scholarly journals Determination of a Bubble Drag Coefficient during the Formation of Single Gas Bubble in Upward Coflowing Liquid

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 999
Author(s):  
Przemysław Luty ◽  
Mateusz Prończuk
Keyword(s):  
Drag Coefficient ◽  
Chemical Engineering ◽  
Liquid Velocity ◽  
Bubble Diameter ◽  
Bubble Formation ◽  
Hydraulic Drag ◽  
Gas Bubble ◽  
Flowing Liquid ◽  
Engineering Research

Bubble flow is present in many processes that are the subject of chemical engineering research. Many correlations for determination of the equivalent bubble diameter can be found in the scientific literature. However, there are only few describing the formation of gas bubbles in flowing liquid. Such a phenomenon occurs for instance in airlift apparatuses. Liquid flowing around the gas bubble creates a hydraulic drag force that leads to reduction of the formed bubble diameter. Usually the value of the hydraulic drag coefficient, cD, for bubble formation in the flowing liquid is assumed to be equal to the drag coefficient for bubbles rising in the stagnant liquid, which is far from the reality. Therefore, in this study, to determine the value of the drag coefficient of bubbles forming in flowing liquid, the diameter of the bubbles formed at different liquid velocity was measured using the shadowgraphy method. Using the balance of forces affecting the bubble formed in the coflowing liquid, the hydraulic drag coefficient was determined. The obtained values of the drag coefficient differed significantly from those calculated using the correlation for gas bubble rising in stagnant liquid. The proposed correlation allowed the determination of the diameter of the gas bubble with satisfactory accuracy.

scholarly journals Comparison of selected theoretical models of bubble formation and experimental results

2014 ◽  
Vol 35 (2) ◽  
pp. 21-36 ◽  
Author(s):  
Mariusz R. Rząsa
Keyword(s):  
Measurement Method ◽  
Formation Rate ◽  
Bubble Formation ◽  
Theoretical Models ◽  
Measuring System ◽  
Gas Bubble ◽  
Measurement Results ◽  
Intermediate States ◽  
Determination Of Parameters

Abstract Designers of all types of equipment applied in oxygenation and aeration need to get to know the mechanism behind the gas bubble formation. This paper presents a measurement method used for determination of parameters of bubbles forming at jet attachment from which the bubles are displaced upward. The measuring system is based on an optical tomograph containing five projections. An image from the tomograph contains shapes of the forming bubbles and determine their volumes and formation rate. Additionally, this paper presents selected theoretical models known from literature. The measurement results have been compared with simple theoretical models predictions. The paper also contains a study of the potential to apply the presented method for determination of bubble structures and observation of intermediate states.

Bubble Diameter and Effective Interfacial Area in a Novel Hybrid Rotating and Reciprocating Perforated Plate Bubble Column

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Dhanasekaran S ◽  
Karunanithi T
Keyword(s):  
Liquid Velocity ◽  
Bubble Column ◽  
Bubble Diameter ◽  
Perforated Plate ◽  
Interfacial Area ◽  
Gas Velocity ◽  
The Mean ◽  
Superficial Gas Velocity ◽  
Plate Column

This investigation reports on the experimental and theoretical investigation carried out to evaluate the bubble diameter and effective interfacial area in a novel Hybrid Rotating and Reciprocating Perforated Plate Bubble Column. Air-water system is used in this investigation. Countercurrent mode is employed. The effects of agitation level, superficial gas velocity and superficial liquid velocity on the bubble size distribution are studied. The mean bubble diameter is predicted using photographic technique. A simple correlation is developed for the determination of mean bubble diameter. It is found that the mean bubble diameter values for hybrid column are 1.8 to 2.5 times smaller when compared with conventional reciprocating plate column. The interfacial area is calculated based on the experimental results of the gas holdup and bubble diameter. Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate free area on the interfacial area have been investigated. Correlations are developed for the determination of interfacial area for both mixer-settler and emulsion regions. It could be noted that the interfacial area for the hybrid column is 3 to 6 times higher in both mixer-settler region and emulsion region than that of conventional reciprocating plate column which is quite large.

scholarly journals Evaluation of velocity fields in horizontal gas-liquid intermittent flows using Stereoscopic-PIV and instantaneous masking procedure

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Leonardo Soares Fernandes ◽  
Rodrigo dos Santos Navarro De Mesquita ◽  
Fabio Jessen Werneck de Almeida Martins ◽  
Luis Fernando Alzuguir Azevedo
Keyword(s):  
Liquid Velocity ◽  
Numerical Models ◽  
Velocity Fields ◽  
Gas Bubble ◽  
Complex Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Stereoscopic Piv ◽  
Liquid Flows

The main goal of this work was to obtain well-converged liquid velocity profiles for intermittent gas-liquid flows in a horizontal pipe. To this end, air and water with superficial velocities of JG = 0.5 m/s and JL = 0.3, 0.4 and 0.5 m/s, respectively, were driven into a 18-m acrylic test section with an inner diameter of 40 mm. All three-components of the velocity vectors were measured in a pipe cross-section using a highfrequency stereoscopic PIV system, together with the laser induced fluorescence technique. Photogates were used to measure the unit cell translational velocity, as well as to trigger data acquisition, allowing the calculation of ensemble-averaged velocity fields at specific positions, referenced to the gas-bubble nose tip position. An instantaneous image masking procedure was implemented, allowing the determination of non-dimensional ensemble-averaged velocity profile in the liquid film, referenced to gas-bubble boundary. The high-frequency system employed allowed the determination of the influence of the faster-moving gas bubble on the liquid velocity field in the plug region. The data presented are relevant to the validation and improvement of one-dimensional two-phase numerical models, as well as to better understand this complex flow.

