The near field of coaxial air jets, with swirl in the outer one, was investigated experimentally. Axial and azimuthal velocities were mapped using hot-wire anemometry, and static pressure measurements were obtained using a pitot tube. The flow was visualized using a double-pass schlieren system. The flow is sensitive to both the amount of swirl, characterized by the swirl number S, and the mass flow ratio between the outer and inner jets, mr. A necessary condition for recirculation to occur was that S > 0.58 and mr > 8.5. The magnitude of a pressure deficit in the centerline strongly depends on mr, while the existence of swirl appears to have a triggering effect on setting up this pressure gradient. Spectral analysis shows distinct characteristics dependent on the occurrence of recirculation. Because these features were observed upstream of the recirculation region, the vortex breakdown in this experiment may be related to flow instabilities.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/291734 |
| Date | January 1993 |
| Creators | Ben-Yeoshua, Moshe, 1957- |
| Contributors | Champagne, F. H. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Thesis-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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