Transient aeroelastic responses and flutter analysis of a variable-span wing during the morphing process

To investigate the transient aeroelastic responses and flutter characteristics of a variable-span wing during the morphing process, a novel first-order state-space aeroelastic model is proposed. The time-varying structural model of the morphing wing is established based on the Euler–Bernoulli beam theory with time-dependent boundary conditions. A nondimensionalization method is used to translate the time-dependent boundary conditions to be time-independent. The time-domain aerodynamic forces are calculated by the reduced-order unsteady vortex lattice method. The morphing parameters, i.e., wing span length and morphing speed, are of particular interest for understanding the fundamental aeroelastic behavior of variable-span wings. A test case is proposed and numerical results indicate that the flutter characteristics are sensitive to both of the two morphing parameters. It could be noticed that the aeroelastic characteristics during the wing extracting process are more serious than those during the extending process at the same morphing speed by transient aeroelastic response analysis. In addition, a faster morphing process can get better aeroelastic performance while the mechanism complexity will arise.