中文摘要：

由于燃料球的随机分布和球床的壁面效应,球床式高温气冷堆堆芯孔隙率分布会有一定的不均匀性。深入认识壁面漏流、随机孔隙率对球床温度分布均匀性的影响对进一步提高高温气冷堆冷却剂出口温度及其安全性具有重要意义。本文采用多孔介质模型实现了对堆芯球床壁面漏流、随机孔隙率效应的数值模拟。结果表明,由于壁面漏流效应,壁面附近局部区域冷却剂最大速度会比中心高50%,对球床温度影响则不大。中心区域局部极小、极大孔隙率只对很小区域内流速和温度有影响,但温度变化幅值很小。球床中心随机孔隙率使冷却剂速度波动小于13%,对球床温度影响很小。

英文摘要：

The porosity in the reactor core of HTGR is not uniform due to the random stack of the fuel pebbles and the wall effect.Understanding of the influences of wall channelling and random porosity on the non-uniformity of temperature distribution in the reactor core is very important for further increasing the outlet coolant temperature and safety of HTGR.In this paper,the wall channelling and random porosity effects were numerically simulated using porous medium method. The results showed that,due to the wall channelling effect,the maximum coolant velocity near the wall was 50%higher than that at the core centre,while its influence on reactor core temperature was little.Maximum or minimum porosity in certain regions only caused changes in local velocity and temperature,and the magnitude of temperature variation is limited.The coolant velocity fluctuation caused by random porosity is below 13%,and its influence on core temperature is very little.