| Summary: | This thesis is directed at developing and assessing a multifidelity model-based methodology for the flight performance analysis and multidisciplinary optimisation of flexible wing aerofoils. Such a strategy is pursued because of the high computational cost involved of solving such optimisation problems via high-fidelity simulations only. The methodology is applied to the preliminary design of a small flexible winged Unmanned Air Vehicle (UAV), the likes of which are particularly susceptible to wind gusts. The strategy adopted is directed at optimising both the passively adaptive structure and the shape of the flexible UAV wing for aerodynamic performance (i.e., drag reduction), weight reduction and gust response alleviation, formulated as an unsteady coupled Fluid- Structure Interaction (FSI) problem. A metamodel of the high-fidelity model response, based on a tuned low-fidelity one, is built in order to verify and validate the approach for aeroelastic problems. Both models are based on solutions of the aeroelastic equations for the wing Typical Section and the low-fidelity response tuned accordingly as prescribed by suitable Design of Experiments (DOEs). Several levels of complexity and computational cost are employed for modelling aerodynamics and structural dynamics. The role of aerodynamic damping, structural nonlinearities and turbulent Computational Fluid Dynamics (CFD) is investigated. Good agreement between the high-fidelity results and corrected low-fidelity ones shows that the methodology is suitable for use m aeroelastic performance optimisation problems. Using the multifidelity strategy developed, the flexible wing of a small UAV is optimised for best flight efficiency under aero-structural constraints. The wing structure is assumed fully flexible and a semi-analytical model for the aeroelastic analysis and gust response of a flexible Typical Section developed. Having tuned the low-fidelity response, a Genetic Algorithm (GA) is employed to fmd the global optimum, showing that a flexible wing aerofoil is characterised by a higher aerodynamic efficiency than its rigid counterpart.
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