Analyzing viscoelastic effects in piston skirts EHL at small radial clearances in initial engine start up

Non-Newtonian engine lubricant and EHL film enhance engine life at small clearance in normal engine operation. It is not so in initial engine startup. This study models 2-D Maxwell viscoelastic hydrodynamic and EHL of piston skirts in initial engine startup. The 2-D Reynolds equation and the inverse solution technique are used for EHL solutions. Numerical solutions predict viscoelastic effects on piston eccentricities, hydrodynamic pressures and EHL films at different small radial clearances. Results are compared with Newtonian model, which suggest that viscoelasticity is beneficial for skirts lubrication at small radial clearances. Outcomes optimize small radial clearance in initial engine startup.

► Modeling viscoelastic lubricant characteristics in engine startup. ► Viscoelastic characteristics enhance load capacity of lubricant. ► Thicker hydrodynamic film compared to Newtonian lubricant. ► Viscoelasticity reduces wear at small radial clearances. ► Radial clearance Optimization for few startup cycles.