The object of this paper is to furnish the engineer with reliable data on the friction factors to be used in computing the pressure losses for turbulent flow in smooth curved pipes. The empirical formulas proposed, backed by theoretical considerations, appear to define the influence of curvature upon the law of resistance with satisfactory accuracy.

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No abstract

The friction factor for fully developed flow in smooth wall straight pipes of circular cross section rotating at a constant angular velocity about an axis perpendicular to its own has been measured in the Reynolds number range from 20 to 60,000.Empirical equations for friction factors for small values of Ra/R were presented for both laminar and turbulent flow.In the case of laminar flow, an approximate analysis based on the assumption that the flow consists of a frictionless central core surrounded by a boundary layer was presented.The residts were in good qualitative agreement with experimental results in regard to the friction factor, velocity distribution in the plane of symmetry and pressure distribution along the circumferential wall of the pipe.

The loss coefficients for smooth, sharp-edged tees of circular cross-section with the area ratio of 11.44 were determined experimentally for five branch angles which ranged from 45 deg to 135 deg giving special consideration to all configurations of flow through the tees. The Reynolds number, in the leg carrying the combined flow, was kept to a constant value, i.e., 10 5 for the branch pipe and 3ϫ10 4 for the main pipe, respectively. The equations for loss coefficients developed from the continuity, energy, and momentum principles give good agreement with the experimental results for tees with large area ratios provided that correction factors are introduced. The correction factors were determined by the analysis of the experimental data with the relative uncertainties from 0.9 to 3.3% according to the configurations of flow. The results constitute a useful guide to the determination of the loss coefficients for tees with large area ratios.