Premium
Flow patterns and mixing rates in agitated vessels
Author(s) -
Norwood K. W.,
Metzner A. B.
Publication year - 1960
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.690060317
Subject(s) - baffle , reynolds number , mixing (physics) , impeller , mechanics , volumetric flow rate , flow (mathematics) , newtonian fluid , work (physics) , materials science , thermodynamics , physics , turbulence , quantum mechanics
Mixing rates in agitated vessels are predicted through measurement of the flow patterns which determine them. These measurements suggest the use of a model that assumes that nearly all the mixing occurs in a small “perfectly mixed” region near the impeller, with flow throughout the remainder of the tank serving primarily to bring the fluid into this region of the impeller. On the basis of this model, equations were developed for relating volumetric flow rates, hence the mixing rates, to the operating variables. While the theory could be checked directly only to Reynolds numbers of slightly over 600 (owing to limitations of the experimental technique employed in this part of the mixing‐rate studies), the volumetric flow rates could be measured from Reynolds numbers of 36 to 1.7 × 10 4 . The times required for completion of an acid‐base neutralization (terminal mixing) were also measured from Reynolds numbers of 1.6 to 1.8 × 10 5 . Flat‐blade, dimensionally similar turbines with diameters of 2, 4, and 6 in. were used. Tank diameters ranged from 5.76 to 15.5 in. The baffle width equaled one tenth of the tank diameter in all runs. All the data were for Newtonian fluid systems, but the extension of this work to non‐Newtonian materials is discussed briefly.