Parametric Deformation of Discrete Geometry for Aerodynamic Shape Design

Abstract

We present a versatile geometry platform for shape optimization of aerospace vehicles. The platform deforms discrete surface meshes using the computational geometry kernel of an open-source modeling tool called Blender. Several parametric deformation techniques are available, including lattice and cage-based deformation, as well as more intuitive skeletal and direct-manipulation techniques. Deformations are invoked through a back-end scripting interface, which we also use to implement custom deformation algorithms as plugins. Surface sensitivities are provided to support gradient-based optimization. The platform can be used in sequence with other geometry tools to enable flexible manipulation that a single constructive modeler (e.g. CAD) cannot always achieve alone. We also present an intuitive constraint-based deformation technique in which a sparse set of surface points serve as design variables. We test our platform on several standard aerodynamic design problems, including inverse airfoil design, shape-matching, and lift-constrained drag minimization for an airfoil with thickness constraints. A wing-fuselage integration problem demonstrates the approach in 3D. In a final example, our platform is pipelined with a constructive modeler to parabolically sweep a wingtip while applying a 1-G loading shape along the wingspan. This work is part of our larger goal of improving the flexibility and usability of discrete aerospace geometry tools by capitalizing on the computer graphics industry's sustained investment in geometry processing techniques.

Optimized Off-Design Performance of Flexible Wings with Continuous Trailing-Edge Flaps

“…Fortunately, 3-D soft-body animation tools are very accustomed to morphing geometric objects in a smooth and realistic fashion. The Blender 15 discrete geometry modeler is an open-source tool which has already been effectively used for shape optimization 16 and the aeroelastic analysis method. 7 For this work, the Blender modeler has been further enhanced to install a user-defined VCCTEF system on a typical discrete wing geometry.…”

Free-form deformation, mesh morphing and reduced-order methods: enablers for efficient aerodynamic shape optimisation

“…For a deeper insight, see Lassila and Rozza (2010); Koshakji, Quarteroni, and Rozza (2013); Forti and Rozza (2014) and Sieger, Menzel, and Botsch (2015) for an application very similar to ours. A comprehensive dissertation on different geometry deformation techniques (in particular FFD based techniques) can be found in Anderson, Aftosmis, and Nemec (2012).…”

Wing aerostructural optimization using the Individual Discipline Feasible Architecture

“…In this figure a sphere is morphed into a blended wingbody. From a sphere to a blended-wing-body [35] Due to this large deformation freedom with only relatively few design variables FFD is a very efficient parametrization technique which is increasingly being used in aerospace design by for example Nielsen and Anderson [36], Anderson et al [37], Samareh [32] and Palacios et al [27]. For example, Samareh [38] uses the FFD not only to change the airfoil shape in the deformation to aerodynamic shape design variables such as thickness,camber, twist, shear, and planform.…”