Effects of flexible surface deformation on aerodynamic characteristics of a high-aspect-ratio wing

The aeroelastic deformation of high-aspect-ratio wings in lightweight solar-powered unmanned aerial vehicles (UAVs) inevitably causes deviations between their designed and real-world flight performance. The implementation of flexible membrane skins brings the wing a more complex fluid–structural coupling deformation problem. This study presents a high-fidelity bidirectional aeroelastic analysis on the high-aspect-ratio wing of a solar-powered UAV. The research aims to conduct an in-depth and comprehensive investigation of the combined influence mechanism exerted by the deformation of the wing's main structure and flexible skin on aerodynamic performance, laminar flow characteristics, and flow separation behavior. The results indicate that the wing deformation, primarily that of the flexible wing surface, causes an earlier laminar–turbulent transition, an increase in the drag coefficient, a severe deterioration of the stall characteristics, and thereby a notable degradation in the aerodynamic performance. The findings of this work significantly contribute to filling the knowledge gap in the coupling interactions between the flexible wing surface and flow field at a Reynolds number around 3 × 105, and provide a crucial theoretical foundation for the aerodynamic design and flight performance optimization of solar-powered UAVs. The loosely coupled analysis method developed in this study can serve as a reliable and accurate analysis tool for the evaluation of next-generation solar-powered UAVs during the design phase.