Axial Development of Vertical Upward Bubbly Flow in a Minipipe

2005 ◽  
Author(s):  
Tatsuya Hazuku ◽  
Naohisa Tamura ◽  
Norihiro Fukamachi ◽  
Tomoji Takamasa ◽  
Takashi Hibiki ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Constitutive Relations ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Local Flow ◽  
Interfacial Area Concentration ◽  
Drift Flux Model

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. Mechanistic modeling of the interfacial area concentration entirely relies on accurate local flow measurements over extensive flow conditions and channel geometries. From this point of view, accurate measurements of flow parameters such as void fraction, interfacial area concentration, gas velocity, bubble Sauter mean diameter, and bubble number density were performed by the image processing method at five axial locations in vertical upward bubbly flows using a 1.02 mm-diameter pipe. The frictional pressure loss was also measured by a differential pressure cell. In the experiment, the superficial liquid velocity and the void fraction ranged from 1.02 m/s to 4.89 m/s and from 0.980% to 24.6%, respectively. The obtained data give near complete information on the time-averaged local hydrodynamic parameters of two-phase flow. These data can be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow. As the first step to understand the flow characteristics in mini-channels, the applicability of the existing drift-flux model, interfacial area correlation, and frictional pressure correlation was examined by the data obtained in the mini-channel.

Axial Development of Gas-Liquid Two-Phase Flow in Mini-Channels

2006 ◽  
Author(s):  
Junichi Uematsu ◽  
Yoshinori Hirose ◽  
Tatsuya Hazuku ◽  
Tomoji Takamasa ◽  
Takashi Hibiki
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Local Flow ◽  
Interfacial Area Concentration ◽  
Drift Flux Model ◽  
Mini Channels

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. Mechanistic modeling of the interfacial area concentration entirely relies on accurate local flow measurements over extensive flow conditions and channel geometries. From this point of view, accurate measurements of flow parameters such as void fraction, interfacial area concentration, gas velocity, bubble Sauter mean diameter, and bubble number density were performed by the image processing method at five axial locations in vertical upward bubbly flows using 1.02 and 0.55 mm-diameter pipes. The frictional pressure loss was also measured by a differential pressure cell. In the experiment, the superficial liquid velocity and the void fraction ranged from 0.475 m/s to 4.89 m/s and from 0.980% to 28.6%, respectively. The obtained data give near complete information on the time-averaged local hydrodynamic parameters of two-phase flow. These data can be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow. As the first step to understand the flow characteristics in mini-channels, the applicability of the existing drift-flux model, interfacial area correlation, and frictional pressure correlation was examined by the data obtained in the mini-channels.

Axial Development of Local Flow Parameters in Bubbly Two-Phase Flow in Normal and Microgravity Conditions

2009 ◽  
Author(s):  
Yutaka Takata ◽  
Dong Chang Xing ◽  
Yutaka Fukuhara ◽  
Tatsuya Hazuku ◽  
Tomoji Takamasa ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Interfacial Area ◽  
Axial Distance ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Local Flow ◽  
Flow Parameters ◽  
Microgravity Conditions ◽  
Axial Development

In relation to the development of the interfacial area transport equation, a precise database of the axial development of void fraction profile, interfacial area concentration and Sauter mean bubble diameter in an adiabatic nitrogen-water bubbly flow in a 9 mm-diameter pipe was constructed for normal and microgravity conditions using stereo image-processing. The flow measurements were performed at four axial locations (axial distance from the inlet normalized by the pipe diameter, z/D = 5, 20, 40 and 60) and with various flows: superficial gas velocity of 0.00840–0.0298 m/s, and superficial liquid velocity of 0.138–0.914 m/s. The effect of gravity on radial distribution of bubbles and the axial development of two-phase flow parameters is discussed in detail based on the obtained database and visual observation.

Interfacial Area Concentration and Void Fraction of Two-Phase Flow in Narrow Rectangular Vertical Channels

1997 ◽  
Vol 119 (4) ◽  
pp. 916-922 ◽  
Author(s):  
T. Wilmarth ◽  
M. Ishii
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Ccd Camera ◽  
Interfacial Area ◽  
Separate Flow ◽  
Image Processing Technique ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Local Average

Adiabatic concurrent vertical two-phase flow of air and water through narrow rectangular channels, gap widths 1 mm and 2 mm, was investigated. This study involved the observation of flow using a charge coupled device (CCD) camera. These images were then digitized and examined by applying an image processing technique to determine local average void fraction and local average interfacial area concentration. The void fraction data were then plotted using a drift flux plot to determine the distribution parameter and vapor drift velocity for each separate flow regime.

