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Multimodality in Aerodynamic Wing Design Optimization

TitleMultimodality in Aerodynamic Wing Design Optimization
Publication TypeConference Papers
Year of Publication2017
AuthorsBons, NP, He, X, Mader, CA, Martins, JRRA
Conference Name18th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference
Date Published06/2017
Conference LocationDenver, CO
Keywordsaerodynamic, design, multimodality, optimization, shape, wing
The application of gradient-based optimization to wing design could potentially reveal revolutionary new wing concepts. Giving the optimizer the freedom to discover novel wing designs may increase the likelihood of multimodality in the design space. To address this issue, we investigate the existence and possible sources of multimodality in the aerodynamic shape optimization of a rectangular wing. Our test case, specified by the ADODG Case 6, has a high dimensionality design space and a large degree of flexibility within that design space. We study several subproblems of this benchmark test case and analyze the multimodality introduced by each set of variables. We find evidence of multimodality with both inviscid and viscous analysis. In the full case we find that optimization with inviscid analysis yields multiple non-intuitive local minima. Adding consideration of viscous effects does not remove the multimodality, but allows the multiple local minima to be explained with physical reasoning. Additionally, we find that the shape of the optimized wing is highly dependent on the interplay between induced and viscous drag, providing more incentive to consider viscous effects in the analysis. The best result found by the optimizer reduces the total drag of the baseline wing by 22%.
Citation Key1229