Wing Modulation and Aerodynamics of Hoverflies in Gust Perturbations

摘要

Flapping-Wing Micro-Air Vehicles are likely to suffer from airflow perturbations.They can mimic the wing modulation of insects in airflow perturbations.However,our knowledge of wing modulation of insects to airflow perturbations remains limited.Here,we subjected hoverflies to headwind and lateral gust perturbations and filmed their wing motions.Then,computational fluid dynamics was employed to estimate the effects of hoverflies’wing kinematic modulations.We also clipped off the antennae of hoverflies to test whether the wing kinematic modulations were different.Results show that hoverflies increase the mean positional angle and modulate the deviation angle to make the wing tip paths of upstroke and downstroke close to compensate for the pitch moment perturbations in the headwind gust.Hoverflies employ asymmetric responses in positional angle in the lateral gust.The stroke amplitude of the left(right)wing increases(decreases)and the mean positional angle of the left(right)wing decreases(increases)during the right lateral gust.Antennae have little effect on the wing kinematic modulations in the lateral gust.These asymmetric responses produce a roll moment,tilting the body to resist the side force generated by the gust.This is a typical helicopter model employed by hoverflies to alleviate the gust.These results provide insight into the remarkable capacity of hoverflies to contend with gusts and can also inspire the design of flapping-wing micro-air vehicles.