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Nowadays, the use of numerical simulations is an important tool in order to optimize the engine and components behaviors, directly contributing to the emissions and lead-time development project reduction. With the increase of engine thermal specific loading, excessive piston carbon build-up may be an issue, eventually causing liner polishing and excessive Lube Oil Consumption (OC). During the development of a Cummins heavy duty 8.9L engine, preliminary engine test results indicated excessive OC levels, above the engine specification limits. Also, a considerable carbon build-up, mainly in the second ring groove, was observed. This paper presents the application of piston rings numerical simulation to predict the piston ring pack behavior and evaluate potential sources of OC which may explain the excessive values obtained in engine tests.

For the development of engine components like pistons and rings, several numerical tools are employed of their performance evaluation in order to reduce the number of costly engine tests and samples required. An important limitation of the currently available codes that simulate piston ring dynamics is that they can be only used to study steady state engine conditions not allowing for the analysis of transient loads, for instance. This paper describes a proposed methodology for the simulation of transient loads yet employing existing codes. The method is used to study a real case of a diesel engine that showed excessively high blow-by fluctuations during its conventional running in cycle, more specifically at the load change from idle speed to peak torque. All assumptions and methodology are fully described, and predicted results for solution proposals are compared to engine tests in order to validate the procedure.