Development of Transient Knock Prediction Technique by Using a Zero-Dimensional Knocking Simulation with Chemical Kinetics

A transient knock prediction technique has been developed by coupling a zero-dimensional knocking simulation with chemical kinetics and a one-dimensional gas exchange engine model to study the occurrence of transient knock in SI engines. A mixed chemical reaction mechanism of the primary reference fuels was implemented in the two-zone combustion chamber model as the auto-ignition model of the end-gas. An empirical correlation between end-gas auto-ignition and knock intensity obtained through intensive analysis of experimental data has been applied to the knocking simulation with the aim of obtaining better prediction accuracy. The results of calculations made under various engine operating parameters show good agreement with experimental data for trace knock sensitivity to spark advance. A one-dimensional gas exchange engine model of a 4-cylinder turbocharged SI engine was developed by using GT-Power so that gas properties such as temperature and residual gas ratio in the combustion chamber during acceleration can be calculated for use in the knocking simulation as the initial conditions of the auto-ignition calculation. This combined method of predicting transient knock phenomena has been successfully demonstrated and the cause of transient knock during acceleration is discussed.