A dimensional analysis approach for modelling the size of droplets formed by bi-fluid atomization
Résumé
This paper presents a dimensional analysis (DA) § approach of the atomisation process using a bi-fluid
nozzle, allowing to predict droplet sizes of model solutions and skimmed milk concentrates in large
ranges of operating conditions. Experimental results confirmed the atomisation mechanism described
in the literature, by underlining that the spraying operation is controlled by the coupling of liquid physicochemical
properties (viscosity, surface tension, density) and operating conditions (air pressure and
liquid flow rate). It was also highlighted that droplet coalescence occurs from a certain distance to the
nozzle, counteracting the atomisation mechanism and leading to a reincrease in the droplet size when
moving away from the nozzle. Consequently, the modelling of droplet size by DA was improved by adapting
the model coefficients of the dimensionless process relationship to the involved mechanisms: either
atomisation only close to the nozzle outlet or atomisation followed by droplet coalescence at longer distance
to the nozzle.
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