A Lubrication and Oil Transport Model for Piston Rings Using a Navier-Stokes Equation with Surface Tension

A numerical study of the interactions between hydrodynamic lubrication, oil transport and radial dynamics of a piston ring using a Navier-Stokes equation solution including surface tension effect is presented. The scheme, which is outlined in this investigation, facilitates the calculation of the distribution of oil accumulating at the leading and trailing areas surrounding the piston ring as it scrapes against the liner and explains the experimentally observed lubricating oil free surface profiles. The calculation of this oil distribution 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.