Atomization and Sprays

IMPINGEMENT OF HIGH-PRESSURE GASOLINE SPRAYS ON ANGLED SURFACES

ABSTRACT

A combination of visualization and local measurements of velocity and droplet size characteristics of normal and angled impinging sprays at an injection pressure of 80 bar, chamber pressures of atmospheric and 12 bar, and injection duration of 3.2 ms has shown the formation of a spray moving along the wall after impingement. Angled plates at 80° and 45° produced nonuniform wall sprays, with the difference between maximum and minimum radii from impingement increasing with plate angle. The penetration of the wall spray was less at the higher chamber pressure, and much of the injected fuel appeared to form a liquid film on the surface, although this could not be verified from the images. The velocities of the droplets inside the wall spray showed that its thickness was less at the higher chamber pressure with smaller velocities and larger diameters. The average droplet diameter was smaller than that in the spray prior to impingement for both chamber pressures so that they were better able to follow the induced airflow circulation. The results also showed that the 45° impingement resulted in similar droplets to those of normal impingement. In general, the droplets forming the jet wall spray with both angles were mainly transported from the main spray, with contributions from splashing and reatomization closer to the main spray and from stripping of the liquid film farther downstream, where the wall spray tended to turn upward.