An Adjoint-based Derivative Evaluation Method for Time-dependent Aeroelastic Optimization of Flexible Aircraft

The goal of this paper is to develop techniques to enable the use of aeroelastic constraints within a high-fidelity design optimization framework. As a first-step towards this goal we have developed a fully-coupled aeroelastic analysis tool that includes a coupled structural and aerodynamic analysis as well as rigid-body degrees of freedom. This work departs from previous efforts in two important ways: first, we use solution techniques that are tailored for high-performance parallel computing; second, we implement a fully-coupled adjoint method using a coupled-Krylov approach for the evaluation of derivatives of time-dependent functions of interest. The coupled Newton–Krylov approach enables us to perform simulations in the full structural space without modal reduction. The timedependent adjoint approach enables us to evaluate the gradient of functions of interest for cases with hundreds or thousands of design variables in a cost similar to the time-dependent simulation. In order to demonstrate our framework, we verify the gradient accuracy of some preliminary simulations of three transport aircraft wings with increasing span subject to gust loads.