Meeting Abstract
Owls are a master to achieve silent flight in gliding and flapping flights under natural turbulent environments owing to their unique wing morphologies, normally characterized by leading-edge serrations, trailing-edge fringes and velvet-like surfaces. How these morphological features affect aerodynamic force production and aeroacoustic noise suppression is of significance for aerodynamic / aeroacoustic control in biomimetic designs of owl-inspired adaptations for various fluid machineries. In this study, we address a large-eddy simulation-based study of owl-inspired single feather wing models with and without leading-edge serrations over a broad range of angles of attack (AoAs) from 0° to 20°. Our results show that leading-edge serrations can passively control the laminar-turbulent transition over the upper wing surface, and hence stabilize the suction flow. We also find that there exists a tradeoff between force production and turbulent flow control (i.e. aeroacoustic control): poor at lower AoAs but capable of achieving equivalent aerodynamic performance at higher AoAs > 15° compared to the clean model. Furthermore, through mimicking wind-gusts under a longitudinal fluctuation in free-stream inflow and a lateral fluctuation in pitch angle, it is revealed that the serration-based passive flow control mechanisms and the tradeoff hold independently to the wind-gust environments, demonstrating the aerodynamic robustness associated with the leading-edge serrations.
