Measurement of heat-transfer and friction coefficients for flow of air in noncircular ducts at high surface temperatures /
by Warren H. Lowdermilk, Walter F. Weiland, Jr., and John N.B. Livingood.
Description
- Language(s)
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English
- Published
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Washington, D.C. : NACA, 1953.
- Summary
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Abstract: Measurements of average heat-transfer and friction coefficients were obtained with air flowing through electrically heated ducts having square, rectangular (aspect ratio, 5), and triangular cross sections for a range of surface temperature from 540À to 1780À R and Reynolds number from 1000 to 330,000. The results indicated that the effect of heat flux on correlations of the average heat-transfer and friction coefficients is similar to that obtained for circular tubes in a previous investigation and was nearly eliminated by evaluating the physical properties and density of the air at a film temperature halfway between the average surface and fluid bulk temperatures. With the Nusselt and Reynolds numbers based on the hydraulic diameter of the ducts, the data for the noncircular ducts could be represented by the same equations obtained in the previous investigation for circular tubes. Correlation of the average difference between the surface corner and midwall temperatures for the square duct was in agreement with predicted values from a previous analysis. However, for the rectangular and triangular ducts, the measured corner temperature was greater by approximately 20 and 35 percent, respectively, than the values predicted by analysis.
- Note
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"Report date October 9, 1953."
Also available in electronic format.
- Physical Description
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26 p. :
ill. ;
28 cm.
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