Study on instability strengthening of flow field in stirred tank

Background: Low-frequent instabilities within flow pattern of stirred tank (ST) which well-known as macroinstability (MI) further as flow field instability has significant additional effect to common turbulence concerning effectivity of mixing process. Methods: In this work, numerical simulation methods were used to study the impact of baffle on flow field instability. Significant Findings: The results showed that flow field instability in baffled stirred tank (BST) was full of global tank compared with unbaffled stirred tank (Un-BST), and the instability of near baffle zone was stronger than that in near impeller zone. By comparing the power consumption in ST equipped with different structure baffles, find that the punched baffle stirred tank (Pun-BST) and isolated baffle stirred tank (IsoBST) system have lower power consumption than the traditional baffle stirred tank (Trad-BST) system. Also, the degree of global instability decreased partly. In addition, the instability intensity of near baffle zone in the Pun-BST system was lifted locally, and the maximum increase can be as much as 4 times, compared with Un-BST. (c) 2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

The baffle has a significant impact on the flow field instability in the stirred tank, with higher intensity in the overall tank and particularly in the vicinity of the baffle. The punched baffle and isolated baffle systems have lower power consumption and partially reduce the overall instability.