THE CFD APPROACH FOR SHEAR ANALYSIS OF MIXING REACTOR: VERIFICATION AND EXAMPLES OF USE

The paper presents experimental evidence for the potentials of CFDmethodology in revealing external flow and inner flow shear deformation ratesin stirred tanks. Two basic issues are considered: could CFD produce validsolutions for shear rates in mixing vessels, and could practical shear ratedifferences relevant to specific impeller designs be reproduced by CFD. In afirst part, the shear rate distribution in the flow fields of two basic impellerscomprising flat and fluid-foil blades have been simulated and compared withmeasurement data obtained by electro-diffusion. Based on these and otherreference data, coincidence of measured and simulation shear rates has beenfound. In a second part, a CFD shear deformation analysis procedure has beenintroduced and validated and shear rate functions relevant to two applications inviscous flow have been generated. The procedure is illustrated by practicalexamples showing its versatility for prompt characterisation of impeller sheardeformation performance. Straight forward impeller selection by using CFD isimplied.