Analysis of Two-Phase Air/Water Bubbly Flow Experiment

2002 ◽  
Author(s):  
Donald R. Todd ◽  
Yassin A. Hassan ◽  
Javier Ortiz-Villafuerte
Keyword(s):  
Particle Image ◽  
Bubbly Flow ◽  
Continuous Phase ◽  
Three Dimensions ◽  
Dispersed Phase ◽  
Two Dimensional ◽  
Two Phase ◽  
Image Velocimetry ◽  
Flow Experiment ◽  
Shadow Image Velocimetry

Two different techniques, the Particle Image Velocimetry (PIV) and the Shadow-Image Velocimetry (SIV) techniques have been used to capture detailed two-phase bubbly flow experimental data. The PIV has provided a two-dimensional velocity field of the liquid phase for analysis of the continuous phase. The SIV has utilized to reconstruct the bubble shape and velocity of the dispersed phase in three-dimensions.

Abstract 14952: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV)

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Ahmad Falahatpisheh ◽  
Arash Kheradvar
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Contrast Echocardiography ◽  
Ultrasound Contrast Agent ◽  
Three Dimensions ◽  
Small Scale ◽  
High Temporal Resolution ◽  
Two Dimensional ◽  
Particle Image Velocimetry Technique ◽  
Image Velocimetry

Introduction: The two-dimensional (2D) echocardiographic particle image velocimetry technique that was introduced in 2010 received much attention in clinical cardiology. Cardiac flow visualization based on contrast echocardiography results in images with high temporal resolution that are obtainable at relatively low cost. This makes it an ideal diagnostic and follow-up tool for routine clinical use. However, cardiac flow in a cardiac cycle is multidirectional with a tendency to spin in three dimensions rather than two-dimensional curl. Here, for the first time, we introduce a volumetric echocardiographic particle image velocimetry technique that robustly acquires the flow in three spatial dimensions and in time: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV). Methods: V-Echo-PIV technique utilizes matrix array 3D ultrasound probes to capture the flow seeded with an ultrasound contrast agent (Definity). For this feasibility study, we used a pulse duplicator with a silicone ventricular sac along with bioprosthetic heart valves at the inlet and outlet. GE Vivid E9 system with an Active Matrix 4D Volume Phased Array probe at 30 Hz was used to capture the flow data (Figure 1). Results: The 3D particle field was obtained with excellent spatial resolution without significant noise (Figure 1). 3D velocity field was successfully captured for multiple cardiac cycles. Flow features are shown in Figure 2 where the velocity vectors in two selected slices and some streamlines in 3D space are depicted. Conclusions: We report successful completion of the feasibility studies for volumetric echocardiographic PIV in an LV phantom. The small-scale features of flow in the LV phantom were revealed by this technique. Validation and human studies are currently in progress.

Three-Dimensional Bubble Reconstruction in a Pipe Flow Using Shadow Technique

2002 ◽  
Author(s):  
Javier Ortiz-Villafuerte ◽  
Yassin A. Hassan ◽  
Toru Furukawa
Keyword(s):  
Pipe Flow ◽  
Particle Image ◽  
Three Dimensional ◽  
Bubbly Flows ◽  
Three Dimensional Reconstruction ◽  
Two Phase ◽  
Generalized Hough Transform ◽  
Image Velocimetry ◽  
Dimensional Reconstruction ◽  
Shadow Image Velocimetry

Two different three-dimensional reconstruction techniques for the shape of gas bubbles flowing in a liquid are presented. The first technique is based on the Dynamic Generalized Hough Transform Algorithm, and the second on the Metaball Model. These techniques are suitable for analysis of turbulent two-phase bubbly flows. Both techniques require at least two views of the bubble intended for three-dimensional reconstruction, and can be used in either stereoscopic or orthogonal camera setups. Once the reconstruction is accomplished, the bubble images can be accurately removed from the images acquired during Particle Image Velocimtery or Shadow Image Velocimetry measurements. After removing the bubble images from PIV images, a typical analysis of the liquid phase can be performed. This improves the accuracy of the statistical analysis of the parameters of each phase.

Determination of Flow Structure in a Tube Array by Particle Image Velocimetry

2011 ◽  
Author(s):  
Njuki Mureithi ◽  
Claude Masabarakiza
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Structure ◽  
Particle Image ◽  
Flow Behavior ◽  
Bubbly Flow ◽  
Large Area ◽  
Two Phase ◽  
Piv Measurements ◽  
Void Fractions ◽  
Image Velocimetry

Particle Image Velocimetry (PIV) presents a possible approach to measuring two-phase flow parameters over a large area, leading to a snap shot of flow behavior in complex geometries such as tube bundles. Tests have been conducted in a 2m long wavy wall channel simulating the open lane within a rotated triangular array. The results show that liquid phase PIV measurements must be limited to very low void fractions. On the other hand, much information can be gained from the gas phase data. The details of the flow structure within the array are revealed. Current measurements, performed in the bubbly flow regime, show that even in this regime, the flow structure is significantly non-uniform and complex. Bubble diameters have been found to be strongly dependent on flow velocity; the effect of turbulence shear at high flow rates breaking up the bubbles to smaller sizes. The PIV measurements yield the complete averaged velocity vector field in the measurement region. The velocity profiles across the measurement section are also obtained. The non-uniform profiles show the challenges associated with attempts to estimate average void fractions and slip ratios in the array.

