Biofuel is an attracted alternative fuel. While biofuel-gasoline blends are used for substituting some part of gasoline, and to some extent it is favorable to direct injection homogeneous charge combustion ignition (DI-HCCI) engine application, improving auto-ignition ability and reducing high-pressure pump friction. In this study, the spray characteristics of various blends of the biofuel and gasoline (10%, 20% and 30% biofuel made from edible waste oil) as well as pure gasoline were investigated by means of high-speed shadow photography technique, employing a multi-hole DISI engine injector with asymmetrical nozzle-hole arrangement. A comparative analysis of spray characteristics of biofuel-gasoline blends and pure gasoline was presented as well. Such the parameters as spray tip penetration, spray cone angle, spray tip speed and spray projection area were calculated by means of the spray images. The results showed that the initial spray pattern of the blends with different biofuel fraction in the gasoline is distinct. The spray tip penetration and the spray tip speed increased with the increase in biofuel volume fraction, due mainly to an increase in fuel viscosity preventing the breakup of the spray jet, resulting in an increase in the size of the spray droplets. In addition, Regardless of the biofuel fraction in the gasoline, the spray fuel concentrations were richer and richer with the increase in the injection pressure, due to increasing the fuel injection rate.
