Numerical and experimental study of isothermal water flow downstream of split-type spacer grids in rod bundles. OECD/NEA benchmark MATiS-H

Single phase water flow in a 5 x 5 rod bundle is studied within the OECD/NEA benchmark MATiS-H (Measurement and Analysis of Turbulent Mixing in Subchannels - Horizontal). In the benchmark two types of spacer grids are used in the tests, the swirl type and the split type. The flow behind these spacers is investigated for the benchmark study. Comparisons of some CFD results performed in Karlsruhe Institute of Technologie (KIT) with experimental results obtained by KAERI (Korea Atomic Energy Research Institute) are presented for the split type grids. Velocities in three directions along selected lines are measured and compared to CFD results. Numerical results are obtained by using the STAR CCM+ -CFD code. The Realized k-ε model is used for this study. Comparisons with experimental results show quantitative and qualitative agreement for the averaged values of velocity components in the compared regions. (orig.)