通道尺寸对稠密栅元内湍流流体的影响

Effect of Channel Size on Turbulent Flow in Tight Lattice

利用CFD软件FLUENT对37棒束内的湍流流体进行分析,利用实验数据对计算结果进行验证,然后分析棒-棒间隙的减小对稠密栅元内流动交混和相干结构的影响。随着P/D的减小,大尺度相干结构运动越来越显著,由此带来的横向动量和能量交换也越来越明显。栅元的临界P/D约为1.03,此时栅元的换热条件基本上处于最佳状态。当P/D=1.01时,栅元内几乎不存在大尺度相干结构,此时通道间几乎没有动量和能量交换,换热条件也非常不理想。

The turbulent flow in 37 rod bundles is investigated with CFD code FLUENT.The calculation results are validated with experimental data at first.Then the effects of diminishing rod-rod gap size on turbu-lent mixing and coherent structure in tight lattice are analyzed.As the P/D decreases,the large scale coherent structure becomes more significant,and the resulted transverse momentum and energy exchange become more obvious.When the critical pitch to diameter ratio is about 1.03,the heat transfer in this kind of tight lat-tice is at the best.As P/D=1.01,there is nearly no large scale coherent structure in the tight lattice.There is also nearly no momentum and energy exchange and the heat transfer is not very good.