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The paper concerns with gas exchange and combustion process in a 2T high speed gasoline engine and presents the results of a numerical-experimental investigation, in which zero-dimensional, one dimensional and three dimensional calculation schemes are used and the tuning between numerical and experimental results is performed. The different flow patterns from which the efficiency of the scavenging strongly depends are analysed, the variation with time of the spatial distribution of the fresh charge and combustion product in the cylinder is evaluated. The combustion process is simulated and the influence of geometric parameters of the ports on the scavenging efficiency, on the emission of hydrocarbons in the exhaust system and on the performance of the combustion process is investigated.

In two stroke engines, the scavenging process has direct influence in the performance of combustion process and then retains great importance in the strategies oriented towards solutions characterized by improvements of fuel efficiency, engine power output and reductions of pollutant emissions. The authors have developed an integrated numerical-experimental predictive tool, based on a two-step procedure, in which zero-dimensional, one-dimensional and three-dimensional simulation models are applied. In this paper, the attention is focused on the analysis in detail of different flow patterns which contribute to determine the scavenging process in order to provide a better comprehension and then to get improvement of such complex process. Since the scavenging efficiency strongly depends on the geometry of the engine system, the effect of a variation of the geometrical parameters on the flow paths and on the distribution of the scavenge streams is investigated.