Modifications to COBRA-TF to model dispersed flow film boiling with two flow,four field Eulerian–Eulerian approach – Part 2

In the first part of the paper, the modifications performed to improve the dispersed flow film boiling model in COBRA-TF have been described. The improvements were achieved by adding a small droplet field to the code’s solution scheme. The conservation equations, the source terms for the equations and the models developed were summarized. In this paper, the effects of spacer grids on the dispersed flow heat transfer and COBRA-TF modifications for the spacer grid models are presented. The results of the code predictions are presented by comparing the experimental data from Rod Bundle Heat Transfer experiments with the results of code simulations performed with original and modified code. Measurements and calculations for the spacer grid temperature have been compared. The results of the analysis performed with the modified code indicate the improvement in code predictions for the spacer grid temperature.     

Simulations of air–water flow and subcooled boiling flow using the CUPID code

This paper summarizes the physical models and a modified numerical procedure for the lift force of the CUPID code to simulate a subcooled boiling flow. A part of these physical models and the numerical procedure were verified through a calculation of air–water flow tests. A subcooled boiling flow was then calculated to assess the whole implementation. These assessments indicate that the implementation of the physical models and a modified numerical scheme are appropriate, and that the calculated primary variables of a subcooled boiling flow such as the liquid velocity and void fraction profiles can be acceptable in general, though IATE and a turbulence model for a two-phase flow are needed to be improved for a better prediction.     

Anisotropic flow in high baryon density region

Collective flow is a powerful tool used to analyze the properties of a medium created during high-energy nuclear collisions. Here, we report a systematic study of the first two Fourier coefficients v₁ and v₂ of the proton and π⁺from Au+Au collisions in the energy range (s_NN)^1/2=2.11–4.9 GeV within the framework of a hadronic transport model（UrQMD）. Recent results from the STAR experiment were used to test the model calculations. A meanfield ...     

Two-phase slug flow in vertical and inclined tubes

Gas-liquid slug flow is investigated experimentally in vertical and inclined tubes.The non-invasive measuremnts of the gas-liquid slug flow are taken by using the EKTAPRO 1000 High Speed Motion Analyzer.The information on the velocity of the Talyor bubble,the size distribution of the dispersed bubbles in the liquid slugs and some characteristics of the liquid film around the Taylor bubble are obtained.The experimental results are in good agreement with the available data.     

Analysis of flow instabilities in forced-convection steam generator

1 Introduction Flow instability appears in a number of two-phase boiling systems, such as reactors, various chemical-process equipments, and phase-change heat exchangers. Steam generators applied in nuclear plant may lead to high-quality density-wave instabilities under some conditions. Oscillations of the flow rate and system pressure are undesirable as they can cause mechanical vibrations, high pressures, and problem of system control, and in extreme circumstances can dis- turb the heat-tran…     

Phase idstribution in horizontal gas-liquid two-phase bubbly flow

An investigation on phase distribution in air-water two-phase flow in horizontal circular channel was conducted by using the double-sensor resistivity probe.The variations of phase distribution with variations of gas and liquid volumetric fluxes were analyzed and the present data were com0pared with some of other researcher‘s data and existing models,It was fund there exists more complicated phase distribution pattern in horizontal flow system than invertical flow.The radial local void fraction profiles are similar at the same measurement angle with various gas and liquid flow rates.However,an asymmetric profile can be observed at a given slice of the pipe cross-section.     

Number-of-constituent-quark scaling of elliptic flow:a quantitative study

The number-of-constituent-quark（NCQ） scaling behavior of the elliptic flow of identified particles produced in A+A collisions is studied quantitatively using an empirical function that fits the experimental v₂ data available from the RHIC and LHC. The most common approach for NCQ scaling involves（1） doing a scaling of the experimental v₂ data of an identified particle with its NCQ,（2） doing the same to its transverse momentum or energy,then（3） combining all the scaled data ...     

Distribution of void fraction for gas-liquid slug flow in an inclined pipe

In order to investigate the effect of inclination angle on the spatial distribution of phases,experiments on gas-liquid two-phase slug flow in an inclined pipe were carried out by using the optical probe and an EKTAPRO 1000 high speed motion analyzer.It has been demonstrated that the inclination angle and the mixture velocity are important parameters to influence the distribution of void fraction for upward slug flow in the inclined pipe.At high mixture velocity,the gas phase profile is axial symmetry in the cross-section of the pipe.This is similar to that for vertical slug flow.In contrast.most of the gas phase is located near the upper pipe wall at low mixture velocity.By measuring the axial variation of void fraction along the liquid slug.it can be concluded that there is a high void fraction wake region with length of 3-4D in the front of liquid slug.In the fully developed zone of liquid slug.the peak value of the void fraction is near the upper wall.     

