Abstract
It is important in design and development of reactor cores to increase knowledge of turbulent flows in rod bundles. In this study, we therefore measured velocity in single-phase and bubbly flows by installing a small LDV probe into a rod of a 2x2 rod bundle. The diameter and the pitch of the rods were 10 and 13 mm, respectively. The liquid volume flux was 1 m/s, and the gas volume flux in the bubbly flow was 0.08 m/s. The local time-averaged velocity and turbulent intensity were obtained from 10,000 instantaneous velocities at each measurement point. As a result, the following conclusions were obtained: (1) The distribution of liquid velocity in the bubbly flow is flatter than that in the single-phase flow, and the velocity gradient near the wall increases due to the presence of bubbles. (2) Local wall shear stress on the rod wall depends on the azimuthal localtion, and the distributions of dimensionless liquid velocities near the wall in inner subchannel agree with the universal dimensionless mean velocity profile of wall turbulence.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
