EXPERIMENTAL STUDY ON CROSS-FLOW MIXING EFFECT BETWEEN ROD BUNDLE SUBCHANNELS

In the subchannel analysis method, the cross-flow mixing effect should be an important part of the lateral mixing between the rod bundle subchannels, which is mainly caused by the pressure difference between the subchannels. Cross-flow mixing is accompanied by the exchange of mass, momentum and energy, which affects the velocity and temperature distribution in the rod bundles. The research on it is helpful to improve the critical heat flux density of the reactor core and thus improve the safety of the nuclear reactor. In this paper, with the help of an inverted U-shaped manometer which can measure small pressure difference, the experiment of cross-flow mixing effect between rod bundle subchannels under single-phase and two-phase flow at room temperature and pressure has been completed. Through the analysis of the experimental results, the action law of the cross-flow mixing effect between the rod bundle subchannels under single-phase and two-phase flow is obtained. In single-phase flow, the cross-flow resistance coefficient decreases with the increase of Reynolds number and the ratio of lateral velocity to axial velocity, while in two-phase flow, the cross-flow resistance coefficient decreases with the increase of the ratio of lateral velocity to axial velocity, and the interfacial friction factor decreases with the increase of Reynolds number.