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

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

Research output: Contribution to journalArticle

25 Citations (Scopus)

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 1992

Fingerprint

flow visualization
Flow visualization
nozzles
Schlieren photography
interactions
hydraulic jets
air jets
Photography
jet flow
photography
Nozzles
metal spinning
contraction
dyes
curvature
wire
causes
rings
Coloring Agents
excitation

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Computational Mechanics
  • Fluid Flow and Transfer Processes

Cite this

Flow visualization of interactions among large coherent structures in an axisymmetric jet. / Paschereit, C. O.; Oster, D.; Long, T. A.; Fiedler, H. E.; Wygnanski, Israel J.

In: Experiments in Fluids, Vol. 12, No. 3, 01.1992, p. 189-199.

Research output: Contribution to journalArticle

Paschereit, C. O. ; Oster, D. ; Long, T. A. ; Fiedler, H. E. ; Wygnanski, Israel J. / Flow visualization of interactions among large coherent structures in an axisymmetric jet. In: Experiments in Fluids. 1992 ; Vol. 12, No. 3. pp. 189-199.
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