Flow separation in a diverging conical duct: Effect of Reynolds number and divergence angle

E. M. Sparrow, J. P. Abraham, W. J. Minkowycz

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91 Scopus citations

Abstract

Fluid flows in passages whose cross-sectional area increases in the streamwise direction are prone to separation. Here, the flow in a conical diffuser fed by a fully developed velocity at its inlet and mated at its downstream end to a long circular pipe is investigated by means of numerical simulation. A universal flow-regime model was used to accommodate possible laminarization of flows having moderate-turbulent and transitional Reynolds numbers at the diffuser inlet. It was found that flow separation occurred for a diffuser expansion angle of 5° for inlet Reynolds numbers less than about 2000. This finding invalidates a prior rule-of-thumb that flow separation first occurs at a divergence angle of seven degrees. Results from the 10 and 30° simulations showed separation at all investigated Reynolds numbers. The largest streamwise length of the separation zones occurred at the lower Reynolds numbers.

Original languageEnglish (US)
Pages (from-to)3079-3083
Number of pages5
JournalInternational Journal of Heat and Mass Transfer
Volume52
Issue number13-14
DOIs
StatePublished - Jun 1 2009

Keywords

  • Cross-sectional enlargement
  • Diffuser
  • Flow separation
  • Flow transitions
  • Laminarization

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