中文摘要：

为研究燃料球和慢化球呈双区分布的球床式高温气冷堆球流运动的规律，以二维双区球流运动实验台架为参照，采用离散单元法（DEM ）进行数值模拟。从唯象的角度对模拟结果进行分析，研究了双区分布的形成过程、中心区、交混区与滞留区以及速度分布等问题。模拟结果表明：在当前模拟条件下，可形成稳定的中心区，中心区与环形区之间存在交混区，且存在滞留区。本体内越靠近底部卸料口，竖直方向速度分布越不均匀，水平方向的扩散越来越大。

英文摘要：

Discrete element method was used to simulate the pebble dynamics in the high-temperature gas-cooled reactor core ,based on the two-dimensional pebble dynam-ics experiments . Phenomenological method was used to analyze the formation of the two-region distribution ,the central ,mixing and stagnant regions ,and the velocity dis-tribution .The simulation results show that a stable central region is formed ,mixing zones between the central and annular regions and stagnant regions are observed in current simulation .The closer to the bottom of the pebble bed ,the more uneven the vertical pebble velocity and the bigger the horizontal diffusion .