Effect of Compressibility on Hyperbolicity and Choke Flow Criterion of the Two-phase Two-fluid Model

In this paper, two-phase flow dynamics in a micro channel with various wall conditions are both experimentally and theoretically investigated. Annulus, wavy and slug flow patterns are observed and location of liquid phase on different wall condition is visualized. The impact of flow structure on two-phase pressure drop is explained. Two-phase pressure drop is compared to a two-fluid model with relative permeability correlation. Optimization of correlation is conducted for each experimental case and theoretical solution for the flows in a circular channel is developed for annulus flow pattern showing a good match with experimental data in homogeneous channel case.

A Physically Based, One-Dimensional Two-Fluid Model for Direct Contact Condensation of Steam Jets Submerged in Subcooled Water

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4029417 ◽

2015 ◽

Vol 1 (2) ◽

Cited By ~ 6

Author(s):

David Heinze ◽

Thomas Schulenberg ◽

Lars Behnke

Keyword(s):

Direct Contact ◽

Two Phase Flow ◽

Fluid Model ◽

Interfacial Area ◽

Phase Flow ◽

Two Phase ◽

One Dimensional ◽

Two Fluid Model ◽

Contact Condensation ◽

Two Fluid

A simulation model for the direct contact condensation of steam in subcooled water is presented that allows determination of major parameters of the process, such as the jet penetration length. Entrainment of water by the steam jet is modeled based on the Kelvin–Helmholtz and Rayleigh–Taylor instability theories. Primary atomization due to acceleration of interfacial waves and secondary atomization due to aerodynamic forces account for the initial size of entrained droplets. The resulting steam-water two-phase flow is simulated based on a one-dimensional two-fluid model. An interfacial area transport equation is used to track changes of the interfacial area density due to droplet entrainment and steam condensation. Interfacial heat and mass transfer rates during condensation are calculated using the two-resistance model. The resulting two-phase flow equations constitute a system of ordinary differential equations, which is solved by means of the explicit Runge–Kutta–Fehlberg algorithm. The simulation results are in good qualitative agreement with published experimental data over a wide range of pool temperatures and mass flow rates.

Numerical Simulation of Boiling Two-Phase Flow in Tight-Lattice Rod Bundle by 3-Dimensional Two-Fluid Model Code ACE-3D

Volume 3: Thermal Hydraulics; Instrumentation and Controls ◽

10.1115/icone16-48715 ◽

2008 ◽

Author(s):

Hiroyuki Yoshida ◽

Takeharu Misawa ◽

Kazuyuki Takase

Keyword(s):

Void Fraction ◽

Lift Force ◽

Fluid Model ◽

Phase Flow ◽

Two Phase ◽

Rod Bundle ◽

Fraction Distribution ◽

Two Fluid Model ◽

Tight Lattice ◽

Two Fluid

Two-fluid model can simulate two phase flow less computational cost than inter-face tracking method and particle interaction method. Therefore, two-fluid model is useful for thermal hydraulic analysis in large-scale domain such as a rod bundle. Japan Atomic Energy Agency (JAEA) develops three dimensional two-fluid model analysis code ACE-3D, which adopts boundary fitted coordinate system in order to simulate complex shape channel flow. In this paper, boiling two-phase flow analysis in a tight lattice rod bundle is performed by ACE-3D code. The parallel computation using 126CPUs is applied to this analysis. In the results, the void fraction, which distributes in outermost region of rod bundle, is lower than that in center region of rod bundle. At height z = 0.5 m, void fraction in the gap region is higher in comparison with that in center region of the subchannel. However, at height of z = 1.1m, higher void fraction distribution exists in center region of the subchannel in comparison with the gap region. The tendency of void fraction to concentrate in the gap region at vicinity of boiling starting point, and to move into subchannel as water goes through rod bundle, is qualitatively agreement with the measurement results by neutron radiography. To evaluate effects of two-phase flow model used in ACE-3D code, numerical simulation of boiling two-phase in tight lattice rod bundle with no lift force model (neglecting lift force acting on bubbles) is also performed. From the comparison of numerical results, it is concluded that the effects of lift force model are not so large on overall void fraction distribution in tight lattice rod bundle. However, higher void fraction distribution in center region of the subchannel was not observed in this simulation. It is concluded that the lift force model is important for local void fraction distribution in rod bundles.

