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Structure thermique transitoire, turbulence et transfert de chaleur dans l'écoulement recollant d'un jet.

Transient thermal structure, turbulence, and heat transfer in a reattaching slot jet flow.

Auteurs : NARAYANAN V., SEYED-YAGOOBI J., PAGE R. H.

Type d'article : Article

Résumé

The role of turbulent fluctuations on the mean heat transfer coefficient in a reattaching slot jet flow was studied experimentally. The convective heat transfer rate and near-wall fluid flow were examined in the recirculation, reattachment, and post-reattachment regions for two nozzle-to-surface spacings of 0.25 and 0.75 times the width of the nozzle bottom plate. In the reattachment region, results indicate a strong correspondence between variances of near-wall velocity fluctuation and peak heat transfer rate for both spacings. Thermal structures that vary in the span-wise direction were identified in the recirculation region from low-frequency transient infrared thermographs of the heated surface. While these thermal structures are confined to regions in the vicinity of nozzle bottom plate for the low nozzle spacing, they span the entire recirculation region at larger spacings. Thermal streaks are observed past reattachment for the larger nozzle spacing, suggesting a periodic break-up and re-formation of the jet curtain. The scaling of heat transfer distribution is affected by the flow structure in the geometrically non-similar area of the recirculating flow beneath the nozzle. A correlation for peak Nusselt number is presented.

Détails

  • Titre original : Transient thermal structure, turbulence, and heat transfer in a reattaching slot jet flow.
  • Identifiant de la fiche : 2005-0614
  • Langues : Anglais
  • Source : International Journal of Heat and Mass Transfer - vol. 47 - n. 24
  • Date d'édition : 11/2004

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