Co-Current Gas-Liquid Smooth-Stratified Flow in a Horizontal Reduced T-Junction Including Wavy and Slug Regime Transition Boundaries

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Robert C. Bowden ◽  
Ibrahim G. Hassan
Keyword(s):  
Single Phase ◽  
Inlet Pipe ◽  
Critical Height ◽  
Two Phase ◽  
Gas Entrainment ◽  
Inlet Length ◽  
Phase Liquid ◽  
The Relationship ◽  
Stratified Regime ◽  
Good Agreement

Experiments were performed in a horizontal reduced T-junction using a branch diameter of 6.35 mm and an inlet pipe diameter of 50.8 mm. The inlet length was 1.8 m and three branch orientations were tested at 0, 45, and 90 degrees down from the horizontal. Water and air, operating at 206 kPa, were used to provide an adiabatic two-phase environment. Both fluids flowed co-currently within the inlet towards the branch in the smooth-stratified regime. Results demonstrate the relationship between the interface height and the inlet and branch two-phase quantities, including the inlet superficial liquid and gas velocities, and branch two-phase mass flow rate and quality. In certain instances transitions to wavy-stratified or slug regimes were observed and these limits are quantified for each branch orientation. Flow visualization was used to identify the initiation of two-phase flow in the branch, including the onsets of gas and liquid entrainment. The critical height at the onset of gas entrainment was quantified as a function of the single phase liquid branch Froude number for the 45 and 90 degree branches, respectively. The branch quality results were scaled using the critical height and showed good agreement with selected models.

Experimental Investigation of Two-Phase Flow in a Multi-Branch Reduced T-Junction With Co-Current Stratified Gas-Liquid Flow

2011 ◽  
Author(s):  
Robert Bowden ◽  
Ibrahim Hassan
Keyword(s):  
Single Phase ◽  
Phase Flow ◽  
Inlet Pipe ◽  
Critical Height ◽  
Two Phase ◽  
Gas Entrainment ◽  
Inlet Length ◽  
Phase Liquid ◽  
Gas Liquid Flow ◽  
Stratified Regime

Experiments were performed in a horizontal reduced T-junction using a branch diameter of 6.35 mm and an inlet pipe diameter of 50.8 mm. The inlet length was 1.8 m, and three branch orientations were tested at 0, 45, and 90 degrees from horizontal. Air and water, operating at 206 kPa, were used to provide a two-phase environment. Both fluids flowed co-currently within the inlet towards the branch in the smooth-stratified regime. Flow visualization was used to identify the onset of gas entrainment. The critical height at the onset of gas entrainment was quantified as a function of the single phase liquid branch Froude number for the 45, and 90 degree branches, respectively.

The Onset of Gas Entrainment From a Stratified Two-Phase Region Through a Single Side-Oriented Branch

2002 ◽  
Author(s):  
M. Ahmed ◽  
K. Lenard ◽  
I. Hassan ◽  
N. Esmail
Keyword(s):  
Inclination Angle ◽  
Density Ratio ◽  
Phase Region ◽  
Data Sets ◽  
Critical Height ◽  
Two Phase ◽  
Gas Entrainment ◽  
Single Side ◽  
Inclination Angles ◽  
Predicted Values

A new theoretical investigation has been conducted for the prediction of the critical height at the onset of gas entrainment during single discharge from a stratified two-phase region through a branch installed on an inclined flat wall. Two models have been developed; a simplified point-sink model and a more-accurate finite-branch. The predicted critical height at the onset of gas entrainment was proven to be a function of Froude number (Fr) and density ratio of the interface fluids. The results of the predicted critical height at the onset of gas entrainment, at low values of Fr (<10), were found to be more accurate when using the finite-branch analysis compared to the results found using the pink-sink analysis. Whereas, with increasing Fr, the predicted values of both models converged to the same value. Furthermore, the point-sink analysis was demonstrated to be independent of wall inclination angle, while the finite-branch analysis showed a slight decrease in the value of the critical height with increasing wall inclination angle. Three different experimental data sets at wall inclination angles of zero, 45 and 90 degrees (i.e. side, inclined and bottom branches) were used in the following study for the comparisons between the experimental and theoretically predicted results. A good concurrence was illustrated between the experimental and theoretical values.

