Unsteady aerodynamics of elastic avian-inspired morphing wing during the folding process

This paper presents an aeroelastic analysis and aerodynamic load prediction framework for elastic avian-inspired morphing wings, in which the time-varying features of structural folding are added to the simulation. The framework uses the viscous vortex particle method to establish the unsteady aerodynamic model, and parameterizes the structural dynamic model by manifold tangent space interpolation. The transient response of the time-varying structure is solved through time finite element formulations. A wing prototype is manufactured for wind tunnel testing to initially validate the effectiveness of the method proposed, verifying that the prediction error of unsteady aerodynamic loads of our method is not more than 8.9% compared with the experimental data. The result shows that the in-plane folding process will cause the actual aerodynamic loads to deviate from the steady state and the hysteresis loop in lift response, which depends on the folding direction and the morphing rate.