Evaluation of Various Knock Control Methods in a Spark Ignition Engine Fuelled with Natural Gas through a Three Zone Quasi-Dimensional Combustion Model

Detection of knock onset to control abnormal combustion is one of the most important targets in SI engine modeling. The present contribution describes a refined analytical approach to knock occurrence simulation and its intensity. In the quasi-dimensional model used in this research, the homogeneous charge of the cylinder during the combustion period is assumed to be divided into three parts; These include: burned product, unburned reactant, which comprises the end gas region, and flame front. One of the advantages of this research is its application of turbulent flame propagation to mass burning rate estimation and its use of kinetic reactions mechanism in both burned and unburned zones. A 32 step- and 14 species- mechanism is applied to examine the behavior of the end gas region. Finally, operating parameters, factors affecting knock onset and its intensity (e.g. inlet pressure and temperature, equivalence ratio, spark timing, compression ratio, etc.) have been examined. Moreover, the effects of EGR on knock occurrence and engine output are evaluated as an effective method, and are compared against other factors. The predictive engine model has been validated through comparing the calculated results with the experimental data from an actual engine, and the results show a significant agreement between the two.