Aeroelastic Concepts in Civil Aircraft Wings Design
Commercial aircraft conceptual designers generally use a combination of experimental and relatively low fidelity analytical methods and simplify the design problem by quantifying design parameters based on experience and a historical database of existing aircrafts. Although, these methods are an effective approach early in civil aircraft design, their efficiency may be restricted when designing for many new technologies. Using a design situation that includes parameterization of design and analysis models and also the models and conceptual design parameters would enable us to update higher reliability models as the conceptual design parameters are changed. This is a particular requirement in the current context of increasing complexity and challenging economic situations. Higher fidelity methods could be employed, with this capability, to make better decisions during aircraft conceptual design. Aircraft designers have generally tried to limit the effects of aeroelastic deformations. However, due to the fact that lightweight aircraft design has received a considerable attention in recent years, the aeroelastic study of aircraft parts such as a wing has become really important. As structural flexibility increases, aeroelastic interactions with aerodynamic forces become an increasingly important consideration in aircraft design and aerodynamic performance. Consequently, accurate prediction of the aeroelastic instabilities is really important to estimate actual flight performance in the design procedure. Furthermore, loading heavy engine nacelles that are subjected to enormous follower forces is the basic configuration of the most modern transport aircrafts. The geometrical and physical parameters of a high thrust heavy engine changes the aeroelastic characteristics of the original wing and have a complicated influence on the aeroelastic characteristics of aircraft wings [1-4]. This occurs because of the engine inertial and elastic coupling effect with the wing. In this paper, the aeroelastic analysis of a commercial aircraft wing in the conceptual design phase is considered. The aeroelastic analysis is performed using NASTRAN and ZAERO software. The aircraft wing structure is modelled in NASTRAN. Then the aerodynamic loadings due to the wing structure deflections are computed in ZAERO. By coupling these two software, the aeroelastic analysis of the wing is conducted and flutter and divergence speeds are identified (figure 1). Results show that the aircraft fuselage and the fuel located in the wing fuel tanks have considerable role on static and dynamic aeroelastic instabilities.