THE EFFECT OF TURBULENCE PROMOTERS ON MASS-TRANSFER - NUMERICAL-ANALYSIS AND FLOW VISUALIZATION

Abstract

Numerical investigations are made on mass transfer in a 2-dim. flow between two parallel plates with turbulence promoters fixed to the lower and/or the upper walls. The ‘zigzag-type’ and ‘cavity-type’ geometries are used, for which mass transfer and flow visualization studies are conducted in the laminar flow regime. The numerical results show that turbulence promoters enhance the mass transfer by forming a recirculating flow which causes a convective mass transfer effect and increases the wall shear stress in the main stream. The flow separations observed by visualization studies are in good agreement with the predictions made by the numerical analysis at Reynolds numbers ranging from 20 to 150. Also the visualization shows that the unsteady flow in the channel begins at Reynolds numbers of 250–300 for both geometries with the aspect ratio of 5.