Characteristics of Air-Oil Two-Phase Flow Across a Sudden Expansion

2003 ◽  
Author(s):  
W. H. Ahmed ◽  
C. Y. Ching ◽  
M. Shoukri
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Pressure Recovery ◽  
Sudden Expansion ◽  
Phase Flow ◽  
Sudden Increase ◽  
Two Phase ◽  
Recovery Coefficient ◽  
Dynamic Head ◽  
Experimental Pressure

The pressure recovery and void fraction change of air-oil two-phase flow across a sudden expansion has been investigated experimentally over a range of flow conditions. The pressure upstream and downstream of a half-inch to one-inch sudden expansion was measured using a series of pressure taps, and capacitance sensors were used to measure the void fraction along the test section. The void fraction increases as the flow approaches the sudden expansion section, with a sudden increase immediately downstream of the expansion followed by a gradual relaxation to the fully developed value further downstream. The normalized pressure recovery coefficient using the dynamic head based on the homogeneous density and two-phase velocity is found to collapse when plotted as a function of the mass quality. The experimental pressure recovery data are compared with predictions from existing models, and are found to be in good agreement with the Delhaye model with the void fraction relation of Wallis.

Numerical Investigation of Air-Oil Two-Phase Flow Pattern Transition in the Scavenge Line of an Aeroengine

2021 ◽  
Author(s):  
Ghofrane Sekrani ◽  
Jean-Sebastien Dick ◽  
Sébastien Poncet ◽  
Sravankumar Nallamothu
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Numerical Models ◽  
Interfacial Area ◽  
Sudden Expansion ◽  
Phase Flow ◽  
Two Phase ◽  
Ansys Fluent ◽  
Before And After ◽  
Interfacial Area Density

Abstract Since most research investments in aeroengines have been targeted at the hot and cold sections, the oil system has remained an area poorly understood. Optimum sizing of the oil system can directly reduce the engine’s weight and specific fuel consumption while maximizing service life. The understanding of air/oil interaction in scavenge lines is required to influence the design of the oil systems and achieve those objectives. The challenge is in the existence of numerous possible flow regimes and phase interactions. In scavenge lines, a complex two-phase flow results from the interaction of sealing airflow and lubrication oil. Scavenge lines can have bends, junctions and sudden area changes which complicates their modeling by amplifying pressure gradients and turbulence generation, and causing the flow to change morphology (annular, slug, stratified, bubbly, mist, etc.). Several multiphase flow approaches have been developed to model two-phase flow in straight scavenge lines. However, up until now, no methodology is preferred by the community for simulating two-phase flow in such application. There are still many unknowns regarding the modeling of turbulence, phase interaction and the compressibility of immiscible mixtures such as air and oil. The present study compares the performance of two numerical models: Volume of Fluid (VOF) and Algebraic Interfacial Area Density (AIAD), for simulating the air/oil flow in a suddenly expanding scavenge line against the experimental data of Ahmed et al. [1–2]. The AIAD model is a two-fluid Eulerian approach newly implemented on Ansys Fluent. Discrepancies between the two models for predicting pressure loss and void fraction are evaluated and discussed into details. The flow regime before and after the sudden expansion is identified using iso-surfaces of the void-fraction and compared against visual data. Based on the results presented, recommendations are formulated for further work regarding the calibration of AIAD modeling parameters.

Flow Patterns of Gas-Liquid Two-Phase Flow in Round Tube With Sudden Expansion

2002 ◽  
Author(s):  
Koichi Kondo ◽  
Kenji Yoshida ◽  
Tadayoshi Matsumoto ◽  
Tomio Okawa ◽  
Isao Kataoka
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Flow Analysis ◽  
Sudden Expansion ◽  
Phase Flow ◽  
Round Tube ◽  
Two Phase ◽  
Fraction Distribution ◽  
Saddle Shape

Experimental studies were made on the multi-dimensional behavior of upward gas-liquid two-phase flow through the vertical round tube with an axisymmetric sudden expansion, which is one of the typical multi-dimensional channel geometry. The aims of this study are to clarify the multi-dimensional behavior of bubbly or slug flow affected by sudden expansion channel geometry, and to accumulate the experimental data for two-phase flow analysis, which is applicable to predict with appropriate accuracy the multi-dimensional its behavior. The direct observation using high-speed video camera was performed and revealed the multi-dimensional dynamic flow behavior with bubbles and gas-slug affected by the sudden expansion part (20 mm-tube to 50 mm-tube). The characteristic phenomena were observed such as bubble break-up, deformation due to the strong shear of liquid flow, or liquid micro jet penetration through the gas-slug, and so on. From these results, the flow regime map and the flow patterns at the below and above of the sudden expansion part were classified in relation to the bubble diameter. Additionally, the measurement of the void fraction profiles in the tube cross sections of sudden expansion were conducted at the different axial positions. The void fraction was measured using a point-electrode resistivity probe. The void fraction measurements in this study showed in detail that how the two phase flow develops along the direction of the downstream of the sudden expansion. In just above the sudden expansion, the void fraction distribution appeared the wall peak or the core peak in void fraction in the upstream of the sudden expansion. In the downstream of the sudden expansion, the void fraction distribution changes from a saddle shape or power-low shape into finally the saddle shape as the bubbly flow develops along the downstream of the sudden expansion. These experimental data in the sudden expansion of a vertical upward bubbly flow would become benchmark with respect to the multi-dimensional behavior of the two-phase flow analysis.

EXPERIMENTAL STUDY ON VOID FRACTION OF ECCS TWO-PHASE FLOW

2017 ◽  
Author(s):  
Guojun Yu ◽  
Wuyue Ren ◽  
Jiawei Bian ◽  
G. H. Su ◽  
Wenxi Tian ◽  
...  
Keyword(s):  
Experimental Study ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase

A model to predict void-fraction in two-phase flow

1969 ◽  
Vol 24 (9) ◽  
pp. 1483-1489 ◽  
Author(s):  
Ronald W. Brown ◽  
Albert Gomezplata ◽  
Joseph D. Price
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase

scholarly journals Pressure drop and average void fraction measurements for two-phase flow through highly permeable porous media

2016 ◽  
Vol 94 ◽  
pp. 422-432 ◽  
Author(s):  
N. Chikhi ◽  
R. Clavier ◽  
J.-P. Laurent ◽  
F. Fichot ◽  
M. Quintard
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through

Countercurrent Two-Phase Flow Regimes and Void Fraction in Vertical and Inclined Channels

1995 ◽  
Vol 119 (3) ◽  
pp. 182-194 ◽  
Author(s):  
S. M. Ghiaasiaan ◽  
K. E. Taylor ◽  
B. K. Kamboj ◽  
S. I. Abdel-Khalik
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Inclined Channels

Void fraction measurement of the air-water two-phase flow in the sub-channel of a rod bundle geometry based on an impedance meter

2018 ◽  
Vol 115 ◽  
pp. 480-486 ◽  
Author(s):  
Bin Yu ◽  
Wenxiong Zhou ◽  
Liangming Pan ◽  
Hang Liu ◽  
Quanyao Ren ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Rod Bundle ◽  
Fraction Measurement ◽  
Impedance Meter
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