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

The paper presents experimental evidence for the potentials of CFD methodology in revealing external flow and inner flow shear deformation rates in stirred tanks. Two basic issues are considered: could CFD produce valid solutions for shear rates in mixing vessels, and could practical shear rate differences relevant to specific impeller designs be reproduced by CFD. In a first part, the shear rate distribution in the flow fields of two basic impellers comprising flat and fluid-foil blades have been simulated and compared with measurement data obtained by electro-diffusion. Based on these and other reference data, coincidence of measured and simulation shear rates has been found. In a second part, a CFD shear deformation analysis procedure has been introduced and validated and shear rate functions relevant to two applications in viscous flow have been generated. The procedure is illustrated by practical examples showing its versatility for prompt characterisation of impeller shear deformation performance. Straight forward impeller selection by using CFD is implied.