A three-dimensional particle tracking velocimetry (3D-PTV) system based on a high-speed camera with a four-view splitter is described here. The technique is applied to a jet flow from a circular pipe in the vicinity of ten diameters downstream at Reynolds number Re ≈ 7,000.
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Method Article
Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow
In This Article
Summary
Abstract
3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic recording of image sequences. The basic components, features, constraints and optimization tips of a 3D-PTV topology consisting of a high-speed camera with a four-view splitter are described and discussed in this article. The technique is applied to the intermediate flow field (5 <x/d <25) of a circular jet at Re ≈ 7,000. Lagrangian flow features and turbulence quantities in an Eulerian frame are estimated around ten diameters downstream of the jet origin and at various radial distances from the jet core. Lagrangian properties include trajectory, velocity and acceleration of selected particles as well as curvature of the flow path, which are obtained from the Frenet-Serret equation. Estimation of the 3D velocity and turbulence fields around the jet core axis at a cross-plane located at ten diameters downstream of the jet is compared with literature, and the power spectrum of the large-scale streamwise velocity motions is obtained at various radial distances from the jet core.
Introduction
Turbulent jet flows are ubiquitous in engineering applications. Detailed characterization of such flows is crucial in a wide spectrum of practical problems spanning from large-scale environmental discharge systems to electronic micro-scale devices. Because of its impact on a number of broad applications, jet flows have been studied in depth1-4. Several experimental techniques, including hotwire anemometry4-8, Laser Doppler Velocimetry (LDV)4,9-12, and Particle Image Velocimetry (PIV)12-16, have been used to character....
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Protocol
1. Lab Safety
- Review the safety guidelines of the selected illumination source (e.g. laser, industrial LED, halogen).
Note: in this experiment, a set of five 250 Watts halogen spotlights are used as illumination. Basic safety and recommendation aspects for this light source are described as follows.- Avoid direct contact with halogen lights, which operate at high temperatures (~3,000 K color temperature).
- Keep the light ON only when acquiring data to avoid heating the flow under consideration.
- Keep away all burnable materials near the light source, including paper of any kind.
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Results
A photograph and a schematic of the setup are shown in Figures 1 and 2. The calibration target, the fiducial marks reflected on the view-splitter and 3D calibration reconstruction are illustrated in Figure 3. The RMS of the recognized calibration targets is 7.3 µm, 5.7 µm and 141.7 µm in the streamwise x, spanwise y, and depth z directions. The relative higher RMS in the z-coordinate is due to th.......
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Discussion
3D-PTV has great potential to unravel the complex physics of a variety of turbulent flows such as large-scale turbulent motions in the lower atmosphere25, indoor air distribution26, or pulsatile flows in aortic topology28 among many others. However, an understanding of its advantages and limitations as well as experience is essential to maximize its potential. Trial and error preliminary testing and exhaustive iterations for optimum settings, including frame rate, illumination source, G&#.......
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Disclosures
The authors declare that they have no competing financial interest.
Acknowledgements
This work was supported by the Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, as part of the start-up package of Leonardo P. Chamorro.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Mikrotron 4CXP 4 lanes CXP-6 CoaXPress | ImageOps | CAMMC4082 | High-speed camera |
| Active Silicon FireBird CoaX Frame Grabber | ImageOps | FBD-4XCXP6 | Frame Grabber |
| 100 μm silver-coated hollow ceramic spheres | Potters Industries LLC | AG-SL150-30-TRD | Seeding Paritcles |
| StreamPix6 | Upstate Technical Equipment CO.,INC | MISNOR-STP-6-S-CL | Camera appliation |
| Four-view splitter | Photrack AG | Customized part and necessary if performing 3D-PTV with one camera | |
| 250 Watts Spotlight Halogen | General Electrics | 23719 | Light source |
| OpenPTV (Software) | OpenPTV (http://www.openptv.net) | Open source particle tracking software (Note: available as a service for anyone who wants to use it without all the installation mess or computer power availability problems). |
References
- Wygnanski, I., Fiedler, H. Some measurements in the self preserving jet. , Cambridge university press. (1968).
- Rajaratnam, N. Turbulent jets. , Elsevier. (1976).
- Panchapakesan, N., Lumley, J.
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