Airfoil design using numerical optimization has addressed the problem of minimizing drag for a given lift constraint for one or more flight conditions. However, designers often want to avoid separation at off-design conditions regardless of the drag. This paper develops a separation constraint formulation for airfoil shape optimization. We perform multipoint optimizations and demonstrate how a separation constraint yields practical airfoil shapes. We compare results from single-point optimizations with and without a leading-edge radius constraint, which is a simple approach used as a surrogate to avoid separation, to an optimization where separation is constrained at a low-speed high-lift off-design point. Constraining the leading-edge edge radius improves the high-lift performance of the airfoil but not as much as constraining separation at the off-design point. We also compare the results of separation-constrained optimizations with optimizations where the drag at an off-design point is included in the objective. The latter formulation also produces optimal designs that are separation-free at the off-design points. However, the separation-constrained formulation produces airfoils with better cruise performance. Finally, we demonstrate the separation constraint efficacy at the off-design point with multiple cruise points. The results help guide parameterization and constraint formulation for airfoil design optimization problems.


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    Title :

    Airfoil Separation Constraint Formulation for Aerodynamic Shape Optimization



    Published in:

    Journal of Aircraft ; 62 , 1 ; 48-61


    Publication date :

    2025-01-01




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English




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