Numerical Evaluation of Fluid Mixing Phenomena in Boiling Water Reactor Using Advanced Interface-Tracking Method

Thermal-hydraulic design of the current boiling water reactor (BWR) is performed by correlations with empirical results of actual-size tests. Then, for the Innovative Water Reactor for Flexible Fuel Cycle (FLWR) core, an actual size test that simulates its design is required to confirm or modify the correlations. Development of a method that enables the thermal-hydraulic design of nuclear rectors without these actual size tests is desired, because these tests take a long time and entail great cost. For this reason we developed an advanced thermal-hydraulic design method for FLWRs using innovative two-phase flow simulation technology. In this study, detailed two-phase flow simulation code using advanced interface tracking method: TPFIT is developed to get the detailed information of the two-phase flow. In this paper, firstly, we tried to verify the TPFIT code comparing with the existing 2-channel air-water mixing experimental results. Secondary, the TPFIT code was applied to simulation of steamwater two-phase flow in modeled two subchannels of current BWRs rod bundle. The fluid mixing was observed at a gap between the subchannels. The existing two-phase flow correlation for fluid mixing is evaluated using detailed numerical simulation data. From the data, pressure difference between fluid channels is responsible for the fluid mixing, and effects of the time averaged and fluctuating pressure difference must be incorporated in the two-phase flow correlation for fluid mixing.

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Analytical Procedure on Fluid Mixing Phenomena in Boiling Water Reactor Core With Advanced Interface Tracking Method

Volume 2: Fora, Parts A and B ◽

10.1115/fedsm2007-37675 ◽

2007 ◽

Author(s):

Hiroyuki Yoshida ◽

Takeharu Misawa ◽

Kazuyuki Takase ◽

Hajime Akimoto

Keyword(s):

Two Phase Flow ◽

Flow Simulation ◽

Boiling Water ◽

Fluid Mixing ◽

Boiling Water Reactor ◽

Phase Flow ◽

Two Phase ◽

Water Reactor ◽

Hydraulic Design ◽

Actual Size

Thermal-hydraulic design of a boiling water reactor (BWR) is performed by correlations with empirical results of actual-size tests. Then, when the reactor of a new design is developed, an actual size test that simulates its design is required to confirm or modify the correlations. Development of a method that enables the thermal-hydraulic design of nuclear rectors without these actual size tests is desired, because these tests take a long time and entail great cost. For this reason we developed an advanced thermal-hydraulic design method for BWRs using an innovative two-phase flow simulation technology. For this design method, we are developed an advanced interface tracking method that improves fluid volume conservation, to enable high accuracy prediction of two-phase flow fluid mixing phenomena in the fuel bundles. It was incorporated in the detailed two-phase flow simulation code: TPFIT. And the vectorization and parallelization of TPFIT code was conducted to analyze enormous amounts of data. In this study, to verify the TPFIT code performance, the TPFIT code was applied to the air-water and steam-water bubbly two-phase flow in various flow channels and the numerical results were compared with experimental results. Furthermore, the numerical results applied to the fluid mixing phenomena in boiling water reactor rod bundles are shown, and the existing correlations for the fluid mixing phenomena are evaluated by use of these results.

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1416 Investigation on the Interface-Tracking Method Based on Cahn-Hilliard Equation for the Two-Phase Flow

The Proceedings of the Fluids engineering conference ◽

10.1299/jsmefed.2009.457 ◽

2009 ◽

Vol 2009 (0) ◽

pp. 457-458

Author(s):

Tomoki WADA ◽

Koichi TSUJIMOTO ◽

Toshihiko SHAKOUCHI ◽

Toshitake ANDO

Keyword(s):

Two Phase Flow ◽

Interface Tracking ◽

Phase Flow ◽

Two Phase ◽

Tracking Method ◽

Hilliard Equation ◽

Cahn Hilliard Equation

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Development of Advanced Two-Fluid Model for Boiling Two-Phase Flow in Rod Bundles

18th International Conference on Nuclear Engineering: Volume 4, Parts A and B ◽

10.1115/icone18-30219 ◽

2010 ◽

Cited By ~ 1

Author(s):

