Maynard F. Taylor
Published: 1967
Total Pages: 28
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The existing conventional methods of correlating and predicting friction coefficients for laminar and turbulent flow, where the physical properties and density do not vary greatly, are shown to give friction coefficients that are in poor agreement with the measured values when there are large variations in the physical properties, that is, large ratios of surface to fluid-bulk temperature. The local and average friction coefficients used were measured by seven investigators for laminar and turbulent flow of helium, hydrogen, nitrogen, carbon dioxide, and air through smooth tubes. Inside diameters varied from 0.115 to 0.569 inches (0.292 to 1.445 cm); ratios of surface to fluid-bulk temperature ranged from 0.35 to 7.35; and modified surface Reynolds numbers ranged from 170 to 550,000. These data were used to determine the best methods of correlating and predicting local friction coefficients for ratios of distance from entrance of test section to inside diameter of test section (x/D) from 16 to 113 and average friction coefficients for ratios of length to diameter (L/D) from 21 to 200. The recommended correlation equation for modified surface Reynolds numbers less than 3000 us f/2 = 8/Re), where f/2 is half friction coefficient and Re) is the modified surface Reynolds number. For modified surface Reynolds numbers of 3000 or greater, the recommended correlation is f/2 = (0.0007 + 0.0625/Re)0.32) (Tb/T))0.5, where Tb and T) are the bulk and surface temperatures, respectively. The foregoing smooth tube relations also correlated laminar and turbulent friction coefficients for flow between parallel plates.
