An Analysis of Oil Film Temperature, Oil Film Thickness and Heat Transfer on a Piston Ring of Internal Combustion Engine: The Effect of Local Lubricant Viscosity 2004-32-0024

The effect of local lubricant viscosity on the temperature and thickness of oil film on a piston ring in a diesel engine is analyzed by using the Reynolds equation, and unsteady and two-dimensional energy equation with heat generated from viscous dissipation. The oil film viscosity for a multi-grade oil is then estimated by using the local oil film temperature and the local shear rate. Moreover, the heat transfer between ring and liner surfaces is examined. The oil film thickness calculated from this method is lesser than that of the case where the viscosity is based on the liner temperature and the mean shear rate. Maximum values of heat transfer at the ring and liner surfaces are obtained at the vicinity of crank angle where the oil film thickness is at a minimum.