Gasoline Mixture Combustion in Direct Fuel Injection SI Two-Stroke Engine

Process of gasoline mixture combustion in two-stroke engines is much more complicated than in four stroke engines. In order to decrease fuel consumption and exhaust gas emission, particularly hydrocarbons, two-stroke engines should have direct fuel injection systems. The paper presents results of both simulation and experimental tests on a small power gasoline two-stroke engine. The special high pressure injection system was elaborated in Cracow University of Technology for engine with capacity 115 cm 3 . The most important factor in such engine is small time for fuel evaporation and obtaining a homogeneous mixture in the combustion chamber. The gas flow in the cylinder (tumble and swirl) causes a certain deviation of fuel stream during injection and therefore location of the injector has big significance on the combustion process. The paper shows results of fuel distribution in the cylinder for different crank angles obtained from spatial simulation (KIVA3V) and propagation of the flame during combustion process. Experimental work was carried out on the engine in order to determine influence of injection parameters on engine work and combustion process. On the basis of pressure traces at different loads and rotational speeds heat release rates were calculated and Vibe functions were found. The paper presents the engine experimental stand and results of decreasing of important exhaust gases components at the same engine working parameters as in carburetted engine. 1. Problems of direct fuel injection in spark ignition two-stroke engines Combustion speed can be increased by higher turbulence of the charge, which is caused by special design of the combustion chamber. The results of simulation were inputs for designing of the experimental injection system. The engine was fuelled by conventional automotive direct fuel injection FSI and was not completely suitable for such small engine. The standard carburetted engine was tested on the laboratory stand to achieve working parameters as a data, which have been compared with the data obtained from engine equipped with direct fuel injection system. The engine with direct fuel injection indicated much smaller specific fuel consumption and very low exhaust gas emission, for example