TY - JOUR
T1 - Evaluation of structural effect of BWR spacers on droplet flow dynamics
AU - Okawa, Riichiro
AU - Furuya, Masahiro
AU - Arai, Takahiro
AU - Iiyama, Tsugumasa
N1 - Funding Information:
A part of this study was carried out under the auspices of the Nuclear Regulation Authority (NRA), Japan. The authors are grateful for many constructive suggestions made by Dr. Junichi Kaneko, Dr. Naofumi Tsukamoto and Mr. Yasuhiro Masuhara of NRA, Japan. Thanks are extended to Mr. Tatsumi Ikeda, Mr. Tsutomu Sakuma, Mr. Takumi Yasuoka and Mr. Yuhei Kaji of Techno Service Co. Ltd. for helping in the experiments for this study.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/6
Y1 - 2021/6
N2 - We have established an experimental system to visualize a droplet flow in a simulated BWR fuel sub-channel optically and measure the diameter and velocity of droplet after passing through a spacer. For representative spacers of ferrule and grid type, an effect of them on downstream droplets was evaluated with the experimental system. When a ferrule type spacer was simulated and implemented in both the center and side sub-channel, the vertical velocity of droplets got faster especially in the range of small diameter compared to the case of no spacer. When a grid type spacer was simulated and implemented in the center sub-channel especially, a large dispersion of vertical velocity of droplets occurred especially in the range of small diameter compared to the case of no spacer. By a computational fluid dynamics analysis for gas phase flow to drive the droplets in the sub-channel, it was confirmed qualitatively that the characteristics of droplet behavior observed in this experiment were dependent on the structure and geometry of spacer and sub-channel. Furthermore, it was revealed that a relation between a droplet diameter and velocity can be organized with a non-dimensional function derived from a momentum equation of particle in driving fluid and its drag coefficient has linear correlation with a gas Froude number.
AB - We have established an experimental system to visualize a droplet flow in a simulated BWR fuel sub-channel optically and measure the diameter and velocity of droplet after passing through a spacer. For representative spacers of ferrule and grid type, an effect of them on downstream droplets was evaluated with the experimental system. When a ferrule type spacer was simulated and implemented in both the center and side sub-channel, the vertical velocity of droplets got faster especially in the range of small diameter compared to the case of no spacer. When a grid type spacer was simulated and implemented in the center sub-channel especially, a large dispersion of vertical velocity of droplets occurred especially in the range of small diameter compared to the case of no spacer. By a computational fluid dynamics analysis for gas phase flow to drive the droplets in the sub-channel, it was confirmed qualitatively that the characteristics of droplet behavior observed in this experiment were dependent on the structure and geometry of spacer and sub-channel. Furthermore, it was revealed that a relation between a droplet diameter and velocity can be organized with a non-dimensional function derived from a momentum equation of particle in driving fluid and its drag coefficient has linear correlation with a gas Froude number.
KW - BWR fuel sub-channel
KW - Droplet
KW - Particle Tracking Velocimetry (PTV)
KW - Shadow imaging
KW - Spacer
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U2 - 10.1016/j.nucengdes.2021.111155
DO - 10.1016/j.nucengdes.2021.111155
M3 - Article
AN - SCOPUS:85102550697
SN - 0029-5493
VL - 377
JO - Nuclear Engineering and Design
JF - Nuclear Engineering and Design
M1 - 111155
ER -