Effect of the nozzle geometry on fuel dispersion in non-evaporative and evaporative conditions for a diesel injector

Schlieren - Mie-scattering combined technique for image acquisition were built-up to study the liquid and vapor phases of a diesel fuel at engine-like conditions. The sprays were generated by a Common Rail injection system fuelling two axially-disposed single-hole injectors with k-factors 0 and 1.5. Three injection pressures were explored, 70, 120, and 180 MPa, while the sprays developed in a quiescent vessel filled with inert gas. The gas temperature varied from 373 to 900 K realizing both non-vaporizing and vaporizing conditions at back-densities typical of a diesel engine. Spray contours and penetrations of the liquid and vapor phase were extracted by processing the images of the spray acquired by a high-speed camera (40,000 fps) and enlightened by two pulsed LED light sources. The images were analyzed by digital processing software for distinguishing fuel spray from ambient gas. Mie-scattering for liquid phase and schlieren imaging visualization techniques for fuel evaporation were applied and the effects of the nozzle shapes on the fuel dispersion will be discussed.