Effect of Branch Orientation on Annular Two-Phase Flow in T-Junctions

1996 ◽  
Vol 118 (1) ◽  
pp. 166-171 ◽  
Author(s):  
F. Peng ◽  
M. Shoukri ◽  
A. M. C. Chan
Keyword(s):  
Annular Flow ◽  
Two Phase Flow ◽  
Mechanical Energy ◽  
Phase Flow ◽  
Two Phase ◽  
Experimental Conditions ◽  
Present Test ◽  
Modelling Studies ◽  
Pressure Changes ◽  
Energy Balances

Experimental data on dividing steam-water two-phase annular flow in T-junctions with horizontal inlet and downwardly inclined branches were obtained. The experiments were performed under experimental conditions which have not been examined before. The branch orientation was found to be a significant parameter affecting phase redistribution in the junction. Increasing the downward inclination of the branch was found to reduce the degree of phase separation in the junction under the present test conditions. This is caused by the nonuniform distribution of the liquid film thickness associated with the horizontal inlet annular flow. The phase redistribution data were compared with available models. The need for additional modelling studies was evident. The pressure changes of two-phase flow in the junction were closely correlated with the phase redistribution phenomenon. The data on pressure changes in the junction were correlated using simple models based on momentum and mechanical energy balances.

On Instabilities in Horizontal Two-Phase Flow

1994 ◽  
Vol 59 (12) ◽  
pp. 2595-2603
Author(s):  
Lothar Ebner ◽  
Marie Fialová
Keyword(s):  
Differential Equation ◽  
Flow Regime ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Annular Flows ◽  
Flow Regime Maps

Two regions of instabilities in horizontal two-phase flow were detected. The first was found in the transition from slug to annular flow, the second between stratified and slug flow. The existence of oscillations between the slug and annular flows can explain the differences in the limitation of the slug flow in flow regime maps proposed by different authors. Coexistence of these two regimes is similar to bistable behaviour of some differential equation solutions.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

scholarly journals Behavior of a Horizontal Gas-Liquid Two-Phase Flow under Microgravity. Flow Pattern and Film Construction in Annular Flow Region.

1992 ◽  
Vol 58 (555) ◽  
pp. 3286-3291 ◽  
Author(s):  
Terushige FUJII ◽  
Takeshi NAKAZAWA ◽  
Hiroyuki YAMADA ◽  
Osamu MURAGISHI ◽  
Nobuyuki TAKENAKA ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Region ◽  
Phase Flow ◽  
Two Phase

Flow Characteristics of Adiabatic Gas-Liquid Two-Phase Flow in a Horizontal Flat Rectangular Microchannel

2011 ◽  
Author(s):  
Hideo Ide ◽  
Kentaro Satonaka ◽  
Tohru Fukano
Keyword(s):  
Void Fraction ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Phase Flow ◽  
Similar Data ◽  
Two Phase ◽  
The Mean

Experiments were performed to obtain, analyze and clarify the mean void fraction, the mean liquid holdup, and the liquid slug velocity and the air-water two-phase flow patterns in horizontal rectangular microchannels, with the dimensions equal to 1.0 mm width × 0.1 mm depth, and 1.0 mm width × 0.2 mm depth, respectively. The flow patterns such as bubble flow, slug flow and annular flow were observed. The microchannel data showed similar data patterns compared to those in minichannels with the width of 1∼10mm and the depth of 1mm which we had previously reported on. However, in a 1.0 × 0.1 mm microchannel, the mean holdup and the base film thickness in annular flow showed larger values because the effects of liquid viscosity and surface tension on the holdup and void fraction dominate. The remarkable flow characteristics of rivulet flow and the flow with a partial dry out of the channel inner wall were observed in slug flow and annular flow patterns in the microchannel of 0.1 mm depth.

INVESTIGATION ON VOID FRACTION FOR TWO-PHASE FLOW PRESSURE DROP OF EVAPORATIVE R-290 IN HORIZONTAL TUBE

2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Agus Sunjarianto Pamitran ◽  
Sentot Novianto ◽  
Normah Mohd-Ghazali ◽  
Nasruddin Nasruddin ◽  
Raldi Koestoer
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Homogeneous Model ◽  
Saturation Temperature ◽  
Horizontal Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Experimental Conditions

Two-phase flow boiling pressure drop experiment was conducted to observe its characteristics and to develop a new correlation of void fraction based on the separated model. Investigation is completed on the natural refrigerant R-290 (propane) in a horizontal circular tube with a 7.6 mm inner diameter under experimental conditions of 3.7 to 9.6 °C saturation temperature, 10 to 25 kW/m2 heat flux, and 185 to 445 kg/m2s mass flux. The present experimental data was used to obtain the calculated void fraction which then was compared to the predicted void fraction with 31 existing correlations. A new void fraction correlation for predicting two-phase flow boiling pressure drop, as a function of Reynolds numbers, was proposed. The measured pressure drop was compared to the predicted pressure drop with some existing pressure drop models that use the newly developed void fraction model. The homogeneous model of void fraction showed the best prediction with 2% deviation

