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Elham A.,Technical University of Delft | Elham A.,Flight Performance and Propulsion Group | Van Tooren M.J.L.,Technical University of Delft | Van Tooren M.J.L.,Flight Performance and Propulsion Group
AIAA Journal | Year: 2014

Amethod for wing-shape optimization is presented, in which the wing outer shape is optimized not only for the best aerodynamic efficiency but also for the minimum structural weight. The so-called airfoil effective distance is used to capture the influence of the wing outer shape on the wing-box structural weight. The airfoil weight index is defined based on the airfoil effective distance. Increasing the airfoil weight index results in decreasing the structural weight. The weight indexing method is used for airfoil multi-objective optimization for minimizing the aerodynamic drag as well as maximizing the weight index. The Pareto front for the drag and weight is found, and the airfoils on the Pareto front are used as the basis airfoils for a three-dimensional wing-shape optimization. The same method is applied to optimize the outer shape of three-dimensional wings for two objective functions: minimizing the wing drag and minimizing the wing structural weight. A response surface methodology is used to reduce the computational costs of the wing-shape optimization. The influence of the material used in the wing-box structure on the wing optimum outer shape is also investigated. Three different composite layups together with a metal alloy are tested. The aircraft maximum takeoff weight and the aircraft direct operating cost are used as the design figures of merit to identify the best wings among the wings on the Pareto fronts. The results show that the optimum wing outer shape is significantly influenced by the material used in the wing-box structure. Copyright©2013 by Ali Elham. Published by the American Institute of Aeronautics and Astronautics, Inc. Source


Mariens J.,Technical University of Delft | Mariens J.,Flight Performance and Propulsion Group | Elham A.,Technical University of Delft | Elham A.,Flight Performance and Propulsion Group | And 2 more authors.
Journal of Aircraft | Year: 2014

This paper presents the development of a quasi-three-dimensional aerodynamic solver, which provides accurate results for wing drag comparable to the higher-fidelity aerodynamic solvers at significantly lower computational costs. The proposed solver calculates the viscous wing drag using the combination of a two-dimensional airfoil analysis tool with a vortex lattice code. Validation results show that the results of the quasi-three-dimensional solver are in good agreement with higher-fidelity computational fluid dynamics solvers. The quasi-three-dimensional solver is used for a wing shape multidisciplinary design optimization. A multidisciplinary design optimization problem is formulated to design the wing shape of a typical passenger aircraft. The aircraft maximum takeoff weight is considered as the objective function. Two optimization algorithms, a local and a global optimum finder, are implemented in the multidisciplinary design optimization system. The optimization results indicate that the global optimization algorithm shows a slightly greater reduction in maximum takeoff weight. However, finding the global optimum needs about 20 times the computational time of the local optimization algorithm. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source

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