A numerical study about the flight of the dragonfly: 2D gliding and 3D hovering regimes

The dragonflys ability of gliding and performing dexterous maneuvers during flight attracts the interest of scientists and engineers who aim at replicating its performances in micro air vehicles. The great efficiency of its flight is achieved thanks to the vortices generated by wing movements and thanks to the corrugations on their surfaces. The high freedom of control of each wing has been proved to be the secret behind the dragonfly capability to carry out incredible flight manoeuvers. The study presented in this paper analyzes two of the most common flight regimes of the dragonfly. Firstly, some CFD simulations of gliding are performed and drag and lift coefficients have been calculated, showing a good match with experimental data found in literature. Then, hovering has been studied using a methodology inspired to the Blade Element Momentum (BEM) theory, which is usually applied in the context of wind turbines design. The lift force calculated with this simulation corresponds to the weight of dragonfly, suggesting the correctness of this analysis.