Development of Sodium Two-Phase Flow Model for KALIMER Core Analysis

2002 ◽  
Author(s):  
W. P. Chang ◽  
Dohee Hahn
Keyword(s):  
Liquid Metal ◽  
Single Phase ◽  
System Analysis ◽  
Flow Model ◽  
Two Phase Flow ◽  
Water System ◽  
Phase Flow ◽  
Two Phase ◽  
Applicable Range ◽  
Further Development

An algorithm for sodium boiling is developed in order to extend the applicability of SSC-K, which is a main system analysis code for the KALIMER (Korea Advanced LIquid MEtal Reactor) conceptual design. As the capability of the current SSC-K version is limited to simulation of only a single-phase sodium flow, its applicable range should not be enough to assess the fuel integrity under some of HCDA (Hypothetical Core Disruptive Accident) initiating events where sodium boiling is anticipated. The two-phase flow model similar to that used for the light water system is known to be no more effective directly to liquid metal reactors, because the phenomena observed between two reactor coolant systems are definitely different. The developing algorithm is based on a multiple-bubble slug ejection model, which allows a finite number of bubbles in a channel at any time. The present work is a continuous effort following the former study to confirm a qualitative acceptance on the model. Since the model has been applied only to the active fuel region in the former study, a part of its qualification seems to have already been demonstrated. For its application to the whole KALIMER core channel, however, the model needs to be examined the applicability to the fuel regions other than the active fuel. The present study primarily focuses on that point. In a result, although the model may be improved in a sense through the present study over the previous modeling, a clear limitation is also confirmed with the validity of the model. The further development, therefore, is required for this model to achieve its goal by resolving such limitations.

scholarly journals An Explicit Analytical Solution for Transient Two-Phase Flow in Inclined Fluid Transmission Lines

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 300
Author(s):  
Taoufik Wassar ◽  
Matthew A. Franchek ◽  
Hamdi Mnasri ◽  
Yingjie Tang
Keyword(s):  
Steady State ◽  
Analytical Model ◽  
Transmission Lines ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Mechanistic Model ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

Due to the complex nonlinearity characteristics, analytical modeling of compressible flow in inclined transmission lines remains a challenge. This paper proposes an analytical model for one-dimensional flow of a two-phase gas-liquid fluid in inclined transmission lines. The proposed model is comprised of a steady-state two-phase flow mechanistic model in-series with a dynamic single-phase flow model. The two-phase mechanistic model captures the steady-state pressure drop and liquid holdup properties of the gas-liquid fluid. The developed dynamic single-phase flow model is an analytical model comprised of rational polynomial transfer functions that are explicitly functions of fluid properties, line geometry, and inclination angle. The accuracy of the fluid resonant frequencies predicted by the transient flow model is precise and not a function of transmission line spatial discretization. Therefore, model complexity is solely a function of the number of desired modes. The dynamic single-phase model is applicable for under-damped and over-damped systems, laminar, and turbulent flow conditions. The accuracy of the overall two-phase flow model is investigated using the commercial multiphase flow dynamic code OLGA. The mean absolute error between the two models in step response overshoot and settling time is less than 8% and 2 s, respectively.

Study on Aeration for Disengaged Wet Clutches Using a Two-Phase Flow Model

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Shihua Yuan ◽  
Kai Guo ◽  
Jibin Hu ◽  
Zengxiong Peng
Keyword(s):  
Rotational Speed ◽  
Computational Models ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Critical Rotational Speed ◽  
Friction Plate ◽  
Aeration Process

The existing computational models for disengaged wet clutches are deduced based on the single-phase flow theory. However, the complex gas-liquid two-phase flow is formed due to aeration at high rotational speeds. The objective of this study is to use a two-phase flow model to demonstrate the aeration process at different rotational speeds not only of the friction plate but also of the separator plate. A nongrooved, steady-state, two-phase flow computational fluid dynamics model is built using FLUENT, and it is validated by experimental data. The results reveal that air enters the clearance at a critical rotational speed, which causes the drag torque to sharply decrease. The aeration mode and flow pattern are obtained via simulations. The rotational speed of the separator plate has a significant effect on the aeration, including the speed magnitude and direction.

