Influence of Biodiesel Blended in Gasoline-Based Fuels on Macroscopic Spray Structure from a Diesel Injector

Abstract

This research investigates the spray characteristics of gasoline-biodiesel blended fuels (GB), which expected to be utilized in a gasoline compression ignition engine. Commercial gasoline blended with 0 ∼ 20 % by volume of biodiesel, called GB00 – GB20, were used to experiment. In addition, neat biodiesel and pure gasoline were also investigated as the references. Firstly, the chemical and physical properties of the GB blends were characterized to clarify the effect of biodiesel content. Then, spray macroscopic visualization was performed by the shadowgraph technique. The test fuels at injection pressures of 1,000, 1,200, and 1,350 bar were injected into a constant volume combustion chamber (CVCC). The constant back pressures in the CVCC were set at 30 bar and 50 bar. The spray penetrating length and cone angle were analyzed by an image processing technique. Biodiesel is characterized as the widest angle and longest spray length while gasoline has the narrowest cone angle and shortest penetration. There is no correlation between the spray angle/penetration length and the percentage of biodiesel in the blends among the GB. When the injection pressure was increased, the spray cone angle was slightly decreased, while the spray-penetrating length was increased for all test fuels.