Friction losses modeling of piston rings for various combustion pressures in diesel engine

This paper describes a numerical simulation of the lubrication between the first compression piston ring and the cylinder liner in a typical diesel engine, using the one-dimensional Reynolds equation. The geometric profiles of piston rings are axisymmetric. The inlet boundary is assumed to be fully flooded, but Reynolds cavitation boundary conditions are assumed for the outlet boundary. Cavitation boundaries, frictional forces, friction coefficients, lubrication regimes and power losses are determined for various combustion pressures, which were induced by varying the injection strategy at fixed injection quantity and constant engine speed. Results of the simulation show a dependence of the frictional force on the combustion pressure. Power losses due to the frictional force are obtained as a function of crank angle.