Analytical studies of turbulent friction in annular conduits; effect of inserted pipe on flow capacity of sewers report 2

An analytical solution for fully developed turbulent flow in an annular conduit is presented. The solution procedure is somewhat similar to that employed by Deissler and Taylor2* and is performed with the aid of a digital computer. To account for the observed divergence of the velocity traverses of recent investigations with increasing radius ratio, a modified wall law-core law velocity formulation is adopted. The effect of variations in radius ratio, eccentricity, and roughness upon the location of maximum velocity, velocity distribution, and friction are discussed. The radius of maximum velocity is found to be nearer the inner wall for smooth annuli and independent of Reynolds number for values of IF > 40,000. Friction decreases with increased eccentricity but is considerably less affected by changes in the radius ratio. Variations in wall roughness cause the greatest alteration in the flow occurrences in annular conduits. Using the modified two-law velocity distribution, a new prediction of friction is given for the limiting case a à 1. Even though equivalent magnitudes were not achieved for experimental and analytical results, the trends are similar.Task 12 of the ASCE Combined Sewer Separation Project, Contract FWPCA No. 14-12-29 for the Federal Water Pollution Control Administratio