Elliptic jets. part 3. dynamics of preferred mode coherent structure

Hyder S. Husain, Fazle Hussain

Research output: Contribution to journalArticlepeer-review

92 Scopus citations

Abstract

The dynamics of the preferred mode structure in the near field of an elliptic jet have been investigated using hot-wire measurements. A 2:1 aspect ratio jet with an initially turbulent boundary layer and a constant momentum thickness all around the nozzle exit perimeter was used for this study. Measurements were made in air at a Reynolds number Re "SUB De" (identical toU "SUB e" D "SUB e" / nu)=3.5 X10 "SUP 4" . Controlled longitudinal excitation at the preferred mode frequency (St "SUB De" identical tofD "SUB e" /U "SUB e" =0.4) induced periodic formation of structures, allowing phase-locked measurements with a local trigger hot wire. The dynamics of the organized structure are examined from reduced fields of coherent vorticity and incoherent turbulence in the major and minor symmetry planes at five successive phases of evolution, and are also compared with corresponding data for a circular jet. Unlike in a circular jet, azimuthally fixed streamwise vortices (ribs) form without the aid of azimuthal forcing. The three-dimensional deformation of elliptic vortical structures and the rib formation mechanism have also been studied through direct numerical simulation. (from Authors)

Original languageEnglish (US)
Pages (from-to)315-361
Number of pages47
JournalJournal of Fluid Mechanics
Volume248
DOIs
StatePublished - Jan 1 1993

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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