Instructions to Contributors

Plasma Science and Technology ( ISSN 1009-0630, CN 34-1187/TL ), an English journal of the Institute of Plasma Physics, the Chinese Academy of Sciences (ASIPP) and the Chinese Society of Theoretical and Applied Mechanics, accepts papers about new achievements and phase results of plasma physics. Specific interest areas include: fundamental research, experiment facility construction and applications on high temperature plasma, low temperature plasma, astronomy and space plasma and discharge plasma. It also publishes reviews of new development of these areas as well as current progress of interdisciplinary and application sciences relating to plasma physics.     

Investigation on two-phase flow instability in steam generator of integrated nuclear reactor

In the pressure range of 3-18MPa,high pressure steam-water two-phase flow density wave instability in vertical upward parallel pipes with inner diameter of 12mm is studied experimentally.The oscillation curves of two-phase flow instability and the effects of several parameters on the oscillation threshold of the system are obtained.Based on the small pertubation linearization method and the stability principles of automatic control system,a mathematical model is developed to predict the characteristics of density wave instability threshold.The predictions of the model are in good agreement with the experimental results.     

Effect of steam quality on two-phase flow in a natural circulation loop

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Experimental study on the mechanism of flow blockage formation in fast reactor

Various sources of solid particles might exist in the coolant flow of a liquid metal cooled fast reactor (e.g., through chemical interaction between the coolant and impurities, air, or water, through corrosion of structural materials, or from damaged/molten fuel). Such particles may cause flow blockage accidents in a fuel assembly, resulting in a reduction in coolant flow,which potentially causes a local temperature rise in the fuel cladding, cladding failure, and fuel melt. To understand the bl...     

Upward air–water bubbly flow characteristics in a vertical square duct

In nuclear engineering fields, gas–liquid bubbly flows exist in channels with various shape and size cross-sections. Although many experiments have been carried out especially in circular pipes, those in a noncircular duct are very limited. To contribute to the development of gas–liquid bubbly flow model for a noncircular duct, detail measurements for the air–water bubbly flow in a square duct (side length: 0.136 m) were carried out by an X-type hot-film anemometry and a multi-sensor optical probe. Local flow parameters of the void fraction, bubble diameter, bubble frequency, axial liquid velocity and turbulent kinetic energy were measured in 11 two-phase flow conditions. These flow conditions covered bubbly flow with the area-averaged void fraction ranging from 0.069 to 0.172. A pronounced corner peak of the void fraction was observed in a quarter square area of a measuring cross-section. Due to a high bubble concentration in the corner, the maximum values of both axial liquid velocity and turbulent kinetic energy intensity were located in the corner region. It was pointed out that an effect of the corner on accumulating bubble in the corner region changed the distributions of axial liquid velocity and turbulent kinetic energy intensity significantly.     

Experimental study on steam-water two-phase flow frictional pressure drops in helical coils

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Experimental research on dryout point of flow boiling in narrow annular channels

1 Introduction There are basically two classes of critical heat flux (CHF) situations: departure from nucleate boiling (DNB) and dryout (DO) [1]. DO is also sometimes known as burnout or departure from forced convective boiling in vapor-continuous flow. From the point of view of engineering, the CHF caused by the DO mechanism is of particular importance since boiling annular flow is one of the most common flow patterns in gas–liquid two-phase flow and occurs in a wide range of vapor qua…     

Instructions to Contributors

Plasma Science and Technology (ISSN 1009-0630, CN 34-1187/TL ), an English journal of the Institute ofPlasma Physics, the Chinese Academy of Sciences (ASIPP) and the Chinese Society of Theoretical and AppliedMechanics, accepts papers about new achievements and phase results of plasma physics. Specific interest areasinclude: fundamental research, experiment facility construction and applications on high temperature plasma,low temperature plasma, astronomy and space plasma and discharge plasma. It also publishes reviews of newdevelopment of these areas as well as current progress of interdisciplinary and application sciences relating toplasma physics. Plasma Sciences and Technology has been published bimonthly from December, 1999. The main columns     

Instructions to Contributors

Plasma Science and Technology ( ISSN 1009-0630, CN 34-1187/TL ), an English journal of the Institute of Plasma Physics, the Chinese Academy of Sciences (ASIPP), accepts papers about new achievements and phase results of plasma physics. Specific interest areas include: fundamental research, experiment facility construction and applications on high temperature plasma, low temperature plasma, astronomy and space plasma and discharge plasma. It also publishes reviews of new development of these areas as well as current progress of interdisciplinary and application sciences relating to plasma physics.     

Instructions to Contributors

Plasma Science and Technology (ISSN 1009-0630, CN 34-1187/TL ), an English Journal of the Instituteof Plasma Physics, the Chinese Academy of Sciences (ASIPP), accepts papers about new achievements andphase results of plasma physics. Specific interest areas include: fundamental research, experiment facilityconstruction and applications on high temperature plasma, low temperature plasma, astronomy and spaceplasma and discharge plasma. It also publishes reviews of new development of thes…