Optimization of rib-roughened annular gas-coolant channels

A. Rashkovan, J. Aharon, M. Katz, G. Ziskind

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

The present study deals with the effects of wall geometry on the fluid flow and heat transfer in an annulus. Rectangular-rib structural wall roughness on the inner wall is considered. This roughness is characterized by rib height, width and pitch. A detailed parametric investigation of the effect of rib width-to-height ratio on the friction coefficient is performed for different rib pitches. This ratio varies from 0.125 to 6.0. Various rib pitches are considered, from those corresponding to a smooth wall, and up to the pitch-to-rib-height ratio of 16. The hydraulic diameter and the flow Reynolds number serve as additional parameters. Numerical simulations are performed using a modified k-ε turbulence model, which makes possible the prediction of flow separation, reattachment and adverse pressure gradients. The model is validated by comparing its results with experimental and numerical results reported in the literature. The results of the present study indicate that for the given hydraulic diameter of the annulus and flow Reynolds number, the pitch that corresponds to maximal flow resistance depends on the rib width-to-height ratio. It appears that when the width-to-height ratio decreases, this optimal pitch approaches an asymptotic value. On the other hand, the optimum rib distance-to-height ratio remains almost constant. These findings are discussed in context of the available literature.

Original languageEnglish
Title of host publicationProceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12
StatePublished - 1 Dec 2007
Event12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12 - Pittsburgh, PA, United States
Duration: 30 Sep 20074 Oct 2007

Publication series

NameProceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12

Conference

Conference12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12
Country/TerritoryUnited States
CityPittsburgh, PA
Period30/09/074/10/07

Keywords

  • Annular channel
  • Heat-transfer enhancement
  • Rib-roughened wall

ASJC Scopus subject areas

  • Nuclear Energy and Engineering
  • Nuclear and High Energy Physics

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