypass Flow in Pebble-Bed High-Temperature Gas-Cooled Reactor

针对球床式高温气冷堆中散体布置的石墨砖等结构带来的旁流问题,数值模拟了高温气冷堆满功率稳态运行时卸料管、控制棒通道及窄缝中的旁流特征。通过结合华能集团自主研发的HN-750型球床式高温气冷堆的结构特点和流道特征,建立了包含窄缝、顶反射层、堆芯球床、底反射层及底部球腔的反应堆三维几何模型和近真实物理数学模型,生成了网格数为2.6亿的混合网格。结果表明,总旁流占总流量比例为29.25%,窄缝旁流占总流量比例为24.43%,并且呈现出回流特性,卸料管旁流占比3.87%,控制棒通道旁流占比0.95%。该研究考虑了非轴对称的进出口结构,是对现有的球床式高温气冷堆二维轴对称模型的补充和提升;该研究针对球床式高温气冷堆的大规模三维数值计算,为球床式高温气冷堆的热工水力优化和安全分析提供了丰富的数据支撑。

The bypass flow characteristics in such structures as graphite brick arranged in the pebble-bed high-temperature gas-cooled reactor(HTGR)during full-power steady-state operation is numerically simulated.In view of the structural features and flow characteristics of the HN-750 pebble-bed HTGR developed independently by Huaneng Group,a three-dimensional geometric model of the reactor including narrow gaps,top reflector layer,core pebble bed,bottom reflector layer,and bottom pebble cavity,along with a physically realistic mathematical model,is established.A hybrid grid with a mesh count of 260 million is generated.The results indicate that the total bypass flow accounts for 29.25% of the total flow rate,with narrow gap bypass flow with reflux characteristics occupying 24.43%,discharge pipe bypass flow occupying 3.87%,and control rod channel bypass flow occupying 0.95%.The non-axisymmetric inlet and outlet structures are considered in this research,serving as a complement and enhancement to the existing two-dimensional axisymmetric models of pebble-bed HTGR.Large-scale three-dimensional numerical calculations for pebble-bed HTGRs are represented,with abundant data support being provided for the thermal-hydraulic optimization and safety analysis of pebble-bed HTGRs.