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Proceedings Paper

ESPI of a transient shock wave flow using an ultrafast digital camera
Author(s): Roland Andrag; Filipe Jose Barbosa; Beric W. Skews
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Paper Abstract

The application of electronic speckle pattern interferometry (ESPI) to the visualization of a typical high-speed compressible flow is investigated. ESPI is an interferometric technique that has established itself as a reliable alternative to holographic interferometry in the measurement of small displacements and of vibrations, and is increasingly being used in flow visualization. It can instantly and in real time produce interferometric images in digital form on a video screen, with no photographic processing being required. In this paper two flows are examined, the one a low speed flow of a thermal plume arising from a hot soldering iron, for which real-time visualization is achievable; and the other single frame imaging of a shockwave emerging from a small round open- ended shock tube. ESPI is shown to be a valuable tool in the visualization of compressible flows, and a good alternative to holographic interferometry in obtaining quantitative density data about a flow field. A method for obtaining interferograms with finite fringe-width is presented. The main benefit of using ESPI for flow visualization is that the interferometric image is immediately accessible for viewing on a monitor, so avoiding the tedious photographic holographic reconstruction process. Advances in camera technology are fast overcoming its disadvantage, low image resolution.

Paper Details

Date Published: 17 April 2001
PDF: 9 pages
Proc. SPIE 4183, 24th International Congress on High-Speed Photography and Photonics, (17 April 2001); doi: 10.1117/12.424330
Show Author Affiliations
Roland Andrag, Univ. of the Witwatersrand (South Africa)
Filipe Jose Barbosa, Univ. of the Witwatersrand (South Africa)
Beric W. Skews, Univ. of the Witwatersrand (South Africa)

Published in SPIE Proceedings Vol. 4183:
24th International Congress on High-Speed Photography and Photonics
Kazuyoshi Takayama; Tsutomo Saito; Harald Kleine; Eugene V. Timofeev, Editor(s)

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