Approximate calculations of the hydrodynamic characteristics of turbulent fluid flow in annular ducts

A simple solution is given for the problem of the radius of the peak-velocity line in an annular duct; the solution is obtained on the basis of the assumption that an annular duct and an equivalent circular tube have identical turbulent characteristics. The method of Rothfus is used to derive an equation for the friction coefficient in annular ducts. The results of the calculations are compared with experimental data.