展向自适应机翼总体气动特性分析

To determine the effect of folding angle on aerodynamic characteristics of spanwise adaptive wing, configuration with a 7:1 ratio between internal and external segments based on classical airfoil NACA0012 was designed. According to the structured grid and Reynolds averaged Navier-Stokes equations, the codes developed by ourselves were employed to investigate the overall aerodynamic performance and maneuverability in various speed domains and at different folding angles. The overall aerodynamic efficiency and folding angle effect on flow field characteristics at different folding angles of external wing were compared in terms of the lift-to-drag ratio and the wing surface pressure distribution. It is found that the symmetric folding of the spanwise adaptive wing can increase the aerodynamic efficiency significantly at appropriate folding angle in subsonic and supersonic flight regimes by up to 28%; the high aerodynamic efficiency in subsonic flight results from the combination of lift enhancement and drag reduction, while the high aerodynamic efficiency in supersonic flight mainly results from drag reduction; the aerodynamic characteristics in transonic flight conditions do not change significantly with the folding process. In addition, asymmetric folding of the external wing can also be used for maintain roll and yaw control over the entire flight envelope of the vehicle. By folding the external segment wing at different angles, the spanwise adaptive wing can adapt to different flight conditions and obtain better aerodynamic benefits, which can be applied to the next generation of subsonic or supersonic airplanes.