Pavel Novosad (University of Brno) and Michele Cattini (Aarhus University)

Analysis of effervescent spray stability using proper orthogonal decomposition

Effervescent atomization is influenced by the atomizer's internal geometry, operational parameters, and additional components, such as bubble-breakers or velocity profile modifying inserts. This study investigates the liquid discharge of three effervescent atomizers with a central liquid inlet at gas-to-liquid mass ratios (GLR) from 1 to 10%. The atomizers differ by having inserts in the liquid inlet line. These inserts aim to improve discharge stability by changing liquid velocity profile at the aeration point and reducing pressure waves through increase in liquid pressure-drop. Proper orthogonal decomposition (POD) analysis shows that the inserts reduce spray unsteadiness and change dominant flow patterns. This results in finer sprays without presence of liquid jets. The stable configurations also show less variance concentrated in the dominant modes.

Michele Cattini, Aarhus University, Danemark

Title to be announced

Coalescence of bubbles attached to solid substrates can lead to detachment at much smaller diameters than
what would be required for buoyancy-driven detachment. Understanding of this phenomenon can be important
in certain applications, e.g. electrochemical hydrogen production where bubble detachment controls bubble
coverage on the surface, and thereby the energy efficiency of the process. In the present study, the volume-of-
fluid implementation in Basilisk software is used to study the problem at a range of parameters including bubble
size (or Ohnesorge number), size ratio of two bubbles, and curvature of the substrate.