Aerodynamic Optimisation of Modern Transport Wing using Efficient Variable Fidelity Shape Parameterisation

Abstract

Generic wrap-around aerodynamic shape optimisation technology is presented, and applied to a modern commercial aircraft wing in transonic cruise. The wing geometry is parameterised by a novel domain element method, which uses efficient global interpolation functions to deform both the surface geometry and corresponding CFD volume mesh. The technique also provides a method that allows geometries to be parameterised at various levels, ranging from global three-dimensional planform alterations to detailed local surface changes. Combining all levels of parameterisation allows for free-form design control with very few design variables. The method provides an efficient combined shape parameterisation and high quality mesh deformation technique that is totally independent of mesh type (structured or unstructured). Optimisation independence from the flow solver is achieved by obtaining sensitivity information for an advanced gradient-based optimiser (FSQP) by finite-differences. Results are presented for highly constrained optimisations of the modern aircraft wing in transonic cruise, using three levels of parameterisation (number of design variables), to assess the effect of parameterisation fidelity on the optimisation. The highest fidelity optimisation results in a totally shock-free geometry with an associated substantial reduction in drag.