Experimental measurements of bubble convection models in two-phase stratified liquids

2017 ◽  
Vol 83 ◽  
pp. 69-77 ◽  
Author(s):  
Hassan Abdulmouti
Keyword(s):  
Experimental Measurements ◽  
Two Phase ◽  
Bubble Convection

Experimental Measurements and Numerical Simulations of Two-Phase Stratified, Wavy and Slug Flow in a Narrow Rectangular Channel

2005 ◽  
Author(s):  
Steven P. O’Halloran ◽  
B. Terry Beck ◽  
Mohammad H. Hosni ◽  
Steven J. Eckels
Keyword(s):  
Numerical Simulations ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Measurement Techniques ◽  
Narrow Channel ◽  
Experimental Measurements ◽  
Phase Flow ◽  
Two Phase ◽  
Two Fluids

Flow pattern transitions in two-phase flow are important phenomena for many different types of engineering applications, including heat exchangers. While two-phase flow is not understood as well as single-phase flow, advancements in both measurement techniques and numerical simulations are helping to increase the understanding of two-phase flow. In this paper, stratified/wavy flow is investigated, along with the transition from wavy to slug flow. For the experimental setup, a narrow channel with a length of 600 mm, height of 40 mm, and a width of 15 mm was fabricated using clear acrylic plastic, and water and air were the two fluids used for testing. The water in the channel was initially at rest, and the transition in flow patterns was created by increasing the velocity of air flowing over the water surface. Particle image velocimetry (PIV) was used to measure the velocity of the flow for stratified and wavy flow conditions, and also the velocity at the onset of slug flow. Along with the experimental measurements, computational fluid dynamics (CFD) simulations were conducted on a similar geometry using the volume of fluid (VOF) two-phase model. A commercial CFD software package was used for the simulations, and comparisons were made between the experimental measurements and numerical results. Favorable agreement was found between the experimental measurements and the numerical simulations. In particular, the transition from wavy to slug flow compared well to previously developed two-phase flow transition models, including the slug transition developed by Taitel and Dukler.

scholarly journals Operation technological process research in the cleaning system of the grain combine

2021 ◽  
Vol 52 (2) ◽  
Author(s):  
Ildar Badretdinov ◽  
Salavat Mudarisov ◽  
Eduard Khasanov ◽  
Ruslan Nasyrov ◽  
Marat Tuktarov
Keyword(s):  
Technological Process ◽  
Process Research ◽  
Experimental Measurements ◽  
Phase Flow ◽  
Work Process ◽  
Two Phase ◽  
Existing Structures ◽  
Cleaning System ◽  
Airflow Distribution ◽  
Combine Harvester

The purpose of this study is to increase the efficiency of the technological process of a combine harvester cleaning system. It involved the simulation of the actual work process, the identification of problem areas and the uniform airflow distribution across the width of the sieve mill. The method for determining the class of ‘air-grain heap’ flow in the combine harvester cleaning system is presented in order to provide the mathematical description of its technical work process. As a result, the volumetric (Q = 8·10–6 ÷ 2.5·10–4) and mass (W = 0.01 ÷ 0.3) concentration of a grain heap in different sections of the sieve mill of the combine harvester cleaning system. The experimental measurements of the airflow speed on the sieve mill’s surface for the existing structures of the cleaning system in modern grain harvesters were 3.75 ÷ 10.2 m/s. The data obtained will be used in the future to implement a mathematical model for a complete description of the technological process of a combine harvester cleaning system using methods based on two-phase flow mechanics.

scholarly journals Investigating the Characteristics of Two-Phase Flow Using Electrical Capacitance Tomography (ECT) for Three Pipe Orientations

Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 51 ◽  
Author(s):  
Zeyad Almutairi ◽  
Fayez M. Al-Alweet ◽  
Yusif A. Alghamdi ◽  
Omar A. Almisned ◽  
Othman Y. Alothman
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Electrical Capacitance Tomography ◽  
Experimental Measurements ◽  
Phase Flow ◽  
Electrical Capacitance ◽  
Liquid Holdup ◽  
Two Phase ◽  
Capacitance Tomography

Experiments of gas–liquid flow in a circular pipe for horizontal and inclined positions (upward/downward) are reported. The characteristics of two-phase flow in terms of liquid holdup (ε(L)) and induced flow patterns are studied using three experimental techniques; time-averaged ε(L) from permittivity profiles using electrical capacitance tomography (ECT), instantaneous ε(L) using two fast-closing valves (TFCV), and high-speed camera images (HSCI) to capture/identify the formed flow patterns. Thus, this experimental setup enables the development of more well-defined flow patterns in gas–liquid two-phase flow and allows for multi-technique verification of the results. Taken from experimental measurements, a model is proposed to predict ε(L) for high and low situations. The correlations are a function of the hydrodynamic dimensionless quantities which provide hydrodynamic similarity. Regarding different pipe orientations, ε(L) predictions are comparable to ε(L) from experimental measurements with accepted accuracy: 88% of the predictions are within ±5–15% and 98% are below ±20%. The correlations also were validated by reported results and against correlations available in the literature and show higher prediction accuracy. It is confirmed that the kinematic similarity which is achieved by the gas–liquid velocity ratios and the inertial forces influence the flow pattern and the liquid holdup.

