Two-Phase Flow in Miniature Geometries: Comparison of Gas-Liquid and Liquid-Liquid Flows

2019 ◽  
Vol 6 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Raj Kumar Verma ◽  
Sumana Ghosh
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Liquid Flows

Modeling of Sodium Two-Phase Flow With the TRACE Code

2009 ◽  
Author(s):  
Aurelia Chenu ◽  
Konstantin Mikityuk ◽  
Rakesh Chawla
Keyword(s):  
Single Phase ◽  
Two Phase Flow ◽  
Flow Simulation ◽  
Phase Flow ◽  
Fluid Models ◽  
Code System ◽  
Two Phase ◽  
Liquid Flows ◽  
Transfer Mechanisms ◽  
Two Fluid

In the framework of PSI’s FAST code system, the TRACE thermal-hydraulics code is being extended for representation of sodium two-phase flow. As the currently available version (v.5) is limited to the simulation of only single-phase sodium flow, its applicability range is not enough to study the behavior of a Sodium-cooled Fast Reactor (SFR) during a transient in which boiling is anticipated. The work reported here concerns the extension of the two-fluid models, which are available in TRACE for steam-water, to sodium two-phase flow simulation. The conventional correlations for ordinary gas-liquid flows are used as basis, with optional correlations specific to liquid metal when necessary. A number of new models for representation of the constitutive equations specific to sodium, with a particular emphasis on the interfacial transfer mechanisms, have been implemented and compared with the original closure models. As a first application, the extended TRACE code has been used to model experiments that simulate a loss-of-flow (LOF) accident in a SFR. The comparison of the computed results, with both the experimental data and SIMMER-III code predictions, has enabled validation of the capability of the modified TRACE code to predict sodium boiling onset, flow regimes, dryout, flow reversal, etc. The performed study is a first-of-a-kind application of the TRACE code to two-phase sodium flow. Other integral experiments are planned to be simulated to further develop and validate the two-phase sodium flow methodology.

An Evaluation of Existing Two-Phase Flow Correlations for Use With ASME Sharp Edge Metering Orifices

1977 ◽  
Vol 99 (3) ◽  
pp. 343-347 ◽  
Author(s):  
L. T. Smith ◽  
J. W. Murdock ◽  
R. S. Applebaum
Keyword(s):  
Natural Gas ◽  
Data Base ◽  
Root Mean Square ◽  
Two Phase Flow ◽  
Salt Water ◽  
Sharp Edge ◽  
Phase Flow ◽  
Mean Square ◽  
Two Phase ◽  
Liquid Flows

The two-phase flow correlations developed by Murdock, James, Marriott, and Smith and Leang are evaluated for the case of flow through sharp edge measuring orifices which physically meet ASME standards for flow measurement. The evaluation is based on two sets of consistent orifice flow data. The first data base consists of 34 test points for the flow of steam-water mixtures. The second data base consists of 81 data points for the flow of air-water, natural gas-water, natural gas-salt water, and natural gas-distillate mixtures. The root mean square fractional deviation of each correlation is used to determine its predictive reliability. Computed root mean square fraction deviations for steam-water flows are: James, ±0.081; Marriott, ±0.114; Murdock, ±0.141; Smith and Leang, ±0.218. For the case of gas-liquid flows, the values are: Murdock, ±0.074; James, ±0.178; Smith and Leang, ±0.183; Marriott, ±0.458.

Two-Phase Flow in Liquid Filled Vessels During the Depressurization by Periodic Venting

2003 ◽  
Author(s):  
Dieter Mewes ◽  
Dirk Schmitz
Keyword(s):  
Single Phase ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Exothermic Reaction ◽  
Liquid Mixtures ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Losses ◽  
Short Period ◽  
Liquid Flows

Pressurized chemical reactors or storage vessels are often partly filled with liquid mixtures of reacting components. In case of an unexpected and uncontrolled exothermic reaction the temperature might increase. By this the pressure follows and would exceed a critical maximum value if there would be no mechanism to decrease the pressure and the temperature in a very short period of time. A sudden venting by the opening of a safety valve or a rupture disc causes a rapid vaporization of the reacting liquid mixture. A two-phase flow will pass the ventline. Since two-phase gas-liquid flows cause high pressure losses and give rise to limited mass flows leaving the reactor, single-phase gas flows are preferred. This is emphasized by a periodic venting mechanism of the pressurized vessel. Each time the two-phase flow from the bubbling-up liquid inside the vessel reaches a certain cross-section close the entrance of the ventline. The outlet-valve is closed. Inside the vessel the increasing pressure stops the two-phase flow and only single phase flow is leaving the vessel. The two-phase bubbly flow inside the vessel is detected by a tomographic measurement device during the venting process. Experimental results for local and time dependant phase void fractions as well as pressures are compared with those obtained by numerical calculations of the instationary bubble swarm behavior inside the vessel.