Prediction of Two-Phase Pressure Drop and Density Distribution From Mixing Length Theory

1963 ◽  
Vol 85 (2) ◽  
pp. 137-150 ◽  
Author(s):  
S. Levy
Keyword(s):  
Single Phase ◽  
Continuous Medium ◽  
Phase System ◽  
Mixing Length ◽  
Test Results ◽  
Two Phase ◽  
Pressure Drops ◽  
Mixing Length Theory ◽  
Phase Pressure ◽  
Good Agreement

Single-phase turbulent mixing length methods are used to predict two-phase flow. Two-phase density and velocity distributions and two-phase pressure drops are derived by treating the two-phase system as a continuous medium where the turbulent exchanges of momentum and density are equal. Good agreement is obtained between test results and analytical predictions.

A Robust Asymptotically Based Modeling Approach for Two-Phase Flow in Porous Media

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
M. M. Awad ◽  
S. D. Butt
Keyword(s):  
Porous Media ◽  
Pressure Gradient ◽  
Single Phase ◽  
Present Model ◽  
Flow In Porous Media ◽  
Pressure Gradients ◽  
Two Phase ◽  
New Model ◽  
Proposed Model ◽  
Phase Liquid

A simple semitheoretical method for calculating the two-phase frictional pressure gradient in porous media using asymptotic analysis is presented. The two-phase frictional pressure gradient is expressed in terms of the asymptotic single-phase frictional pressure gradients for liquid and gas flowing alone. In the present model, the two-phase frictional pressure gradient for x≅0 is nearly identical to the single-phase liquid frictional pressure gradient. Also, the two-phase frictional pressure gradient for x≅1 is nearly identical to the single-phase gas frictional pressure gradient. The proposed model can be transformed into either a two-phase frictional multiplier for liquid flowing alone (ϕl2) or a two-phase frictional multiplier for gas flowing alone (ϕg2) as a function of the Lockhart–Martinelli parameter X. The advantage of the new model is that it has only one fitting parameter (p), while the other existing correlations, such as the correlation of Larkins et al., Sato et al., and Goto and Gaspillo, have three constants. Therefore, calibration of the new model to the experimental data is greatly simplified. The new model is able to model the existing multiparameter correlations by fitting the single parameter p. Specifically, p=1/3.25 for the correlation of Midoux et al., p=1/3.25 for the correlation of Rao et al., p=1/3.5 for the Tosun correlation, p=1/3.25 for the correlation of Larkins et al., p=1/3.75 for the correlation of Sato et al., and p=1/3.5 for the Goto and Gaspillo correlation.

The constitution of alloys of iron and manganese with transition elements of the first long period

1957 ◽  
Vol 249 (968) ◽  
pp. 417-459 ◽  
Keyword(s):  
Solid Solutions ◽  
Iron Alloys ◽  
Continuous Series ◽  
Size Factor ◽  
General Effect ◽  
Transition Elements ◽  
Two Phase ◽  
Phase Liquid ◽  
The Stability ◽  
Good Agreement

