SOME MEASUREMENTS IN THE SELF-PRESERVING JET

Israel J Wygnanski, H FIEDLER H

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Abstract

The axisymmetric turbulent incompressible and isothermal jet was investigated by use of linearized constant-temperature hot- wire anemometers. It was established that the jet was truly self- preserving some 70 diam downstream of the nozzle and most of the measurements were made in excess of this distance. The quantities measured include mean velocity, turbulence stresses, intermittency, skewness and flatness factors, correlations, scales, low-frequency spectra and convection velocity. The rms values of the various velocity fluctuations differ from those measured previously as a result of lack of self-preservation and insufficient frequency range in the instrumentation of theprevious investigations. It appears that Taylor's hypothesis is not applicable to this flow, but the use of convection velocity of the appropriate scale for the transformation from temporal to spatial quantities appears appropriate. The energy balance was calculated from the various measured quantities and the result is quite different from the recent measurements of S. Sami, which were obtained 20 diam diwnstream from the nozzle. In light of these measurements some previous hypotheses about the turbulent structure and the transport phenomena are discussed.

Original languageEnglish (US)
Pages (from-to)577-612
Number of pages36
JournalJournal of Fluid Mechanics
Volume38
Issue numberpt 3
Publication statusPublished - Jan 1 1969
Externally publishedYes

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ASJC Scopus subject areas

  • Computational Mechanics
  • Mechanics of Materials
  • Physics and Astronomy(all)
  • Condensed Matter Physics

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