INSTABILITY STUDY OF AN ANNULAR LIQUID SHEET OF POLYMER PRODUCED BY ATOMIZATION
Advancing the chemical engineering fundamentals
Multifase Flows (T2-5P)
Keywords: non-Newtonian fluid; polymers; atomization; dispersion; air-blast atomizer; stability
A temporal stability analysis was carried out to model the atomization of a swirling viscous non Newtonian annular liquid sheet emanating from an air-blast atomizer subject to inner and outer inviscid swirling air streams. The dimensionless dispersion equation that governs the instability of a viscous annular liquid sheet under swirling air streams is derived. Numerical solutions to the dispersion equation under a wide range of flow conditions are carried out to investigate the effects of the liquid and gas flow on the maximum growth rate. The growth rate can be related to the breakup length of the liquid sheet.
It has been observed that when the liquid flow decrease, the growth rate increase, which indicates shorter breakup length and smaller drops because of lower values of liquid flow rate result in thinner films that break down into smaller drops.
An analysis of the dispersion diagrams shows that when the air flow increase, the growth rate increase, which indicates shorter breakup length and smaller drops, because of the liquid/air interaction produces waves that become unstable and disintegrate into fragments, and contract into ligaments, which in turn break down into drops.
When the liquid viscosity decrease, the growth rate increases, this indicates shorter breakup length and smaller drops.
The theoretical behaviour predicted by the dispersion diagrams were compared with the experimental results obtained from the atomization of alginate solution using an air-blast atomizer. It was found that the instability model proposed justify the experimental effects found for the atomization of a non-Newtonian fluid and under the work range for alginate flow rate and viscosity and air flow rate.
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Presented Tuesday 18, 13:30 to 15:00, in session Multifase Flows (T2-5P).
