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采用雷诺时均模拟(RANS)和大涡模拟(LES)对MATi S-H实验进行模拟计算,得到格架交混后棒束通道内冷态单相湍流流场,通过比较格架下游特定位置处速度分量分布,发现采用精细网格的LES能够较为准确地计算湍流流场平均速度以及脉动速度的分布,与实验结果符合较好。LES结果表明,棒束通道内格架交混湍流流场具有明显的波动,脉动峰值离散分布;子通道内瞬时时刻的涡旋因子SM沿轴向也并非单调衰减,而是具有相对持续的脉动特征,最大脉动值大约是SM最大值的5%;LES的瞬时速度场计算结果可以为进一步的力学分析提供参考。
The Reynolds averaged simulations (RANS) and large eddy simulation (LES) were used to simulate the MATi SH experiment. The flow field of the cold single-phase turbulent flow in the bundle passage was obtained by comparing the velocities It is found that the LES with fine grid can calculate the average velocities of turbulent flow field and the pulsation velocity more accurately, which is in good agreement with the experimental results. The results of LES show that the turbulent flow field in the bevel crossbar has obvious fluctuations and the peak of the pulsation is discretely distributed. The vortex factor SM at the instantaneous moment in the subchannel is not monotonically decreasing in the axial direction, but has relatively continuous pulsation The maximum pulsation value is about 5% of the maximum SM value. The calculation results of instantaneous velocity field of LES can provide references for further mechanical analysis.