He will be deeply missed by all who knew him.
Break-up and atomization of liquid surfaces or liquid/gas interfaces have widespread applications, ranging from two phase combustion to household sprays. For this reason, atomization and related problems have received considerable attention and various correlations, relating for instance the drop size to the flow variables, have been proposed. Recent, more deterministic approaches, aimed at understanding the mechanisms, attempted to relate the drop size to the relevant instabilities. The present talk will be focused on these, more deterministic studies.
After a rapid discussion of the different types of liquid jet instabilities and the relevant governing parameters, experimental results on Kelvin-Helmholtz instability of a gas/liquid shear layer will be presented. These results, together with a stability analysis, clearly show that when the gas momentum flux is large, the most amplified wavelength of this primary instability is controlled by the vorticity layer of the gas jet at the nozzle exit. However, no direct relationship between the droplet size and this wavelength emerges. The mean droplet size is rather related with the wavelength of a secondary, transverse instability. Various secondary instability scenarii have been proposed, the most likely one being a Rayleigh-Taylor instability of the liquid crests resulting from the primary instability. Recent experimental results will be presented which support such a Rayleigh-Taylor instability mechanism leading to droplet formation.
the Chesebrough Auditorium,
This also is the Mechanical Engineering Sesquicentennial Lecture. A reception in the Chesebrough lobby will immediately follow the lecture.