Contribution to the Study of Turbulent Flow in Annular Conduits. Universal Velocity Profiles.[UN CONTRIBUTO ALLO STUDIO DEL MOTO TURBOLENTO IN CONDOTTI ANULARI PROFILI UNIVERSALI DI VELOCITA.]

A correlation, independent by Reynolds number, among inner, and outer and null shear stress radius, is utilized with the consequent shear stress distribution in order to obtain the velocity and length scales being in the turbulent velocity log-law for a fully developed turbulent flow in annular axisymmetric tubes. Present non-dimensionalizing of experimental data concerning the velocity profiles of different values of the Reynolds number and the radius ratio x = r SUB i/r SUB e, characterising the annulus geometry, singles out a logarithmic law valid for all experimental data concerning the outer region. By the continuity conditions of axial velocity and turbulent diffusivity at the null shear stress radius the trends of coefficients K SUB 1 and B SUB 1, in the log-law concerning the inner region ar determined. the comparison with the non-dimensional distribution, have obtained from the experimental data, points out that their weak dependence on the Reynolds number and suggests, for low x values, the influence of the inner radius on the same distributions. (English abstract)