Multidisciplinary design optimization for the preliminary design of aeronautical configurations

The paper presents an approach developed primarily by the authors for the integrated modeling of structures, aerodynamics, aeroelasticity and flight mechanics. The motivation for the formulation is MDO/PD (Multi-Disciplinary Optimization for Preliminary Design) for innovative aircraft configurations, and is therefore first-principle based, since in this case the designer cannot rely upon past experience. The methodology is geared specifically towards MDO/PD for civil aviation. The emphasis here is on wing design - the fuselage is assumed as given. The stress analysis is based on finite elements for beams, rods and in-plane loaded plates, whereas the structural dynamics is based upon natural modes, which are evaluated by the same finite-element algorithm. For the aerodynamic analysis, a boundary-element quasi-potential-flow method is used for both steady and unsteady aerodynamics. An elementary boundary layer model is used to include the steady viscous effects and estimate the drag. A reduced order model (ROM) for the unsteady-aerodynamics forces is used in dynamic aeroelasticity. The numerical formulation has been applied to a specific test case - an innovative box-wing configuration denoted as Prandtlplane, which has, as a distinguishing feature, a low induced drag. The numerical results obtained for this configuration are presented, along with the comparison with those for an equivalent conventional wing configuration. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.