Preliminary Aero-Elastic Optimization of a Twin-Aisle Long-Haul Aircraft with Increased Aspect Ratio

Abstract

This paper presents a preliminary study on the improvement of the fuel efficiency of a civil transport aircraft, focusing on the aero-elastic optimization of an increased aspect ratio wingbox. The wing is stretched, increasing its aspect ratio, and a trade-off between the improved aerodynamic efficiency and the structural mass identifies an optimal aspect ratio for such aircraft. The aeroelastic optimization is performed with NeOPT, a structural optimizer for conceptual and preliminary design phases. The analysis considers different materials and structural solutions for the wingbox and tackles aeroelastic constraints, such as flutter and aileron efficiency, from the preliminary design phases. The fuel consumption of the sized aircraft is evaluated with a simplified approach that provides an indication of the fuel efficiency. The results show how a composite wing with increased aspect ratio can save up to 6.9% of fuel burnt with respect to the baseline aluminum wing. The results are extended at fleet level, achieving a 2-million-ton cut in CO2 emissions and a saving of USD 1.28 million on fuel-related costs.

High Aspect Ratio Composite Wings: Geometrically Nonlinear Aeroelasticity, Multi-Disciplinary Design Optimization, Manufacturing, and Experimental Testing

“…A lighter wing reduces stress in the structure, improves fuel efficiency, and enhances overall performance. It is vital for striking the right balance among structural, aeroelastic, and material requirements in high aspect ratiohigh aspect ratio wing designs [1]. These wings endure substantial bending and torsional loads, demanding proper design to prevent failure.…”

A Study on the Surrogate-Based Optimization of Flexible Wings Considering a Flutter Constraint

“…Even though reduced-order and surrogate models have been applied to aeroelasticity problems for some time [13], especially to study unsteady nonlinear aeroelasticity problems that arise from unconventional features such as limit-cycle oscillations [14][15][16], their usage for MDO problems considering flutter is scarce [17][18][19] in the open literature, particularly for MDO problems considering aerodynamic performance and structural weight. For instance, Sohst et al [17] developed an MDO strategy that uses multi-fidelity solvers and surrogate models to design strut-braced and high-aspect-ratio wings considering flutter and stress constraints.…”

“…Cea and Palacios [18] implemented an optimization framework based on ROMs that couples different open-source codes, including SHARPy, for minimizing the mass of a flexible strut-braced wing while accounting for flutter speed as a constraint. Toffol and Ricci [19] developed a methodology combining in-house codes with surrogate models to optimize the structural layout of a conventional aircraft such that its mass is minimized while considering stress and flutter constraints. The application of surrogate models based on machine learning is scarcer.…”

Flutter Optimization of Large Swept-Back Tri-Wing Flight Vehicles

“…Aeroelastic instabilities are some of the critical issues affecting the reliability and safety of military and commercial aircraft [1][2][3]. The tri-wing configuration is usually adopted for large swept-back hypersonic flight vehicles [4,5], such as the American X-37B, the Soviet Union's Buran, the British Hotol, and the German Sanger [6][7][8]. The aileron structure of such flight vehicles is thin, which may lead to the flutter behavior.…”