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采用不可压N-S方程、标准k-e湍流模型、SIMPLE算法,对某压水堆的两跨距5×5燃料组件的水循环区域流动进行了数值分析.通过对比流道横截面上的压降、速度及其横向分量的相对误差,得出了计算域的进出口段长度、网格形式、网格尺寸的选取标准.结果显示,计算域的进口段、出口段长度不宜过短或过长,分别应约为2.0倍、2.3-2.8倍格架中心距长度;对于网格形式,从残差小、总计算量小的角度考虑,格架区宜采用非结构蜂窝网格,光棒区宜采用结构网格;对于网格密度,格架区网格尺寸可取约0.3mm,最大不宜超过0.35mm,而结构网格横向尺寸可取0.3-0.5mm,纵向稀疏比应小于1.5为宜.满足计算域和网格的上述标准,数值分析即能保证较高的可信度,同时保持可接受的计算量.
Numerical simulation of the flow field in a water cycle of a 5 × 5 fuel assembly at a two-span PWR using the incompressible Navier-Stokes equations, the standard ke turbulence model, and the SIMPLE algorithm is carried out. By comparing the pressure drop across the cross-section, The results show that the length of inlet section and outlet section of calculation domain should not be too short or too long, About 2.0 times, 2.3-2.8 times the grid spacing from the grid; for the grid form, from the perspective of small residuals, the total amount of calculation is small, the grid area should adopt unstructured cellular grid, light bar area should adopt the structure For the grid density, the grid size of the grid area should be about 0.3mm and the maximum should not exceed 0.35mm, while the horizontal dimension of the grid structure should be 0.3-0.5mm, and the vertical sparse ratio should be less than 1.5. The above grid of standards, numerical analysis can guarantee a high degree of credibility, while maintaining an acceptable amount of computation.