Piston ring-cylinder bore friction modeling in mixed lubrication regime: Part I - Analytical results

An axi-symmetric, hydrodynamic, mixed lubrication model has been developed using the averaged Reynold's equation and asperity contact approach in orde r to simulate frictional performance of piston ring and cylinder liner cont act. The friction force between piston ring and cylinder bore is predicted considering rupture location, surface flow factors, surface roughness and m etal-to-metal contact lending. A fully flooded inlet boundary condition and Reynolds boundary conditions for cavitation outlet zone are assumed. Reyno lds boundary conditions have been modified for non-cavitation zones. The pr essure distribution along the ring thickness and the lubricant film thickne ss are determined for each crank angle degree. Predicted friction force is presented for the first compression ring of a typical diesel engine as a fu nction of crank angle position.