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

Basic characteristics of prototype intermittent swirl-generating nozzles fo r gasoline direct injection were investigated. These prototype swirl nozzle s were fabricated by modifying commercial multipoint injection (MPI) nozzle s to operate at higher pressures. Experimental parameters included injectio n pressure, injection duration, and ambient pressure. Spray tip penetration and atomization performance were examined as a function of these parameter s. 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, a nd 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.