A computationally efficient two-phase hydro-sediment-morphdynamic model and its preliminary field applications  

2021 ◽  
Author(s):  
Binghan Lyu ◽  
Peng Hu ◽  
Ji Li ◽  
Zhixian Cao ◽  
Wei Li ◽  
...  
Keyword(s):  
Yangtze River ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Measure Data ◽  
Special Focus ◽  
Phase Flow ◽  
Computationally Efficient ◽  
Single Phase Flow ◽  
Two Phase

<p>While fluvial flows carrying relatively coarse sediments involve strong two-phase interactions, existing numerical modeling in the field-scale is mostly based on quasi-single phase flow model. Here a computationally efficient two-phase hydro-sediment-morphodynamic model is developed with a special focus on field applications. The hybrid LTS/GMaTS method originally developed for quasi-single flow model is extended to the present two-phase flow model, of which the achieved reduction in the computational cost facilitates the present field applications in the Taipingkou Waterway, Middle Yangtze River. To overcome numerical instabilities arising from the relatively large spatial and time steps in field case that lead to an issue of stiff source term, the following numerical treatments are proposed: implementation of theoretically-derived lower and upper limits for the inter-phase interactive forces. Moreover, to improve the numerical accuracy, the HLLC approximate Riemann solver is used for the water phase, whereas the FORCE solver is used for the sediment phase. Both the present two-phase flow model and the existing quasi-single-phase flow model are applied to a series of typical cases, including refilling of a dredged trench, a full dam-break flow in an abruptly widening channel and reproduction of the Taipingkou waterway, Middle Yangtze River. Compared with the quasi-single-phase flow model, the two-phase flow model has better performance as compared to the measure data and has more profound physical significance.</p>

Analysis of Friction Factor of Two-Phase Flow in Helically Coiled Tubes

2021 ◽  
Author(s):  
Baihui Jiang ◽  
Zhiwei Zhou ◽  
Yu Ji
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Friction Factor ◽  
Single Phase ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Steam Generators ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Applicable Range

Abstract With compact structure and enhanced heat transfer capacity, helical-coiled once through steam generators (HTSGs) are widely used in the small modular reactors (SMRs). Nevertheless, the inside centrifugal forces make the flow more complicated, and increase the frictional pressure drop, which is closely related to the dual test of alternating thermal stress and flow instability. Therefore, the analysis of the friction factor in helically coiled tubes is significant to the efficient and safe operation of HTSGs. While the friction factor of single-phase flow in helically coiled tubes was fully studied and extensive correlations have been validated by a large amount of experimental data, the friction factor of two-phase flow still lacks feasible prediction due to its much more complexity. The existed correlations of two-phase flow in helically coiled tubes are mostly based on specified experimental parameters, so the applicable range is limited. Few scholars have tried to extend these correlations to broader applicability, but the trivial applicable range is unsuitable for program development or engineering design, which needs an accurate prediction of friction factor in a wider range. In this paper, existing frictional pressure drop correlations are investigated. The accuracy of single-phase frictional pressure drop correlations is verified through the comparison of calculation results. Since the known experimental data cannot cover a wide range of parameters, two assumptions are proposed, and the rationality is verified through the existing experimental data and calculation analysis. Based on the two assumptions and calculation, a set of calculation correlations for frictional pressure drop of two-phase flow in helically coiled tubes are proposed. The accuracy of this calculation model is validated by experimental data. The scope of application of this model is: D / d = 15–100, P = 0.12–6.3MPa, G = 200–1500kg / m2s, which is sufficient to support the design and operation of steam generators and the development of the simulation programs.

