Experimental investigation on the aerodynamic behavior of square cylinders with rounded corners

• Wind-tunnel tests on square cylinders with rounded corners.
• Rounded corners reduce the critical angle of incidence.
• Rounded corners produce an intermittent behavior at the critical angle of incidence.
• Observed a reattaching-flow regime for r/b=2/15 with the inversion of the lift slope for zero angle of incidence.

The influence of corner shaping on the aerodynamic behavior of square cylinders is studied through wind tunnel tests. Beside the sharp-edge corner condition considered as a benchmark, two different rounded-corner radii (r/b=1/15 and 2/15) are studied. Global forces and surface pressure are simultaneously measured in the Reynolds number range between 1.7×104 and 2.3×105. The measurements are extended to angles of incidence between 0° and 45°, but the analysis and the discussion presented herein is focused on the low angle of incidence range. It is found that the critical angle of incidence, corresponding to the flow reattachment on the lateral face exposed to the flow, decreases as r/b increases and that an intermittent flow condition exists. In the case of turbulent incoming flow, two different aerodynamic regimes governed by the Reynolds number have been recognized.