Multicomponent Gasoline Modeling : Influence on Combustion and Knock Occurrence in a Direct Injection Engine(S.I. Engines, G.D.I. Modelling)

Abstract

As the new emissions standards lead to a reduction of the exhaust pollutants and fuel consumption, the engine efficiency must be improved. The knock phenomenon represents the main limitation for the performance of gasoline engines, especially in the downsizing turbo-charged direct injection approach. The aim of this paper is to study the influence of the gasoline representation (single or multicomponent) on the knock timing and position in the combustion chamber. Using a gasoline lumping model, in which the octane number is one of the main parameters, two different fuels were computed : Rl with only one pseudo-component and R3 with three pseudo-components. The average octane number in the cylinder for the R3 fuel was calculated with a non-linear method. In parallel, a multicomponent evaporation model has been developed in the multidimensional IFP-C3D code to be able to simulate the vapor distribution of each pseudo-component in a gasoline direct injection (GDI) engine. Comparing the results between the Rl and R3 fuels, it has been shown that the stratification of the pseudo-components has an impact on the flame propagation and on the octane number cartography in the combustion chamber. Moreover, with the R3 fuel, position and timing of the knock are very close to experimental results.