The photograph illustrates water drop formation by a spray-plate type nozzle where a high velocity turbulent jet of water impacts the center of a circular plate and spreads concentrically outward. The resultant water film flows radically outward on the plate, detaches from the plate as a liquid fan sheet which breaks into concentric ligaments, and then breaks into individual drops with an approximately log-normal diameter distribution. The objective of the research was to obtain knowledge of the mechanisms of drop formation and to measure drop size distributions (using both photographs and a phase Doppler particle analyzer) as a function of the relevant parameters, such as nozzle velocity and diameter, and plate diameter for optimizing drop size distributions for center-pivot irrigation applications.

The photograph was obtained with a 4x5 inch view camera by back-illuminating the spray with a four microsecond duration electronic flash.

Reference:

McCreery, G.E., and Stoots, C.M., "Drop Formation Mechanisms and Size Distributions for Spray Plate Nozzles," Intl. J. Multiphase Flow, 22 431-452 (1996).