Factors Influencing the Circumferential Liquid Distribution From Pressure-Swirl Atomizers

Measurements of circumferential liquid distribution are carried out over ranges of injection pressure from 0.34 to 1.72 MPa (50 to 250 psi) using five different simplex nozzles to achieve variations in the discharge orifice length/diameter ratio from 0.5 to 4.0. Two additional simplex nozzles of the same flow number are also examined in order to ascertain the effect of variations in the number of swirl chamber feed slots on circumferential liquid distribution. Mixtures of water and glycerine are used to provide a twelve to one variation in liquid viscosity. The results obtained show that spray uniformity improves markedly at higher injection pressures. Increase in liquid viscosity also has a beneficial effect on spray uniformity. The most uniform circumferential liquid distributions are obtained with nozzles having a discharge orifice length/diameter ratio of between 1 1/2 and 2.