WALL VISUALIZATION OF SWIRLING DECAYING FLOW USING A DOT-PAINT METHOD

This paper deals with the visualization of swirling decaying flow in a n annular cell fitted with a tangential inlet. A wall visualization me thod, the so-called dot-paint method, allows the determination of the flow direction on both cylinders of the cell. This study showed the co mplex structure of the flow field just downstream of the inlet, where a recirculation zone exists, the effects of which are more sensitive o n the inner cylinder. The flow structure can be considered as three-di mensional in the whole entrance section. The swirl number and the entr ance length were estimated using the measured angle of the streamlines . Experimental correlations of these two parameters, taking into accou nt the Reynolds number and the axial distance from the tangential inle t, are given.