Aerodynamic characteristics of rounded-corner rectangular cylinders based on wind tunnel model test

Through rigid model pressure wind tunnel tests and numerical simulations, the wind pressure for a right-angled rectangular cylinder with an aspect ratio of 2, and for rounded-corner rectangular cylinders with corner radius ratios (R/D) of 0.1, 0.2, 0.3, 0.4, and 0.5 was measured in a uniform flow field. The Reynolds number for the tests was 1.2 × 10⁵, and the wind direction angle (α) ranged from 0° to 90°. A detailed analysis examined the effects of wind direction angle and corner radius ratio on the aerodynamic parameters, including the mean drag/lift coefficients, fluctuating drag/lift coefficients and Strouhal number, and the flow mechanism was explained. The results indicate that at 0° wind direction angle, increasing R/D induces three distinct flow patterns: continuous separation, separation followed by reattachment, and attached flow without separation. Furthermore, two critical wind direction angles, α_cr1 (smaller) and α_cr2 (larger), categorize wind direction angles into three regimes: small (0° < α < α_cr1), intermediate (α_cr1 ≤ α ≤ α_cr2), and large (α_cr2 < α < 90°). The specific ranges of these regimes vary with the cylinder. Notably, α_cr1 exhibits a non-monotonic trend (first decreasing then increasing) with increasing R/D, whereas α_cr2 increases monotonically. Aerodynamic parameters vary more significantly within the small and large wind direction angle regimes than in the intermediate regime. These critical wind direction angles signify transitions in the surface flow state. These findings provide valuable insights for wind-resistant design optimization of rounded-corner rectangular structures in engineering applications.