G050056 Void Fraction and Frictional Pressure Loss in Gas-Liquid Two-Phase Slug Flow in a Micro Tube

2011 ◽  
Vol 2011 (0) ◽  
pp. _G050056-1-_G050056-5
Author(s):  
Hisato MINAGAWA ◽  
Takahiro YASUDA ◽  
Shingo SUGIMOTO
Keyword(s):  
Void Fraction ◽  
Slug Flow ◽  
Pressure Loss ◽  
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.

Analysis of Turbulence Structure and Void Fraction Distribution in Gas-Liquid Two-Phase Flow Under Bubbly and Slug Flow Regime

2011 ◽  
Author(s):  
Isao Kataoka ◽  
Kenji Yoshida ◽  
Tsutomu Ikeno ◽  
Tatsuya Sasakawa ◽  
Koichi Kondo
Keyword(s):  
Void Fraction ◽  
Turbulence Model ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Turbulence Structure ◽  
Phase Flow ◽  
Two Phase ◽  
Void Fraction Distribution ◽  
Fraction Distribution

Accurate analyses of turbulence structure and void fraction distribution are quite important in designing and safety evaluation of various industrial equipments using gas-liquid two-phase flow such as nuclear reactor, etc. Using turbulence model of two-phase flow and models of bubble behaviors in bubble flow and slug flow, systematic analyses of distributions of void fraction, averaged velocity and turbulent velocity were carried out and compared with experimental data. In bubbly flow, diffusion of bubble and lift force are dominant in determining void fraction distribution. On the other hand, in slug flow, large scale turbulence eddies which convey bubbles into the center of flow passage are important in determining void fraction distribution. In turbulence model, one equation turbulence model is used with turbulence generation and turbulence dissipation due to bubbles. Mixing length due to bubble is also modeled. Using these bubble behavior models and turbulence models, systematic predictions were carried out for void distributions and turbulence distributions for wide range of flow conditions of two phase flow including bubbly and slug flow. The results of predictions were compared with experimental data in round straight tube with successful agreement. In particular, concave void distributions in bubbly flow and convex distribution in slug flow were well predicted based on the present model.

scholarly journals Optimization and Extended Applicability of Simplified Slug Flow Model for Liquid-Gas Flow in Horizontal and Near Horizontal Pipes

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 842
Author(s):  
Tea-Woo Kim ◽  
Nam-Sub Woo ◽  
Sang-Mok Han ◽  
Young-Ju Kim
Keyword(s):  
Slug Flow ◽  
Pressure Loss ◽  
Gas Flow ◽  
Flow Model ◽  
Flow Coefficient ◽  
Coefficient Of Determination ◽  
Liquid Holdup ◽  
Two Phase ◽  
Horizontal Pipes ◽  
Image Velocimetry

The accurate prediction of pressure loss for two-phase slug flow in pipes with a simple and powerful methodology has been desired. The calculation of pressure loss has generally been performed by complicated mechanistic models, most of which require the iteration of many variables. The objective of this study is to optimize the previously proposed simplified slug flow model for horizontal pipes, extending the applicability to turbulent flow conditions, i.e., high mixture Reynolds number and near horizontal pipes. The velocity field previously measured by particle image velocimetry further supports the suggested slug flow model which neglects the pressure loss in the liquid film region. A suitable prediction of slug characteristics such as slug liquid holdup and translational velocity (or flow coefficient) is required to advance the accuracy of calculated pressure loss. Therefore, the proper correlations of slug liquid holdup, flow coefficient, and friction factor are identified and utilized to calculate the pressure gradient for horizontal and near horizontal pipes. The optimized model presents a fair agreement with 2191 existing experimental data (0.001 ≤ μL ≤ 0.995 Pa∙s, 7 ≤ ReM ≤ 227,007 and −9 ≤ θ ≤ 9), showing −3% and 0.991 as values of the average relative error and the coefficient of determination, respectively.

Two-Phase Flow Modeling in a Pipe Related to Flow-Induced Vibration

2005 ◽  
Author(s):  
W. G. Sim ◽  
N. W. Mureithi ◽  
M. J. Pettigrew
Keyword(s):  
Void Fraction ◽  
Power Law ◽  
Slug Flow ◽  
Momentum Flux ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Fluid Dynamic ◽  
Phase Flow ◽  
Two Phase ◽  
Slip Ratio

To understand the fluid dynamic forces acting on a structure subjected to two-phase flow, it is essential to get detailed information about the characteristics of two-phase flow. The distributions of flow parameters across a pipe, such as gas velocity, liquid velocity and void fraction, may be assumed to follow a power law (Cheng 1998, Serizawa et al. 1975). The void fraction profile is, for example, uniform for bubbly flow while it is more or less parabolic for slug flow. In the present work, the average values of momentum flux, slip ratio, etc. are derived by integral analysis, based on approximate power law distributions. A parametric study with various distributions was performed. The existing empirical formulations for average void fraction, proposed by Wallis (1969), Zuber et al. (1967) and Ishii (1970), are considered to obtain the present results. In particular, the unsteady momentum flux for slug flow is approximated.