Regimes of Formation of Bubbly Flows

2016 ◽  
Author(s):  
O. N. Kashinsky ◽  
M. A. Vorobyev ◽  
P. D. Lobanov ◽  
A. V. Chinak
Keyword(s):  
Gas Flow ◽  
Liquid Velocity ◽  
Bubble Diameter ◽  
Bubble Formation ◽  
Bubble Size Distribution ◽  
Liquid Temperature ◽  
Gas Flow Rate ◽  
Mixture Formation ◽  
Bubble Detachment ◽  
Different Temperatures

An experimental study of the process of bubble detachment from a single capillary was performed. Glycerin was used as a test liquid. To study the effect of physical properties of liquid on the process of bubble formation the experiments were conducted at different temperatures. The dependencies of mean bubble diameter on gas flow rate, liquid temperature and liquid velocity along with the size of capillary are presented. The data on the most typical regimes of bubbly mixture formation are obtained. The bubble coalescence near the capillary is shown to be the process which determines the shape of bubble size distribution in the flow.

The motion of a large gas bubble rising through liquid flowing in a tube

1978 ◽  
Vol 89 (3) ◽  
pp. 497-514 ◽  
Author(s):  
R. Collins ◽  
F. F. De Moraes ◽  
J. F. Davidson ◽  
D. Harrison
Keyword(s):  
Velocity Profile ◽  
Liquid Velocity ◽  
Approximate Solutions ◽  
Initial Distribution ◽  
Turbulent Velocity ◽  
Bubble Velocity ◽  
Published Data ◽  
Gas Bubble ◽  
Flowing Liquid ◽  
Bubble Rising

The theory presented here describes the motion of a large gas bubble rising through upward-flowing liquid in a tube. The basis of the theory is that the liquid motion round the bubble is inviscid, with an initial distribution of vorticity which depends on the velocity profile in the liquid above the bubble. Approximate solutions are given for both laminar and turbulent velocity profiles and have the form \begin{equation} U_s = U_c+(gD)^{\frac{1}{2}}\phi(U_c/(gD)^{\frac{1}{2}}), \end{equation}Us being the bubble velocity, Uc the liquid velocity at the tube axis, g the acceleration due to gravity, and D the tube diameter; ϕ indicates a functional relationship the form of which depends upon the shape of the velocity profile. With a turbulent velocity profile, a good approximation to (1) which is suitable for many practical purposes is \begin{equation} U_s = U_s + U_{s0}, \end{equation}Us0 being the bubble velocity in stagnant liquid. Published data for turbulent flow are known to agree with (2), so that in this case the theory supports a well-known empirical result. Our laminar flow experiments confirm the validity of (1) for low liquid velocities.

MODELING OF NONLINEAR VIBRATION PROBLEMS WITH FLUID FLOWS THROUGH PIPELINES

2018 ◽  
pp. 44-47
Author(s):  
F.J. Тurayev
Keyword(s):  
Differential Equations ◽  
Nonlinear Vibration ◽  
Viscoelastic Properties ◽  
Construction Material ◽  
Fluid Flows ◽  
Variable Coefficients ◽  
Algebraic Equations ◽  
Flowing Liquid ◽  
Vibration Problems

In this paper, mathematical model of nonlinear vibration problems with fluid flows through pipelines have been developed. Using the Bubnov–Galerkin method for the boundary conditions, the resulting nonlinear integro-differential equations with partial derivatives are reduced to solving systems of nonlinear ordinary integro-differential equations with both constant and variable coefficients as functions of time.A system of algebraic equations is obtained according to numerical method for the unknowns. The influence of the singularity of heredity kernels on the vibrations of structures possessing viscoelastic properties is numerically investigated.It was found that the determination of the effect of viscoelastic properties of the construction material on vibrations of the pipeline with a flowing liquid requires applying weakly singular hereditary kernels with an Abel type singularity.

Simplified and rapid determination of Ca, K, Mg, and Na in fruit juices by flowing liquid cathode atmospheric glow discharge optical emission spectrometry

2021 ◽  
Author(s):  
Monika Gorska ◽  
Pawel Pohl
Keyword(s):  
Glow Discharge ◽  
Rapid Determination ◽  
Optical Emission ◽  
Fruit Juices ◽  
Emission Spectrometry ◽  
Atmospheric Pressure Glow Discharge ◽  
Flowing Liquid ◽  
Liquid Cathode ◽  
Pressure Glow Discharge

Atmospheric pressure glow discharge (APGD) microplasma, sustained between a flowing liquid cathode (FLC) and a tungsten anode, was applied for the determination of Ca, K, Mg, and Na in fruit juices with a simplified sample preparation procedure.

Local Study on Hydrogen and Hydrogen Gas Bubble Formation on a Platinum Electrode

2019 ◽  
Vol 123 (17) ◽  
pp. 10849-10856 ◽  
Author(s):  
Alberto Battistel ◽  
Christopher R. Dennison ◽  
Andreas Lesch ◽  
Hubert H. Girault
Keyword(s):  
Platinum Electrode ◽  
Bubble Formation ◽  
Hydrogen Gas ◽  
Gas Bubble ◽  
Local Study
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