Investigation of Streaming Flow Patterns in a Thermoacoustic Device Using PIV

2010 ◽  
Author(s):  
Hadi Babaei ◽  
Kamran Siddiqui
Keyword(s):  
Particle Image ◽  
Velocity Fields ◽  
Two Dimensional ◽  
Cold Side ◽  
Velocity Magnitude ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Streaming Velocity ◽  
The Difference ◽  
Streaming Flow

We report on an experimental study conducted to study the streaming velocity fields in the vicinity of the stack in a thermoacoustic device. Synchronized Particle Image Velocimetry (PIV) technique was used to measure the two-dimensional streaming velocity fields. The streaming velocity fields were measured at both sides of the porous stack over a range of pressure amplitudes (drive ratios). The results show that the streaming flow structure is significantly different on hot and cold sides of the stack. The hot side of the stack experienced higher magnitudes and higher spatial variability of the streaming velocities compared to the cold side. The difference in the velocity magnitude between the hot and cold sides of the stack showed a significant increase with an increase in the drive ratio.

Experimental Study of the Characteristics of Gas Impinging Streams Using PIV Technique

2013 ◽  
Author(s):  
Wei Wei ◽  
ZhiYi Li ◽  
Fengxia Liu ◽  
Zhijun Liu
Keyword(s):  
Mass Transfer ◽  
Experimental Study ◽  
Flow Field ◽  
Flow Rate ◽  
Particle Image ◽  
Velocity Fields ◽  
Experimental Equipment ◽  
Piv Technique ◽  
Tracer Particles ◽  
Image Velocimetry

Impinging streams technology has been widely used in many applications in recent years because of its enhancement to the heat and mass transfer between phases. In this paper, in order to investigate the influences of the impinging distance and flow rate on the characters of the flow field, gas-gas impinging streams flow fields are tested experimentally and analyze qualitatively with particle image velocimetry (PIV). The experimental equipment consists of two opposite nozzles which are the same axis. A PIV system is used to measure the characters of the 2-D flow field between two opposite nozzles. The gas is delivered by a compressor through two opposite jets which could be seeded with oil droplets as tracer particles. The effects of the flow rate and impinging distance on the velocity fields of impinging zone are investigated in detail. As the flow rate increases from 0.2 m3/h to 0.8 m3/h, the width of impinging zone increases from 0.25 to 0.5. However, the range of impinging zone does not change significantly as the impinging distance increases from 61mm to 94mm. The results indicate that the PIV technique is an effective method to measure and analyze the characters of impinging streams.

Fuel Composition Effects on the Velocity Field in a Lean Premixed Swirl-Stabilized Combustor

2003 ◽  
Author(s):  
Donald M. Wicksall ◽  
Ajay K. Agrawal ◽  
Robert W. Schefer ◽  
Jay O. Keller
Keyword(s):  
Velocity Field ◽  
Atmospheric Pressure ◽  
Particle Image ◽  
Velocity Fields ◽  
Fuel Composition ◽  
Composition Effects ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Lean Premixed ◽  
Recirculation Zones

Fuel composition effects on the flow-field of a lean premixed swirl-stabilized burner were studied. Methane (CH4) was enriched with hydrogen (H2) to vary the fuel composition. The burner inlet had 28-degree swirl vanes located in the annulus around a centerbody. Combustion occurred in an air-cooled quartz chamber at atmospheric pressure. The measurements were obtained, using the particle image velocimetry (PIV) technique, which allowed the 2-D velocity and vorticity fields to be examined for different fuels. The average velocity field was significantly altered, including the shape of the central and corner recirculation zones in the H2 enriched flames. The instantaneous velocity fields showed corresponding differences as well. The length scales and vorticity levels of the time-averaged velocity field differed from those for the instantaneous fields, indicating the importance of temporally resolved measurements.

