Analysis of knock intensity in spark-ignition engines

An analysis of the pressure oscillations, knock intensity and knock occurrence in spark ignition engines has been performed. Successive cylinder pressure data were generated cycle-by-cycle from a Ricardo E6 laboratory variable compression ratio engine under varying knock intensity conditions. Knock intensity is calculated from the pressure data. The effects of some operating conditions on the occurrence knock and knock intensity is discussed. A formulated dimensionless knock parameter (K-P) based on the values of maximum rate of pressure rise, maximum of cylinder pressure and ignition angle is calculated. It is shown that when knock happens in a cycle the value of (K-P) remains at a constant level. Also it is shown that the use of this knock indicator generates results that are in good agreement with experimental results.