A Mixed Lubrication and Oil Transport Model for Piston Rings Using a Mass-Conserving Algorithm

A numerical study of the interactions between hydrodynamic/boundary lubrication, oil transport, and radial dynamics of a piston ring using a mass-conserving (cavitation) algorithm is presented. The scheme outlined in this investigation facilitates the calculation of the volume of oil accumulating at the leading and trailing edges of the piston ring as it scrapes against the line. The calculation of this oil accumulation is important in the estimation of lubricating oil consumption in engines. The numerical procedure employed in this study is capable of depicting the transition between the various modes of piston ring lubrication (hydrodynamic, mixed, and boundary) over an engine cycle, including the detachment of oil film from the ring and its subsequent re-attachment. Additionally, the effects of (a) liner lubricant availability and (b) ring face profiles on the oil accumulation are also discussed.