带MVG和MSMG的5×5全长棒束单相流场和温度行为数值分析

定位格架作为燃料组件的关键部件之一，直接影响到燃料组件的热工性能。本文对带结构格架（MVG）和跨间搅混格架（MSMG）的5×5全长加热棒束单相流场和温度场采用计算流体力学（CFD）程序进行数值分析研究，获得该特征棒束组件出口二次流场以及温度场分布特性。研究表明，定位格架下游流场受定位格架和距离的影响，定位格架上游流场对下游二次流几乎无影响，定位格架导致流体强烈的横向二次流，增强了流体和加热棒之间的换热能力，使得棒束子通道截面流体温度更加均匀。与5×5全长棒束出口子通道温度的实验数据对比分析表明，获得的计算模型可以较好地分析该型棒束组件结构温度场行为。 

Numerical Analysis of Single Phase Flow and Temperature Characteristics in 5×5 Rod Bundle with MVG and MSMG

As one of the key components of nuclear fuel assembly, the mixing grid has an effect on thermal performance. In this paper, the single-phase flow field and temperature field of 5×5 full-length heated rod bundle with mixing van grid(MVG) and mid-span mixing grids(MSMG) are numerically analyzed and studied by CFD program, and the distribution characteristics of secondary flow field and temperature field at the outlet of the bundle section are obtained. The research shows that the downstream flow field of the grid is affected by the grid and distance, the upstream flow field of the grid has little influence on the downstream secondary flow, and the grid causes strong transverse secondary flow of the fluid. The heat exchange capability between the fluid and the heater rod is enhanced, so that the fluid temperature in the cross section of the rod bundle sub-channel is more uniform. By comparing and analyzing the experimental and calculated temperature of the 5×5 full-length rod bundle outlet sub-channel, the temperature field of the rod bundle assembly can be well analyzed by the obtained calculation model.