Theoretical Analysis of Piston-Ring Lubrication Part II—Starved Lubrication and Its Application to a Complete Ring Pack

Most studies of piston-ring lubrication assume fully flooded lubrication in the cylinder-bore and piston-ring conjunction. However, the lubricant supply is not always adequate for fully flooded lubrication. This study incorporates the effects of lubricant starvation into the one-dimensional piston-ring analysis developed earlier and applies it to a complete ring pack. A system of three nonlinear equations is derived to solve the starved lubrication problem. A postulate for lubricant transport in a complete ring pack is also proposed. A computer code is developed to apply the starved lubrication model to a complete ring pack. The findings reveal that lubricant starvation has an important effect on the minimum film thickness of a ring pack, especially at mid-stroke for compression rings. The role of oil-control rings and the evaluation of ring performance as a complete ring pack are also discussed.