Multiphase Science and Technology A Quarterly

ISSN for PRINT: 0276-1459

For Online Access

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2006, Volume18

Issue 1

114 pages

DOI: 10.1615/MultScienTechn.v18.i1

Issue price - $150.00

Akimaro Kawahara
Dept. of Mechanical System Engineering, Kumamoto University, Kumamoto, 860-8555, Japan

Michio Sadatomi
Dept. of Mechanical System Engineering, Kumamoto University, Kumamoto, 860-8555, Japan

K. Kano
Dept. of Mechanical Engineering and Materials Science, Kumamoto University, Kumamoto, 860-8555, Japan

Y. Sasaki
Dept. of Mechanical Engineering and Materials Science, Kumamoto University, Kurokami 2-39-1, Kumamoto City, 860-8555, Japan

H. Kudo
Dept. of Mechanical Engineering and Materials Science, Kumamoto University, Kurokami 2-39-1, Kumamoto City, 860-8555, Japan

To improve a void drift model incorporated in a subchannel analysis code, experimental data have been obtained for vertical air-water two-phase flows in several test channels of two- and multi-subchannel systems. In order to know the effects of the lattice of fuel rods on the void drift, the channels made up of two subchannels (i.e., the two-subchannel system) surrounded by square lattice rods or triangle tight lattice rods were included in the experiment. In addition, to know the effects of the number of subchannels, as the multi-subchannel system the channel consisted of six subchannels simulating a square lattice BWR fuel rod bundle was included. In each test channel, the data have been collected on the axial redistributions of flow rates of both phases and void fraction in the respective subchannels. In order to study the effects of two-phase flow regimes or void fraction on the void drift, the flow regimes covered were slug, churn and annular flows with various combinations of air and water flow rates. By fitting the above data with Lahey et al.'s void settling model, we have determined a void diffusion coefficient in their model. The void diffusion coefficient data were compared between the respective test channels as well as Tapucu et al.'s data for a square lattice two-subchannel system. It was found that the void diffusion coefficient was much smaller in the tight lattice channel than the square lattice channels, i.e., a channel size effect. Furthermore, the void diffusion coefficient could be well correlated with the turbulent Peclet number using a subchannel geometry factor, regardless of both the gap clearance between subchannels and the number of subchannels. It was also found that the correlation depends on the rod lattice.

DOI: 10.1615/MultScienTechn.v18.i1.20 Download article, 31-54 pages

Article price - $45.00

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