Enhancement of laminar mixing by an anchor impeller with rotationally reciprocating motion

Abstract

Rotationally reciprocating mixing, in which a plate impeller slowly rotates back and forth for only half a rotation, shows excellent fluid mixing performance at Re > 40. On the other hand, since vertical flow disappears at Re < 10, two-dimensional fluid mixing proceeds in the horizontal cross section of a cylindrical vessel, producing segmented mixing regions with a pair of central poor mixing zones. In this study, we investigated the usefulness of an anchor-type impeller in the expectation of enhancing two-dimensional fluid mixing under a laminar regime by utilizing the fluid flow through the central clearances. First, we examined the effect of the clearance size on the spreading behavior of tracer particles by numerical simulation. Time series of Poincaré sections are used to classify the tracer particles depending on their spreading behavior, which is then quantified by newly defined mixing ability. It is then elucidated that even a narrow central clearance could avoid the segmentation of the mixing region, while a vast central clearance produces additional isolated mixing regions in the clearance due to stable vortex flows. The tracer particles could uniformly spread in the entire circular cross section by increasing the impeller width and adjusting the flow rate in the central and wall clearances without segmentation. Furthermore, the experimental observation of streaklines could also demonstrate that the uniformity of the fluid mixing performance is improved considerably.

Investigation of mixing viscoplastic fluid with a modified anchor impeller inside a cylindrical stirred vessel using Casson–Papanastasiou model

“…The findings established Nusselt number correlations with Reynolds number and found the thermal behavior's dependence on inertia parameters. Additionally, additional experimental experiments were conducted to investigate and improve the thermal behavior of stirred vessels; SK et al 18 , Perarasu et al 19,20 , Kong et al 21 , Naik and Vinod 22 , Mahir et al 23 , Komoda and Date 24 .…”

Agitation of Viscoplastic Fluid in a Rotating Vessel Using Close Clearance Agitators

“…Their findings highlighted the impact of different rheological parameters on the flow pattern, heat exchange and power consumption. Later, Komoda et al [21] conducted a numerical investigation on the effect of various geometric parameters of the anchor impeller on fluid mixing characteristics, with a specific focus on achieving uniform fluid spreading. Following this, the authors conducted experimental observations of streaklines in the horizontal cross-section to validate the optimized anchor impeller design.…”