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, Kemal Hanjalić

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)678-698
Number of pages21
JournalJournal of Turbulence
Volume17
Issue number7
DOIs
Publication statusPublished - 2 Jul 2016

Keywords

  • experimental techniques
  • low-dimensional models
  • rotating turbulence
  • Vortex dynamics

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