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In the present paper, an analysis of non-evaporating, transient Diesel sprays generated by an automotive common-rail, electronic controlled injection system is described. A standard Diesel fuel and a pure Biodiesel were used for the tests, with sprays evolving in a pressurized test chamber and generated by both cylindrical and conical hole nozzles. The spray analysis is performed mainly by means of a laser sheet technique in order to obtain global spray data suitable for tuning direct injection systems to such fuels and for numerical codes validation. A dispersion analysis among different jets was also performed, along with the injection rate measurement. A PDA system was also used to characterize the behavior of the two fuels with the prototype injector nozzles at ambient conditions.

The injection rate modulation and the spray characteristics are determining factors for the quality of mixture formation when applying GDI. Their variation with load and speed is a basic criterion for the adaptability of a type of injection system to an engine with known requirements. The increased interest for the utilization of regenerative fuels - such as methanol obtained from biomass - as well as the success of previous utilization scenarios of variable gasoline/methanol mixture using manifold injection formed the base of the present analysis: the paper describes the results concerning injection performances and spray characteristics when using gasoline/methanol mixtures with different ratios in a direct injection system with high pressure modulation. The results are compared for different parameters of the injection systems as follows: injection volume, injector opening pressure, needle lift, pintle/seat geometry.