Optimization and comparison of strut-braced and high aspect ratio wing aircraft configurations including flutter analysis with geometric non-linearities

Abstract

Novel aircraft designs employing wings with high aspect ratio, such as the strut-braced wing (SBW), are one way to reduce their environmental impact. However, the flexibility of longer and more slender wings leads to higher deformations in cruise flight and off-design conditions. Therefore, the interdependence between aerodynamics and structure should be assessed in a multi-disciplinary design optimization (MDO) framework. Although MDO is computationally expensive, it can be mitigated by the use of surrogate models and efficient global optimization methods. This work aims to optimize a SBW aircraft using surrogate models considering flexibility effects. Another objective is to compare the resulting SBW aircraft with a similarly optimized conventional high aspect ratio wing (HARW) aircraft. Both optimized designs are compared regarding their potential fuel consumption and mass benefits under structural and aeroelastic constraints. Despite slightly heavier, the SBW design was found to improve the aerodynamic efficiency compared to an equally optimized HARW configuration. Further, non-linear aeroelastic analyses using multi-fidelity tools were carried out to assess if geometric non-linearities affect the optimized designs. These, while expensive to assess, offer further optimization potential for complex structures.