Combustion Process in a Spark Ignition Engine: Analysis of Cyclic Maximum Pressure and Peak Pressure Angle

In this paper we analyze the cycle-to-cycle variations of maximum pressure pmax and peak pressure angle αpmax in a four-cylinder spark ignition engine. We examine the experimental time series of pmax and αpmax for three different spark advance angles. Using standard statistical techniques such as return maps and histograms we show that depending on the spark advance angle, there are significant differences in the fluctuations of pmax and αpmax. We also calculate the multiscale entropy of the various time series to estimate the effect of randomness in these fluctuations. Finally, we explain how the information on both pmax and αpmax can be used to develop optimal strategies for controlling the combustion process and improving engine performance.