PIV Analysis of Instantaneous Flow Structures in an Inkjet Printhead

1999 ◽  
Author(s):  
Hongsheng Zhang ◽  
Carl D. Meinhart
Keyword(s):  
Particle Image ◽  
Fluid Velocity ◽  
Ccd Camera ◽  
Velocity Fields ◽  
Flow Structures ◽  
Instantaneous Flow ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Piv Analysis ◽  
Inkjet Printhead

Abstract This paper presents experimental measurements and observations of instantaneous flow structures inside an inkjet printhead, using a micron-resolution Particle Image Velocimetry (PIV) system to record visualized flows and calculate velocity fields. The PIV technique uses 700 nm diameter fluorescent flow-tracing particles, a pulsed Nd:YAG laser, an epi-fluorescent microscope and an interline-transfer CCD camera to record images of a flow at two successive instances in time. By measuring how far a set of particles move during a specified duration of time, an estimate of the local fluid velocity can be obtained. An electronic timing strategy has been developed to synchronize the PIV lasers, the CCD camera and the drop ejection system. An overall flow pattern during a 500 μs ejection cycle has been observed by phase-averaging hundreds of instantaneous velocity fields, which were recorded at 2–5 μs intervals throughout the cycle. A velocity field with spatial resolution of approximately 10 μm was obtained near the inkjet nozzle. Meniscus and nodes inside the printhead were also observed and recorded.

Influence of Drag-Reducing Surfactant Additives on Vortex Structures and Turbulent Events in a Channel Flow

Volume 1 ◽  
2004 ◽  
Author(s):  
Feng-Chen Li ◽  
Yasuo Kawaguchi ◽  
Takehiko Segawa ◽  
Koichi Hishida
Keyword(s):  
Particle Image ◽  
Velocity Fields ◽  
Vortex Structures ◽  
Instantaneous Velocity ◽  
Two Dimensional ◽  
Instantaneous Velocity Field ◽  
Contour Maps ◽  
Image Velocimetry ◽  
Swirling Strength ◽  
Characteristic Angle

The characteristics of vortex structures and turbulent events of drag-reducing surfactant (CTAC) solution flows in a two-dimensional channel have been studied using particle image velocimetry (PIV) to measure the instantaneous velocity fields in a streamwise-wall-normal plane. Through visualizing the instantaneous velocity field, contour maps of the swirling strength and instantaneous value of uv, the characteristic angle of vortex packets was quantified, and it was shown that the drag-reducing CTAC additive reduced both the strength and frequency of turbulent bursts near the wall, and that the characteristics of vortex structures and bursts were not only dependent on drag-reduction level but also on concentration of additive. Based on the quantified parameters characterizing turbulent events in a wall-bounded turbulent flow, a model of turbulent contribution to the friction factor, fT, was proposed. It was obtained that fT was linearly proportional to the product of frequency and strength of turbulent events.

PIV Measurement of the Transient Fluid Flow due to the Adsorption of Particles

2014 ◽  
Author(s):  
Naga A. Musunuri ◽  
Pushpendra Singh ◽  
Ian S. Fischer
Keyword(s):  
Particle Size ◽  
Particle Image ◽  
Small Particles ◽  
Flow Strength ◽  
Piv Technique ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Line Passing ◽  
Particle Adsorption ◽  
Streaming Flow

The particle image velocimetry (PIV) technique is used to study the physics of particle adsorption and the spontaneous dispersion of powders that occurs when particles come in contact with a fluid-liquid interface. The dispersion can occur so quickly that it appears explosive, especially for small particles on the surface of mobile liquids like water. The measurements show that the adsorption of a spherical particle causes an axisymmetric streaming flow about the vertical line passing through the center of the particle. The fluid directly below the particle rises upward, and near the surface, it moves away from the particle. The flow, which develops within a fraction of second after the adsorption of the particle, persists for several seconds. The flow strength, and the volume over which it extends, decrease with decreasing particle size. The streaming flow induced by the adsorption of two or more particles is a combination of the flows which they induce individually.

PIV MEASUREMENTS AND NUMERICAL VALIDATION OF END-TO-SIDE ANASTOMOSIS

2010 ◽  
Vol 10 (01) ◽  
pp. 123-138 ◽  
Author(s):  
AMAL OWIDA ◽  
HUNG DO ◽  
WILLIAM YANG ◽  
YOS S. MORSI
Keyword(s):  
Particle Image ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Velocity Fields ◽  
Flow Conditions ◽  
Ansys Software ◽  
Piv Measurements ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Glass Model

In this article, particle image velocimetry (PIV) technique was used to determine the instantaneous velocity fields inside a model of end-to-side anastomosis under various physiological flow conditions. Using ANSYS software, a three-dimensional (3D) computational model at the peak systolic blood flow was simulated. The numerical and experimental results were presented and discussed in terms of velocity fields at various locations along the graft and the host artery. The numerical results were then compared with the experimental data and a large difference was found, which was attributed to the imperfection of manufacturing the glass model and measurements error associated with PIV. The findings indicated in general that the analysis at peak systole, steady flow could help in providing essential quantitative information of the hemodynamics in anastomotic artery.