Estimation of Two-Phase Flow Heat Transfer in Pipes

1999 ◽  
Vol 121 (2) ◽  
pp. 75-80 ◽  
Author(s):  
R. D. Kaminsky
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Small Diameter ◽  
Estimation Methods ◽  
Prediction Methods ◽  
Phase Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Models ◽  
Liquid Flows

Heat transfer can be of importance in the design of multiphase petroleum flowlines. However, heat transfer data for gas-liquid flows are available only for small-diameter pipes at low pressures. Moreover, existing prediction methods are largely not suited to petroleum pipeline conditions due to implicit use of simplistic two-phase flow models. In this work heat transfer estimation methods are derived for nonboiling gas-liquid flow in pipes of high Prandtl number liquids, such as crude oil. The methods are readily evaluated for engineering applications and are applicable to all flow regimes, except those with low liquid holdup. Comparison is made with literature data. Accuracies of ±33 percent are obtained in general. The methods explicitly couple with arbitrary prediction methods for two-phase flow pressure drop and liquid holdup. This explicit coupling makes plausible the hypothesis that predictions will be robust at conditions well beyond the range of the existing experimental data.

scholarly journals Two-phase flow separation in axial free vortex flow

2017 ◽  
Vol 9 (3) ◽  
pp. 105-113
Author(s):  
Mohammad Aghaee ◽  
Rouhollah Ganjiazad ◽  
Ramin Roshandel ◽  
Mohammad Ali Ashjari
Keyword(s):  
Vortex Flow ◽  
Two Phase Flow ◽  
Petroleum Industry ◽  
Tangential Velocity ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Simple Method ◽  
Free Vortex ◽  
Liquid Flows

Multi-phase flows, particularly two-phase flows, are widely used in the industries, hence in order to predict flow regime, pressure drop, heat transfer, and phase change, two-phase flows should be studied more precisely. In the petroleum industry, separation of phases such as water from petroleum is done using rotational flow and vortices; thus, the evolution of the vortex in two-phase flow should be considered. One method of separation requires the flow to enter a long tube in a free vortex. Investigating this requires sufficient knowledge of free vortex flow in a tube. The present study examined the evolution of tube-constrained two-phase free vortex using computational fluid dynamics. The discretized equations were solved using the SIMPLE method. It was determined that as the liquid flows down the length of the pipe, the free vortex evolves into combined forced and free vortices. The tangential velocity of the free and forced vortices also decreases in response to viscosity. It is shown that the concentration of the second discrete phase (oil) is greatest at the center of the pipe in the core of the vortex. This concentration is at a maximum at the outlet of the pipe.

Gas Absorption, Aeration, by Fluidic Oscillator Operated by Gas-Liquid Two-Phase Flow

2003 ◽  
Author(s):  
Toshihiko Shakouchi
Keyword(s):  
Dissolved Oxygen ◽  
Two Phase Flow ◽  
Gas Absorption ◽  
Phase Flow ◽  
Compact Type ◽  
Two Phase ◽  
Mean Velocity ◽  
Fluidic Oscillator ◽  
Operation Conditions ◽  
Liquid Flows

It is known that a conventional feedback type and other type of fluidic oscillators can be operated not only by gas or liquid single phase flow but also by gas(air)-liquid(water) two-phase flow (Shakouchi, 1989, 2001). The two-phase jet flow oscillates periodically of the oscillator under some conditions, and then the gas, air bubble, and liquid flows are mixed and stirred forcibly. The contact area and time between gas and liquid flows increase considerably and then the much increasing of mass transfer, the diffusion or absorption of gas into liquid, will be expected. It may be able to construct an entirely new compact type gas-absorber, aerator, with a simple construction. In this paper, first the performance of fluidic oscillator operated by gas-liquid two-phase flow is made clear experimentally. Next, the aeration performance of the oscillator, namely the diffusion or absorption rate of air, dissolved oxygen, into water under various kind of operation conditions are examined experimentally. The following major results will be shown. (1) The oscillatory frequency f increases linearly with increasing the Re number (= udf/ν, u: mean velocity of water flow at the nozzle exit, df: nozzle width, ν: kinematic viscosity) and the void fraction α. (2) The pressure loss, flow resistance, Δp of the oscillator or increases rapidly with increasing Ref and linearly increasing α. (3) Dissolved oxygen in water can be increased considerably by fluidic oscillator operated by air-water two-phase flow, and it was well known that a new compact type aerator can be constructed by fluidic oscillator.

