Evolutionary optimization of aerofoil profile

Simon Beltram (2017) Evolutionary optimization of aerofoil profile. EngD thesis.

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Abstract

This thesis deals with the heuristic optimization of an F1A free flight airfoil. The goal is to generate an airfoil that is better than the ones currently in use. We implemented three optimization algorithms, differential evolution (DE), Firework algorithm (FA) and Particle swarm optimization (PSO). Currently used airfoils, called LDA (Low-drag airfoil) are able to obtain high speed in the phase of climbing but in the free flight phase they fly poorly compared to their predecessors. With the help of optimization methods we aim to find an airfoil that performs both tasks well. All heuristic algorithms were developed in java programming language using a customized JMetal library. Each airfoil is presented with two Bézier curves, one for the upper and one for the lower half of the foil. This kind of presentation gives us more freedom and control, but it comes at a price - the software may generate irregular shapes due to randomness. That is why it is important to pay attention to structural constraints (i.e. airfoil thickness). Airfoils are evaluated using Xfoil [3] which calculates the characteristics of an airfoil. Our experiments show that L/D ratio is not a good indicator of airfoil quality and one has to take into account other parameters as well. A multi-objective criteria function would therefore be advisable.

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