Numerical modeling of thermophoretic deposition on cylinder liner of a diesel engine using a sectional soot model

Abstract

Soot deposition on combustion chamber walls of a diesel engine is one of the key concerns among diesel engine manufacturers as it affects the durability and wear of the power cylinder components. The deposition of soot on the liner also gets scraped to the crank case and leads to soot in the lubrication oil. In this work, a modeling framework is presented to estimate the deposition of soot on the liner walls. Three-dimensional computational fluid dynamic combustion simulations are performed at two operating loads for a direct injection heavy duty diesel engine. A sectional soot model coupled with gas phase chemical kinetics is used to model soot in the combustion chamber. The combustion and soot models are validated by comparing in-cylinder pressure, heat release rate and soot mass from simulations with the experimental data. A thermophoretic soot deposition model is presented which transports soot from combustion to the liner walls. Detailed in-cylinder soot mass fraction contours are used to explain the deposition phenomenon. The deposition of soot on the liner is qualitatively compared to measured soot in the lubrication oil and a good agreement is observed. The proposed modeling framework shall be helpful for optimizing combustion systems to reduce degradation of lubrication oil.