Aerodynamic analysis of gull-inspired flapping wings with spanwise folding

To investigate the aerodynamic effects of bird-inspired wing folding, an imitation seagull flapping-wing model was analyzed using overlapping and dynamic meshes. Results show: 1) Negative folding amplitudes (-20°) induce aerodynamic coefficient phase shifts, boosting lift by 12.9%; 2) Larger phase angles enhance aerodynamic coefficients and vortex structure complexity; 3) Increased initial folding angles reduce aerodynamic performance, particularly impacting lift. Vortex visualizations reveal that parameters primarily regulate unsteady forces through outer-wing vortex ring formation-shedding, with minimal inner-wing vortex variation. This work advances avian flight understanding and informs bionic flapping-wing vehicle design.