Influence of the Thermal Field on the Resistance Law in the Turbulent Bearing-Lubrication Theory

Abstract

In recent years, a joint theoretical and experimental research programme has been carried out by ANSALDO, ENEL, and the Department of Mechanics of the Milan Polytechnic. The purpose of this paper is to investigate the effects of the thermal field on the resistance law. In particular, a study is made of the behavior of the lubricating film of an infinite and inclined-plane slider-bearing, using a turbulence model similar to that employed by Launder and Leschziner. In our method, the complete boundary layer equations of mass, momentum, and energy are solved numerically, by a finite-difference technique in the plane normal to the sliding surface. The equations are discretized on a staggered grid, in which the scalar quantities (pressure, viscosity, and temperature) are located at the nodes and the velocity components between them. Having assumed arbitrary distribution of velocity at the inlet and pressure distribution, the set of conservation equations can be solved at the downstream stations. Since the velocity field obtained does not satisfy the global mass conservation law at every station, a Poisson-type equation for pressure correction is derived by imposing such a mass conservation condition. Velocity and pressure distribution at the inlet are then corrected, and a new computation performed. This iterative procedure is repeated until the solution is no longer significantly modified. The numerical results show that the resistance coefficients obtained taking into account the thermal field, are lower than those obtained in isothermal conditions.