Correlation of Ignition Delay for Various Methane Based Fuel Blends

It is very well known that the efficiency of an SI engine is limited by knock occurrence. As a compromise between knocking combustion avoidance and an accepted level of efficiency, an engine is typically operated at very close to the knocking boundary. However, the position of an engine knocking boundary is shifted if the fuel composition changes. The description of this abnormal combustion is therefore a challenging task in engine development. There is a requirement to use a model description in the early stage of engine design. The objective of this paper is to introduce a knock model based on the calculation of exhausted auto-ignition delay. A term containing the methane number of the relevant fuel blend was incorporated into a formula describing the ignition delay. This formula is applicable for prediction of knock occurrence during engine operation on various fuel blends.