STUDY OF THE DROPLET SPRAY CHARACTERISTICS OF A SUBSONIC WIND-TUNNEL

A finite difference, two-dimensional potential flow solver, and a three-dimensional particle trajectory code have been written to compute water droplet trajectories in a subsonic incompressible now wind tunnel. This method was used to study the spray cloud in the test section of a two-dimensional wind tunnel resulting from the injection of a distribution of water droplets in the settling chamber ahead of the inlet. The results of this computational study showed that the trajectories of the larger water droplets were affected by the droplet inertia and gravity more dramatically than that for the smaller particles. The calculated liquid water content across the test section indicated a high concentration near the tunnel centerline. The largest droplets were present at the test section only in the center one-third of the wind tunnel, whereas the smaller droplets spanned almost the entire test section width. This resulted in a computed droplet size distribution skewed toward the larger droplets in comparison with the initial Langmuir-D distribution. The distribution of particle sizes and concentrations required at the droplet injection point in the settling chamber for a Langmuir-D distribution of uniform liquid water content in the center third of the test section was computed.