Numerical Simulation of Countercurrent Gas-Liquid Flow in a PWR Hot Leg Using VOF Method
NURETH-14 - 2011 September 25-30

Presented at:
2011 September 25-30
Toronto, Canada
Session Title:
B2-1 Computational Multi-Fluid Dynamics and Validation/Verification/Applications

Michio Murase (Institute of Nuclear Safety System, Inc.)
Ikuo Kinoshita (Institute of Nuclear Safety System, Inc.)
Chihiro Yanagi (Institute of Nuclear Safety System, Inc.)
Takashi Takata (Osaka University)
Akira Yamaguchi (Osaka University)
Akio Tomiyama (Kobe University)


In order to evaluate flow patterns and CCFL (countercurrent flow limitation) characteristics in a PWR hot leg under reflux condensation, numerical simulations have been done using a two-fluid model and a VOF (volume of fluid) method implemented in the CFD software, FLUENT6.3.26. The two-fluid model gave good agreement with CCFL data under low pressure conditions but did not give good results under high pressure steam-water conditions. On the other hand, the VOF method gave good agreement with CCFL data for tests with a rectangular channel but did not give good results for calculations in a circular channel. Therefore, in this paper, the computational grid and schemes were changed in the VOF method, numerical simulations were done for steam-water flows at 1.5 MPa under PWR full-scale conditions with the inner diameter of 0.75 m, and the calculated results were compared with the UPTF data at 1.5 MPa. As a result, the calculated flow pattern was found to be similar to the flow pattern observed in small-scale air-water tests, and the calculated CCFL characteristics agreed well with the UPTF data at 1.5 MPa except in the region of a large steam volumetric flux.

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