Prediction of Parameters Distribution of Upward Boiling Two-Phase Flow With Two-Fluid Models

10th International Conference on Nuclear Engineering, Volume 3 ◽

10.1115/icone10-22463 ◽

2002 ◽

Cited By ~ 4

Author(s):

Wei Yao ◽

Christophe Morel

Keyword(s):

Void Fraction ◽

Fluid Model ◽

Constitutive Relations ◽

Turbulent Dispersion ◽

Dispersion Force ◽

Liquid Temperature ◽

Two Phase ◽

Radial Profiles ◽

Two Fluid Model ◽

Two Fluid

In this paper, a multidimensional two-fluid model with additional turbulence k–ε equations is used to predict the two-phase parameters distribution in freon R12 boiling flow. The 3D module of the CATHARE code is used for numerical calculation. The DEBORA experiment has been chosen to evaluate our models. The radial profiles of the outlet parameters were measured by means of an optical probe. The comparison of the radial profiles of void fraction, liquid temperature, gas velocity and volumetric interfacial area at the end of the heated section shows that the multidimensional two-fluid model with proper constitutive relations can yield reasonably predicted results in boiling conditions. Sensitivity tests show that the turbulent dispersion force, which involves the void fraction gradient, plays an important role in determining the void fraction distribution; and the turbulence eddy viscosity is a significant factor to influence the liquid temperature distribution.

Validation of three-dimensional simulation method for two-phase flow in triangular-pitch tube bundle in secondary side of steam generators on porous two-fluid model

Journal of Nuclear Science and Technology ◽

10.1080/00223131.2021.1954102 ◽

2021 ◽

pp. 1-18

Author(s):

Yoshiteru Komuro ◽

Atsushi Kodama ◽

Yoshiyuki Kondoh ◽

Seinosuke Azuma ◽

Hideyuki Morita ◽

...

Keyword(s):

Tube Bundle ◽

Fluid Model ◽

Three Dimensional ◽

Simulation Method ◽

Steam Generators ◽

Two Phase ◽

Two Fluid Model ◽

Dimensional Simulation ◽

Secondary Side ◽

Two Fluid

An Upwind Numerical Method for a Hyperbolic One-Dimensional Two-Fluid Model

ASME 2011 Pressure Vessels and Piping Conference: Volume 3 ◽

10.1115/pvp2011-58007 ◽

2011 ◽

Author(s):

Youn-Gyu Jung ◽

Moon-Sun Chung ◽

Sung-Jae Yi

Keyword(s):

Numerical Method ◽

Fluid Model ◽

Equation System ◽

Benchmark Problems ◽

Two Phase ◽

One Dimensional ◽

Flow Problems ◽

Complete Set ◽

Two Fluid Model ◽

Two Fluid

This study discusses on the implementation of an upwind method for a one-dimensional two-fluid model including the surface tension effect in the momentum equations. This model consists of a complete set of six equations including two-mass, two-momentum, and two-internal energy conservation equations having all real eigenvalues. Based on this equation system with upwind numerical method, the present authors first make a pilot code and then solve some benchmark problems to verify whether this model and numerical method is able to properly solve some fundamental one-dimensional two-phase flow problems or not.

A two-fluid model for avalanche and debris flows

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2005.1596 ◽

2005 ◽

Vol 363 (1832) ◽

pp. 1573-1601 ◽

Cited By ~ 245

Author(s):

E. Bruce Pitman ◽

Long Le

Keyword(s):

Debris Flows ◽

Fluid Model ◽

Solid Material ◽

Fluid Inertia ◽

Two Phase ◽

Engineering Research ◽

Mass Flows ◽

Two Fluid Model ◽

Two Fluid ◽

Geophysical Mass Flows

Geophysical mass flows—debris flows, avalanches, landslides—can contain O (10 6 –10 10 ) m 3 or more of material, often a mixture of soil and rocks with a significant quantity of interstitial fluid. These flows can be tens of meters in depth and hundreds of meters in length. The range of scales and the rheology of this mixture presents significant modelling and computational challenges. This paper describes a depth-averaged ‘thin layer’ model of geophysical mass flows containing a mixture of solid material and fluid. The model is derived from a ‘two-phase’ or ‘two-fluid’ system of equations commonly used in engineering research. Phenomenological modelling and depth averaging combine to yield a tractable set of equations, a hyperbolic system that describes the motion of the two constituent phases. If the fluid inertia is small, a reduced model system that is easier to solve may be derived.

A Linear Stability Analysis for an Improved One-Dimensional Two-Fluid Model

Journal of Fluids Engineering ◽

10.1115/1.1537256 ◽

2003 ◽

Vol 125 (2) ◽

pp. 387-389 ◽

Cited By ~ 3

Author(s):

Jin Ho Song

Keyword(s):

Stability Analysis ◽

Linear Stability ◽

Linear Stability Analysis ◽

Fluid Model ◽

Two Phase ◽

One Dimensional ◽

Proposed Model ◽

Two Fluid Model ◽

The One ◽

Two Fluid

A linear stability analysis is performed for a two-phase flow in a channel to demonstrate the feasibility of using momentum flux parameters to improve the one-dimensional two-fluid model. It is shown that the proposed model is stable within a practical range of pressure and void fraction for a bubbly and a slug flow.