2x2ロッドバンドル流路内気液二相気泡流における乱流特性

抄録

Experimental databases and knowledge of turbulent flows in rod bundles are required for validation and improvement of numerical prediction methods for two-phase flow in rod bundles. In this study, we therefore measure liquid velocity in single-phase and bubbly flows by installing a small LDV probe into a rod in a 2x2 rod bundle. The diameter and the pitch of the rods are 10 and 13 mm, respectively. The liquid volume flux is 0.5 m/s and the gas volume flux in the bubbly flow is 0.08 m/s. The experimental results show that (1) the Reynolds shear stress is enhanced in the vicinity of the rod surface due to the increase in velocity gradient at the wall, (2) the ratio of Reynolds shear stress to the axial turbulence energy decreases due to the presence of bubbles, (3) the Prandtl’s mixing length hypothesis holds in the vicinity of the rod even in the bubbly flow and the mixing length in the core region is close to the bubble radius.