Characterization of solid-cone simplex mist nozzles

Water mist system with single-fluid low-pressure nozzle is studied. Three solid-cone simplex nozzles with X-type swirl-insert and orifice diameters of 1.65, 1.9, and 2.45 mm are characterized in detail. Discharge coefficients, spray cone angles, and mass flux density in the spray are measured for various injection pressures. Droplet size distribution is measured using particle/droplet image analyser system at various axial distances from the nozzle (0.55 <= z <= 1.75 m) and injection pressures (6-10 bar). Experimentally measured droplet number distributions are fitted by the log-normal distribution. Rosin-Rammler distribution is calculated from the experimental data and compared with measured droplet volume distributions. Relative span factor, Sauter mean diameter, volume median diameter, and average velocity of the spray are also measured. A relation between the mean diameter and characteristic diameter of the spray with its drop size distribution is attempted. Empirical correlations are developed for those characteristics of the spray which vary with axial distance from the nozzle. Correlations are presented as functions of experimental variables in the non-dimensional form such that generality is achieved for all the nozzles of the same design. Similar correlation is extended for the SMD of the spray from the nozzles of different design in the literature.