Paper 15: Critical Conditions during the Flow of Two-Phase Mixtures through Nozzles

1967 ◽  
Vol 182 (8) ◽  
pp. 145-151
Author(s):  
D. Chisholm
Keyword(s):  
Experimental Data ◽  
Water Flow ◽  
Liquid Mixtures ◽  
Critical Conditions ◽  
Sonic Velocity ◽  
Two Phase ◽  
Flow Through

Equations are developed for the flow of gas-liquid mixtures through nozzles under conditions of critical or ‘choking’ flow. The equations are compared with experimental data obtained during air-water flow through nozzles and pipes at almost atmospheric pressures. Comparison is also made with data on the sonic velocity in mixtures. Additional problems arising with vapour-liquid mixtures are also discussed.

An Experimental Investigation of Oil-Water Flow Patterns in Horizontal Pipes

2004 ◽  
Author(s):  
Hai-Yuan Yao ◽  
Jing Gong
Keyword(s):  
Experimental Data ◽  
Water Flow ◽  
Flow Patterns ◽  
Critical Conditions ◽  
New Classification ◽  
Two Phase ◽  
Factors Affecting ◽  
Horizontal Pipes ◽  
Transition Mechanism ◽  
Oil Water

In this paper, an experimental research on the oil-water liquid-liquid two-phase flow patterns and their transitions in horizontal pipes are carried out. According to online oil-water flow structures and the analysis of pressure drop signals., different flow patterns are defined and distinguished. A new classification for oil-water flow patterns is proposed. The flow pattern maps are obtained from the experimental data, and the factors affecting the transition mechanism of different flow regimes are discussed. In addition, some semi-theoretical criteria for the transition between different flow patterns are proposed. Especially, an accurate model is developed to predict the critical conditions for phase inversion. Comparisons of the proposed criteria with other experimental data show reasonable agreements.

scholarly journals Determination of cross-sectional void fraction in a two-phase water flow through a PVC pipe

2021 ◽  
Vol 655 (1) ◽  
pp. 012024
Author(s):  
O.H. Ajesi ◽  
M.B. Latif ◽  
S.T. Gbenu ◽  
C. A. Onumejor ◽  
M. K. Fasasi ◽  
...  
Keyword(s):  
Water Flow ◽  
Void Fraction ◽  
Two Phase ◽  
Cross Sectional ◽  
Flow Through ◽  
Pvc Pipe ◽  
Phase Water

Study of Bubbly Flow Through a Packed Bed

2011 ◽  
Author(s):  
Daeseong Jo ◽  
Shripad T. Revankar
Keyword(s):  
Experimental Data ◽  
Comparative Study ◽  
Bubble Size ◽  
Bubbly Flow ◽  
Packed Bed ◽  
Bubble Coalescence ◽  
Size Distributions ◽  
Two Phase ◽  
Bubble Breakup ◽  
Flow Through

A two phase bubbly flow through a packed bed was studied for dominant bubble breakup and coalescence mechanisms through experiments and CFD modeling. Data on various two-phase parameters, such as local void fraction, bubble velocity, size, number, and shape were obtained from the high speed video images. Results indicated that when a flow regime changed from bubbly to either trickling or pulsing flow, the number of average size bubbles significantly decreased and the shape of majority of bubbles was no longer spherical. The bubble coalescence and breakup mechanisms depend on local conditions such as local velocity of the bubble and pore geometry. The CFD analysis using CFX software package was carried out to study bubble size distributions. In the analysis the models for interactions were examined for each case of bubble breakup flow and bubble coalescence. A comparative study was performed on the resulting bubble size distributions, breakup and coalescence rates estimated by individual models. For change of bubble size distributions along the axial direction medians was used as an comparative parameter and the CFD results on bubble medians were compared against the experimental data. This comparative study showed that the predictions estimated by CFD analyses with the bubble breakup and coalescence models currently available in the literature do not agree with the experimental data.

Experimental Characterization of Two-Phase Flow Through Valves Applied to Liquid-Assisted Gas-Lift

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Renato P. Coutinho ◽  
Paulo J. Waltrich ◽  
Wesley C. Williams ◽  
Parviz Mehdizadeh ◽  
Stuart Scott ◽  
...  
Keyword(s):  
Water Flow ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Water Flow Rate ◽  
Phase Flow ◽  
Experimental Characterization ◽  
Two Phase ◽  
Flow Through ◽  
Gas Lift

Abstract Liquid-assisted gas-lift (LAGL) is a recently developed concept to unload wells using a gas–liquid fluid mixture. The success deployment of the LAGL technology is related to the behavior of two-phase flow through gas-lift valves. For this reason, this work presents an experimental and numerical study on two-phase flow through orifice gas-lift valves used in liquid-assisted gas-lift unloading. To the knowledge of the authors, there is no investigation in the literature on experimental characterization of two-phase flow through gas-lift valves. Experimental data are presented for methane-water flow through gas-lift valves with different orifice port sizes: 12.7 and 17.5 mm. The experiments were performed for pressures ranging from 1.00 to 9.00 MPa, gas flow rates from 0 to 4.71 m3/h, and water flow rate from 0 to 0.68 m3/min. The experimental results are compared to numerical models published in the literature for two-phase flow through restrictions and to commercial multiphase flow simulators. It is observed that some models developed for two-phase flow through restrictions could successfully characterize two-phase flow thorough gas-lift valves with errors lower than 10%. However, it is first necessary to experimentally determine the discharge coefficient (CD) for each gas-lift valve. The commercial flow simulators showed a similar performance as the models available in the literature.