scholarly journals Sensitivity of the Coefficients of the Closure Model of the Interfacial Transfer in Bubble Columns

Mechanika ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 22-30
Author(s):  
Hamdi AYED ◽  
Abir MOULDI ◽  
Khaled KHEDHER
Keyword(s):  
Two Phase Flow ◽  
Bubble Column ◽  
Bubble Diameter ◽  
Bubble Columns ◽  
Phase Flow ◽  
Closure Model ◽  
Two Phase ◽  
Interfacial Transfer ◽  
Two Phases ◽  
Liquid Flows

This article presents a numerical simulation of hydrodynamics in a bubble column. Numerical simulations have been carried out using the Eulerian model which provides specific modeling adapted to gas-liquid flows and allows a reasonable representation of the two-phase flow structure (fields of mean velocities and volumetric fractions of the two phases) as well as the important modulation of turbulence in the two-phase flow. In these simulations, we tested the sensitivity of the coefficients of the closure model of the interfacial transfer (drag, lift and added mass) on the prediction of the fields of average velocities and volumetric fractions of the two phases. The results are compared with the experimental data available in the literature using an average bubble diameter approach.

CHARACTERIZATION OF HORIZONTAL GAS–LIQUID TWO-PHASE FLOW USING MARKOV MODEL-BASED COMPLEX NETWORK

2013 ◽  
Vol 24 (05) ◽  
pp. 1350028 ◽  
Author(s):  
LI-DAN HU ◽  
NING-DE JIN ◽  
ZHONG-KE GAO
Keyword(s):  
Complex Networks ◽  
Complex Network ◽  
Chemical Engineering ◽  
Two Phase Flow ◽  
Transition Probability ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Markov Transition ◽  
Liquid Flows

Horizontal gas–liquid two-phase flow widely exists in many physical systems and chemical engineering processes. Compared with vertical upward gas–liquid two-phase flow, investigations on dynamic behavior underlying horizontal gas–liquid flows are quite limited. Complex network provides a powerful framework for time series analysis of complex dynamical systems. We use a network generation method based on Markov transition probability to infer directed weighted complex networks from signals measured from horizontal gas–liquid two-phase flow experiment and find that the networks corresponding to different flow patterns exhibit different network structure. To investigate the dynamic characteristics of horizontal gas–liquid flows, we construct a number of complex networks under different flow conditions, and explore the network indices for each constructed network. In addition, we investigate the sample entropy of different flow patterns. Our results suggest that the network statistic can well represent the complexity in the transition among different flow patterns and further allows characterizing the interface fluctuation behavior in horizontal gas–liquid two-phase flow.

Study of Liquid Atomization in an Internally Mixed Liquid Atomizer

2001 ◽  
Author(s):  
A. Kushari ◽  
Y. Neumeier ◽  
E. Lubarsky ◽  
B. T. Zinn
Keyword(s):  
Liquid Flow ◽  
Two Phase Flow ◽  
Turbine Engines ◽  
Phase Flow ◽  
Gas Turbine Engines ◽  
Two Phase ◽  
Liquid Drops ◽  
Droplet Sizes ◽  
Liquid Injector ◽  
Liquid Flows

This paper presents the results of experimental and theoretical studies of an internally mixed liquid injector. In this type of injector atomization is attained by injecting a small amount of air into a liquid stream within the injector. The results presented in this paper suggest that the investigated injector could be used to control the flow rate and spray characteristics, e.g., droplet size and spray penetration, and hence, a “controlled” version of the investigated injector may find applications in modern gas turbine engines. This paper also describes the development and predictions of a heuristic model that depicts the two-phase flow inside an internally mixed atomizer. The developed model assumes that the formation of liquid drops, due to the interaction between the air and liquid flows, occurs inside the injector. Basic conservation equations, along with appropriate boundary conditions, are used to model the two-phase air-liquid flow inside the injector. A statistically distributed Weber number criterion is used to estimate the sizes of the droplets being produced in the process. The liquid flow rates and the droplet sizes predicted by the model are compared with the experimental data and they are found to be in fair agreement with each other, suggesting that the model properly describes the physics of the two-phase flow within the injector.

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