Visualization of Taylor-Dean flow in a curved duct of square cross-section

The secondary flow in a curved duct of square cross-section is investigated experimentally using a visualization method. Three walls of the duct (except the outer wall) rotate around the center of curvature and an azimuthal pressure gradient is imposed. Photographs of the flow in a cross-section at 180° downstream from the curved duct entrance are taken by changing the flux (Dean number) at a constant rotational speed (Taylor number) of the duct walls. Several types of secondary flow are detected. The variation of the flow patterns with change of flow parameters is compared with that of numerical calculations and is found to be in good agreement. The diagram showing types of secondary flow patterns in the Taylor-Dean number plane is obtained.