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Turbulent flow in concentric and eccentric annuli Denton, John Douglas


The turbulent flow of air through the annular gap between two tubes was studied experimentally, both with the tubes concentric and with the inner tube at eccentricities of 50% and 100%. Air velocities were measured using small traversable impact tubes. The shear stresses on the boundaries were studied both by measuring the pressure gradient and by means of a calibrated shear probe attached to the inner tube. For all three annuli complete nondimensional velocity profiles were obtained at Reynolds numbers around 55,000 and the variation of average friction factor with Reynolds number was studied in the Reynolds number range 20,000 -55,000. The variation of local shear stress around the surface of the inner tube was obtained for the eccentric annuli. The results for the concentric annulus agree well with previous investigations. For the eccentric annuli the results are compared qualitatively with Deissler and Taylor's semi-theoretical investigation. The agreement is not good and this is thought 'to show that the Deissler-Taylor method is not applicable to annuli. It is concluded that the study of velocity profiles in non-symmetrical ducts is of little help in obtaining quantitative heat transfer data.

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