Vortex Shedding and Aerodynamic Performance of Airfoil with Multiscale Trailing-Edge Modifications

Abstract

An experimental investigation was conducted into the nature of the vortex shedding generated by truncated and nonflat serrated trailing edges of a NACA 0012 wing section as well as the aerodynamic performance of such trailing edges. In line with previous findings, the truncated trailing edge generates a significant amount of vortex shedding, while increasing both the maximum lift and drag coefficients, resulting in an overall reduction in the maximum lift-to-drag ratio compared to a plain NACA 0012 wing section. By decreasing the chevron angle of the nonflat trailing-edge serrations (i.e., by making them sharper), the energy of the vortex shedding significantly decreases, and the lift-to-drag ratios increase compared to a plain NACA 0012 wing section. Fractal/multiscale patterns made of scaled-down repetitions of these serrations were also investigated with a view to further improve performance. It was found that the energy of the vortex shedding increases with an increasing fractal iteration if the chevron is broad () but decreases for sharper chevrons (). It is believed that if is too big, the multiscale trailing edges are too far away from each other to interact and break down the vortex shedding mechanism. Fractal/multiscale trailing edges are also able to improve aerodynamic performance compared to the NACA 0012 wing section.