The heat transfer characteristics of turbulent air flow in a two-pass channel were studied via the naphthalene sublimation technique. The test section, which consisted of two straight, square channels joined by a sharp 180 deg turn, resembled the internal cooling passages of gas turbine airfoils. The top and bottom surfaces of the test channel were roughened by rib turbulators. The rib height-to-hydraulic diameter ratio (e/D) was 0.063 and the rib pitch-to-height ratio (P/e) was 10. The local heat/mass transfer coefficients on the roughened top wall, and on the smooth divider and side walls of the test channel, were determined for three Reynolds numbers of 15,000, 30,000, and 60,000, and for three angles of attack (α) of 90, 60, and 45 deg. The results showed that the local Sherwood numbers on the ribbed walls were 1.5 to 6.5 times those for a fully developed flow in a smooth square duct. The average ribbed-wall Sherwood numbers were 2.5 to 3.5 times higher than the fully developed values, depending on the rib angle-of-attack and the Reynolds number. The results also indicated that, before the turn, the heat/mass transfer coefficients in the cases of α = 60 and 45 deg were higher than those in the case of α = 90 deg. However, after the turn, the heat/mass transfer coefficients in the oblique-rib cases were lower than those in the traverse-rib case. Correlations for the average Sherwood number ratios for individual channel surfaces and for the overall Sherwood number ratios are reported.
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April 1988
Research Papers
Effect of Rib Angle on Local Heat/Mass Transfer Distribution in a Two-Pass Rib-Roughened Channel
P. R. Chandra,
P. R. Chandra
Turbomachinery Laboratories, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843
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J. C. Han,
J. C. Han
Turbomachinery Laboratories, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843
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S. C. Lau
S. C. Lau
Turbomachinery Laboratories, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843
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P. R. Chandra
Turbomachinery Laboratories, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843
J. C. Han
Turbomachinery Laboratories, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843
S. C. Lau
Turbomachinery Laboratories, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843
J. Turbomach. Apr 1988, 110(2): 233-241 (9 pages)
Published Online: April 1, 1988
Article history
Received:
February 6, 1987
Online:
November 9, 2009
Citation
Chandra, P. R., Han, J. C., and Lau, S. C. (April 1, 1988). "Effect of Rib Angle on Local Heat/Mass Transfer Distribution in a Two-Pass Rib-Roughened Channel." ASME. J. Turbomach. April 1988; 110(2): 233–241. https://doi.org/10.1115/1.3262186
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