Flow Factor Modeling of Power-Cylinder Components in Hydrodynamic Lubrication


Alex J. Locker IV, Robert L. Jackson, Hamed Ghaednia, and Arup Gangopadhyay


Department of Mechanical Engineering, 1418 Wiggins Hall, Auburn University, AL 36849-5341, USA.

FORD Motor Company, Powertrain Research and Advanced Engineering, 2101 Village Road, Dearborn, MI, USA

ABSTRACT

This work analyzes the modification of the Reynolds equation for computational efficiency by analyzing rough surfaces in the hydrodynamic flow regime through the use of flow factors. This analysis is aimed towards modeling the surface interactions and pressure variations across power cylinder components of an internal combustion engine, namely the piston ring and cylinder wall. These interacting surfaces were measured directly through the use of a profilometer. Statistical flow factors are derived and included in the Reynolds equation to model the pressure and shear variations across the asperities of interacting surfaces. These flow factors can then be used to consider the effect of roughness in lubrication problems without deterministically modeling roughness. Through the use of these measured surface properties, surface specific flow factors are derived by numerical flow simulation. This derivation methodology can be used in the determination of flow factors for any pair of interacting surfaces. The governing flow factors for a pair of surfaces are expressed as empirical relations in terms of the film ratio (h/σ).