A versatile droplet on demand generator based on active pressure control

The development of a novel on-demand droplet generator is reported in this paper based on off-the-shelf electromechanical components. With the ability to produce a broad range of droplet sizes, this device was designed to have minimum components without compromising reliability. The generator performance was assessed by producing water droplets for fire dynamics and suppression studies. Droplet formation at the tip of the nozzle was visualized using high-speed imaging. Stable and unstable regions can be identified easily through the images. Interchangeable nozzles can be used, allowing different droplet sizes. The setting parameters of the device allow accurate control of droplet size and initial speed. The device controls the liquid pressure actively and precisely. The active control of pressure and the ability to have specific droplet ejection parameters ensured the repeatability of droplet conditions. Characterization of the device is presented along with the calibration data, which can be collected in an efficient methodology. These data enable the selection of droplet size and speed when required. This system could easily be implemented in other research areas. Hence, the intention is to share and highlight the generator features for its use in a range of other scientific applications.