Large-eddy simulation of turbulent gas–particle flow in a vertical channel: effect of considering inter-particle collisions

2001 ◽  
Vol 442 ◽  
pp. 303-334 ◽  
Author(s):  
Y. YAMAMOTO ◽  
M. POTTHOFF ◽  
T. TANAKA ◽  
T. KAJISHIMA ◽  
Y. TSUJI
Keyword(s):  
Gas Flow ◽  
Vertical Channel ◽  
Stokes Number ◽  
Particle Collision ◽  
Experimental Measurements ◽  
Particle Collisions ◽  
Two Phase ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Good Agreement

The interaction between a turbulent gas flow and particle motion was investigated by numerical simulations of gas–particle turbulent downward flow in a vertical channel. In particular the effect of inter-particle collision on the two-phase flow field was investigated. The gas flow field was obtained by large-eddy simulation (LES). Particles were treated by a Lagrangian method, with inter-particle collisions calculated by a deterministic method. The spatial resolution for LES of gas–solid two-phase turbulent flow was examined and relations between grid resolution and Stokes number are presented. Profiles of particle mean velocity, particle wall-normal fluctuation velocity and number density are flattened as a result of inter-particle collisions and these results are in good agreement with experimental measurements. Calculated turbulence attenuation by particles agrees well with experimental measurements for small Stokes numbers, but not for large Stokes number particle. The shape and scale of particle concentrations calculated considering inter-particle collision are in good agreement with experimental observations.

A comparative study of treatment of two-dimensional two-phase flows of steam by a Runge-Kutta and by Denton's methods

2007 ◽  
Vol 221 (6) ◽  
pp. 689-706 ◽  
Author(s):  
F Bakhtar ◽  
M Y Zamri ◽  
J M Rodriguez-Lelis
Keyword(s):  
Comparative Study ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Oscillating Flows ◽  
Two Phase ◽  
Time Marching ◽  
Runge Kutta ◽  
Refined Grid

This paper describes a comparative study of the treatment of two-dimensional nucleating flows of steam using two different time-marching numerical schemes. A treatment based on Denton's scheme but a refined grid has been available from earlier work. To compare with this a treatment based on the Runge-Kutta scheme has been developed, which is described. Solutions using this scheme and a simple mesh are compared with experimental results and with solutions using the earlier treatment. The agreement obtained between the two schemes and with the experimental results is satisfactory. Oscillating flows in a convergent-divergent nozzle are also examined and excellent agreement obtained with experimental measurements.

Experimental Investigation and Performance Evaluation of Isothermal Frictional Two Phase Pressure Drop Correlations in Vertical Downward Gas-Liquid Two Phase Flow

2012 ◽  
Author(s):  
Swanand M. Bhagwat ◽  
Mehmet Mollamahmutoglu ◽  
Afshin J. Ghajar
Keyword(s):  
Performance Evaluation ◽  
Pressure Drop ◽  
Void Fraction ◽  
Accurate Estimation ◽  
Correct Prediction ◽  
Experimental Measurements ◽  
Fluid Viscosity ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Phase Pressure

The correct prediction of gas-liquid two phase pressure drop is of immense significance for proper sizing of industrial equipment and safety operations involved in chemical, energy and petrochemical applications. The hydrostatic component of the two phase pressure drop is predicted based on the accurate estimation of void fraction. However, there exists a complexity in correct estimation of the frictional component of two phase pressure drop owing to interfacial friction at dynamic gas-liquid interface. The present study is focused on the experimental measurements of gas-liquid two phase frictional pressure drop and the performance evaluation of eleven correlations for its prediction in vertical downward orientation. The experimental determination of two phase frictional pressure drop is carried out for a 0.01252 m I.D. pipe with surface roughness of 0.0000152 m using air-water as the fluid combination. Unlike most of the other studies centered towards annular flow, this experimental study is spanned over different flow patterns and the entire range of the void fraction. In addition to the experimental measurements, the scope of this study also includes the performance analysis of eleven frictional pressure drop correlations available in the literature. These correlations are those based on the separated flow model initially proposed by Lockhart and Martinelli [1].The available frictional pressure drop correlations are compared against the data measured in the present study. Based on the experimental data available in the literature, the influence of the pipe diameter and fluid viscosity on the frictional pressure drop is also analyzed.

Sign in / Sign up

Export Citation Format

Share Document