Figure 10 TheSauter mean diameter
(d32) and the maximum stable drop diameter
(dmax) in this study (a) versusWe-0.6; (b) comparison between the experimental
data with the predicted values.
Usually, the mechanism of drop deformation is deemed to be the
consequence of eddy-drop interaction. A drop lied in a turbulent flow
field undergoes the external disruptive stress and self-restoring
stress. Whether a drop breaks up or not and how the drop deforms depend
on the relative magnitudes of the two stresses. And the critical point
determines the maximum stable diameter of the drop,d max, the drop can break up only if its diameter
is larger than d max. For the given system and
operating conditions, the drop is more unstable when the drop size is
further from the equilibrium size, and the drop is more likely to be
deformed and broken.36 In other words, the multiple
breakup characteristics of the drop are also more distinct. Generally,
the percentage of binary breakup can be used to characterize the
multiple drop breakup behaviors. Figure 11a presented the proportion of
binary breakage for all systems in this study. It is indicated that the
percentage of the binary breakup is lower for the larger drop, and
varies with different systems and rotating speeds. According to the
previous analysis, the influence of the above factors can be
characterized by the relative distance to thed max. By defining a dimensionless parameterη = d / d max, Figure 11a is
transferred into Figure 11b. Meanwhile, we compared results in this
study with the experimental results of Hao Zhou et
al.44 in a pulsed disc and doughnut column. It can be
seen from Figure 11b that all data points lied within a narrow strip,
which indicates that the defined parameter η is appropriate to
describe the relative stability of a drop.