Abstract
The objective of this research is to include mixed friction effects into existing models of hydrodynamic journal bearings. The considerations in this paper are devoted to partial hydrodynamic lubrication effects in typical cylindrical transverse journal bearings applied for supporting of heavy rotor-shafts of the rotating machines. For this purpose there is used an average flow theory for an oil film interaction with the rough journals and bushings. In order to carry out a qualitative analysis of the problem a simple mechanical model of the partially lubricated “super-bearing” is assumed. These viscoelastic properties of the oil film in such bearing are determined by numerical solving of the average Reynolds’ equation describing partial oil flow between the rough journal and bushing. Here, the pressure flow factors and the shear flow factors standing in the average Reynold’s equations are determined analytically using proper empirical formulae obtained by numerical simulations of the model flows between partially lubricated surfaces for various roughness geometry and average oil film thicknesses. Solving in this way the average Reynolds equation for the entire oil gap by means of the finite difference method enables us to determine resultant viscous friction retarding force as well as transverse hydrodynamic load of the bearing. In the numerical examples numerous roughness amplitudes of the journal and the bushing surface as well as various directional orientations of roughness asperities, which follow from final machining of the journal and the bushing, are taken into consideration in order to investigate their influence on kineto-static and dynamic behaviour of the transverse oil-film bearing.