Aerostructural Optimization of Nonplanar Lifting Surfaces

Abstract

to findoptimalnonplanarliftingsurfacesandtoexplainthevariousfactorsandtradeoffsatplay.Apanelmethodand anequivalentbeam finite-elementmodelareusedtoexplorenonplanarliftingsurfaces,whiletakingintoaccountthe coupling and design tradeoffs between aerodynamics and structures. Both single-discipline aerodynamic optimization and multidisciplinary aerostructural optimization problems are investigated. The design variables are chosen to give the lifting-surface arrangement as much freedom as possible. This is accomplished by allowing a number of wing segments to vary their area, taper, twist, sweep, span, and dihedral, with the constraint that they must not intersect each other. Because of the complexity of the resulting design space and the presence of multiple localminima, anaugmentedLagrangianparticle swarmoptimizer isusedto solvethe optimizationproblems.When only aerodynamics are considered, closed lifting-surface configurations, such as the box wing and joined wing, are found to be optimal. When aerostructural optimization is performed, a winglet configuration is found to be optimal when the overall span is constrained, and a wing with a raked wingtip is optimal when there is no such constraint.