Gas Void Fraction Measurement in Two-Phase Gas/Liquid Slug Flow Using Acoustic Emission Technology

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
S. Al-lababidi ◽  
A. Addali ◽  
H. Yeung ◽  
D. Mba ◽  
F. Khan
Keyword(s):  
Acoustic Emission ◽  
Flow Regime ◽  
Void Fraction ◽  
Slug Flow ◽  
Chemical Engineering ◽  
Oil And Gas ◽  
Gas Production ◽  
Engineering Industry ◽  
Two Phase ◽  
Gas Void Fraction

The gas-liquid two-phase slug flow regime phenomenon is commonly encountered in the chemical engineering industry, particularly in oil and gas production transportation pipelines. Slug flow regime normally occurs for a range of pipe inclinations, and gas and liquid flowrates. A pipeline operating in the slug flow regime creates high fluctuations in gas and liquid flowrates at the outlet. Therefore, the monitoring of slugs and the measurement of their characteristics, such as the gas void fraction, are necessary to minimize the disruption of downstream process facilities. In this paper, a correlation between gas void fraction, absolute acoustic emission energy, and slug velocities in a two-phase air/water flow regime was developed using an acoustic emission technique. It is demonstrated that the gas void fraction can be determined by measurement of acoustic emission.

Investigation of Slug Flow Structure in Terms of Flow Regime Transition in Co-Current Two-Phase Flow

2017 ◽  
Author(s):  
Muhao Zhang ◽  
Liang-ming PAN ◽  
Peng Ju ◽  
Mamoru Ishii
Keyword(s):  
Turbulent Flow ◽  
Flow Regime ◽  
Void Fraction ◽  
Slug Flow ◽  
Transition Process ◽  
Phase Flow ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Regime Transition ◽  
Wake Effects

In order to investigate the structure parameters evolution characteristics during flow regime transition process in slug flow, the vertical upward slug flow experiment in a wide range of liquid superficial velocity (0.03 < jl < 1.6 m/s) were conducted in a tubular test section with the inside diameter of 25.4 mm. Impedance void meters were employed to measure the void fraction of separated two parts corresponding to Taylor bubble and liquid slug. The present research studied the evolution of length ratio and void fraction in slug unit by keeping the liquid superficial velocity constant while increasing gas flow rate. New structure of slug unit in strong relation with transition process was observed. In specific, it was realized that the proportion of such special structure unit played an important role in transition from slug flow to churn-turbulent flow. The existing transition criteria from slug flow to churn-turbulent flow in upward two-phase flow (entrance effects model, flooding model, wake effects model, bubble coalescence model and Helmholtz instability model) were compared with the experimental identified results obtained by a new objective flow regime identification method, ReliefF-FCM algorithm. The results indicate that the transition model based on the wake effects could be the most appropriate choice to describe the mechanism of transition from slug flow to churn-turbulent flow in present experimental conditions.

Research on the Air-Water Flow Regime and Characteristics in Rectangular Channel

2021 ◽  
Author(s):  
Qingche He ◽  
Liangming Pan ◽  
Luteng Zhang ◽  
Meiyue Yan ◽  
Wangtao Xu
Keyword(s):  
Flow Regime ◽  
Void Fraction ◽  
Slug Flow ◽  
Clustering Algorithm ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Interfacial Structure ◽  
Phase Flow ◽  
Two Phase ◽  
Rectangular Channels

Abstract Two-phase Flow is widely involved in reactor design and is directly relevant to reactor safety. However, the flow regime in narrow rectangular channels still needs further study because it has a considerable difference from tube and bundle channels. To investigate the two-phase flow regime and interfacial structure characteristics, the air-water experiment with an adiabatic vertical channel of 4 × 66 × 1800, 6 × 66 × 1800 mm have been conducted under atmosphere pressure condition. The impedance void meter was used to measure the global void fraction in narrow rectangular channels. A high-speed camera was used to record the profiles of the flow regime. The flow regime was identified by the random forest clustering algorithm based on a training sample. The profiles of different parameters, including void fraction, pressure loss at Z/D = 150, were analyzed in this paper. Furthermore, based on the parameters’ distribution, the regime transition criteria in narrow rectangular channels were discussed. It is shown that the transition from bubble to slug flow always occurred when the average void fraction is 0.17–0.2. The transition value is 0.57–0.62 when the slug Flow changes to the churn-turbulent Flow and 0.78–0.8 from churn-turbulent to annular Flow. The constant used in the Lockhart-Martinelli correlation is found to calculate the frictional pressure drop in a rectangular channel. Furthermore, the drift-model applied to the rectangular channel is verified.

Void Fraction, Pressure Drop, and Flow Pattern Behavior for Two-Phase Non-Newtonian Slug Flow

2021 ◽  
Author(s):  
Faraj Ben Rajeb ◽  
Syed Imtiaz ◽  
Yan Zhang ◽  
Amer Aborig ◽  
Mohamed M. Awad ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Flow Regime ◽  
Void Fraction ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Two Phase

Abstract Slug flow is one of the most common flow patterns in non-Newtonian two-phase flow in pipes. It is a very common occurrence in gas-liquid two-phase flow in the pipe. Usually, it is an unfavorable flow pattern due to its unsteady nature, intermittency as well as high pressure drop. The differences between slug flow and elongated bubble flow are not clear because usually these two types of flow combined under one flow category. In general, these two-phase flow regimes are commonly defined as intermittent flow. In the present study, pressure gradient, and wave behavior in slug flow have been investigated depending on experimental work. In addition, void fraction has been estimated regarding available superficial liquid and gas velocities. The experimental records of superficial velocities of gas and liquid for slug flow and other flow patterns is used to create flow regime map for the gas non-Newtonian flow system. The effect of investigated flow regime velocities for non-Newtonian/gas flow on pressure drop and void fraction is reported. Pressure drop has been discovered to be reduced in slug flow more than other flow patterns due to high shear thinning behavior.

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