A diagnostic bi-zonal combustion model for the study of knock in spark-ignition engines

Abstract

A bi-zonal model for the combustion process in spark-ignition engines was developed to provide thermodynamic information, using experimental pressure records. The model was applied to the knock analysis, introducing a reduced kinetic mechanism. The unburned gas temperature in an adiabatically compressed core region is shown to be a good approximation for the reaction temperature. The activation energy of the forward rate of the isomerization reaction was determined for each of seven fuels by comparison with the experiments. It is shown that the activation energy has an almost linear dependence on the research octane number.