CAD in Aerodynamic Aircraft Design

Abstract

Computational fluid dynamics (CFD) has become a state of the art analysis tool for nearly all phases of aircraft design. In contrast to CFD, computer aided design (CAD) is traditionally used in later design phases of an aircraft, when the design is almost frozen. However, with the appearance of parametric CAD systems a new design methodology was enabled, which was based on the capability of a parametric CAD system to replay construction sequences with varied design parameters. A parametric wing can be re-used to create a vertical tail plane or parts can be associated to other parts, which allow concurrent engineering practices. In the present study, these capabilities have been exploited to generate extremely variable aircraft CAD models ready for CFD. Furthermore, parametric construction strategies, which have been developed in the past, are applied to model the primary aircraft parts, such as wing, fuselage and nacelle and also secondary parts, such as the belly fairing, wing tips and pylon, with the CAD system CATIA V5. For the construction of curves, which are used to create surface lofts, primarily B-splines are utilized, where the coordinates of the control points can later be used as the design parameters. Finally, the capabilities of parametric CAD are demonstrated through design variations performed for conventional configurations and through design studies with non-conventional aircraft configurations, which are in the focus of current research.