Quasi-dimensional modelling of turbulence-driven phenomena in SI engines

In the present work, various basic approaches regarding the quasi-dimensional description of the combustion and the resulting wall heat transfer within SI engines are reviewed and analysed to promote the understanding and to enable modelling improvements. Owing to the dominant role of turbulence, models for the description of the turbulent flow in the combustion chamber are first analysed. The importance of taking into account the influence of combustion when calculating the wall heat transfer of various fuels is shown based on model comparisons. A hypothesis regarding the interaction of turbulence and combustion is also presented. A general formulation of the turbulent flame speed is developed covering the premixed combustion of different fuels. Measurements of the wall heat flux, optical examinations of the flame propagation and thermodynamic measurements are used for validation. Furthermore, good correlations between corresponding measurements and simulations with the derived phenomenological approaches are demonstrated.