On the Determination of Friction Forces in Turbulent Lubrication

Abstract

The mixing length theory, used previously for the determination of the velocity profiles and pressure distributions in turbulent films is now employed in order to determine the friction stresses To, Th on the two lubricated surfaces and their dependence on the Reynolds number and on the pressure distribution. Thus, it results that the curves τo(Bxτ and –τh(Bx) are antisymmetric and that the derivatives τo/τBx, τh/τBx at Bx = 0 have constant values, independent of the Reynolds number. These results allow the determination of simple analytical formulas for the friction stresses τo.h as functions of the Reynolds number and of the parameter Bx, by using a linearization procedure, valid for small and moderate variations of the film thickness. The obtained formulas are then used for the calculation of the friction forces and friction torques in journal bearings and slider bearings. Contributed by the ASLE Technical Committee on Bearings and Bearing Lubrication and presented at the Annual Meeting of the American Society of Lubrication Engineers held in Detroit, Michigan, May, 1965.