A dimensional analysis approach for modelling the size of droplets formed by bi-fluid atomization
2015
Mejean, Serge | Accart, Philippe | Galet, Laurence | Schuck, Pierre | Le Floch-Fouéré, Cécile | Delaplace, Guillaume | Jeantet, Romain
This paper presents a dimensional analysis (DA) § approach of the atomisation process using a bi-fluidnozzle, allowing to predict droplet sizes of model solutions and skimmed milk concentrates in largeranges of operating conditions. Experimental results confirmed the atomisation mechanism describedin the literature, by underlining that the spraying operation is controlled by the coupling of liquid physicochemicalproperties (viscosity, surface tension, density) and operating conditions (air pressure andliquid flow rate). It was also highlighted that droplet coalescence occurs from a certain distance to thenozzle, counteracting the atomisation mechanism and leading to a reincrease in the droplet size whenmoving away from the nozzle. Consequently, the modelling of droplet size by DA was improved by adaptingthe model coefficients of the dimensionless process relationship to the involved mechanisms: eitheratomisation only close to the nozzle outlet or atomisation followed by droplet coalescence at longer distanceto the nozzle.
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