Flow analysis in a 37-pin wire-wrapped rod bundle for sodium-cooled fast reactor using magnetic resonance velocimetry. II. Detailed characterization and influence of wire angular position

In Paper I, we presented comprehensive three-dimensional, three-component (3D, 3C) mean velocity profiles obtained through magnetic resonance velocimetry (MRV) within a 37-pin wire-wrapped rod bundle, elucidating the primary flow dynamics in sodium-cooled fast reactors. Building on this foundation, in this paper, we meticulously examine transverse velocity, helicity, and streamlines around rods, focusing particularly on the wake region of the wire within interior and edge subchannels. Our analysis uncovers a repetitive vortex evolution pattern in the wake, characterized by vortices forming, growing, weakening, and dissipating at 60° intervals of wire angular position. Furthermore, we highlight the significant variation in the azimuthal velocity component near the wire's wake, elucidating the dominant influence of wire orientation. Additionally, we identify the periodicity of flow split factor variations, demonstrating their dependence on wire orientation in interior subchannels and the prevailing impact of edge swirling in edge subchannels. Overall, our quantitatively derived experimental results provide valuable insights into flow patterns within the rod bundle, offering essential information for optimizing reactor design and analysis.