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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Heat transfer from a dimpled surface with and without free stream turbulence in a thermally developing flow

Get access (open in a dialog) DOI: 10.1615/IHTC12.270
6 pages

Аннотация

The objective of this study was to characterize the area averaged heat transfer performance of a dimpled surface in a thermally developing flow with and without free stream turbulence. Two 30 by 30 cm plates, one smooth, one dimpled were constructed and tested in a wind tunnel. The dimples are 3 mm deep with print diameters of 16 mm and are configured in a staggered array of 15 rows and 13 columns. Tests were conducted at channel heights from 1.27 to 3.81 cm and Reynolds numbers (based on hydraulic diameter) from 20,000 to 60,000. The smooth plate results were compared to the Dittus-Boelter equation for turbulent flow in a pipe and found to agree within 5% while the dimpled plate data showed a 30-40% increase in the average heat transfer coefficient. Two different metal mesh grids were placed upstream of the test plate to induce 3-4% and 6-8% turbulence levels in the channel. We found that although the heat transfer coefficients on both the smooth and dimpled plates increased when turbulence was induced in the channel, the overall benefit of the dimpled surface decreased.