Adjoint based design optimization of subsonic airfoils with a panel code

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Berk_Sarıkaya_Thesis.pdf

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2022-7-25

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Sarıkaya, Berk

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An in-house panel code written in Fortran is automatically differentiated and developed into an adjoint-based aerodynamic shape optimization tool for airfoil profiles. The automatic differentiation tool, FDOT, is employed in reverse mode to obtain the discrete-adjoint solver. The adjoint-based sensitivity derivatives (i.e. gradient vector) are validated against the finite difference approach. The computed sensitivity derivatives are then employed for the gradient based aerodynamic shape optimization of subsonic airfoil profiles for given target lift and moment coefficients. In addition, an adverse pressure gradient minimization term is added to the objective function for milder stall characteristics. A multi-point design optimization method is also implemented for an improved off-design performance. Airfoils are parametrized by the Class Shape Transformation. Single and multi-point optimizations are driven by the open-source optimizer, DAKOTA, using a quasi-Newton method. Case studies for cambered airfoils at low angles of attack are presented for single and multi-point design optimizations. The surface pressure distributions and the aerodynamic loads for the optimum airfoil profiles are further verified with the open-source RANS solver, SU2. It is shown that the adjoint based design optimization methodology developed is efficient and robust.

Subject Keywords

panel method, discrete adjoint, aerodynamic optimization, multi-point optimization, adverse pressure gradient

URI

https://hdl.handle.net/11511/98565

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

B. Sarıkaya, “Adjoint based design optimization of subsonic airfoils with a panel code,” M.S. - Master of Science, Middle East Technical University, 2022.