A Comparison Between Round Turbulent Jets and Particle-Laden Jets in Crossflow by Using Time-Resolved Stereoscopic Particle Image Velocimetry

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
F. J. Diez ◽  
M. M. Torregrosa ◽  
S. Pothos
Keyword(s):  
Particle Image Velocimetry ◽  
High Intensity ◽  
Particle Image ◽  
Three Dimensional ◽  
Continuous Phase ◽  
Stereoscopic Particle Image Velocimetry ◽  
Dispersed Phase ◽  
Time Resolved ◽  
Image Velocimetry ◽  
Phase Images

Time-resolved stereoscopic particle image velocimetry (TR-ST-PIV) measurements were performed to compare the velocity and vorticity field, and the three-dimensional high intensity vorticity structures between a round turbulent single-phase jet and a particle-laden jet in crossflow. The experiments involved steady fresh water jet sources with a particle mass loading of ∼2.0% injected into steady fresh water crossflows. The TR-ST-PIV system was combined with a phase discrimination method that separates two-phase stereo PIV images into dispersed phase images and continuous phase images that are analyzed by using particle tracking velocimetry and stereo-PIV algorithms, respectively. The analysis shows the importance of phase separation for accurate velocity results. It provides instantaneous velocity fields where the dispersed phase preferentially concentrated in regions of low vorticity with the velocity not matching the continuous phase. The jet and the particle-laden jets trajectories are compared to each other and with results in the literature. Similarly, a comparison of mean velocity and vorticity fields between both flows suggest enhanced mixing in the particle-laden jet due to the effects of the dispersed phased which lowered the centerline velocities and enhanced the penetration in the cross-stream direction of the continuous phase. The Taylor’s frozen flow hypothesis is applied to reconstruct the 3D high intensity vorticity structures in a volume. The visualization of the three-dimensional structures corresponding to the intermediate scales of the flow shows slightly elongated structures preferentially aligned with the jet centerline axis.

Phase Inversion in Two-Phase Liquid Systems

1992 ◽  
Vol 57 (7) ◽  
pp. 1419-1423
Author(s):  
Jindřich Weiss
Keyword(s):  
Interfacial Tension ◽  
Phase Inversion ◽  
Continuous Phase ◽  
Considerable Effect ◽  
Weak Dependence ◽  
Dispersed Phase ◽  
Two Phase ◽  
Liquid Systems ◽  
Phase Liquid

New data on critical holdups of dispersed phase were measured at which the phase inversion took place. The systems studied differed in the ratio of phase viscosities and interfacial tension. A weak dependence was found of critical holdups on the impeller revolutions and on the material contactor; on the contrary, a considerable effect of viscosity was found out as far as the viscosity of continuous phase exceeded that of dispersed phase.

Formation of Two-Phase Multiple Emulsions by Inclusion of Continuous Phase into Dispersed Phase

Langmuir ◽  
2002 ◽  
Vol 18 (20) ◽  
pp. 7334-7340 ◽  
Author(s):  
Jong-Moon Lee ◽  
Kyung-Hee Lim ◽  
Duane H. Smith
Keyword(s):  
Continuous Phase ◽  
Dispersed Phase ◽  
Two Phase ◽  
Multiple Emulsions

PIV Measurements Within the Waves of Wavy and Wavy-Annular Horizontal Two-Phase Flow

2005 ◽  
Author(s):  
R. E. Foster ◽  
T. A. Shedd
Keyword(s):  
Particle Image ◽  
Image Processing Algorithm ◽  
Two Phase ◽  
Piv Measurements ◽  
Post Process ◽  
Image Velocimetry ◽  
Processed Form ◽  
Image Pairs ◽  
Particle Images ◽  
The Waves

A novel technique of microscopic Particle Image Velocimetry (PIV) is presented for two-phase annular, wavy-annular and stratified flow. Seeding of opaque particles in a water/dye flow allows the acquisition of instantaneous film velocity data in the film cross-section at the center of the tube in the form of digital image pairs. An image processing algorithm is also described that allows numerical velocities to be distilled from particle images by commercial PIV software. The approach yields promising results for stratified and wavy-annular flows, however highly bubbly flows remain difficult to image and post-process. Initial data images are presented in raw and processed form.

Flow analysis of two-dimensional pulsed jets by particle image velocimetry

2001 ◽  
Vol 31 (5) ◽  
pp. 519-532 ◽  
Author(s):  
J. C. Béra ◽  
M. Michard ◽  
N. Grosjean ◽  
G. Comte-Bellot
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Flow Analysis ◽  
Two Dimensional ◽  
Pulsed Jets ◽  
Image Velocimetry
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