Particle Plume Velocities Extracted From High-Speed Thermograms Through Particle Image Velocimetry

Abstract Particle Image Velocimetry (PIV) measurements are commonly used to determine velocity fields from a flow, given that sufficient tracers can be added and tracked to determine their motion. While these types of measurements are typically completed using high-speed cameras to capture the trajectories of the tracer particles, the experiments performed at the University of New Mexico generated extensive time-resolved infrared temperature image (i.e. thermogram) sets of a free-falling particle curtain captured at 300 Hz. The camera used for such measurements was an ImageIR8300 high-speed IR camera which provides a resolution of 640 × 512. The thermogram sets acquired have been extensively analyzed with two commonly used commercial PIV analysis packages, DaVis and PIVlab. The comparison between the two software packages showed consistent velocity fields and contours, along with corresponding average velocity as functions of discharge position. As expected, the vertical velocity component of these gravity-driven curtains follows a trend that resembles a free-falling sphere rather than a falling sphere experiencing drag. The study also found that the discharge velocity showed negligible effects due to the inlet particle temperature of the curtain. These results will be applied to the development of a methodology to estimate the mass flow rate of particle curtain and plumes using a novel non-intrusive image correlation methodology.

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Unsteady Velocity Field Measurements of Outlet Flow in an Automotive Supercharger

Fluids Engineering ◽

10.1115/imece2006-14893 ◽

2006 ◽

Author(s):

Pranay Mahendra ◽

Michael G. Olsen

Keyword(s):

Particle Image Velocimetry ◽

Automotive Industry ◽

High Speed ◽

Particle Image ◽

Flow Characteristics ◽

Field Measurements ◽

Velocity Fields ◽

Positive Displacement ◽

Image Velocimetry ◽

Outlet Flow

Recently the automotive industry has been using superchargers to boost the power generated by the engine, but the noise generated by these superchargers is of great concern. The noise generated during the working of the supercharger is primarily a fluid mechanics phenomenon. Particle Image Velocimetry (PIV) was used to study air flow characteristics of a positive displacement supercharger with an emphasis on gaining insights into strategies for noise reduction. PIV was used to measure the instantaneous and ensemble-averaged velocity fields of the flow at the outlet of the supercharger as a function of blade position, allowing for visualization of the flow as it leave the blades. The preliminary results show that the flow exits the supercharger as a high speed jet at the end closer to the pulley end, and the flow varies with the change in blade position.

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

Polymers ◽

10.3390/polym13081205 ◽

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.

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

Water Science & Technology Water Supply ◽

10.2166/ws.2002.0149 ◽

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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Aerodynamics of manoeuvring flight in brown long-eared bats ( Plecotus auritus )

Journal of The Royal Society Interface ◽

10.1098/rsif.2018.0441 ◽

2018 ◽

Vol 15 (148) ◽

pp. 20180441 ◽

Cited By ~ 3

Author(s):

Per Henningsson ◽

Lasse Jakobsen ◽

Anders Hedenström

Keyword(s):

Particle Image Velocimetry ◽

Wind Tunnel ◽

High Speed ◽

Particle Image ◽

Future Studies ◽

Image Velocimetry ◽

Mechanistic Basis

In this study, we explicitly examine the aerodynamics of manoeuvring flight in animals. We studied brown long-eared bats flying in a wind tunnel while performing basic sideways manoeuvres. We used particle image velocimetry in combination with high-speed filming to link aerodynamics and kinematics to understand the mechanistic basis of manoeuvres. We predicted that the bats would primarily use the downstroke to generate the asymmetries for the manoeuvre since it has been shown previously that the majority of forces are generated during this phase of the wingbeat. We found instead that the bats more often used the upstroke than they used the downstroke for this. We also found that the bats used both drag/thrust-based and lift-based asymmetries to perform the manoeuvre and that they even frequently switch between these within the course of a manoeuvre. We conclude that the bats used three main modes: lift asymmetries during downstroke, thrust/drag asymmetries during downstroke and thrust/drag asymmetries during upstroke. For future studies, we hypothesize that lift asymmetries are used for fast turns and thrust/drag for slow turns and that the choice between up- and downstroke depends on the timing of when the bat needs to generate asymmetries.

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