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Helical Modes in Low- and High-Swirl Jets Measured by Tomographic Piv

Helical Modes in Low- and High-Swirl Jets Measured by Tomographic Piv, Dmitriy M. Markovich, Vladimir M. Dulin, Sergey S. Abdurakipov, Leonid A. Kozinkin, Mikhail P. Tokarev, and Kemal Hanjalic. Journal of Turbulence 2016, 17  (7), 678–698.

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Abstract

We report on a parallel study on properties of large-scale vortical structures in low-and high-swirl turbulent jets by means of the time-resolved tomographic particle image velocimetry technique. The high-swirl jet flow is featured by a well-established bubble-type vortex breakdown with a central recirculation zone. In the low-swirl flow, the mean axial velocity, while intermittently acquiring negative values, remains positive in the mean but with a local velocity defect immediately downstream from the nozzle exit, followed by a spiralling vortex core system and its eventual breakdown. Measurements of the 3D velocity fields allowed direct analysis of the azimuthal/helical modes via Fourier transform over the azimuthal angle and proper orthogonal decomposition ( POD) analysis in the Fourier space. A precessing vortex core is detected for both swirl cases, whereas the POD analysis showed that the one originating in the bubble-type vortex breakdown is much more energetic and easier to detect.

BibTeX

@article{ ISI:000380171000004,
Author = {Markovich, Dmitriy M. and Dulin, Vladimir M. and Abdurakipov, Sergey S. and Kozinkin, Leonid A. and Tokarev, Mikhail P. and Hanjalic, Kemal},
Title = {Helical Modes in Low- and High-Swirl Jets Measured by Tomographic Piv},
Journal = {Journal of Turbulence},
Year = {2016},
Volume = {17},
Number = {7},
Pages = {678-698},
Abstract = {We report on a parallel study on properties of large-scale vortical structures in low-and high-swirl turbulent jets by means of the time-resolved tomographic particle image velocimetry technique. The high-swirl jet flow is featured by a well-established bubble-type vortex breakdown with a central recirculation zone. In the low-swirl flow, the mean axial velocity, while intermittently acquiring negative values, remains positive in the mean but with a local velocity defect immediately downstream from the nozzle exit, followed by a spiralling vortex core system and its eventual breakdown. Measurements of the 3D velocity fields allowed direct analysis of the azimuthal/helical modes via Fourier transform over the azimuthal angle and proper orthogonal decomposition ( POD) analysis in the Fourier space. A precessing vortex core is detected for both swirl cases, whereas the POD analysis showed that the one originating in the bubble-type vortex breakdown is much more energetic and easier to detect.},
DOI = {10.1080/14685248.2016.1173697},
ISSN = {1468-5248},
Unique-ID = {ISI:000380171000004},
}

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