定位格架压降关系式及CFD数值模拟研究

Analysis of Empirical Pressure Drop Correlations and CFD Numerical Study on Spacer Grid

现有格架压降经验关系式中缺少对格架本身结构的描述,导致压降估计不准确。为准确估计格架的压力损失,利用商用计算流体动力学(CFD)软件,从基础研究的角度出发,分别探索刚凸位置、搅混翼排列的边距以及子通道间的互相搅混等对压降及下游流场的影响。在拟合格架压降经验关系式时,需要加入更多的描述格架自身结构的几何参数。在格架设计中要根据不同的格架设计目标和设计功能,针对性地优化刚凸位置、搅混翼排列及子通道的之间的互相搅混。

Estimating pressure drop accurately is the key to develop and design spacer grids. Grid pressure drop prediction models are reviewed. Most of the empirical corrections applied for the pressure drop calculations do not contain any real geometrical parameter to characterize the grid effect. From the aspect of fundamental research, the influence of the dimple location, distance of the mixing vane to the nearest strip and the effect of inter-subcharmel mixing among neighboring subchannels on pressure drop and downstream flow fields are analyzed using the commercial CFD codes. Based on this study, it is concluded that more detailed geometry parameters of spacer grid should be added into the correlation when predicting the pressure drop. Dimple location, configuration of mixing vanes and grid strip opening should be optimized for different design targets and functions when developing spacer grids.