Shear-Heating Effects on Piston Skirts Lubrication in the Initial Engine Start Up

摘要

A 2-D hydrodynamic piston skirts lubrication model during initial engine start up is developed by incorporating shear heating effects due to lubricant flow between piston skirt and liner surfaces. Numerical analysis is presented based on 2D thermal energy equation having adiabatic conduction and convective heat transfer with no source term effects. Viscous dissipation coupled with piston motion, pressure field generation, temperature effects on oil viscosity and subsequent oil film profiles in the contact region are examined and influence of shear heating on hydrodynamic film thickness at the time of engine initial start up are investigated. This study suggests that oil film temperature rise due to shear heating adversely affects lubricant film thickness and hydrodynamic pressures, which in turn affect Newtonian lubricant performance during initial engine start up conditions.