Abstract:
The simulation of premixed combustion in a spark ignition engine with the level set method (G-equation) is the main part of this work. Additionally alternative combustion models, namely ECFM and Weller one equation, were taken as basis of comparison. The G-equation describes the propagation of a 2d flame surface, but can be extended into 3d space by introducing additional properties like a flame thickness. It was shown, that the propagation of these additional properties has to be consistent to the flame surface, which leads to restrictions of the corresponding equations.
One difficulty of simulating combustion is the interaction of turbulence and combustion. The feedback via turbulent flame speed can lead to numerical self acceleration of the flame, which can be avoided by introducing additional turbulence equations for the unburnt gas. Alternatively a method was introduced which calculates the turbulence production terms seperately for the burnt and unburnt gas by utilizing the Hugoniot jump conditions at the flame front. This avoids the generation of artificial turbulence in the partially burnt gas.