EXPERIMENTAL COMPARISON OF ELECTROCHEMICAL AND DOT-PAINT METHODS FOR THE STUDY OF DECAYING SWIRLING FLOW

Swirling decaying flow in an annular cell fitted with a tangential inlet equal in diameter to the gap width was experimentally investigated. The attention was focused on the local flow field on both cylinders, the structure of which was determined using two experimental techniques: wall shear stress measurements achieved by means of the limiting electrodiffusional current on microelectrodes and a wall visualization method, the so-called dot-paint method which was used in order to determine the flow direction. This study showed the complex structure of the flow field just downstream of the tangential inlet, where a recirculation zone is set up, the effects of which are more sensitive on the inner cylinder, and the flow structure can be considered as three-dimensional in the whole entrance section.