球床堆壁面结构效应的模拟研究

高温气冷球床堆的球床内壁附近,燃料球由于随机运动会形成附着于壁面的规则堆积,即球流结晶现象。燃料球的结晶化会导致球床堆内滞留区增大,流场均匀性恶化,影响高温堆的运行安全和效率。实际高温堆中,通过在球床内表面设置壁面结构来减小发生结晶的概率。文章通过DEM方法模拟了壁面结构防止结晶的作用,定义球流流场特征数进一步研究了壁面结构效应,并对不同壁面结构的效果进行比较,为工程中壁面结构设计提供方法。

Crystallization of pebbles in pebble bed is a crucial problem in high temperature gas-cooled pebble-bed reactors.This phenomenon usually happens along the internal surface and leads to a large number of stagnated pebbles,which poses a threat to reactor safety and efficiency.In real reactor engineering,wall structures have been utilized to avoid this problem.This article verifies the crystallization phenomenon through DEM(discrete element method)simulation,and explains how wall structures work in preventing crystallization.Moreover,several kinematic parameters have been adopted to evaluate wall structures with different shapes,sizes and intervals.Detailed information shows the impact of wall structure on flow field in pebble bed.Lastly,the preferred characteristics of an effective wall structure are suggested for reactor engineering.