Experimental studies on bubble breakup mechanism in a venturi bubble generator

The generation IV molten salt reactor will produce a large amount of fission gases during its operation, which will reduce the efficiency of the reactor. To remove these gases, a venturi tube is adopted in the gas removal system to generate bubbles of a particular size. The bubbles absorb the fission gases through the mass transfer, and the mixed gases are finally separated out of the system. The efficiency of the separation depends on the size of bubbles. The bubbles are generated during the process of turbulent breakup in the venturi tube. The mechanism of bubble breakup is studied by experiments. Firstly, the motion and breakup of bubbles in venturi tube under different Reynolds number are obtained through visualization experiment. Combined with image processing, the velocity and shape of bubbles are analyzed. Then the turbulence field in venturi tube is obtained by particle image velocimetry (PIV) technique. And the turbulent kinetic energy and various types of flow patterns in venturi tube are obtained. Finally, through the force analysis of the bubble interface, the deformation and fragmentation of the bubbles are the interaction of the destructive stress (turbulent stress, viscous stress) and allowable stress. Meanwhile the shape of the bubbles also has a great influence on the breakup of the bubbles. The ratio of destructive stress to allowable stress is the criterion for measuring the stability of bubbles (7-11 is estimated in this experiment). This paper provides a theoretical basis for bubble size control of gas-liquid separating technology from the mechanism. (C) 2019 Published by Elsevier Ltd.