Modeling the Non-Newtonian Engine Oil Behavior in 1st Compression Ring Lubrication

Abstract

Advancements in engine design have necessitated use of synthetic, multi-grade engine lubricants to reduce engine friction and wear and enhance its operational life. The modern multi-grade oils exhibit the non-Newtonian characteristics which are beneficial for an effective lubrication of the engines and industrial machinery. In the internal combustion engines, the piston ring assembly is a crucial component of the power plant. In the four stroke cycle the 1st compression ring is an important part of the piston ring pack which sustains the main combustion thrust directly. It is vulnerable to all forms of dynamic loads during the extreme and unusual engine operating conditions. When an engine starts up, the 1stcompression ring is most vulnerable to wear due to the absence of a fully established Elastohydrodynamic Lubricating (EHL) film. In this context, the viscoelastic behavior of anon Newtonian lubricant may contribute towards preventing wear of the interacting surfaces of the top ring and the cylinder liner. Role of oil behavior to minimize adhesive wear of piston skirt and liner surfaces during engine start up conditions under ideal conditions have yet to be properly modeled and thoroughly investigated. This calls for proper investigative research to model rheological behavior of non-Newtonian engine lubricants with particular focus on initial engine start up conditions. This research work will numerically model the hydrodynamic and Elastohydrodynamic Lubrication (EHL) of the 1st compression ring by considering the Newtonian and Non-Newtonian lubricant characteristics for comparative analysis. The secondary dynamics of the piston will be incorporated in the models at the different engine startup speeds, lubricant viscosities and radial clearances for optimum solutions.