Spray Characteristics of SAC Nozzle in Common-Rail System

Diesel nozzle is key interface between injection system and combustion chamber.Characteristics of spray atomization are very important.Single-hole nozzle was designed.The diameters of inlet and outlet were measured by Macrona.Flow rate of the nozzle at 10,MPa pressure were tested.Hydro grinding method was used to increase the flow coefficient by approximately 10%-15%.Injection rate and needle lift curve were measured at a given operation condition on the injection test bench.The results obtained with the home made program from the frozen picture could reflect the spray characteristics.Macroscopic characteristics like spray tip penetration,spray angle and area were investigated at different conditions with SAC nozzle.Increasing outlet diameter and K factor increase the spray tip penetration and the projected area and decreases the spray cone angle.Increasing ambient pressure decreases the tip penetration and the projected area,and increases the spray cone angle.Increasing injection pressure increases the tip penetration and the projected area,while spray cone angle shows decreasing and then increasing.Nozzle with taper hole can increase the flow coefficient to 0.93 compared with the traditional cylindrical hole.Nozzle with smaller outlet is appreciated to get better atomization on the satisfaction of fuel injection quantity and injection duration.