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The paper discusses the analysis of gasoline atomization generated by piezoelectric fuel injectors operating in a high pressure direct injection system. The methodology and tests results of the influence of the fuel injection pressure and combustion chamber back pressure on the changes of the fuel spray geometrical parameters during the injection and on the values characterizing the injection quality have been presented in the paper. It was stated that the growth in the back pressure by 50% results in a decrease in the linear spray penetration by 15% and a change in the injection pressure by 25% reduces the spray penetration by 1.6-4%. Similar relations are found for the fuel spray area and are even stronger for the spray penetration velocity.

The paper discusses the analysis of ethanol (E85) fuel atomization generated by piezoelectric fuel injectors operating in a high-pressure gasoline direct injection system. The methodology and tests results of the influence of the fuel (E85) injection pressure and combustion chamber back pressure on the changes of the fuel spray geometrical parameters during the injection and on the values characterizing the injection quality have been presented in the paper. The tests were performed for one value of the air backpressure (1.5 MPa; as in modern supercharged DI engines) at the injection pressures of 5 and 20 MPa. The following comparative indexes were analyzed: linear and radial spray penetration during the injection and the velocity of the spray propagation. The investigation consisted in a visual recording of the process of fuel (ethanol E85) injection realized into a high pressure chamber.

The paper presents experimental and model research related to the fuel spray - wall interaction in terms of pressure and air back-pressure variability. Using a constant volume chamber the authors performed a qualitative and quantitative analysis of the fuel spray reaching the piston. The experimental research was supported with a model research using the FIRE 2010 software by AVL. On this basis the fuel concentration and its distribution in individual areas of the combustion chamber were determined (in the piston combustion chamber). A greater impact of the injection pressure (rather than the back-pressure) on the fuel spray distribution in the combustion chamber was observed and on the fuel spray interaction with the chamber walls in the piston. In such a case the problems of the contact of a liquid fuel with the cylinder walls and/or the combustion chamber walls is becoming increasingly important in terms of the fuel film formation and HC emission intensification.

The paper discusses the results of investigations into fuel atomization with the use of two high-pressure angularly arranged injectors fitted in a combustion of constant volume chamber. Using two Direct Injection injectors is a new conception, which was not applied yet. Nowadays, the conceptions where two injectors are used, one in direct injection and one in port injection are used. It is expected, that new gasoline Direct Injection system will allow better fuel spray and following combustion process. It is especially important in spray-guided mixture creating. The analysis mainly relates to the parameters of the fuel spray: spray penetration, observed fuel spray area in reference to both a single fuel spray and two angularly fuel sprays. The assessment of the uniformity of the fuel spray penetration for both sprays has been carried out.

The current paper is a continuation of research on fuel atomization presented in SAE 2012-01-1662. The influence of varied position of the injector inside the combustion chamber on combustion, toxic compounds formation and exhaust emission were investigated. The simulation research (injection and combustion with NO formation) was supported with the model using the FIRE 2010 software by AVL. Modelling studies of toxic compounds formation were compared with the results of measurements on single-cylinder AVL 5804 engine. There thermodynamic evaluation indicators and exhaust emission were made.