CiADS带绕丝燃料棒束通道横流特性

CiADS次临界反应堆采用铅铋作为冷却剂，使用绕丝定位的闭式燃料组件。螺旋绕丝能够使流动工质发生横向交混，增强不同子通道间的动量交换。本工作使用ANSYS ICEM和STAR-CCM+软件划分了结构化网格和多面体网格，对CiADS燃料棒束通道横流特性进行研究，分析了结构化网格与非结构化网格对流动特性的影响。结果显示：相比于非结构化网格，结构化网格的子通道间横流量计算结果更接近LES的结果；结构化网格得到的摩擦因子系数与UCTD公式预测值最为接近，多面体网格的结果比经验公式的预测值小。同时，本研究对现有横流特性经验公式进行了改进，可更准确地预测带绕丝燃料棒束横流特性。上述研究成果提供了子通道程序优化的新思路，同时可为CiADS燃料组件热工水力设计与分析提供参考。

Study on the Cross-flow Characteristics of Wire-wrapped Fuel Bundle Channel in CiADS

CiADS subcritical reactor used LBE as coolant and closed fuel assembly mixed by wire wrapped. The wire can make the working fluid cross-mixing, enhancing the momentum exchange between coolant in different subchannel. This study generated structured and unstructured mesh by software ANSYS ICEM and STAR-CCM+, analyzed the cross-flow characteristics in CiADS subcritical reactor and investigated the influence caused by using different mesh structure in CFD simulation. The calculation result showed: comparing with unstructured mesh, the cross g between subchannel calculation in structured mesh is closer to the result in LES. The friction factor calculated by structured mesh is closest to the prediction of UCTD formula, and the factor calculated by unstructured mesh is smaller than all empirical formula. In addition, this research refined existed empirical formula, which could predict cross-flow characteristics more accurate. The conclusions provided a new way refining subchannel progress, and provide data support for thermohydraulic design and analysis in CiADS fuel assembly.