Secondary breakup of inelastic non-Newtonian liquid drops
Abstract
The secondary breakup of inelastic non-Newtonian liquid drops was investigated experimentally using high-speed photography, and then simulated using an extended version of the Taylor analogy breakup (TAB) model. Videos were used to determine breakup morphology and breakup times. The effects of material properties consistency (K) and flow behavior (n) indices on these quantities were also determined. Key findings are: (1) Non-Newtonian drop secondary breakup modes are qualitatively similar to those observed for Newtonian drops. The only major difference is that the bag stretches more before it ruptures and the resulting breakup fragments persist for a much longer time than their Newtonian counterparts. (2) Weber (We) and Ohnesorge (Oh) numbers are appropriate dimensionless groups for characterizing non-Newtonian drop breakup mode boundaries. Values that demark the bag boundaries are close to the corresponding Newtonian ones, while those for multimode breakup are significantly higher then their Newtonian counterparts. (3) Three bag breakup times were defined: initial, Tini, bag breakup time (Tbag), and rim breakup time (Trim). Tini was found to increase with K, but to be independent of n. Tbag and Trim were observed to be directly proportional to both indices. (4) Four multimode breakup times are reported: the first bag breakup time (Tbag1 ), the second bag breakup time (Tbag2), the rim breakup time (Trim) and the stamen breakup time (Tstamen). Similar to the bag breakup times, Tbag1 and Tbag2, as well as Tstamen and Trim were found to decrease with decreases in K and n. (5) The TAB model was extended to non-Newtonian liquids and used to predict Tini for bag breakup and the cross-stream radius at that instant. Predicted drop cross-stream radii were quantitatively closer to their corresponding experimental results, but there was some qualitative disagreement.
Degree
Ph.D.
Advisors
Sojka, Purdue University.
Subject Area
Mechanical engineering
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