Flow analogy of pseudoplastic liquid in geometrically similar stirred vessels based on numerical analysis.

Abstract

Three-dimensional numerical analysis of flow behaviour such as velocity components, shear rate and apparent viscosity of a highly viscous pseudoplastic Ellis liquid in stirred vessels was performed. The vessels used were geometrically similar, non-baffled ones of 0.2 to 0.8 m vessel diameter each with a 6-blade turbine, a paddle and an anchor-type stirring impeller.The analogy of flow fields in model and large-scale stirred vessels was investigated by applying the concept of representative shear rate to estimate the apparent viscosity of a power-law fluid proposed by Metzner et al. and Nagata. It was found that the normalized flow profiles of a pseudoplastic liquid in the scaled-up vessels were nearly consistent with those in the model vessel within the impeller blade region, while it was quantitatively shown that the deviation between the two profiles in the outer region of the impeller expands with increasing vessel diameter.