Shape Optimization and Sensitivity Analysis of a Morphing-Wing Aircraft

Morphing-wing concepts have received growing interests in the recent years for enhancing the multi-mission performance of unmanned aerial vehicle. However, to obtain a feasible morphing strategy, the optimization design studies are required. In this paper, an aerodynamic optimization study for a morphing-wing aircraft with variable sweep, span, and chord length was conducted to obtain the optimum configurations at subsonic, transonic and supersonic conditions. The optimization objective is to obtain maximum lift-to-drag ratios subject to lift coefficients and static stability constraints at each flight condition. A genetic algorithm in conjunction with surrogate models was employed to search optimum solutions in the entire design space. The aerodynamic forces are calculated by an Euler-based solver and friction drag estimation code. The optimum configuration corresponding to any flight condition can be determined through the optimization. A global sensitivity analysis based on the surrogate model was also carried out, hence the contribution of each design variable to the optimization objective can be analyzed. The results indicated that the optimum wing at subsonic speeds have a lower sweep angle and high aspect ratio, and the wing sweep has a primary contribution to lift-to-drag ratios, and the span is secondary; at transonic conditions, the medium-sweep wing is the optimum, and the contribution of the span is far more than other variables; at supersonic conditions, the optimum configuration becomes a high-sweep cropped delta wing, and the span has a dominant contribution, and the sweep is secondary.