Flow Boiling Visualization of R-134a in a Vertical Channel of Small Diameter

2007 ◽  
Author(s):  
Claudi Marti´n-Callizo ◽  
Bjo¨rn Palm ◽  
Wahib Owhaib ◽  
Rashid Ali
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
R 134A ◽  
Heated Length

The present work reports on flow boiling visualization of refrigerant R-134a in a vertical circular channel with internal diameter of 1.33 mm and 235 mm in heated length. Quartz tube with a homogeneous ITO-coating is used allowing heating and simultaneous visualization. Flow patterns have been observed along the heated length with the aid of a digital camera with close-up lenses. From the flow boiling visualization, seven distinct two-phase flow patterns have been observed: Isolated bubbly flow, confined bubbly flow, slug flow, churn flow, slug-annular flow, annular flow, and mist flow. Two-phase flow pattern observations are presented in the form of flow pattern maps. Finally, the experimental flow pattern map is compared to models developed for conventional sizes as well as to a microscale map for air-water mixtures available in the literature, showing a large discrepancy.

Experimental and Numerical Study on Solid Particle Erosion in Elbows Mounted in Series

2017 ◽  
Author(s):  
Alireza Asgharpour ◽  
Peyman Zahedi ◽  
Hadi Arabnejad Khanouki ◽  
Siamack A. Shirazi ◽  
Brenton S. McLaury
Keyword(s):  
Solid Particle ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Flow Direction ◽  
Solid Particle Erosion ◽  
Phase Flow ◽  
Particle Erosion ◽  
Two Phase ◽  
Experimental Conditions ◽  
In Series

Solid particle erosion in elbows is of great importance in the pipeline design process. In many situations, elbows are mounted in series with small distances between each other. Due to changes in flow direction and particles concentration after the first elbow, a significant change in erosion magnitude and pattern in the downstream elbows (second elbow) might be expected. The aim of this study is to investigate the solid particle erosion behavior in the second elbow. In the experimental study using a state-of-art ultrasonic technique, erosion magnitudes in two standard 4-inch elbows separated by a distance of 10 pipe diameter have been measured. Experiments have been conducted in single and two-phase flow regimes for different particle sizes and gas and liquid velocities. In most of the cases, the maximum erosion in the second elbow was less than the first elbow, and the erosion pattern in the second elbow was slightly different than the first elbow. Comparison of single and two-phase flow results for both elbows revealed that in two-phase flow regime a major reduction in erosion magnitude happens as a results of the presence of liquid in the pipe. Additionally, for further considerations, the experimental conditions have been simulated numerically using ANSYS FLUENT software. Simulations have been performed for different mesh grids and turbulence models to examine how they influence the erosion in the second elbow as both can affect the particles trajectories. The accuracy of the numerical results are evaluated with available experimental data. For most of the cases, the erosion predictions are in a good agreement with experimental results. For both elbows by increasing the gas velocity and particle size, the maximum erosion increased.

An Experimental Study on Air-Water Two-Phase Flow Patterns in Pebble Beds

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Bai Bofeng ◽  
Liu Maolong ◽  
Su Wang ◽  
Zhang Xiaojie
Keyword(s):  
Experimental Study ◽  
Flow Pattern ◽  
Test Section ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Pattern Transition

An experimental study was conducted on the air-water two-phase flow patterns in the bed of rectangular cross sections containing spheres of regular distribution. Three kinds of glass spheres with different diameters (3 mm, 6 mm, and 8 mm) were used for the establishment of the test section. By means of visual observations of the two-phase flow through the test section, it was discovered that five different flow patterns occurred within the experimental parameter ranges, namely, bubbly flow, bubbly-slug flow, slug flow, slug-annular flow, and annular flow. A correlation for the bubble and slug diameter in the packed beds was proposed, which was an extended expression of the Tung/Dhir model, Jamialahmadi’s model, and Schmidt’s model. Three correlations were proposed to calculate the void friction of the flow pattern transition in bubble flow, slug flow, and annular flow based on the bubble model in the pore region. The experimental result showed that the modified Tung and Dhir model of the flow pattern transition was in better agreement with the experimental data compared with Tung and Dhir’s model.

Momentum and energy balances for dispersed two-phase flow

1961 ◽  
Vol 10 (1) ◽  
pp. 102-108 ◽  
Author(s):  
J. J. Deemter ◽  
E. T. Laan
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Energy Balances
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