Calculation of mixed lubrication at piston ring and cylinder liner interface

This paper reports on the theoretical analysis of mixed lubrication for the piston ring. The analytical model is presented by using the average flow a nd asperity contact model. The cyclic variations of the nominal minimum oil film thickness are obtained by numerical iterative method. The total frict ion is calculated by using the hydrodynamic and asperity contact theory. Th e effects of the roughness height, pattern, and engine speed on the nominal minimum film thickness, friction force, and frictional power losses are in vestigated. As the roughness height increases, the nominal oil film thickne ss and total friction force increase. Also, the effect of the surface rough ness on the boundary friction is dominant at low engine speed and high aspe rity height. The longitudinal roughness pattern shows lower mean oil film p ressure and thinner oil film thickness compared to the case of the isotropi c and transverse roughness patterns.