| Tóm tắt: | <p>This thesis presents a multidisciplinary and multi-objective design optimisation framework for transonic fan blades of modern high bypass ratio turbofan engines. The optimisation strategy applied is based on a twolevel approach consisting of a Differential Evolution algorithm coupled to a sequentially updated ordinary Kriging metamodel to accelerate the optimisation process. Aerodynamic as well as structural static and dynamic performance criteria are considered by means of high-fidelity threedimensional Computational Fluid Dynamics and Computational Structural Mechanics analysis tools. Multiple key operating points are considered in the optimisation process; aerodynamic performance is evaluated at top-of-climb and cruise conditions, while peak stresses are evaluated at take-off operation, taking into account centrifugal and gas loads. Blade vibration is furthermore assessed over the entire operating range. Aerodynamic performance is separately evaluated for core and bypass flows in order to match the requirements specified by the engine cycle design. The successful application of the optimisation system is demonstrated by example of two complex multi-objective, aerostructural fan blade design problems, including finite element structural models for a full titanium and a composite fan blade made from a carbon-fibre reinforced plastic material.</p> <p>In addition to aerodynamic and structural considerations, aeroelastic effects are becoming of increasing importance for modern lightweight fan blade designs. Flutter, which is a harmful aeroelastic instability, is of particular relevance. An investigation of computational flutter prediction techniques is presented in this thesis with the goal of assessing their potential applicability in an automated optimisation process, showing that today's most commonly applied method, known as the energy method, might lead to mispredictions of flutter stability for modern lightweight, low-stiffness blade designs.</p>
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