Experimental study on fundamental behavior of cavitation due to sub-surface vortex; Influences of fluid viscosity on occurrences of cavitation

Ezure, Toshiki ; Miyake, Yasuhiro*; Tobita, Akira; Kimura, Nobuyuki; Kamide, Hideki 

In the design of JSFR, a two-loop cooling system and a compact reactor vessel are employed to achieve the economical improvement. However, these innovative designs lead to the increase of coolant velocity. As the results, strong vortices at the H/L intake may cause the cavitation (vortex cavitation). Therefore, the evaluation of occurrence behavior of vortex cavitation is the important issue for the structural integrity of reactor. In the present study, fundamental water experiments were performed in the cylindrical tank geometry. The water temperature was varied from 10C to 80C to clarify the influence of kinematic viscosity, . The occurrences behaviors of vortex cavitation were evaluated quantitatively by visualization measurement and image analysis. As the results, it was clarified that there was little dependence on under the small conditions, while it was relatively obvious under the large conditions.