The Influence of Different Frequencies in the Turbulence on Early Flame Development in a Spark Ignition Engine

Two-components cycle-resolved Laser Doppler Velocimetry (LDV) measurements were performed with high data rate to resolve the flow in a spark ignition engine. The velocity measurements were then processed with both a frequency and a time domain filtering technique to obtain the level of turbulence at different frequencies. Simultaneous cylinder pressure measurements gave information of the duration of the early flame development through a heat release calculation. The initial combustion rate was correlated to the turbulence at different frequencies and the results showed a higher correlation for the high frequencies (4-6 kHz) when the engine was run at 700 rpm.