Drop dynamics and size distribution in a dense spray produced by a twin-fluid atomizer

Abstract

Motivated by industrial applications, the spray assessment of twin-fluid atomizers is paramount for improving their design and performance. Although several studies have addressed the spray characteristics, the coupled analysis of the droplet sizes and velocities at high flow rates is still not sufficiently understood. Therefore, the present study investigates the spray instabilities from a specific variance of a Y-jet atomizer correlated to droplet size and axial velocity distribution along the spray centerline. The atomizer was operated at Reynolds numbers in the order of 104, resulting in different air-to-liquid mass ratios. For that, an experimental rig operated with air and water is available for spray analysis. Data obtained with a phase Doppler anemometer showed that the mass flow rate of both fluids is directly proportional to the velocities and inversely proportional to droplet diameters. The size-velocity correlations showed that closer to the spray, the smaller droplets had higher velocities than the bigger ones. As they flowed downstream the nozzle, the impingement between the droplets and their interaction with the surrounding air decelerated them and increased their size.