Influence of Nozzle geometry on spray shape, particle size, spray velocity and Air entrainment of high pressure Diesel spray

International audienceAir/fuel mixing process in the combustion chamber of Diesel engines plays an important role on the combustion efficiency. This mixing depends on the particle size distribution in the spray, on the local velocity of fuel droplets in the spray and on the air entrainment. Nozzle geometry as well as nozzle internal flow conditions influence many of these spray properties. An experimental study of the influence of the nozzle geometry on these properties has been conducted. The spray structure and the particle size distribution are determined using image shadowgraphy, the axial velocities near the nozzle outlet have been measured using Laser Correlation Velocimetry. Gas velocities are measured using Fluorescent Particle Image Velocimetry. It is found that the cavitation plays a role of major importance on the atomization process and on the interaction between the liquid spray and the surrounding gas