Aerodynamic shape design for rotor airfoils via genetic algorithm

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Aerodynamic shape design for rotor airfoils via genetic algorithm

Fanjoy, D.W. / Crossley, W.A.

The GA (Genetic Algorithm) has been shown to be a useful tool in engineering design problems. Here, the GA has been used to solve a helicopter rotor airfoil design problem. A binary tournament, uniform crossover GA was used in conjunction with a panel method/integral boundary layer method aerodynamic code. Twenty-one variables representing the surface of the airfoil were operated on by the GA to maximize lift-to-drag ratio at three flight conditions representing the 75 % radius station of an example rotor in forward flight with constraints on minimum lift coefficient, maximum moment coefficient, and flow separation from the airfoil. It was found that the GA could consistently design a non-traditional airfoil to achieve its objectives, and that the resulting designs exhibited characteristics more favorable than the NACA 0012 section of the original example rotor and the VR-7 section. While using the GA for shape design appears quite promising, an issue with the study is that the quality of the results is a reflection of the accuracy of the aerodynamic analyses used; discussion is provided about this topic. The GA design methodology described in this study shows promise for coupling with airfoil structural constraints and may lead to a more fully developed topology design approach.