Influence of Geometric Features on the Performance of Pressure-Swirl Atomizers

The spray characteristics of several different simplex pressure-swirl nozzles are examined using water as the working fluid. Measurements of mean drop size, dropsize distribution, effective spray cone angle, and circumferential liquid distribution are carried out over wide ranges of injection pressure. Eight different nozzles are employed in order to achieve a wide variation in the length/diameter ratio of the final discharge orifice. Generally, it is found that an increase in discharge orifice length/diameter ratio (l_o/d_o) increases the mean drop size in the spray and reduces the spray cone angle. The circumferential liquid distribution is most uniform when l_o/d_o=2. If l_o/d_o is raised above or lowered below this optimum value, the circumferential uniformity of the liquid distribution is impaired. The observed effects of l_o/d_o on spray characteristics are generally the same regardless of whether the change in l_o/d_o is accomplished by varying l_o or d_o.