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Fundamentals of the hydrodynamic mechanism of splitting in dispersion processes
Author(s) -
Hinze J. O.
Publication year - 1955
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690010303
Subject(s) - breakup , drop (telecommunication) , dimensionless quantity , mechanics , chemistry , weber number , turbulence , viscosity , thermodynamics , physics , reynolds number , telecommunications , computer science
The splitting of globules is an important phenomenon during the final stages of disintegration processes. Three basic types of deformation of globules and six types of flow patterns causing them are distinguished. The forces controlling deformation and breakup comprise two dimensionless groups: a Weber group N We and a viscosity group N Vi . Breakup occurs when N We exceeds a critical value ( N We ) crit . Three cases are studied in greater detail: (a) Taylor's experiments on the breakup of a drop in simple types of viscous flow, (b) breakup of a drop in an air stream, (c) emulsification in a turbulent flow. It is shown that ( N We ) crit depends on the type of deformation and on the flow pattern around the globule. For case (a) ( N We ) crit shows a minimum value ∼ 0.5 at a certain value of ( N Vi ) and seems to increase indefinitely with either decreasing or increasing ratio between the viscosites of the two phases. For case (b) ( N We ) crit varies between 13 and ∞, depending on N Vi and on the way in which the relative air velocity varies with time, the lowest value refers to the true shock case and N vi →0. For case (c) ( N We ) crit , which determines the maximum drop size in the emulsion, amounts to ∼1, and the corresponding values of N Vi appear to be small. A formula is derived for the maximum drop size.