2015 年 81 巻 832 号 p. 15-00395
This paper presents a detailed experimental study to understand the fundamental process of jet breakup during a core disruptive accident of a sodium-cooled fast reactor. The study mainly focuses on hydrodynamic interaction of jet breakup and fragmentation behavior. The experiments were carried out in an immiscible liquid-liquid system. The indices of refraction in the two liquids were matched, so that the vertical plane of jet flow was clearly visualized using laser-induced fluorescence (LIF). The jet breakup length obtained by image processing is compared with the existing correlations. The applicability of the jet breakup length correlations is discussed from the viewpoints of Weber number and film-boiling effect. When the Weber number is from 10 to 1000, and the boiling effect is small enough, it is suggested that jet breakup length is described by Epstein's correlation. Finally, the reduction of jet core diameter is investigated. It is shown, in this experiment, that the mean jet diameter reduces in the flow direction gradually, but it does not reduce linearly.