Computation of Flow and Combustion in Spark Ignition Engine and Comparison with Experiment

A computational fluid dynamics study of the internal flow and the combustion process within two different spark ignition engines has been carried out. Numerical simulations have been performed with the Kiva-II code using an ignition model taking into account the velocity field in the spark plug area and the coherent flame model. This modeling approach was successfully validated in single cylinder research engine under various operating conditions and then was applied in a four valve pent roof production engine. The location and magnitude of heat releases, flame areas and temperature distributions were visualized and analyzed for all cases. The characteristics of these models were also addressed by examining the influence of different engine parameters: speed, load, air-fuel ratio, spark ignition timing. The results were compared with experimental studies including laser Doppler velocimetry, in-cylinder pressure measurements and combustion velocity. Good levels of agreement were obtained using the same modeling approach for all the engine cases.