带有定位格架的超临界反应堆堆芯强制对流换热的数值研究

Numerical Study on Forced Convection in Sub-Channel with Grid Spacer in Supercritical Reactor Core

采用非结构化多面体网格和商业计算流体力学(CFD)软件对两类带有流动强化特征的定位格架对超临界水在反应堆堆芯子通道内流动及换热特性的影响进行数值研究。研究结果表明:定位格架对子通道内超临界水的换热影响显著;在定位格架内部,流通面积减小,流速增加,换热得以有效强化;阻流片型定位格架对子通道中心流体的阻挡和导流能够中和流动阻塞效应,强化其下游窄缝区的局部换热效果;交错叶片型定位格架能够在其下游产生漩涡流,加强相邻子通道间工质的热量和质量交换,强化局部换热;漩涡流也可能导致轴向速度损失,造成局部换热弱化,不利于反应堆的安全性;入口雷诺数Re对交错叶片型定位格架下游局部换热有较大影响。Re较高时,此类定位格架对子通道内局部换热的强化作用更为明显。

Numerical analysis is carded out for the effects of grid spacer on the forced convection of supercritical water in the sub-channels in supercritical reactor core with commercial CFD code using unstructured polygonal mesh. The results show that the grid spacer has great effects on the heat transfer characteristics of supercritical water within sub-channel. The grid spacer with flow-blockage disc can neutralize the aggravated flow chocking effect by blocking and guiding the flow around the sub-channel center and enhance the local heat transfer near the narrow gap region. Obvious swirling flow is created downstream of the grid spacer with split-vans and the heat and mass transfer between adjacent sub-channels is thus enhanced. The swirling flow can also induce velocity deficits and adversely affect the local heat transfer inside a sub-channel. The Re number has obvious effects on the local heat transfer downstream of the grid spacer with split-vans, and the improved heat transfer performance downstream of the grid spacer with split vanes is more pronounced for the higher Reynolds number case.