Short Spray Penetration for Direct Injection Gasoline Engines With Secondary Drop Breakup Simulation Integrated With Fuel Breakup Simulation

Abstract

Direct injection gasoline engines have both better engine power and fuel efficiency than port injection gasoline engines. However, direct injection gasoline engines also emit more particulate matter (PM) than port injection gasoline engines do. To decrease PM, fuel injectors with short spray penetration are required. More effective fuel injectors can be preliminarily designed by numerically simulating fuel spray. We previously developed a fuelspray simulation. Both the fuel flow within the flow paths of an injector and the liquid column at the injector outlet were simulated by using a grid method. The liquidcolumn breakup was simulated by using a particle method. The motion of droplets within the air/fuel mixture (secondarydropbreakup) region was calculated by using a discrete droplet model (DDM). In this study, we applied our fuelspray simulation to sprays for the direct injection gasoline engines. Simulated spray penetrations agreed relatively well with measured spray penetrations. Velocity distributions at the outlet of three kinds of nozzles were plotted by using a histogram, and the relationship between the velocity distributions and spray penetrations was studied. We found that shrinking the highspeed region and making the velocitydistribution uniform were required for short spray penetration.