Enhancing the Learning of Two-Phase Flow Measurement Techniques in a Modern Mechanical Engineering Program

2009 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Arman Molki ◽  
Peter Rodgers ◽  
Shrinivas Bojanampati
Keyword(s):  
Mechanical Engineering ◽  
Two Phase Flow ◽  
Teaching Strategy ◽  
Low Cost ◽  
Measurement Techniques ◽  
Test Facility ◽  
Experimental Setup ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Column

This paper outlines a proposed low-cost experimental setup for the measurement of two-phase liquid-gas flows in a vertical column. The objective of the test facility is to familiarize students with the challenges in applying measurement techniques to characterize such flows. The test facility incorporates two complementary intrusive and non-intrusive measurement techniques for detecting and studying the dynamics of air bubbles transported in water. The intrusive measurement method uses conductivity probes, while the non-intrusive technique is laser based. For both measurement techniques, details of the data acquisition system and the characteristics of sensors employed are presented. In addition, the teaching strategy is discussed for implementing the use of the proposed two-phase flow experimental setup in a Mechanical Engineering curriculum.

scholarly journals Clustering-Based Component Fraction Estimation in Solid–Liquid Two-Phase Flow in Dredging Engineering

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5697
Author(s):  
Chang Sun ◽  
Shihong Yue ◽  
Qi Li ◽  
Huaxiang Wang
Keyword(s):  
Clustering Algorithm ◽  
Two Phase Flow ◽  
Low Cost ◽  
Fast Response ◽  
New Method ◽  
Phase Flow ◽  
Reference Distribution ◽  
Two Phase ◽  
Long Time ◽  
Solid Liquid

Component fraction (CF) is one of the most important parameters in multiple-phase flow. Due to the complexity of the solid–liquid two-phase flow, the CF estimation remains unsolved both in scientific research and industrial application for a long time. Electrical resistance tomography (ERT) is an advanced type of conductivity detection technique due to its low-cost, fast-response, non-invasive, and non-radiation characteristics. However, when the existing ERT method is used to measure the CF value in solid–liquid two-phase flow in dredging engineering, there are at least three problems: (1) the dependence of reference distribution whose CF value is zero; (2) the size of the detected objects may be too small to be found by ERT; and (3) there is no efficient way to estimate the effect of artifacts in ERT. In this paper, we proposed a method based on the clustering technique, where a fast-fuzzy clustering algorithm is used to partition the ERT image to three clusters that respond to liquid, solid phases, and their mixtures and artifacts, respectively. The clustering algorithm does not need any reference distribution in the CF estimation. In the case of small solid objects or artifacts, the CF value remains effectively computed by prior information. To validate the new method, a group of typical CF estimations in dredging engineering were implemented. Results show that the new method can effectively overcome the limitations of the existing method, and can provide a practical and more accurate way for CF estimation.

Imaging and Resistivity Studies of Saturation Gradients in Two-Phase Flow in 3-D Porous Media

1996 ◽  
Vol 464 ◽  
Author(s):  
E. H. Kawamoto ◽  
Po-Zen Wong
Keyword(s):  
Computed Tomography ◽  
Porous Media ◽  
Two Phase Flow ◽  
Water Saturation ◽  
Glass Beads ◽  
Water Phase ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Column ◽  
X Ray

ABSTRACTWe have carried out x-ray radiography and computed tomography (CT) to study two-phase flow in 3-D porous media. Air-brine displacement was imaged for drainage and imbibition experiments in a vertical column of glass beads. By correlating water saturation Sw with resistance R, we find that there is a threshold saturation S* ≈ 0.2, above which R(SW) ∼ Sw−2, in agreement with the empirical Archie relation. This holds true for both drainage and imbibition with littlehysteresis, provided that Sw remains above S*. Should Sw drop below S* during drainage, R(Sw) rises above the Archie prediction, exhibiting strong hysteresis upon reimbibition. This behavior suggests a transition in the connectivity of the water phase near S*, possibly due to percolation effects.

An Experimental Study on Liquid Film Dynamics and Interfacial Wave of Air-Water Two-Phase Flow in a Horizontal Channel

2013 ◽  
Author(s):  
Youjia Zhang ◽  
Weimin Ma ◽  
Shengjie Gong
Keyword(s):  
Liquid Film ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Research Work ◽  
Water Film ◽  
Test Facility ◽  
Phase Flow ◽  
Interfacial Wave ◽  
Film Rupture ◽  
Two Phase

This study is concerned with liquid film dynamics and stability of annular flow, which plays an important role in understanding film rupture and dryout in boiling heat transfer. The research work starts from designing and making a test facility which enables the visualization and measurement of liquid film dynamics. A confocal optical sensor is applied to track the evolution of film thickness. A horizontal rectangular channel made of glass is used as the test section. Deionized water and air are supplied into that channel in such a way that an initial stratified flow forms, with the liquid film on the bottom wall. The present study is focused on characterization of liquid film profile and dynamics in term of interfacial wave and shear force induced film rupture under adiabatic condition. Based on the experimental data and analysis, it is found that given a constant water flowrate, the average thickness of water film decreases with increasing air flowrate, while the interfacial wave of the two-phase flow is intensified. As the air flowrate reaches a critical value, a localized rupture of the water film occurs.

