标准型定位格架对超临界水在堆芯传热和流动影响的数值研究

采用非结构化多面体网格,利用商业软件STARCCM+6.04对标准型定位格架对超临界水在反应堆堆芯子通道内流动及传热特性的影响进行了数值研究。研究结果表明,由于流动阻塞效应的影响,燃料棒覆层表面温度周向分布不均,窄缝区最高、中心区最低。标准定位格架能够强化定位格架内部传热,但会造成其下游局部传热弱化,周向温度分布差异增大,不利于降低覆层温度。标准型定位格架下游的传热弱化现象或许是超临界反应堆紧凑型堆芯的特有现象,须在堆芯设计中加以重视。

Numerical research on heat and mass transfer of supercritical water in reactor core with standard grid spacer

Numerical analysis is carried out for the heat and mass transfer of supercritical water in the sub-channels with standard grid spacer in supercritical reactor core with commercial CFD code using Unstructured polygonal mesh. The results show that the circumferential distribution of cladding temperature, which indicates that the highest and the lowest value appears at the narrow gap region the sub-channel center respectively, is not uniform due to flow choking effects. The local heat transfer is greatly enhanced inside the grid spacer strap due to the increased flow velocity. However, the standard grid spacer is negative for decreasing cladding temperature because it increases circumferential difference of cladding temperature in its downstream region and an obvious decreased heat transfer is caused by the aggravated flow choking effects. The decreased heat transfer just downstream of a standard grid spacer might be a unique feature of the tight rod bundle.