Three-dimensional simulations of oil dilution in DI diesel engines under motoring conditions with varying injection timing

This study presents a simulation method for oil dilution in diesel engines by a post injection to understand the oil dilution mechanism and to improve an empirical model predicting the evolution of oil dilution. To consider the wall film, two-dimensional governing equations are additionally solved along the cylinder wall. Primary critical Weber numbers are used to determine adhesion or a splash of droplets at wall impingements. Motoring engine simulations at different injection timings show that dilution ratios in simulations are in good agreements with those in experiments. Oil dilution is not proportional to injection timings in this motoring conditions.