Hiroyuki Yoshida ◽

Hideaki Hosoi ◽

Takayuki Suzuki ◽

Kazuyuki Takase

Keyword(s):

Constitutive Equations ◽

Two Phase Flow ◽

Fluid Model ◽

Interface Tracking ◽

Phase Flow ◽

Rod Bundles ◽

Two Phase ◽

Tracking Method ◽

Two Fluid Model ◽

Two Fluid

Two-fluid model can simulate two-phase flow by computational cost less than detailed two-phase flow simulation method such as interface tracking method. Therefore, two-fluid model is useful for thermal hydraulic analysis in large-scale domain such as rod bundles in nuclear reactors. However, two-fluid model include a lot of constitutive equations. Then, applicability of these constitutive equations must be verified by use of experimental results, and the two-fluid model has problems that the results of analyses depend on accuracy of constitutive equations. To solve these problems, we have been developing an advanced two-fluid model. In this model, an interface tracking method is combined with the two-fluid model to predict large interface structure behavior accurately. Interfacial structures larger than a computational cells, such as large droplets and bubbles, are calculated using the interface tracking method. And droplets and bubbles that are smaller than cells are simulated by the two-fluid model. Constitutive equations to evaluate the effects of small bubbles or droplets on two-phase flow are required in the advanced two-fluid model as same as a conventional two-fluid model. However, dependency of small bubbles and droplets on two-phase flow characteristic is relatively small, and the experimental results to verify the equations are not required much. In this study, we modified the advanced two-fluid model to improve the stability of the numerical simulation and reduce the computational time. Moreover, the modified model was incorporated to the 3-dimensional two-fluid model code ACE-3D. In this paper, we describe the outline of this model and the modification performed in this study. Moreover, the numerical results of two-phase flow in various flow conditions.

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Bubble flow simulations using the intersection marker (ISM) interface tracking method

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-09-2017-0385 ◽

2018 ◽

Vol 28 (1) ◽

pp. 118-137 ◽

Cited By ~ 3

Author(s):

Mark Ho ◽

Guan Heng Yeoh ◽

John Arthur Reizes ◽

Victoria Timchenko

Keyword(s):

Surface Tension ◽

Two Phase Flow ◽

Front Tracking ◽

Interface Tracking ◽

Phase Flow ◽

Cfd Simulations ◽

Two Phase ◽

Content Type ◽

Tracking Method ◽

Flow Simulations

Purpose Interface distinct two-phase computational fluid dynamics (CFD) simulations require accurate tracking in surface curvature, surface area and volume fraction data to precisely calculate effects such as surface tension, interphase momentum and interphase heat and mass transfer exchanges. To attain a higher level of accuracy in two-phase flow CFD simulations, the intersection marker (ISM) method was developed. The ISM method has cell-by-cell remeshing capability that is volume conservative, maintains surface continuity and is suited for the tracking of interface deformation in transient two-phase flow simulations. Studies of isothermal single bubbles rising in quiescent water were carried out to test the ISM method for two-phase flow simulations. Design/methodology/approach The ISM method is a hybrid Lagrangian–Eulerian front tracking algorithm which can model an arbitrary three-dimensional surface within an array of cubic control volumes. Fortran95 was used to implement the ISM method, which resulted in approximately 25,000+ lines of written code and comments. To demonstrate the feasibility of the ISM algorithm for two-phase flow simulations, the ISM algorithm was coupled with an in-house CFD code, which was modified to simulate two-phase flows using a single fluid formulation. The constitutional equations incorporated terms of variable density and viscosity. In addition, body force source terms were included in the momentum equation to account for surface tension and buoyancy effects. Findings The performance of two-phase flow simulations was benchmarked against experimental data for four air/water bubbles with 1, 2.5, 5 and 10 mm of diameter rising in quiescent fluid. A variety of bubble sizes were tested to demonstrate the accuracy of the ISM interface tracking method. The results attained were in close agreement with experimental observations. Practical implications The results obtained show that the ISM method is a viable means for interface tracking of two-phase flow CFD simulations. Other applications of the ISM method include simulations of solid–fluid interaction and other immersed boundary flow problems. Originality/value The ISM method is a novel approach to front tracking, and the results shown are original in content.

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