Transonic flutter prediction and aeroelastic tailoring for next-generation transport aircraft

Novel commercial transport aircra concepts feature large wing spans to increase their fuel e ciency; these wings are more exible, leading to more potential aeroelastic problems. Furthermore, these aircra y in the transonic ow regime, where utter prediction is di cult. ¿e goals for this thesis are to devise a method to reduce the computational burden of including transonic utter constraints in conceptual design tools, and to o er a potential solution for mitigating utter problems through the use of additive manufacturing techniques, speci cally focusing on a design methodology for lattice structures. To reduce the computational expense of considering transonic utter in conceptual aircra design, a physics-based low-order method for transonic utter prediction is developed, which is based on small unsteady disturbances about a known steady ow solution. ¿e states of the model are the circulation and doublet perturbations, and their evolution equation coe cients are calibrated using o -line unsteady two-dimensional ow simulations. ¿e model is formulated for swept high-aspect ratio wings through strip theory and 3D corrections. ¿e resulting low-order unsteady ow model is coupled to a typical-section structural model (for airfoils) or a beam model (for wings) to accurately predict utter of airfoils and wings. ¿e method is fast enough to permit incorporation of transonic utter constraints in conceptual aircra design calculations, as it only involves solving for the eigenvalues of small state-space systems. ¿is model is used to describe the in uence of transonic utter on nextgeneration aircra con gurations, where it was found that transonic utter constraints can limit the e ciency gains seen by better material technology.