scholarly journals Velocity Field around a Rigid Flapping Wing with a Winglet in Quiescent Water

2020 ◽  
Author(s):  
Srikanth Goli ◽  
Arnab Roy ◽  
Subhransu Roy
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Particle Image ◽  
Added Mass ◽  
Velocity Fields ◽  
Flapping Wing ◽  
Residual Flow ◽  
Two Dimensional ◽  
Image Velocimetry ◽  
Phase Angles

This study investigated the effect of a winglet on the velocity field around a rigid flapping wing. Two-dimensional particle image velocimetry was used to capture the velocity field of asymmetric one-degree-of-freedom flapping motion. A comparison was conducted between wings with and without a winglet at two flapping frequencies, namely 1.5 and 2.0 Hz. The effect of the winglet on the velocity field was determined by systematically comparing the velocity fields for several wing phase angles during the downstroke and upstroke. The presence of a winglet considerably affected the flow field around the wingtip, residual flow, and added mass interaction. The added mass was lower and residual flow was weaker for the wings with a winglet than for the wings without a winglet. The added mass and velocity magnitudes of the flow field increased proportionally with the flapping frequency.

scholarly journals Experimental Validation of Falling Liquid Film Models: Velocity Assumption and Velocity Field Comparison

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1205
Author(s):  
Ruiqi Wang ◽  
Riqiang Duan ◽  
Haijun Jia
Keyword(s):  
Experimental Data ◽  
Particle Image Velocimetry ◽  
Velocity Field ◽  
Experimental Validation ◽  
Particle Image ◽  
Velocity Fields ◽  
Number Range ◽  
Comparison Results ◽  
Image Velocimetry ◽  
Experimental Particle

This publication focuses on the experimental validation of film models by comparing constructed and experimental velocity fields based on model and elementary experimental data. The film experiment covers Kapitza numbers Ka = 278.8 and Ka = 4538.6, a Reynolds number range of 1.6–52, and disturbance frequencies of 0, 2, 5, and 7 Hz. Compared to previous publications, the applied methodology has boundary identification procedures that are more refined and provide additional adaptive particle image velocimetry (PIV) method access to synthetic particle images. The experimental method was validated with a comparison with experimental particle image velocimetry and planar laser induced fluorescence (PIV/PLIF) results, Nusselt’s theoretical prediction, and experimental particle tracking velocimetry (PTV) results of flat steady cases, and a good continuity equation reproduction of transient cases proves the method’s fidelity. The velocity fields are reconstructed based on different film flow model velocity profile assumptions such as experimental film thickness, flow rates, and their derivatives, providing a validation method of film model by comparison between reconstructed velocity experimental data and experimental velocity data. The comparison results show that the first-order weighted residual model (WRM) and regularized model (RM) are very similar, although they may fail to predict the velocity field in rapidly changing zones such as the front of the main hump and the first capillary wave troughs.

Analysis of local velocity gradients in rapid mixer using particle image velocimetry technique

2002 ◽  
Vol 2 (5-6) ◽  
pp. 47-55
Author(s):  
N.-S. Park ◽  
H. Park
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Velocity Fields ◽  
Local Velocity ◽  
Mixing Condition ◽  
Particle Image Velocimetry Technique ◽  
Velocity Gradients ◽  
Image Velocimetry ◽  
Current Design ◽  
G Value

Recognizing the significance of factual velocity fields in a rapid mixer, this study focuses on analyzing local velocity gradients in various mixer geometries with particle image velocimetry (PIV) and comparing the results of the analysis with the conventional G-value, for reviewing the roles of G-value in the current design and operation practices. The results of this study clearly show that many arguments and doubts are possible about the scientific correctness of G-value, and its current use. This is because the G-value attempts to represent the turbulent and complicated factual velocity field in a jar. Also, the results suggest that it is still a good index for representing some aspects of mixing condition, at least, mixing intensity. However, it cannot represent the distribution of velocity gradients in a jar, which is an important factor for mixing. This study as a result suggests developing another index for representing the distribution to be used with the G-value.

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