Using metals of the highest purity, the constitutions of iron-rich and manganese-rich binary alloys with the sequence of elements Ti-V-Cr-(Mn, Fe)-Co-Ni-Cu have been investigated by specially accurate thermal analysis, supplemented by microscopical and X-ray work. The liquidus and solidus curves have been determined accurately, and also the forms of the A 4 (Y/O) transformations in the iron alloys, and of the (Y/O) and (Y/B) transformations in the manganese alloys. The complete liquidus and solidus were determined for the system Fe—Mn, and the equilibrium diagrams of the systems Fe-Ti and Mn-Ti were studied as far as 52 at. % Ti. O-Mn (b.c.c.) and y-Mn (f.c.c.) have the same crystal structures as O-Fe and y-Fe respectively, and the corresponding parts of the equilibrium diagrams are thus structurally comparable. In general, there is a remarkable correspondence between the effects of the different elements in stabilizing the b.c.c. or f.c.c. phases. The closed y-loops in the systems Fe-Ti, Fe—V and Fe-Cr are paralleled by closed y-fields in the Mn alloys, whilst Mn (in Fe), Fe (in Mn) and Ni produce open or expanded y-fields; Cu behaves abnormally in both series of alloys. In the Mn alloys, the stability and range of the B-Mn phase reach a maximum in the system Mn-Co, where the B-Mn phase is so stable that it comes into equilibrium with the liquid, and prevents the formation of a continuous series of solid solutions between Y-Mn and B-Co (f.c.c.). For the iron alloys the size factors are favourable for all the solutes examined, except Ti, which lies on the borderline of the favourable zone. With O-Mn and Fe-Mn as solvents, the size factors are all favourable, although that for Ti is still appreciable ( ca. 10%). The effect of size factor is shown by steep depression of the O-liquidus and O-solidus curves in the systems Fe-Ti and Mn—Ti. For the iron alloys the relative depressions of liquidus and solidus at equal atomic percentages of solute are in the order Ti > V > Cr and Co < Ni < Cu, and these sequences are the same as those for the lattice distortions produced by equiatomic percentages of the same solutes; the effect of Mn lies out of sequence in both cases. These and other relations are discussed. When compared with previous diagrams, the general effect of the present work is to indicate a much narrower two-phase (liquid and solid) range for both O-Fe and Y-Fe solid solutions. In marked contrast to previous diagrams, the present liquidus and solidus curves can all be reconciled with the existence of monatomic solutions in both liquid and solid phases. For Fe-Mn alloys the equations for dilute solutions are in good agreement with thermal data for pure iron up to 30 at. % Mn.

Modeling of the Onset of Gas Entrainment Through a Finite-Side Branch

2003 ◽  
Vol 125 (5) ◽  
pp. 902-909 ◽  
Author(s):  
M. Ahmed ◽  
I. Hassan ◽  
N. Esmail
Keyword(s):  
Froude Number ◽  
Three Dimensional ◽  
Phase Region ◽  
Side Branch ◽  
Critical Height ◽  
Two Phase ◽  
Gas Entrainment ◽  
Branch Model ◽  
Predicted Values ◽  
New Criterion

A theoretical investigation has been conducted for the prediction of the critical height at the onset of gas entrainment during single discharge from a stratified, two-phase region through a side branch with a finite diameter. Two different models have been developed, a simplified point-sink model and a three-dimensional finite-branch model. The two models are based on a new criterion for the onset of gas entrainment. The results of the predicted critical heights at the onset of gas entrainment showed that the finite-branch model approaches the physical limits at low Froude numbers. However, as the values of the Froude number increased, the predictions of both models eventually converged to the same value. Based on the results of the models, the critical height corresponding to the onset of gas entrainment was found to be a function of Froude number and fluid densities. The results of both models are compared with available experimental data. The comparisons illustrate a very good agreement between the measured and predicted values.

Experimental Study on Two-Phase Flows in Scavenge Pump for Aircraft Engine Oil System

2016 ◽  
Author(s):  
Laurent Ippoliti ◽  
Olivier Berten ◽  
Patrick Hendrick
Keyword(s):  
Single Phase ◽  
Aircraft Engine ◽  
Engine Oil ◽  
Test Rig ◽  
Feed Pump ◽  
Two Phase ◽  
Turbofan Engine ◽  
Flow Capacity ◽  
Scavenge System ◽  
Phase Liquid

This work is the continuation of previous studies on gerotor-type pump performance in turbofan engine oil systems operated as feed pumps in single-phase liquid oil. The focus here is on scavenge pumps whose role is to pump a mix of air and oil. This paper is intended to present the modifications that had to be made on the test rig from the previous studies to model a scavenge system and more generally to add two-phase flow capacity. The paper presents results from the first successful experimental test campaign. The aim is to characterize the performance of a typical pump, already tested as a feed pump, in the scavenge system. The critical performance parameter studied is the volumetric efficiency which determines the size and weight of the pump. This paper ends by drawing conclusions on the rig and the results, and linking them with the previous single-phase flows studies.

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