Variable-fidelity aerodynamic shape optimisation of single-element airfoils at high-lift conditions

A computationally efficient simulation-driven variable-fidelity design methodology for single-element airfoils at high-lift conditions is described. Direct optimisation of an accurate but computationally expensive high-fidelity simulation model based on the Reynolds-averaged Navier-Stokes equations and a one equation turbulence model is replaced by iterative updating and re-optimisation of a cheap surrogate. The surrogate model exploits a low-fidelity model (a polynomial approximation of the high-fidelity model data) and appropriate correction that aim at aligning its corresponding airfoil surface pressure distribution and skin friction distribution with that of the high-fidelity model using a shape-preserving response prediction technique. The test cases include lift coefficient maximisation of single-element airfoils at high-lift conditions, subject to a constraint on the drag coefficient. Over 83% reduction in the number of high-fidelity model simulations is demonstrated when compared to high-fidelity model optimisation using a pattern-search algorithm.