Gasohol Sprays Simulations of a Multi-Hole GDI Injector in Engine-Like Conditions 2021-01-0549

Mixture formation in GDI engine is considered crucial in determining combustion and emissions characteristics, which mainly depend on fuel spray quality. However, spray characteristics change with variations in control parameters such as fuel injection parameters, fuel injection strategy, engine operating conditions, and fuel properties. Growing research interest in the use of methanol as an additive with gasoline has motivated the need for deeper investigations of spray characteristics of these fuels. Although, it can be noted that sufficient literature is available in the area of spray characterization under several independent influencing factors, however, comparative analysis of gasohol spray behavior under different ambient conditions is hardly studied. This study is aimed at investigating the spray morphology, and evaporation and mixing characteristics of M15 (15% v/v methanol in iso-octane) and M85 (85% v/v methanol in iso-octane) in comparison to iso-octane at early injection and late injection conditions. CFD simulation studies were performed using multi-hole GDI injector in a constant volume spray chamber (CVSC) using Converge software. Numerical model used for the analysis was validated using experimental spray penetration measurements, available at the ECN. The results highlighted that effect of methanol properties on spray penetration and SMD of fuel droplets diminished under high temperature-high pressure conditions. Although, substantial difference in droplets evaporation was found among the test fuels due to inferior volatility of methanol, which definitely demands optimization of fuel injection parameters for adapting methanol blends in the engine. However, despite lower droplet evaporation, equivalence ratio distribution for methanol blends was more shifted towards stoichiometric conditions due to inherent fuel oxygen content.