Investigating Effects of Spray Characteristics on Fuel-Air Mixture Formation

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The Ohio State University

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Fuel-air mixture formation is an important research topic in the internal combustion (IC) engine field with respect to fuel consumption and emissions of a vehicle. Spray characteristics have significant effects on fuel-air mixture formation. In this research, spray and fuel-air mixture formation processes in the gasoline direction injection (GDI) engine are simulated in the pre-built models in the commercial software Converge CFD with emphasis on the effects of spry characteristics on such processes. The focus is placed on the effects of the injector configuration and operating conditions. A pre-built model is modified by adding spray modeling including injector and nozzles. The shape of the nozzles is initially designed as an equilateral hexagon. To improve undesired spray characteristics observed in the simulation results, the shape of the nozzles is changed as an equilateral triangle and the overall angle of the nozzles is changed downward. To mimic the effects of the injection pressure and the geometry and investigate the effects of modeled evaporation rates, the droplet size and the transfer coefficients in the droplet evaporation model are adjusted. Results of this study ideally illustrate the working process, discrete phase modeling and relationship among different variables that substantially influence the stability, efficiency and emission. By changing the shape of nozzles, less fuel is sprayed on Intake Port. Adjusting droplet size and scaling parameters would optimize fuel-air mixture formation as less fuel sprayed on the equipment and the equivalence ratio distribution improves by the adjustment. However, while idealizing certain aspects of the fuel-air mixture formation, other issues emerge due to the change of parameters, which still need more work to optimize the case.



injector, fuel-air mixture formation, spray characteristic, nozzle, droplet size, scaling