Experimental investigation of droplet coalescence in a full-cone spray from a two-fluid nozzle using laser diffraction measurements

Droplet mean sizes and size distributions were measured in a water spray from a two-fluid nozzle with a full-cone spray by means of a light-scattering technique. The range of operating conditions was water flow rates from 16.7 to 40 ml/min and airflow rates from 11.5 to 14.6 liters/min. The measurements were taken at various axial locations from 45 to 245 mm downstream of the nozzle exit, in order to study the droplet size evolution with distance. The aim was to determine how the amount of droplet coalescence can be increased, and to study the effects of different operating conditions and multinozzle atomization on coalescence. The results showed that droplet coalescence along the spray axis can be increased by decreasing the water flow rate and increasing the airflow rate. Multinozzle atomization has also been studied by pointing two nozzles toward each other. Under these conditions, the particle number density increases, which increases the collision rates and thus the probability of subsequent coalescence.