UO2核芯还原炉设计模拟研究

以N-S方程和k-ε湍流模型为基础，针对UO₂核芯颗粒制备过程中的焙烧还原炉设备，采用计算流体力学方法模拟考察了南非和国内正在使用的两种还原炉体设计及入流速度对内部流场的影响。从模拟结果中可发现，两种炉体设计均无法实现气流在轴向上的均匀分布，而是呈现出炉体顶部气量大、底部气量小的分布状态，这是导致颗粒还原不均匀的原因之一，且这种不均匀性随气速增加变化不大。在分析轴向压力变化影响径向气流分布的基础上对还原炉体进行了改进，提出了一种新型设计，模拟结果证实改进后的炉体设计能够实现径向气流在轴向上更为均匀的分布，因而可推定该新型炉体设计可使炉内不同轴向高度处的颗粒还原更加均匀。

Simulation Study of UO2 Kernel Reduction Furnace Design

Based on the N-S equations and the k-ε turbulence model, different kinds of UO₂ kernel reduction furnace equipments in PBMR, South Africa and INET, China were numerically simulated using computational fluid dynamics method. The simulation results show that these two kinds of furnace designs can not be achieved on the uniform distribution of gas flow in the axial direction, but show large volume at the top and small volume at the bottom of the furnace, and this is one of the reasons of non-uniform particle reduction. Improved design was proposed based on the analysis of changes of axial pressure in the furnace. Simulation results demonstrate that the improved furnace design is suitable for obtaining a more uniform distribution of the gas in the axial direction. It can be concluded that the improved furnace design will improve particle reduction effects.