Study on droplet generation of the surface collision jet

Oya, Naoki*; Okawa, Tomio*; Enoki, Koji*; Ohno, Shuji  ; Aoyagi, Mitsuhiro 

It is important to set the diameter of leakage sodium droplet mechanistically for appropriate numerical evaluations of sodium leak and fire behavior in a sodium-cooled fast reactor plant. We performed a fundamental experiment with water in order to clarify mechanism of droplet generation in this study. Impinging water jet on a flat plate was tested for various cases of jet velocity, nozzle diameter and nozzle height. The impinging behavior was visualized by using a high-speed video camera. We measured the amount of generated droplet and the maximum droplet diameter. Observed jet flow was categorized into following three modes: drop mode which is droplet state flow, jet mode which is straight flow and lump mode which is partially constricted flow. The amount of generated droplet had a strong correlation with the impact frequency. Larger droplet diameter was observed for the drop and lump modes.