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Reynolds Number Effects on the Near-Exit Region of Turbulent Jets |
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| Authors: | Arjun Tandalam Ram Balachandar Ronald Barron |
| Affiliation: | 1Graduate Student, Dept. of Mechanical, Automotive, and Materials Engineering, Univ. of Windsor, 401 Sunset Ave., Windsor, ON, Canada N9B 3P4. 2Professor, Dept. of Civil and Environmental Engineering, Univ. of Windsor, 401 Sunset Ave., Windsor, ON, Canada N9B 3P4 (corresponding author). E-mail: rambala@uwindsor.ca 3Professor, Dept. of Mathematics and Statistics, Univ. of Windsor, 401 Sunset Ave., Windsor, ON, Canada N9B 3P4. |
| Abstract: | In this paper, attention has been focused on the near-exit region of a round turbulent free jet to study the large-scale coherent structures and to document the signatures of the vortices over a range of Reynolds numbers. Particle image velocimeter measurements were conducted at three jet exit Reynolds numbers of 10,000, 30,000, and 55,000. The large-scale structures in the near field (X/D<12) were investigated by performing a proper orthogonal decomposition analysis of the velocity fields. A vortex identification algorithm was complemented by swirling strength maps to identify the vortex centers, rotational sense, size, and circulation of the vortices. The influence of the Reynolds number on the distribution of the number, size, and circulation of the identified vortices was studied. Proper orthogonal decomposition of the velocity fields revealed that Reynolds number has a strong influence on the mean circulation of vortices. The present results show that the axial location where vortices first appear and the number of vortices close to the nozzle exit (X/D<5) are dependent on the Reynolds number. |
| Keywords: | Jets, fluid Reynolds number Hydraulic structures |