| The production of droplets smaller than the nozzle diameter of a pneumatic drop-on-demand generator has been investigated. The theory governing the formation of these droplets and accordingly, the required pressure variation within the droplet generator has been studied. Experiments were carried out using water/glycerin mixtures with different glycerin concentrations and molten tin. To produce small droplets, various experimental settings were studied and the formation of droplets was photographed using a CCD camera. When producing molten tin droplets, to prevent oxidation effects, droplets were produced in a chamber with low oxygen concentration (<150 ppm), which required modifications to the system.; Finally, the effect of experimental parameters on formation of small droplets and size distribution has been studied. These parameters include the gas supply pressure, pressure pulse width, diameter and number of nozzles, exit vent tube length, and ejection rate. |
