Optical characterization of Diesel and water emulsion fuel injection sprays using shadowgraphy

•Fuel injection sprays have been examined using a focused shadowgraph system.•Diesel and Diesel and water emulsions containing 10% and 20% water examined.•Temporal evolution of the spray cone angle and tip penetration have been measured.•Emulsification reduced the cone angle at injection pressure of 500 bar.•Emulsification had no discernable influence on the tip penetration.

Diesel fuel and water emulsions have been shown to reduce emissions of NOx and PM from compression ignition engines. There is a lack of work examining the influence of emulsification on the sprays formed during injection. This work examines the spray cone angle and tip penetration of Diesel fuel and water emulsions, containing 10% and 20% water (by mass). All experiments were conducted under non-reacting, non-vaporizing conditions in a constant volume pressure chamber filled with nitrogen. A focused shadowgraph system, with high speed photography, coupled with a research, high current LED system was used. Differences in the spray cone angle suggest the emulsification did have an effect for the injections at a pressure of 500 bar. Emulsification had no discernible effect on the spray tip penetration. Spray tip penetration showed agreement with previous trends in terms of proportionality to time after start of injection however agreement with models found in the literature was not consistent.