Investigation of the aerodynamic characteristics of leading-edge tubercles on biomimetic wings

In this study, the wave geometry in humpback whale flippers was modeled with a more realistic approach and the effects of the leading-edge tubercles on wing aerodynamics were investigated. Force measurements and flow visualization experiments were performed to investigate the effects of the leading-edge tubercles. The experiments were conducted in the Reynolds number range of 50000 – 120000 using 8 flipper models and 4 rectangular NACA 0020 airfoil models. According to the force measurements, the wavy models exhibited enhancement in lift compared to the baseline model at post-stall. Flow visualization results indicated the formation of counter-rotating vortex pairs on the wavy wing instead of the laminar separation bubble observed on the baseline wing. Similar trends were observed in the force measurement of the rectangular and flipper models. Models C3 and C6, which had the same non-dimensional Ms number defining the wave geometry, were identified as models with higher aerodynamic performance compared to both the baseline model and wavy models. The C6 model provided about 16% increase in maximum lift at Re=120000 compared to the baseline model. In addition, all flipper models having wave geometry improved stall characteristics by delaying the stall angle.