scholarly journals Study of interface gas-liquid flow characteristics in a rectangular microchannel for wavy-annular flow

2021 ◽  
Vol 2119 (1) ◽  
pp. 012059
Author(s):  
G V Bartkus ◽  
V V Kuznetsov
Keyword(s):  
Layer Thickness ◽  
Liquid Layer ◽  
Liquid Flow ◽  
Annular Flow ◽  
Maximal Amplitude ◽  
Short Side ◽  
Wide Range ◽  
Rectangular Slit ◽  
Liquid Layer Thickness ◽  
Gas Liquid Flow

Abstract The aim of this work is an experimental study of a gas-liquid flow in a rectangular slit microchannel with a cross-section of 200 × 2045 μm. Ethanol/water (95/5) mixture and nitrogen are used as working liquid and gas, accordingly. The external T-mixer is used for obtaining of wavy-annular flow pattern. The experimental data on interfacial waves and their characteristics in the meniscus area on the short side of the microchannel are obtained using high-speed visualization for a wide range of gas and liquid superficial velocities. Images are processed using the Python libraries to define the average liquid layer thickness and maximum amplitude of waves. An increase of gas superficial velocity causes decreasing in the average liquid layer thickness and maximal amplitude of the liquid layer thickness. The waves on the liquid layer surface (maximal amplitude) can be three times larger than the average liquid layer thickness for presented liquid and gas velocities. With increasing gas superficial velocities more liquid displace from the meniscus area to the liquid film on the wide side of the microchannel.

Criteria for mucus transport in the airways by two-phase gas-liquid flow mechanism

1986 ◽  
Vol 60 (3) ◽  
pp. 901-907 ◽  
Author(s):  
C. S. Kim ◽  
C. R. Rodriguez ◽  
M. A. Eldridge ◽  
M. A. Sackner
Keyword(s):  
Layer Thickness ◽  
Liquid Layer ◽  
Liquid Flow ◽  
Critical Conditions ◽  
Airflow Rate ◽  
Tube Model ◽  
Flow Mechanism ◽  
Two Phase ◽  
Liquid Layer Thickness ◽  
Gas Liquid Flow

The critical conditions for mucous layer transport in the respiratory airways by two-phase gas-liquid flow mechanism were investigated by using 0.5- and 1.0-cm-ID tube models. Several test liquids with rheological properties comparable to human sputum were supplied continuously into the vertically positioned tube models in such a way that the liquid could form a uniform layer while traveling upward through the tube with a continuous upward airflow. The critical airflow rate and critical liquid layer thickness required for the upward transport of the liquids were determined. The critical airflow rate was in the Reynolds number (Re) range of 142–1,132 in the 0.5-cm-ID tube model and 708–2,830 in the 1.0-cm-ID tube model depending on the types of liquids tested. In both models, the critical airflow rate was lower with viscoelastic liquids than with viscous oils. The critical liquid layer thickness ranged from 0.2 to 0.5 mm in the 0.5-cm-ID tube model and 0.8 to 1.4 mm in the 1.0-cm-ID tube model at Re of 2,800. These values decreased rapidly with increasing airflow rate. The critical thickness relative to the tube diameter ranged from 3 to 15% of the respective tube diameter and was lower by approximately 30–50% in the 0.5-cm-ID tube model than in the 1.0-cm-ID tube model over the entire Re range tested. The results indicate that the critical conditions for the mucus transport by two-phase gas-liquid flow mechanism are within the range that can be achieved in patients with bronchial hypersecretions during normal breathing.

Determination of Entrained Fraction in Vertical Annular Gas/Liquid Flow

1999 ◽  
Vol 122 (1) ◽  
pp. 146-150 ◽  
Author(s):  
Barry J. Azzopardi ◽  
Sohail H. Zaidi
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Annular Flow ◽  
Flow Model ◽  
Liquid Flow Rate ◽  
Measured Concentration ◽  
Diameter Pipe ◽  
A New Technique ◽  
Gas Liquid Flow

A new technique for the measurement of drop concentration in annular gas/liquid flow is presented. This is based on scattering of light by the drops. From the measured concentration, entrained liquid flow rate and thence the entrained fraction can be determined. The technique has been employed to obtain new data for vertical upward annular flow in a 0.038 m diameter pipe. The results have been compared with data from different pipe diameters and with the predictions of an annular flow model. [S0098-2202(00)02201-X]

scholarly journals The effect of the liquid layer thickness on the evaporation intensity

2018 ◽  
Vol 194 ◽  
pp. 01030
Author(s):  
Aleksei Kreta ◽  
Vyacheslav Maksimov
Keyword(s):  
Experimental Study ◽  
Layer Thickness ◽  
Liquid Layer ◽  
Flow Rate ◽  
Gas Flow ◽  
Shear Stresses ◽  
Gas Velocity ◽  
Evaporation Intensity ◽  
Liquid Layer Thickness ◽  
Thermocapillary Forces

