Virtual Method for the Investigation of Dynamic Emission Formation for Gasoline Engines

Abstract

Significantly reduced development times of today's powertrains as well as steadily increasing requirements regarding fuel consumption and pollutant emissions require a continuous refinement of the development methods for internal combustion engines. The presented simulation method focuses on the new and tightened approval cycles for passenger car engines; more particularly on the start-up phase as well as on sharp load changes, which lead to increased engine out emissions. The aim of this study is to create a simulation tool for the investigation and the evaluation of the emissions during the dynamic engine operation. Established simulation methods, such as Computational Fluid Dynamics (CFD), are bundled in such a way that transient processes can be simulated within a reasonable calculation time without significant loss of information. The tool is based on a 1D gas exchange simulation software. Herein, detailed reaction kinetics are used to simulate the combustion process, which also takes the thermal boundary conditions (wall temperatures) and the quality of the mixture formation into account. For this purpose, the gas exchange model is extended with a thermal network and the mixture formation process is assessed with CFD. Suitable test bench data serve to validate the whole process chain. In addition to the improvement of the CAE-based assessment for the development of virtual engines, the simulation tool should provide an understanding of the phenomena leading to emission formation under the transient engine operation. Furthermore, using such a tool can contribute to the development of alternative driving concepts like plug-in hybrid electric vehicles (PHEV) and exhaust aftertreatment systems.

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