Search Results

Multidimensional modeling of in-cylinder processes has traditionally relied upon comparison with experimentally determined gross quantities, such as swirl ratio or valve discharge coefficient. Recent experimental studies have focused on accurate in-cylinder measurement of quantities such as velocity fields, species concentration distributions and distributions or turbulent kinetic energy. Since the most important engine design parameters, including filling efficiency, flame stability and pollutant formation depend on the local flow field, the ability to accurately predict these details is a key requirement for successful application of computational fluid dynamics techniques to engine design.

Variations in the in cylinder flow field which result from differences in the intake flow are known to have important effects on the performance and emissions behavior of diesel engines. The intake flow and combustion in a heavy duty DI diesel engine with a dual valve port have been simulated using the computational fluid dynamics code KIVA-3. Variation of the in-cylinder flow field has been achieved by varying the intake valve timing. Variations in the in-cylinder flow, including a range of length scales, degrees of inhomogeneity in a number of scalar and vector quantities, and the persistence of various flow structures, are compared, and their significance to combustion and emissions parameters are assessed. The interaction of fuel spray parameters, particularly spray-wall interaction with structures present in the flow field are evaluated.