Validating surrogate models and incorporating uncertainty quantification in multi-element airfoil design optimisation

Abstract

This work deals with the aerodynamics optimisation of a generic two-dimensional three element high-lift configuration. Specifically, it focuses on the development and validation of surrogate models, as well as their integration with optimisation algorithms, uncertainty quantification method, and other computational design tools in order to define and develop a better design methodology for high-lift systems. Special emphasis is put into the process itself to make it fast and highly automated yet keeping accuracy uncompromised. Although the high-lift system is applied only during take-off and landing in the low speed phase of the flight the cost efficiency of the airplane is greatly influenced by it. The ultimate goal of an aircraft high-lift system design team is to define the simplest configuration which, for prescribed constraints, will meet the take-off, climb, and landing requirements usually expressed in terms of maximum L/D and/or maximum CL. The ability of the calculation method to accurately predict changes in objective function value when gaps, overlaps and element deflections are varied is therefore critical. Despite advances in computer capacity, the enormous computational cost of running complex engineering simulations makes it impractical to rely exclusively on simulation for the purpose of design optimisation. To cut down the cost, surrogate models, also known as metamodels, are constructed from and then used in place of the actual simulation models. A detailed analysis of the integrated design system, the methods as well as the optimisation results are provided.