Combined Aerostructural Wing and High-Lift System Optimization

Abstract

A coupled-adjoint aerostructural wing optimization tool has been modi_ed to include the optimization of high-lift devices from the start of the optimization process. The aerostruc- tural tool couples a quasi-three-dimensional method with a _nite beam element model. In this paper, the quasi-three-dimensional method is modi_ed using the _ method of Van Dam to enable high-lift aerodynamic analysis. In order to estimate the maximum wing lift coe_cient of an elastic wing, the Pressure Di_erence Rule is coupled with the aerostruc- tural tool. The proposed method is able to compute wing drag and maximum wing lift coe_cient with reasonable accuracy compared to high-_delity CFD tools that require much higher computational cost. The coupled systems are solved using the Newton method for iteration. The sensitivities of the outputs of the tool with respect to the input variables are computed through combined use of the chain rule of di_erentiation, automatic di_eren- tiation and coupled-adjoint method. Using the presented tool, a sequential and combined gradient based optimization is performed in order to minimize the fuel weight of a Fokker 100 class aircraft. The combined optimization results in a fuel weight reduction of 4.1% while achieving a maximum wing lift coe_cient in both takeo_ and landing con_guration equal to that of the initial wing.