Aspects of Lubrication in a Reciprocating Single-ring Test Rig and Further Implementation to Engine Applications

A major concern in modern engine design is the issue of the lubrication regime at the piston-liner assembly. To fully understand the complex lubrication phenomena between the piston-rings and cylinder liner in reciprocating engines and at the same time achieve minimal energy losses with the oncoming emission regulations, it is important to characterize the developing oil film. This dynamic process involves many factors, such as piston-ring and piston dynamics, starved lubrication, liner geometry deformation, lubricant - additive degradation and blow-by, which, in turn, enhance the difficulty of interpreting engine experimental results. The simplified test rig is used as a platform to develop oil film measuring techniques and study experimental results from different sensors by means of a robust and solid technique without the engine testing ambiguities, at different lubrication regimes. This paper is focused on experimental findings from the simplified test rig and how these can be applied on specially modified engines, with the respective sensors fitted. A comparison between the single-ring test rig and the engine visualization results is attempted so that similar forms of cavitation identified, be further studied. Moreover, a calibration coefficient for LIF engine experiments can be derived via the simplified test rig arrangement.