Measurement of propagating flame in a gasoline engine under transient operating conditions using a multiple-ion probe

The propagating flame in a 2-stroke gasoline engine under WOT or transient operating conditions was measured with up to 12 ion probes. Flame arrival time data obtained from multiple-ion probes were statistically compared between arrival time data obtained by different ion probes or between data obtained by the same ion probe for different cycles to investigate the spatial and temporal characteristics of flame propagation behavior. Spatial statistical data analysis revealed that the propagating flame is strongly influenced by the in-cylinder flow prior to ignition. Temporal statistical data analysis revealed that the state of flame propagation, starting from any given cycle and continuing in subsequent cycles, shows a tendency similar to that of the initial cycle for some time, and that the original tendency is completely lost after about 50 cycles.