An experimental study of the influence of thermo-capillary forces and shear stresses with the side of the gas flow to the evaporation flow rate has been made. The experiments were carried out at various thicknesses of the liquid layer and constant gas velocity. The influence of the thickness of the liquid layer on the evaporation flow rate (the intensity of evaporation) has been analyzed. It is shown that the thermocapillary forces have a direct effect on the evaporation flow rate of the liquid layer.

scholarly journals Investigations of mass transfer in annular gas-liquid flow in a microreactor

2016 ◽  
Vol 37 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Paweł Sobieszuk ◽  
Karolina Napieralska
Keyword(s):  
Mass Transfer ◽  
Cross Section ◽  
Chemical Reaction ◽  
Liquid Flow ◽  
Annular Flow ◽  
Gas Flow ◽  
Absorption Rate ◽  
Transfer Coefficients ◽  
Water Solutions ◽  
Gas Liquid Flow

Abstract The paper presents an investigation of mass transfer in gas-liquid annular flow in a microreactor. The microreactor had a meandered shape with a square cross-section of the channel (292×292 μm, hydraulic diameter 292 μm) and 250 mm in length. The rate of CO2 absorption from the CO2/N2 mixture in NaOH (0.1 M, 0.2 M, 0.7 M, 1.0 M and 1.5 M) water solutions was measured. Two velocities of gas flow and two velocities of liquid flow were used. In two cases a fully developed annular flow at the beginning of the channel was observed, whilst in two cases annular flow was formed only in about 2/3 of the microchannel length. Based on the measurements of CO2 absorption rate, the values of volumetric liquid - side mass transfer coefficients with the chemical reaction were determined. Then physical values of coefficients were found. Obtained results were discussed and their values were compared with the values predicted by literature correlations.

scholarly journals Application of the laser-induced fluorescence to study local characteristics of a gas-liquid flow in rectangular microchannel

2021 ◽  
Vol 2127 (1) ◽  
pp. 012008
Author(s):  
G V Bartkus ◽  
V V Kuznetsov
Keyword(s):  
Liquid Film ◽  
Liquid Flow ◽  
Phase Distribution ◽  
Laser Induced Fluorescence ◽  
Rectangular Microchannel ◽  
Rectangular Slit ◽  
Taylor’S Law ◽  
Elongated Bubble ◽  
Gas Liquid Flow ◽  
Working Liquid

Abstract The Laser-Induced Fluorescence (LIF) method was used to characterize liquid phase distribution in rectangular slit microchannel with cross-section 200×1205 μm for horizontal gas-liquid flow. Ethanol and nitrogen were used as working liquid and gas accordingly. The feature of this study is an application of hydraulic focusing cross-junction mixer for obtaining elongated bubble and transition flows in the microchannel with a high aspect ratio. Using LIF measurements for elongated bubble and transition flows the liquid film distributions were obtained for different distances from the bubble top and average liquid film thickness was compared with the prediction according to Taylor’s law.

Experimental Investigation Of Detailed Structure Of Gas-Liquid Flow In Rectangular Microchannel

2016 ◽  
Vol 11 (1) ◽  
pp. 73-79
Author(s):  
German Bartkus ◽  
German Bartkus ◽  
Vladimir Kuznetsov ◽  
Vladimir Kuznetsov
Keyword(s):  
Liquid Flow ◽  
High Speed ◽  
Rectangular Cross Section ◽  
Rectangular Channel ◽  
Detailed Structure ◽  
Rectangular Microchannel ◽  
Flow Rates ◽  
Wide Range ◽  
Gas Liquid Flow ◽  
Vertical Microchannel

The detailed structure of upward gas-liquid flow of water and nitrogen in a vertical microchannel with a rectangular cross-section 420 × 280 µm was experimentally investigated. The experiments were conducted using the methods of high-speed video and laser-induced fluorescence. In a wide range of flow rates the characteristic regimes of the gas-liquid flow were defined, velocity of elongated bubbles and the local thickness of the liquid film were measured. The dependence of the local film thickness on the capillary number was determined and it was found that the Taylor Law for rectangular channel is not fully implemented due to the deformation of the interface and the contraction of the liquid into the corners of the channel by capillary force.

scholarly journals Experimental determination of change in the liquid layer thickness on the heated surface by confocal sensor

2017 ◽  
Vol 159 ◽  
pp. 00011 ◽  
Author(s):  
Dmitry Feoktistov ◽  
Sergey Misyura ◽  
Anastasia Islamova ◽  
Kseniya Batishcheva
Keyword(s):  
Experimental Determination ◽  
Layer Thickness ◽  
Liquid Layer ◽  
Heated Surface ◽  
Liquid Layer Thickness
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