Natural coherent structure dynamics in near field of fully turbulent axisymmetric jet


Aydore S., Disimile P.

AIAA JOURNAL, vol.35, no.7, pp.1171-1178, 1997 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 35 Issue: 7
  • Publication Date: 1997
  • Doi Number: 10.2514/2.240
  • Title of Journal : AIAA JOURNAL
  • Page Numbers: pp.1171-1178

Abstract

Natural coherent structures in the near field of an axisymmetric jet have been educed, and their dynamics studied experimentally using hot-wire anemometry. The jet, originating from a fully developed turbulent pipe flow, was positioned four jet diameters upstream from an impingement plate. Based on the pipe diameter, a jet Reynolds number of 1.3 x 10(4) was maintained. Using the life cycle method for coherent structure eduction, phased-averaged vorticity contours were obtained in the jet near field, within 2.3 diameters of the pipe exit. Vorticity contours suggest that large coherent structures exist in the middle of the shear layer at approximately one jet diameter downstream from the pipe exit. Their size, 40% of the initial jet diameter, is maximum at this location. A decay region was also observed 1.6 diameters downstream from the pipe exit. Individual terms in the coherent vorticity equation were evaluated and significant terms examined.