Atomization Uniformity in Gas -

There are two important aspects to good injector performance in rocket engines—the atomization performance (droplet size and distribution, for example) and uniformity of operation (even distribution of droplets in time and space). In general, both of these aspects are affected by the geometry and operating conditions of the injector. In studying atomization performance, prior work has largely focused on the atomization performance, partially because uniformity, especially temporal uniformity, can be difficult to quantify. Attempts are made here to correlate the behavior of large-scale disturbances on the surface of the film with spray behavior. While correspondences were difficult to determine when comparing film video to by-eye observations of the spray, comparisons to spray video were more promising. High speed video of the spray showed a richness of behavior not observed with the naked eye. It also provides more quantitative data on nonuniformities, particularly the degree to which the spray and injector centerline are not aligned. Finally, comparisons of dominant frequencies in the spray and film show that upstream flow disturbances propagate downstream leading to spray nonuniformities. Overall a clearer understanding of spray nonuniformities is emerging.