scholarly journals CFD Code Validation against Stratified Air-Water Flow Experimental Data

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
F. Terzuoli ◽  
M. C. Galassi ◽  
D. Mazzini ◽  
F. D'Auria
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Water Flow ◽  
Nuclear Reactor ◽  
Cold Water ◽  
Three Dimensional ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Two Phase ◽  
Code Validation

Pressurized thermal shock (PTS) modelling has been identified as one of the most important industrial needs related to nuclear reactor safety. A severe PTS scenario limiting the reactor pressure vessel (RPV) lifetime is the cold water emergency core cooling (ECC) injection into the cold leg during a loss of coolant accident (LOCA). Since it represents a big challenge for numerical simulations, this scenario was selected within the European Platform for Nuclear Reactor Simulations (NURESIM) Integrated Project as a reference two-phase problem for computational fluid dynamics (CFDs) code validation. This paper presents a CFD analysis of a stratified air-water flow experimental investigation performed at the Institut de Mécanique des Fluides de Toulouse in 1985, which shares some common physical features with the ECC injection in PWR cold leg. Numerical simulations have been carried out with two commercial codes (Fluent and Ansys CFX), and a research code (NEPTUNE CFD). The aim of this work, carried out at the University of Pisa within the NURESIM IP, is to validate the free surface flow model implemented in the codes against experimental data, and to perform code-to-code benchmarking. Obtained results suggest the relevance of three-dimensional effects and stress the importance of a suitable interface drag modelling.

scholarly journals Periodic Trends in Two-Phase Flow Through a Vertical Minichannel: Wavelet and Multiscale Entropy Analyses Based on Digital Camera Data

2019 ◽  
Vol 13 (1) ◽  
pp. 51-56
Author(s):  
Grzegorz Górski ◽  
Grzegorz Litak ◽  
Romuald Mosdorf ◽  
Andrzej Rysak
Keyword(s):  
Water Flow ◽  
Two Phase Flow ◽  
Digital Camera ◽  
Flow Patterns ◽  
Multiscale Entropy ◽  
Phase Flow ◽  
Periodic Patterns ◽  
Two Phase ◽  
Periodic Sequences ◽  
Flow Through

Abstract By changing the air and water flow relative rates in the two-phase (air-water) flow through a minichannel, we observe aggregation and partitioning of air bubbles and slugs of different sizes. An air bubble arrangement, which show non-periodic and periodic patterns. The spatiotemporal behaviour was recorded by a digital camera. Multiscale entropy analysis is a method of measuring the time series complexity. The main aim of the paper was testing the possibility of implementation of multiscale entropy for two-phase flow patterns classification. For better understanding, the dynamics of the two-phase flow patterns inside the minichannel histograms and wavelet methods were also used. In particular, we found a clear distinction between bubbles and slugs formations in terms of multiscale entropy. On the other hand, the intermediate region was effected by appearance of both forms in non-periodic and periodic sequences. The preliminary results were confirmed by using histograms and wavelets.

Self-aggregation Phenomenon and Stable Flow Conditions in a Two-Phase Flow Through a Minichannel

2015 ◽  
Vol 70 (10) ◽  
pp. 843-849 ◽  
Author(s):  
Grzegorz Górski ◽  
Grzegorz Litak ◽  
Romuald Mosdorf ◽  
Andrzej Rysak
Keyword(s):  
Water Flow ◽  
Light Transmission ◽  
Water Flow Rate ◽  
Air Bubbles ◽  
Two Phase ◽  
Quantification Analysis ◽  
Flow Through ◽  
Stable Flow ◽  
Self Aggregation ◽  
Aggregation Phenomenon

AbstractBy increasing a water flow rate of the two-phase (air–water) flow through a minichannel, both the partitioning of air slugs into air bubbles of different sizes and small air bubbles aggregation into larger air bubbles were identified. These phenomena were studied in detail by using the corresponding sequences of light transmission time series recorded with a laser-phototransistor sensor. To distinguish any instabilities in air slugs along with their break-ups and aggregations, the recurrence plots and recurrence quantification analysis were applied.

CFD Simulation of Gas-Liquid Two-Phase Flow Through an Orifice in Millimeter-Scale Rectangular Channel

2013 ◽  
Author(s):  
Fuad Ismayilov ◽  
Olusegun J. Ilegbusi
Keyword(s):  
Experimental Data ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Phase Transfer ◽  
Rectangular Channel ◽  
Phase Flow ◽  
Two Phase ◽  
Contraction Ratio ◽  
Fraction Distribution ◽  
Flow Through

A numerical model is developed and used to simulate gas-liquid two-phase flow through a plate orifice in a millimeter-scale channel. The channel width is 50 mm and the height is varied from 1.00 mm to 2.00 mm. The contraction ratio and thickness of the orifice are varied over the range 0.04–0.4 and 5–20 mm respectively. The model utilized is based on the multiphase-mixture principle in which transport equations are solved for the mixed phase velocities with allowance for interpenetration of phases and intra-phase transfer processes. The predicted velocity profiles are successfully validated by comparison with the available experimental data for the mixture velocity. The predictions also extend beyond the experimental data to provide the detailed effect of contraction ratio on the flow and gas fraction distribution in the channel. In the range of parameters investigated, the predictions indicate that the flow in such channels will produce no wake in the lee of the orifice for contraction ratios >0.2.

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