Numerical comparison between symmetric and asymmetric flapping wing in tandem configuration

• Published in: Physics of fluids (1994) 2024-04, Vol.36 (4)
• Main Authors: Liu, Fangyuan, Li, Song, Xiang, Jinwu, Li, Daochun, Tu, Zhan
• Format: Article
• Language: English
• Subjects: Asymmetry; Flapping wings; Flight characteristics; Flow characteristics; Fluid flow; Numerical models; Phase shift; Reynolds number; Tandem configuration; Three dimensional analysis; Three dimensional models; Vertical flight; Vertical forces
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/5.0200547

Dragonflies show impressive flight performance due to their unique tandem flapping wing configuration. While previous studies focused on forewing-hindwing interference in dragonfly-like flapping wings, few have explored the role of asymmetric pitching angle in tandem flapping wings. This paper compares the aerodynamic performance of asymmetric dragonfly-like wings with symmetric hummingbird-like wings, both arranged in tandem. Using a three-dimensional numerical model, we analyzed wing configurations with single/tandem wings, advance ratios (J) from 0 to 0.45, and forewing-hindwing phase differences ( ϕ) from 0 ° to 180 ° at a Reynolds number of 7000. Results show that asymmetric flapping wings exhibit higher vertical force and flight efficiency in both single and tandem wing configurations. Increasing the phase difference ( ϕ) improves flight efficiency with minimal loss of vertical force in the asymmetric flapping mode, while the symmetrical flapping mode significantly reduces vertical force at a 180 ° phase difference. Additionally, symmetric tandem flapping wings unexpectedly gain extra vertical force during in-phase flapping. This study uncovers the flow characteristics of dragonfly-like tandem flapping wings, providing a theoretical basis for the design of tandem flapping wing robots.