Model development for bubble turbulent diffusion and bubble diameter in large vertical pipes

Onuki, Akira; Akimoto, Hajime

Journal of Nuclear Science and Technology, 38(12), p.1074 - 1080, 2001/12

https://doi.org/10.3327/jnst.38.1074

Multi-dimensional analyses have been expected recently with expanding computation resources for gas-liquid two-phase flow analyses of advanced nuclear systems such as passive safety systems and natural-circulation-type reactors. However, the applicability of previous constitutive equations for multi-dimensional analyses has not been fully investigated especially for the effects of flow path scale because the equations have been assessed for small-scale experiments. In this study, we analyzed the scale effects by the multi-dimensional two-fluid model code using data in 38 mm and 200 mm diameter pipes. We clarified a key-parameter to model the scale effects and developed models for the effects on phase distribution. The scale effects can be classified by the relative relationship between bubble diameter db and turbulent length scale lT. Bubble-induced turbulence is increased under that db is smaller than lT and bubble coalescence is predominated rather than breakup under that lT is about three times larger than db and under higher void fraction. Based on these findings, we established new models for bubble turbulent diffusion and bubble diameter. The applicability was promising through assessments against the 38 mm and 200 mm pipes under different flow rates and against a database for developing flow along 480 mm pipe.

Development of models for bubble turbulent diffusion and bubble diameter in multi-dimensional two-fluid model

Onuki, Akira; Akimoto, Hajime

Proceedings of 2nd Japanese-European Two-Phase Flow Group Meeting (CD-ROM), 6 Pages, 2000/00

no abstracts in English

Flow characteristics of air-water two-phase flow in a large vertical pipe

Onuki, Akira; Akimoto, Hajime

Proc. of 1st European-Japanese Two-phase Flow Group Meeting, p.1 - 8, 1998/00

no abstracts in English

Multi-dimensional thermal-hydraulics in pressure vessel during reflood phase of a PWR-LOCA

Murao, Yoshio; Iguchi, Tadashi; Adachi, Hiromichi; Sugimoto, Jun; ; Iwamura, Takamichi; Okubo, Tsutomu; Onuki, Akira; Abe, Yutaka

Proc. of the 4th Int. Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Vol. 1, p.54 - 59, 1989/10

no abstracts in English

Statistical Evaluation of Steam Condensation Loads in Pressure Suppression Pool (1) - Full-Scale MarkII CRT Program Test Evaluation Report No.2 -

; ; ; ; ;

JAERI-M 9665, 143 Pages, 1981/10

JAERI-M-9665.pdf:3.73MB

no abstracts in English