Characterization of prototype high-pressure swirl injector nozzles, part I: Prototype development and initial characterization of sprays

Abstract

Basic characteristics of prototype intermittent swirl-generating nozzles for gasoline direct injection were investigated. These prototype swirl nozzles were fabricated by modifying commercial multipoint injection (MPI) nozzles to operate at higher pressures. Experimental parameters included injection pressure, injection duration, and ambient pressure. Spray tip penetration and atomization performance were examined as a function of these parameters. Droplet mean diameter, D-32, of the swirl nozzle ranged from 20 to 28 mu m at an injection pressure of 5 MPa, which was about 30% smaller than that of the base MPI nozzles. Atomization characteristic was closely related to the overall velocity of the injected droplet cloud, ambient air density, and cone angle. Drop size distributions were found to fit to a Rosin-Rammler distribution and to be less dispersed than those of the air-assisted fuel injector.