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An experimental study of the steady and unsteady flow characteristics of stirred reactors

Published online by Cambridge University Press:  21 April 2006

M. Yianneskis ,
Z. Popiolek  and
J. H. Whitelaw
M. Yianneskis
Affiliation:
Kings College London, Mechanical Engineering Department, Strand, London WC2R2LS, UK
Z. Popiolek
Affiliation:
Instytut Ogrzewnictwa, Wentylacji, i Ochrony Powietrza, Politechnika Slaska, 44 – 101 Gliwice, Poland
J. H. Whitelaw
Affiliation:
Fluids Section, Mechanical Engineering Department, Imperial College of Science and Technology, Exhibition Road, London SW7 2BK, UK
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Abstract

Liquid flow in a baffled stirred reactor vessel driven by a six-blade disk impeller has been investigated experimentally. Laser-slit photography provided an overview of the flows which were quantified by measurements of velocity characteristics, obtained with a laser-Doppler anemometer, for an impeller rotational speed of 300 r.p.m. and for three impeller clearances from the bottom of the vessel. The mean flow results show an inclination of the impeller stream and the formation of ring vortices above and below the impeller, which depend on the clearance; the flow was strongly three-dimensional with large regions having circumferential velocities in a direction opposite to that of the impeller rotation. Impeller-induced torque measurements show that the Power number is invariant with clearance for turbulent-flow Reynolds numbers ([ges ] 40000) and increases with impeller diameter. The flow structure was controlled mainly by convection and pressure forces with turbulent mixing important in the impeller region.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 175 , February 1987 , pp. 537 - 555
Copyright
© 1987 Cambridge University Press

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