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.