On Acoustic Propagation and Critical Mass Flux in Two-Phase Flow

1971 ◽  
Vol 93 (4) ◽  
pp. 413-421 ◽  
Author(s):  
D. F. D’Arcy
Keyword(s):  
Void Fraction ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Separated Flow ◽  
Propagation Speed ◽  
Critical Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Void Fractions

Theoretical values for the propagation speed of small pressure disturbances through two-phase fluid have been derived by a method analogous to the well-known method for single-phase fluids and using the well-known separated-flow model of two-phase flow. Since the liquid and vapor phases in general flow at different mean speeds, it is appropriate to compute the propagation speed relative to the laboratory frame of reference, not relative to the fluid as is usually done in single phase. With the extra degree of freedom in two-phase flow, two distinct speeds are found for propagation both upstream and downstream, each representing compatible thermodynamic behavior of both phases. Comparisons between calculations based on the model, and several published sets of experimental values of the speed of sound, tend to confirm the theory at low and at high void fractions. Both propagation speeds have been observed in experiments. Also by analogy with the single-phase case, critical flow is predicted to occur when the upstream propagation speed relative to the laboratory is zero, i.e., when pressure waves cannot travel into the opening from which the flow issues. Flow calculations based on the model under these conditions show agreement with published experimental critical-flow measurements in the regions of low and high void fractions. Thus, a satisfactory explanation of the critical-flow phenomenon in two-phase fluids is obtained in these regions. From the analytical–experimental comparisons it appears that of the two propagation speeds and critical flows, one is observed at low void fraction, and the other at high void fraction. In the intermediate range, the theory and experiment differ and it is probable that the separated-flow model does not adequately represent the flow regimes occurring in this range.

A ONE-DIMENSIONAL TWO-PHASE FLOW MODEL AND EXPERIMENTAL VALIDATION FOR A FLASHING VISCOUS LIQUID IN A SPLASH PLATE NOZZLE

2015 ◽  
Vol 25 (9) ◽  
pp. 795-817 ◽  
Author(s):  
Mika P. Jarvinen ◽  
A. E. P. Kankkunen ◽  
R. Virtanen ◽  
P. H. Miikkulainen ◽  
V. P. Heikkila
Keyword(s):  
Viscous Liquid ◽  
Experimental Validation ◽  
Flow Model ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional

Status of Advanced Two-Phase Flow Model Development for SRM Chamber Flow Field and Combustion Modeling

2004 ◽  
Author(s):  
Gary Luke ◽  
Mark Eagar ◽  
Michael Sears ◽  
Scott Felt ◽  
Bob Prozan
Keyword(s):  
Flow Field ◽  
Flow Model ◽  
Two Phase Flow ◽  
Model Development ◽  
Phase Flow ◽  
Two Phase ◽  
Combustion Modeling

scholarly journals Experimental and Numerical Investigation of Gas-Liquid Metal Two-Phase Flow Pumping

2021 ◽  
pp. 100092
Author(s):  
Josh Rosettani ◽  
Wael Ahmed ◽  
Philip Geddis ◽  
Lijun Wu ◽  
Bruce Clements
Keyword(s):  
Liquid Metal ◽  
Numerical Investigation ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase

scholarly journals Experimental Investigation and Prediction on Pressure Drop during Flow Boiling in Horizontal Microchannels

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 510
Author(s):  
Yan Huang ◽  
Bifen Shu ◽  
Shengnan Zhou ◽  
Qi Shi
Keyword(s):  
Pressure Drop ◽  
Flow Model ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Separated Flow ◽  
Heat Fluxes ◽  
Phase Flow ◽  
Vapor Quality ◽  
Two Phase ◽  
Gas Flux

In this paper, two-phase pressure drop data were obtained for boiling in horizontal rectangular microchannels with a hydraulic diameter of 0.55 mm for R-134a over mass velocities from 790 to 1122, heat fluxes from 0 to 31.08 kW/m2 and vapor qualities from 0 to 0.25. The experimental results show that the Chisholm parameter in the separated flow model relies heavily on the vapor quality, especially in the low vapor quality region (from 0 to 0.1), where the two-phase flow pattern is mainly bubbly and slug flow. Then, the measured pressure drop data are compared with those from six separated flow models. Based on the comparison result, the superficial gas flux is introduced in this paper to consider the comprehensive influence of mass velocity and vapor quality on two-phase flow pressure drop, and a new equation for the Chisholm parameter in the separated flow model is proposed as a function of the superficial gas flux . The mean absolute error (MAE ) of the new flow correlation is 16.82%, which is significantly lower than the other correlations. Moreover, the applicability of the new expression has been verified by the experimental data in other literatures.

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