Study of Flame Characteristics of a Spark Ignition Engine for Gasoline Fuel

The performance and emission of spark ignition engines are optimized using combustion characteristics. The flame characteristics such as flame kernel growth rate, flame speed, flame development angle, rapid burning angle, over all burning angle and drift velocity influence the combustion process of SI engines. In this direction, experiments were conducted to measure flame kernel growth rate in AVL research spark ignition engine using AVL VISIO FEM instrument.

The flame kernel growth rate measured at different engine speeds and spark timing. The measured flame kernel growth rate for gasoline fuel was in the range of 4 to 6 m/s. It was observed from the results that flame kernel growth rate is the highest at MBT spark timing. The effects of flame kernel growth rate on performance and emission characteristics were analyzed in detail. Brake thermal efficiency increases with the increase of flame growth rate. CO emission is good agreement with the kernel growth rate. In addition, drift velocity was also calculated using the experimental data. The drift velocity is an important parameter for optimizing the spark plug position and configuration of combustion chamber geometry in order to avoid knocking. It is well demonstrated through the study that the flame kernel growth rate is an important parameter for optimizing of performance and emission characteristics of any type of SI engine.