Study on Local Sub-Cooling Boiling in the Vertical Upward Pipe

2021 ◽  
Author(s):  
Meng-Meng Liu ◽  
Zhen Zhang ◽  
Xing-Tuan Yang
Keyword(s):  
Physical Mechanism ◽  
Fluid Model ◽  
Predictive Ability ◽  
Flow Region ◽  
Nucleation Density ◽  
Distribution Law ◽  
Void Fractions ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Analyze Data

Abstract In the heat transfer pipes of nuclear reactors with complex mass and heat exchange, there exists phenomenon of local sub-cooling boiling. Based on the Eulerian two-fluid model, this paper studied the local sub-cooling boiling phenomenon in the vertical upward pipe at a pressure of 4.5MPa. Firstly, a closed sub-cooling boiling model was built to make comparison with the existing experimental results of Bartolomei, the result of which is in great agreement with the experimental data. What’s more, the parameters of the experimental working conditions were expanded, it helped to analyze data that could not be directly measured in the experiment. The physical mechanism behind data distribution law mainly included the influence of the wall bubble departure diameter, the wall bubble departure frequency, and nucleation density. It is found that the RPI model has a good predictive ability for the liquid temperature field. The nucleation density model corresponding to KI combined with the wall departure diameter model KI can well predict the distribution of the void fractions in the pipe. Finally, the influence on heat and mass transfer of heating power along the pipe was analyzed. This paper put forward suggestions for the modification of the sub-cooling boiling model to help it predict the distribution of bubbles in the main flow region more precise.

Numerical Modeling of Two-Phase Flows Using Advanced Two Fluid Systems

2002 ◽  
Author(s):  
Anela Kumbaro ◽  
Imad Toumi ◽  
Vincent Seignole
Keyword(s):  
Fluid Model ◽  
Interfacial Area ◽  
Group Model ◽  
Two Phase Flows ◽  
State Equations ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Void Fractions ◽  
Two Fluid Model ◽  
Two Fluid

The purpose of this paper is to report on the development and assessment of approximate Riemann solver methods for the discretization of non-linear non-conservative systems arising in the simulation of two-phase flows. These methods are able to treat general two-phase flow systems with realistic state equations and are flexible enough to be applied on any mesh type, structured as well as unstructured. We will detail models that go from the basic 6 equation two-fluid model to the coupling of this system with one or more transport equations, for instance on volumetric interfacial area concentration, or on partial void fractions of groups of bubbles (MUlti-Size-Group model). This kind of transport equation is useful to predict at a finer level the interfacial patterns or bubble size distribution and takes account of coalescence or breakup rates of inclusions. We make a glimpse at the choices made regarding this aspect. Different physico-numerical benchmarks are provided in order to illustrate the numerical and physical modeling. Confrontation with experimental or analytical reference data are performed whenever possible. Computer simulations are performed using OVAP, a new multidimensional CFD code.

scholarly journals Natural modes of the two-fluid model of two-phase flow

2021 ◽  
Vol 33 (3) ◽  
pp. 033324
Author(s):  
Alejandro Clausse ◽  
Martín López de Bertodano
Keyword(s):  
Two Phase Flow ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Phase ◽  
Natural Modes ◽  
Two Fluid Model ◽  
Two Fluid

Self-consistent hydrodynamic two-fluid model of vortex plasma

2021 ◽  
Vol 33 (3) ◽  
pp. 037116
Author(s):  
Victor L. Mironov
Keyword(s):  
Fluid Model ◽  
Self Consistent ◽  
Two Fluid Model ◽  
Two Fluid

scholarly journals Mathematical study on two-fluid model for flow of K–L fluid in a stenosed artery with porous wall

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
R. Ponalagusamy ◽  
Ramakrishna Manchi
Keyword(s):  
Theoretical Study ◽  
Fluid Model ◽  
Porous Wall ◽  
Governing Equations ◽  
Rate Of Increase ◽  
Special Cases ◽  
Stenosed Artery ◽  
Flow Through ◽  
Two Fluid Model ◽  
Two Fluid

AbstractThe present communication presents a theoretical study of blood flow through a stenotic artery with a porous wall comprising Brinkman and Darcy layers. The governing equations describing the flow subjected to the boundary conditions have been solved analytically under the low Reynolds number and mild stenosis assumptions. Some special cases of the problem are also presented mathematically. The significant effects of the rheology of blood and porous wall of the artery on physiological flow quantities have been investigated. The results reveal that the wall shear stress at the stenotic throat increases dramatically for the thinner porous wall (i.e. smaller values of the Brinkman and Darcy regions) and the rate of increase is found to be 18.46% while it decreases for the thicker porous wall (i.e. higher values of the Brinkman and Darcy regions) and the rate of decrease is found to be 10.21%. Further, the streamline pattern in the stenotic region has been plotted and discussed.

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