3D CFD simulation of the spark ignition process under the consideration of spark channel deflection, diffusion effects, curvature and detailed chemical kinetics

Abstract

The ignition process in turbocharged direct injection spark ignition engines is an important phase during the overall combustion process.

Cyclic variations of e.g. charge motion and mixture formation have a strong impact on the spark ignition process and lead to irregularities in the consecutive combustion process and engine performance.

These phenomena have been observed in extensive experimental studies at BMW and have motivated the development of a detailed spark ignition model for RANS CFD simulations since most of the existing commercial spark ignition models do not comprise detailed models to simulate the phenomena during the spark ignition process.

In this work the advanced Curved Arc Diffusion Ignition Model (CADIM) for gasoline engines is presented which considers the influence of spark-channel deflection and curvature, diffusion and detailed chemical kinetics.

In the advanced Curved Arc Diffusion Ignition Model the spark-channel is tracked by Lagrangian marker particles to account for the deflection of the spark-channel by the local flow field. The high local energy input during the ignition phase leads to steep gradients at the spark-channel, which cause temperature and species diffusion normal to the spark-channel. To account for these diffusion processes, the governing equations for temperature and species are solved normal to the spark-channel surface considering the influence of the spark-channel curvature.