Interfacial Area Transport of Vertical Upward Annular Two-Phase Flow

2005 ◽  
Author(s):  
Tatsuya Hazuku ◽  
Tomoji Takamasa ◽  
Takashi Hibiki ◽  
Mamoru Ishii
Keyword(s):  
Liquid Film ◽  
Concentration Profile ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
One Dimensional ◽  
Drift Flux Model

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. The interfacial area concentration in annular flow and annular mist flow is especially relevant to the transition process to the liquid film dryout, which might lead to fatal problem in the safety and efficient operation of boiling heat transfer system. However, very few experimental and theoretical studies focusing on the interfacial area concentration in annular flow region have been conducted. From this point of view, accurate measurements of annular flow parameters such as local liquid film thickness, one-dimensional interfacial area concentration of liquid film, and local interfacial area concentration profile of liquid film were performed by a laser focus displacement meter at 21 axial locations in vertical upward annular two-phase flow using a 3-m-long and 11-mm-diameter pipe. The axial distances from the inlet (z) normalized by the pipe diameter (D) varied over z/D = 50 to 250. Data were collected for preset gas and liquid flow conditions and for Reynolds numbers ranging from Reg = 31,800 to 98,300 for the gas phase and Ref = 1,050 to 9,430 for the liquid phase. Axial development of the one-dimensional interfacial area concentration and the local interfacial area concentration profile of liquid film were examined with the data obtained in the experiment. Total interfacial area concentration including liquid film and droplets was also discussed with help of the existing drift-flux model, entrainment correlation, and droplet size correlation.

Local and Area-Averaged Flow Structure of Air-Water Two-Phase Flow in a Vertical Annulus

2008 ◽  
Author(s):  
Basar Ozar ◽  
Jae Jun Jeong ◽  
Abhinav Dixit ◽  
Jose Enrique Julia´ ◽  
Takashi Hibiki ◽  
...  
Keyword(s):  
Flow Structure ◽  
Test Section ◽  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Drift Flux Model ◽  
Vertical Annulus

The flow structure of gas-liquid two-phase flow has been investigated in a vertical annulus channel. The annulus consisted of a geometry where the inner diameter was 19.1 mm and the outer diameter was 38.1 mm. The total height of the test section was 4.37 m. Experiments were conducted for nineteen inlet flow conditions. These flow conditions covered bubbly, cap-slug, and churn-turbulent flows. The local flow parameters, such as void fraction, interfacial area concentration, and bubble interface velocity, were measured at nine radial positions within the gap of the annulus at z/Dh = 230 of the test section. Radial distributions of these parameters were interpreted in terms of turbulent velocity profile, lift and wall forces. In addition, the local measurements were used to calculate distribution parameter, C0 in drift-flux model, and area averaged interfacial area concentration. Ishii’s (1977) model was modified and a new correlation of C0 was proposed based on the experimentally obtained C0 values. The area-averaged interfacial area concentration (IAC) values were compared with the most widely used models (Ishii and Mishima, 1980; Spore et al., 1983; Hibiki and Ishii, 2002). The advantages and drawbacks of these models were highlighted.

Numerical Simulation of the Air-Water Two-Phase Flow Across a 90-Degree Vertical-Upward Elbow

2020 ◽  
Author(s):  
Shouxu Qiao ◽  
Wenyi Zhong ◽  
Sijia Hao ◽  
Peiyao Qi ◽  
Sichao Tan
Keyword(s):  
Liquid Phase ◽  
Void Fraction ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Flow Models

Abstract The present study investigates the air-water two-phase flow across a 90-degree vertical-upward elbow with the computational fluid dynamics (CFD) simulation. The Eulerian-Eulerian two-fluid model and the Multi Size Group (MUSIG) model are used to predict the development of the detailed interfacial structures between the two phases. The axial development of the void fraction and the interfacial area concentration are investigated and benchmarked with the experimental data measured using the four-sensor conductivity probe. It is concluded that CFD simulation can predict the characteristics distributions of void fraction and interfacial area concentration and their development downstream of the elbow. The double-peaked void fraction distribution is found to be caused by the secondary flow induced by the elbow. The liquid phase on the outer curvature moves to the inner curvature and forms a double counter rotating vortex, entraining the bubbles to form a double-peaked distribution. The elbow effects become dissipated between 33 and 63 hydraulic diameters. The simulation results of liquid-phase and gas-phase parameters can be used to develop the theoretical two-phase flow models for the elbow region.

Local characteristic of horizontal air–water two-phase flow by wire-mesh sensor

2016 ◽  
Vol 40 (3) ◽  
pp. 746-761 ◽  
Author(s):  
Weiling Liu ◽  
Chao Tan ◽  
Feng Dong
Keyword(s):  
Void Fraction ◽  
Transient Flow ◽  
Two Phase Flow ◽  
Wire Mesh ◽  
Local Characteristic ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Local Flow

Two-phase flow widely exists in many industries. Understanding local characteristics of two-phase flow under different flow conditions in piping systems is important to design and optimize the industrial process for higher productivity and lower cost. Air–water two-phase flow experiments were conducted with a 16×16 conductivity wire-mesh sensor (WMS) in a horizontal pipe of a multiphase flow facility. The cross-sectional void fraction time series was analysed by the probability density function (PDF), which described the void fraction fluctuation at different flow conditions. The changes and causes of PDFs during a flow regime transition were analysed. The local structure and flow behaviour were characterized by the local flow spectrum energy analysis and the local void fraction distribution (horizontal, vertical and radial direction) analysis. Finally, three-dimensional transient flow fluctuation energy evolution and characteristic scale distribution based on wavelet analysis of air–water two-phase flow were presented, which revealed the structural features of each phase in two-phase flow.

Modeling and measurement of interfacial area concentration in two-phase flow

2010 ◽  
Vol 240 (9) ◽  
pp. 2329-2337 ◽  
Author(s):  
Sidharth Paranjape ◽  
Mamoru Ishii ◽  
Takashi Hibiki
Keyword(s):  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration
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