Effect of trailing-edge curvature on airfoil noise source and radiation characteristics

This study investigates the influence of surface curvatures near the trailing edge on acoustic sources and radiation characteristics of a National Advisory Committee for Aeronautics 0018 airfoil, employing wall-resolved large eddy simulations. Two trailing-edge curvature designs are examined: a concave configuration (M1) with a negative boat-tail angle and a convex configuration (M2) with a positive boat-tail angle. The wall-pressure spectrum (WPS) and phase interference characteristics are analyzed and compared for each design. The results reveal that the M1 configuration effectively reduces WPS at low and mid frequencies while exhibiting a modest increase at high frequencies. Overall, the M1 design enhances aerodynamic performance and achieves lower noise levels compared to the baseline airfoil. Conversely, the M2 configuration significantly increases WPS at low frequencies while reducing it at high frequencies. Collectively, the M2 design shows degraded aerodynamic performance and elevated noise levels relative to the baseline. To further assess noise performance, low-fidelity models are utilized to estimate noise levels under equivalent lift conditions. The findings suggest that the M1 design, characterized by a flattened trailing edge, offers noticeable noise reduction benefits under the same aerodynamic performance. This study provides insights into the prevalence of flattened curvature near the trailing edge of bird wings.