Control of jet structure by crown-shaped nozzles

Ellen K. Longmire, John K. Eaton, Christopher J. Elkins

Research output: Contribution to journalArticle

69 Scopus citations

Abstract

Flow visualization and hot-wire anemometry were used to examine the effects of indeterminate-origin nozzles on flow in the near field of an otherwise axisymmetric air jet. The jet Reynolds number based on nozzle exit diameter was 19,000. Flow structure was investigated under both unforced and forced conditions where the forcing frequency corresponded to a Strouhal number based on diameter of 0.51. Time-averaged views of the unforced flow showed significant deviations of the jet from axisymmetry. Phase-averaged slices of forced flow strobed with a copper vapor laser revealed strong variations in entrainment along different azimuthal planes. Also, the phase-averaged visualizations showed repeatable coherent longitudinal vortex structures attached to the larger-scale vortex rings normally observed in round jets. When tooth length and number on the nozzle attachments were varied, the stability and propagation patterns of these longitudinal structures could be altered.

Original languageEnglish (US)
Pages (from-to)505-512
Number of pages8
JournalAIAA journal
Volume30
Issue number2
DOIs
StatePublished - Feb 1992

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