Fully Developed Turbulent Flow in Annuli

Abstract

For annular pipes with diameter ratios from 0.0625 to 0.562 and with Reynolds numbers from 46,000 to 327,000, mean-velocity distributions and the location of the maximum mean velocity for each flow condition are presented. The point of maximum mean velocity in turbulent flow occurs at a smaller radius than in laminar flow. Velocity profiles are compared with the law of the wall and the velocity-defect law and are found to deviate from the usual correlations whenever the radial distribution of Reynolds stress, which was also measured, is far from linear. This occurs in the inner profiles for small diameter ratios. Mixing length and eddy-viscosity distributions were determined from accurate measurements of velocity gradients. Turbulence intensity distributions are presented, and these in conjunction with already published distributions for flow in circular pipes and for flow between parallel planes provide knowledge of turbulence-intensity distributions for all cases of fully developed, one-dimensional flow.