scholarly journals Development of Interfacial Structure in a Confined Air-Water Cap-Turbulent and Churn-Turbulent Flow

2002 ◽  
Author(s):  
Xiaodong Sun ◽  
Seungjin Kim ◽  
Ling Cheng ◽  
Mamoru Ishii ◽  
Stephen G. Beus
Keyword(s):  
Turbulent Flow ◽  
Test Section ◽  
Two Phase Flow ◽  
Flow Direction ◽  
Interfacial Area ◽  
Interfacial Structure ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Bubble Number

The objective of the present work is to study and model the interfacial structure development of air-water two-phase flow in a confined test section. Experiments of a total of 9 flow conditions in cap-turbulent and churn-turbulent flow regimes are carried out in a vertical air-water upward two-phase flow experimental loop with a test section of 200-mm in width and 10-mm in gap. Miniaturized four-sensor conductivity probes are used to measure local two-phase parameters at three different elevations for each flow condition. The bubbles captured by the probes are categorized into two groups in view of the two-group interfacial area transport equation, i.e., spherical/distorted bubbles as Group 1 and cap/churn-turbulent bubbles as Group 2. The acquired parameters are time-averaged local void fraction, interfacial velocity, bubble number frequency, interfacial area concentration, and bubble Sauter mean diameter for both groups of bubbles. Also, the line-averaged and area-averaged data are presented and discussed. The comparisons of these parameters at different elevations demonstrate the development of interfacial structure along the flow direction due to bubble interactions.

Local Interfacial Structure in Downward Two-Phase Bubbly Flow

2002 ◽  
Author(s):  
Hiroshi Goda ◽  
Seungjin Kim ◽  
Sidharth S. Paranjape ◽  
Joshua P. Finch ◽  
Mamoru Ishii ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Bubbly Flow ◽  
Interfacial Area ◽  
Interfacial Structure ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Flow Parameters ◽  
Local Parameters ◽  
Axial Development

The local interfacial structure for vertical air-water co-current downward two-phase flow was investigated under adiabatic conditions. A multi-sensor conductivity probe was utilized in order to acquire the local two-phase flow parameters. The present experimental loop consisted of 25.4 mm and 50.8 mm ID round tubes as test sections. The measurement was performed at three axial locations: L/D = 13, 68 and 133 for the 25.4 mm ID loop and L/D = 7, 34, 67 for the 50.8 mm ID loop, in order to study the axial development of the flow. A total of 7 and 10 local measurement points along the tube radius were chosen for the 25.4 mm ID loop and the 50.8 mm ID loop, respectively. The experimental flow conditions were determined within bubbly flow regime. The acquired local parameters included the void fraction, interfacial area concentration, bubble interface frequency, bubble Sauter mean diameter, and interfacial velocity.

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.

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.

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

Implementation and Validation of an Improved Interfacial Area Concentration Model for Two-Phase Flow CFD Simulations

2021 ◽  
Author(s):  
Xiang Zhang ◽  
Minjun Peng ◽  
Tenglong Cong ◽  
Chuan Lu ◽  
Chenyang Wang
Keyword(s):  
Drag Force ◽  
Drift Velocity ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Concentration ◽  
Boiling Flow ◽  
Improved Model

Abstract The interfacial area concentration (IAC) is an important parameter in the calculation of interfacial transfers in two-fluid model, which can affect the accuracy of the boiling simulations. In this paper, an improved IAC model based on drag force and drift velocity is obtained, which can make full use of the experimental data and the models of the drag force and the drift velocity to avoid the shortage of IAC algebraic model in two-phase flow simulations theoretically. The improved model is validated by the DEBORA boiling flow experiment data. The reasonable radial distributions of void fraction, liquid temperature and phase velocity can be obtained, which indicates that the improved IAC model coupled in boiling flow model can be applied in CFD simulation of two-phase boiling flow. The improved model provides a new calculation approach for the IAC in the boiling flow with multi flow regimes.

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.

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