Aeroelastic Optimization with an Economical Transonic Flutter Constraint Using Navier–Stokes Aerodynamics

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Structural optimization with a flutter constraint for a vehicle designed to fly in the transonic regime is a particularly difficult task. In this speed range, the flutter boundary is very sensitive to aerodynamic nonlinearities, typically requiring high-fidelity Navier–Stokes simulations. However, the repeated application of unsteady computational fluid dynamics to guide an aeroelastic optimization process is very computationally expensive. This expense has motivated the development of methods that incorporate aspects of the aerodynamic nonlinearity, classical tools of flutter analysis, and more recent methods of optimization. Although it is possible to use doublet-lattice method aerodynamics, this paper focuses on the use of an unsteady high-fidelity aerodynamic reduced-order model combined with successive transformations that allows for an economical way of using high-fidelity aerodynamics in the optimization process. This approach is applied to the common research model wing structural design. The high-fidelity aerodynamics produces a heavier wing than that optimized with doublet-lattice aerodynamics. It is found that the optimized lower wing skin thickness distribution using high-fidelity aerodynamics differs significantly from that using doublet-lattice aerodynamics.