Position-dependence straight-wing experiments of artificial coverts in flow separation control at a high Reynolds number高雷诺数下覆羽控制直翼型流动分离的位置影响实验

We experimentally investigate the leading-edge flow separation control effect of the bio-inspired coverts installed on a straight wing model at the chord Reynolds number of 5.0×105. By covert, we indicate the multiple rows of short and flexible contour feathers with serrated tips overlaying on the bird’s wings. They cover the edges of the remiges (long and stiff flight feathers) and keep the bird’s wings in a streamlined shape. When flow separation occurs, these artificial, flexible, and serrated coverts flap and flutter adaptively, driven by the ambient airflow, like the real feathers on the upper surface of a bird’s wing. In the wind tunnel tests, we used time-resolved particle image velocimetry (PIV) to measure the velocity vector fields on the upper surface of the wing, and hot-wire anemometer to measure the turbulent velocity fluctuations in the wake flow. When installed at 20% of the chord length, the coverts flap adaptively driven by the separated flow. When at 80%, on the other hand, the coverts are lifted upwards by the revised flow near the trailing edge and slightly flutter at a quasi-equilibrium state. Both cases show effective flow separation control results with smaller wake areas and attenuated fluctuation intensities.