Atomization
Atomization of liquid jet arises in numerous industrial applications. Injection in gasifiers and spray coating for pharmaceutical tablets are some of the examples. Many of these applications are very sensitive to the droplet size. Therefore, there is a need to understand the underlying mechanism of the breakup of a liquid jet.
We are specifically interested in the gas-assisted atomization. Typically for this type of atomization, the liquid jet is surrounded by a high-speed annular gas stream. The breakup of the liquid jet is mainly determined by the interfacial interaction between the gas and the liquid phase. Our goal is to study this interaction and develop a model to predict droplet size distribution for this type of atomization.
Some of the experimental techniques we use for this study are high-speed flow visualization and Phase Doppler Particle Analysis. The picture below shows a pair of laser beams shine across the spray area, the reflection of the light are collected by the Phase Doppler particle Analyzer (PDPA) and are converted into data such as droplet diameter and velocity. For more information about PDPA, please see the “Facilities & Methods” page.
Another technique used is high speed imaging, which is illustrated in the video below. Two synchronized cameras, perpendicular to each other, image the same region of the flow thanks to back-lights, allowing for the 3D charaterisation of the instabilities responsible for the spray characteristics (spreading, droplets distributions...). This video corresponds to a liquid Reynolds number of 1000 while the gas Reynolds number reaches about 16 000.
Due to the dense nature of the sprays studied, complementary measurements using X-ray imaging are also conducted at the Advanced Photron Source of Argonne National Laboratory: