Characteristics and mechanism of bubble breakup in a bubble generator developed for a small TMSR

In present study, a new bubble generator was designed for TMSR and tested in an experimental loop using water and air as the working fluids. With the help of a high speed camera, the distribution and detailed breakup process of bubbles in the generator were recorded, and accordingly, the mechanism of bubble breakup was tried to be illustrated combined with a numerical simulation by the software of FLUENT. The experimental results showed that the generated small bubbles by the generator had an average diameter about 0.5–0.6 mm and were uniformly dispersed in the main stream when the void fraction covered the range of 0.2%–0.3%, meeting the requirement of xenon removal for a small molten-salt breeder reactor. On the other hand, the numerical results indicated that the sudden deceleration of the bubbles in the diverging part of the generator led to a sharp velocity gradient in the vicinity of the bubble. This resulted in larger shear stress than the surface tension on the bubble surface, which played a dominant role in bubble breakup in the generator.