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Mixing of pseudoplastic fluids using helical ribbon impellers
Author(s) -
Shekhar S. Murthy,
Jayanti S.
Publication year - 2003
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.690491109
Subject(s) - impeller , shear thinning , agitator , mechanics , shear rate , ribbon , mixing (physics) , newtonian fluid , slip factor , non newtonian fluid , rotational speed , rheology , computational fluid dynamics , materials science , power law fluid , shear (geology) , mechanical engineering , physics , engineering , composite material , quantum mechanics
Abstract Helical ribbon impellers are widely used in chemical and process industries for the mixing of pseudoplastic fluids of high viscosity. The design of such impellers is based on an assumed linear relation between shear rate and the rotation speed of the impeller. A number of computational fluid dynamics (CFD) simulations of the flow field have been carried to verify this hypothesis. It is shown that while the shear rate varies greatly within the mixing vessel, there does exist a linear relationship between the impeller speed and the local shear rate near the tip of the impeller. The proportionality constant K s associated with this linear relation is found to be dependent on the geometric parameters of the system, but is largely independent of the flow behavior index. Based on these results, a new correlation, applicable to both Newtonian and power‐law fluids for power consumption, is proposed.