Effects of surface tension and viscosity on liquid jet breakup

Zhan, Y.*; Kuwata, Yusuke*; Maruyama, Kiyotaka*; Okawa, Tomio*; Enoki, Koji*; Aoyagi, Mitsuhiro; Takata, Takashi

Experimental Thermal and Fluid Science, 112, p.109953_1 - 109953_8, 2020/04

https://doi.org/10.1016/j.expthermflusci.2019.109953

A Study on splashing during liquid jet impingement onto a horizontal plate

Kuwata, Yusuke*; Zhan, Y.*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi

Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 10 Pages, 2018/10

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, effect of viscosity on liquid jet impact on solid surface was studied.

Production of droplets during liquid jet impingement onto a flat plate

Yi, Z.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Ohno, Shuji; Aoyagi, Mitsuhiro; Takata, Takashi

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 7 Pages, 2016/11

It is important to set the amount of sodium droplet mechanistically for appropriate numerical evaluations of sodium leak and fire behavior in a sodium-cooled fast reactor plant. In the present work, fundamental experiments were performed to measure the splash ratio during the vertical water jet impact onto a horizontal wall. It was shown that the splash ratio can be correlated well as a function of the impact Weber number, the Strouhal number and the Ohnesorge number of the droplets impinging the liquid film.

Reduction and unusual recovery in the reversible hydrogen storage capacity of VTi during hydrogen cycling

Kim, H.*; Sakaki, Koji*; Saita, Itoko*; Enoki, Hirotoshi*; Noguchi, Kazuo*; Machida, Akihiko; Watanuki, Tetsu; Nakamura, Yumiko*

International Journal of Hydrogen Energy, 39(20), p.10546 - 10551, 2014/07

https://doi.org/10.1016/j.ijhydene.2014.04.128

The effect of the vanadium content on the cyclic stability of V-Ti binary alloys was investigated. VTi, 0.2 and 0.5 samples were hydrogenated and dehydrogenated at 410 K and 553 K respectively, for more than 100 times. During hydrogen cycling, reduction in the reversible hydrogen storage capacity was clearly observed from both samples. In addition, the shape of the pressure-composition-isotherm curves was significantly altered over the testing cycle period; the absorption and desorption plateaus got markedly inclined and the hysteresis became evidently smaller. We found that even after the hydrogen storage capacity of VTi was significantly reduced, at low enough temperature VTi was able to absorb hydrogen as much as it did at the first cycle.

An in situ Mssbauer study using synchrotron radiation

Masuda, Ryo; Mitsui, Takaya; Ito, Keiji*; Sakaki, Koji*; Enoki, Hirotoshi*; Nakamura, Yumiko*; Seto, Makoto

Hyperfine Interactions, 204(1-3), p.139 - 142, 2012/03

https://doi.org/10.1007/s10751-011-0470-x

We have been developing a system for in situ Mssbauer studies using synchrotron radiation (SR) to elucidate the mechanism of hydrogenation processes. In the system, samples reacts in an atmosphere chamber and SR-based Mssbauer spectra using variable-frequency nuclear monochromator and energy spectra of inelastic nuclear resonant scattering (NRS) of SR are measured. As a feasibility study, the temperature dependence of the Mssbauer and inelastic NRS spectra of Fe in -GdFeH under vacuum were measured. In both spectra, clear differences were observed between 373 K and 573 K. These differences can be interpreted by the change of microscopic environment around Fe at the dehydrogenation. Thus, it is confirmed that this system works well enough to perform the in-situ Mssbauer study on the dehydrogenation of -GdFeH.

Effect of viscosity on liquid jet impact on solid surface

Kuwata, Yusuke*; Zhan, Y.*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi

no journal, , 

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, effect of viscosity on liquid jet impact on solid surface was studied.

Splashing droplets during liquid jet collision onto solid surface

Zhan, Y.*; Kuwata, Yusuke*; Maruyama, Kiyotaka*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi

no journal, , 

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, splashing droplets are investigated by observation of liquid jet collision onto a solid surface.

Study on splashing droplets during the breakup liquid jet collision onto solid surface

Zhan, Y.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Ohno, Shuji; Takata, Takashi

no journal, , 

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, droplets were generated by collision of breakup liquid jet onto a solid surface. We studied the mechanism of droplet generation and the empirical correlation of droplet amount.

Study on droplet generation during upward spray flow collision onto a solid surface

Zhan, Y.*; Sun, G.*; Okawa, Tomio*; Enoki, Koji*; Aoyagi, Mitsuhiro; Takata, Takashi

no journal, , 

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, secondary droplets are investigated by observation of upward spray flow collision onto a solid surface.

Study on droplet generation of the surface collision jet

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

no journal, , 

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.

Droplet generation during liquid jet collision onto solid surface

Oya, Naoki*; Zhan, Y.*; Okawa, Tomio*; Enoki, Koji*; Aoyagi, Mitsuhiro; Ohno, Shuji; Takata, Takashi

no journal, , 

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, droplets were generated by collision of downward liquid jet onto a horizontal solid surface. We studied the mechanism of droplet generation and the empirical correlation of droplet amount.