Flow visualization of interactions among large coherent structures in an axisymmetric jet

C. O. Paschereit, D. Oster, T. A. Long, H. E. Fiedler, I. Wygnanski

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Interactions between large coherent structures are visualized with both schlieren photography in two air jets and dye photography in a water jet. The density difference needed for the schlieren technique is provided by an electrically heated wire ring surrounding the jet. External forcing with either single axisymmetric, single non-symmetric, combined axisymmetric or combined non-symmetric modes was applied. It was found that forcing the jet with a pair of different spinning modes leads to azimuthal distortions of the mean flow. This observation confirms and explains existing hotwire data. Simultaneous excitation with two axisymmetric modes may produce structures of higher modes or even cause structurally undistinguishable development. Streamwise structures are observed both in the unforced jet and in the axisymmetrically forced jet. They do not seem to be caused by a Görtier instability from the concave curvature of the conventional nozzle, since they were also found in a jet flow from a specially designed nozzle with only convex contraction surface.

Original languageEnglish (US)
Pages (from-to)189-199
Number of pages11
JournalExperiments in Fluids
Volume12
Issue number3
DOIs
StatePublished - Jan 1 1992

ASJC Scopus subject areas

  • Computational Mechanics
  • Mechanics of Materials
  • Physics and Astronomy(all)
  • Fluid Flow and Transfer Processes

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