Examination of Knock Limits of a Spark Ignited Natural Gas Engine

A zero-dimensional two-zone thermodynamic model was used to examine knock limits of a spark ignited natural gas engine. Experimentally based burning rate models were used for flame initiation and propagation calculations. A knock integral was incorporated with the zero-dimensional model. Comparison of the measured and calculated cylinder pressure data indicated that the model is able to match the measured cylinder pressure data with less than 8% error in magnitudes if the computations are started at experimental spark timing. The knock predictions were agreed with the measurements, also. With the established knock model, it is possible not only to investigate if knock is observed with changing operating and design parameters, but also to evaluate their effects on the maximum possible knock intensity.