scholarly journals Overview of Void Fraction Measurement Techniques, Databases and Correlations for Two-Phase Flow in Small Diameter Channels

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 216
Author(s):  
Álvaro Roberto Gardenghi ◽  
Erivelto dos Santos Filho ◽  
Daniel Gregório Chagas ◽  
Guilherme Scagnolatto ◽  
Rodrigo Monteiro Oliveira ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Measurement Techniques ◽  
Small Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Channel Diameter ◽  
Experimental Database ◽  
Absolute Relative Error ◽  
Fraction Measurement

Void fraction is one of the most important parameters for the modeling and characterization of two-phase flows. This manuscript presents an overview of void fraction measurement techniques, experimental databases and correlations, in the context of microchannel two-phase flow applications. Void fraction measurement techniques were reviewed and the most suitable techniques for microscale measurements were identified along its main characteristics. An updated void fraction experimental database for small channel diameter was obtained including micro and macrochannel two-phase flow data points. These data have channel diameter ranging from 0.5 to 13.84 mm, horizontal and vertical directions, and fluids such as air-water, R410a, R404a, R134a, R290, R12 and R22 for both diabatic and adiabatic conditions. New published void fraction correlations as well high cited ones were evaluated and compared to this small-diameter void fraction database in order to quantify the prediction error of them. Moreover, a new drift flux correlation for microchannels was also developed, showing that further improvement of available correlations is still possible. The new correlation was able to predict the microchannel database with mean absolute relative error of 9.8%, for 6% of relative improvement compared to the second-best ranked correlation for small diameter channels.

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.

Void Fraction Measurements for Air-Water Pipe Flows Using Quick-Closing Valves and Wire-Mesh Sensors

2018 ◽  
Author(s):  
Étienne Lessard ◽  
Jun Yang
Keyword(s):  
Void Fraction ◽  
Test Section ◽  
Two Phase Flow ◽  
Measurement Techniques ◽  
Wire Mesh ◽  
Axial Distance ◽  
Phase Flow ◽  
Flow Conditions ◽  
Flow Loop ◽  
Two Phase

In support of a header/feeder phenomena study, an adiabatic, near-atmospheric, air-water flow loop was commissioned simulating a single feeder of a Pressurized Heavy Water Reactor’s primary heat transport system under a postulated Loss of Coolant Accident scenario. An extensive database in representative two-phase flow conditions was collected, 750 tests in total, in order to create a two-phase flow map to be used in the more complex geometries such as header/feeder systems. The flow loop consists of two vertical test sections, for upwards and downwards flow, and one horizontal test section, each with an inner diameter of 32 mm and at least 120 diameters in length. Superficial velocities extended up to 6 m/s for the water and 10 m/s for the air. Void fraction was measured by means of quick-closing valves and a pair of wire-mesh sensors (WMS) in each test section. Two-phase repeatability tests showed that the liquid and gas superficial velocities varied by 1.1% and 0.6% at reference conditions of 2.0 and 2.8 m/s, respectively. The corresponding void fraction measurements varied for the quick-closing valves by at most 6.8%, which indicates a low sensitivity to the closure time of the valves and an appropriate axial distance between them, and 2.3% for the WMS. For both measurement techniques, the largest variations occurred in the vertical downwards test section. For the formal two-phase tests, over 600 distinct flow conditions were performed. The results showed that the two measurement techniques agreed within 5% at high void fractions and low liquid flow rates in vertical flow. For all other cases corresponding to the transitional or dispersed bubbly flow regime, the WMS over-estimated the void fraction by a consistent bias. An empirical correction is proposed, with a root-mean-square error of 6.6% across all tests. The void fraction map resulting from this database provides validation for the WMS measurements, a quantitative assessment of its uncertainty and range of applicability, and will be used as a reference in future tests under similar scale and flow conditions.

Modeling of Low and High Void Fraction Two-Phase Flow in a Vertical Pipe by Using the Two-Fluid Model

2018 ◽  
Author(s):  
Shimo Yu ◽  
Xiao Yan ◽  
Junyi Zhang
Keyword(s):  
Void Fraction ◽  
Radial Distribution ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Turbulent Dispersion ◽  
Test Facility ◽  
Phase Flow ◽  
Two Phase ◽  
Two Fluid Model ◽  
Two Fluid

Two-phase flow is an important and common phenomenon in nuclear reactor systems, and the characteristics of two-phase flow such as heat transfer and pressure drop strongly depend on the radial distribution of void fraction. This paper is presenting the CFD simulation for void fraction radial distribution of mono- and poly-disperse air-water two phase flow using Euler-Euler two-fluid model. Interfacial forces including transverse forces such as lift, wall and turbulent dispersion forces are taken into account, Furthermore the bubble size distribution and bubble break-up and coalescence processes are taken into account in case of a poly-disperse flow by using the S-Gamma model. The sauter mean diameter and interfacial area concentration (IAC) distribution can also be obtained. The simulation results are compared to an experimental database of MT-LOOP test facility (FZD, Germany)[1].

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