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Journal of Enhanced Heat Transfer
Fator do impacto: 0.562 FI de cinco anos: 0.605 SJR: 0.175 SNIP: 0.361 CiteScore™: 0.33

ISSN Imprimir: 1065-5131
ISSN On-line: 1026-5511

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Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.v3.i4.30
pages 273-280

Heat Transfer and Skin Friction Comparison of Dimpled Versus Protrusion Roughness

Mark E. Kithcart
Mechanical Engineering Department North Carolina A&T State University Greensboro, NC 27411
David E. Klett
Mechanical Engineering Department North Carolina A&T State University Greensboro, NC 27411

RESUMO

This paper presents results of skin friction and heat transfer measurements made on flat plates with closely-spaced, three-dimensional surface roughness elements (hemispherical dimples, hemispherical protrusions, and rectangular protrusions) in turbulent boundary-layer flow at velocities ranging from 18 to 40 m/s (roughness Reynold's nos. from 1500 to 4000). The roughness element densities for each plate were chosen using Simpson's sand-grain roughness correlation to study the effects of spacing on drag and heat transfer in the vicinity of the peak of the Simpson-Dvorak correlation curve. The data is presented in terms of the efficiency factor, n = (Str/Sts/(Cfr/Cfs), to provide a means of comparing the effects on skin friction and heat transfer collectively. Dimpled surfaces have the advantage of significantly increasing heat transfer at a lower penalty in increased drag compared to the protrusion roughness studied.