Effect of geometric parameters on spray characteristics of air assisted pressure swirl atomizer

In the present work, a modified Pressure Swirl Atomizer (PSA) was introduced to operate as an Assisted Pressure Swirl Atomizer (AAPSA). Different mass flow rates of assisted air were experimentally tested. The studied parameters are the orifice length to diameter ratio (L/D-o), swirl chamber length/diameter ratio (L-s/D-s) and swirling passage size (width x depth). The spray characteristics were studied using water as the atomized liquid. The spray was photographed using a high-speed camera to determine the spray shape, the cone angle and the spray breakup length. Moreover, photos taken by the high-speed camera were processed using IMAGE J software to obtain the droplet size diameters. The spray concentrations were measured by the patternator tubes technique. The results indicated that the spray cone angle increased by increasing the value of the L/D-o ratio or by decreasing the assisted air mass flow rate. The spray concentration maximum value is shifted inward with the assist air injection. The breakup length decreased by about 65% for the PSA and 77% for the AAPSA when the value of the L-s/D-s ratio is decreased from 1.163 to 0.664. With the injection of assist air at a rate of 2 g/s, the Sauter Mean Diameter (SMD) is reduced by about 64% compared to a PSA having the same geometry. (C) 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University.