Effect of Swirl Chamber Length on the Atomization Characteristics of a Pressure-Swirl Nozzle

An investigation on characteristics of spray generated by a pressure-swirl atomizer with adjustable swirl chamber length was performed. Spray characteristics were studied within the range of (0.12 < length/diameter < 0.5) using water as the working fluid. Droplet Sauter mean diameter and velocity components were measured using a phase-Doppler particle analyzer device. The spray cone angle was measured from image processing of images captured by a set of Nd-YAG lasers and a high-speed camera. It was found that the swirl chamber length/diameter ratio significantly affects the spray characteristics such as droplet size distribution and mean diameter and also velocity profile. The spray pattern for the smallest ratio was observed as a hollow-cone type and then was changed to a solid-cone type by increasing the investigated parameter. The effective ratio of the swirl chamber was found to be in the range of (0.12 < length/diameter < 0.30), where all the dramatic changes occur.