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Shinozaki, Tatsuya*; Monji, Hideaki*; Kamide, Hideki
no journal, ,
The aim of this study is to reveal the influences of the working fluid properties, the flow configuration and the flow conditions on the characteristics of the free surface vortex. For investigation on the working fluid effect, temperature of the fluid was varied. Flow configuration was altered by changing the water level and by adding structures to the outlet. Then, we investigated the shape of the detached bubble when the surface active agent is added. We found out that all these parameters have considerable influences on the behavior of the free surface vortex.
Oiwa, Hiroshi; Murai, Yuichi*; Yoshikawa, Shinji
no journal, ,
Helically coiled type steam generator is used in Fast Breeder Reactor "Monju". The characteristics of this steam generator is affected by the centrifugal acceleration due to curvature of the heat transfer tube. The centrifugal acceleration forces the liquid phase to the wall of the tube. This phenomenon suppresses the rapid boiling that may induce the hydrodynamic oscillation. In this study, the effect of centrifugal acceleration and inlet conditions of the fluid is investigated by experiment using backlight imaging tomography and numerical simulation using CIP-level set method. We focused on a slug flow regime in which centrifugal acceleration dominates the flow. The present study showed two types of the centrifugal acceleration effects. One is the effect that holds the liquid phase near the tube wall, and another is the liquid-covering effect on the wall by secondary flow.
Nagai, Niro*; Yoshikawa, Shinji
no journal, ,
The helically coiled tube of heat exchanger is used for the evaporator of prototype fast breeder reactor "Monju". This report aims at the grasp of two-phase flow phenomena of forced convective boiling of water inside helically coiled tube, especially focusing on oscillation of dryout point. A shell & tube structure made of glass is used as heat exchanger. Water flows up inside helical tube and the high temperature oil flows down in the outside tube. The oscillation of the dryout point was observed, that is mainly caused by intensive nucleate boiling near the dryout point and evaporation of thin liquid film flowing along the surface. The effects of experimental parameters, such as oil temperature, water temperature, water flow rate, diameter and curvature of the tube, on amplitude and cycle of oscillation were experimentally grasped.