A two-dimensional numerical based performance optimization of a novel integrated distributed horizontal-axis open-rotor propulsion system was performed in this study. The optimization was based on simultaneous geometrical modifications to the rotor blades and the wing structure, in addition to variations in the number of rotor blades. The geometries were defined as high order Bezier curves. The definition for the rotor blades was based on camber line and thickness distribution, while the wing was constructed from three separate Bezier curves for the cavity, pressure and suction sides. The geometrical optimization was carried out by varying the Bezier curve control points and performance evaluation through Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. The compressible flow solutions were obtained using the Fluent (ANSYS) 17 solver with Spalart-Allmaras turbulence closure. A single objective ensuring highest lift and thrust optimization of the geometry was performed for nominal cruise conditions using a meta-model based approach. This technique enables for the mathematical correlation between the geometrical variables and the objective function. The basic component of the proposed meta-model is the Kriging algorithm, which serves as the central information-processing hub for inference and optimization. The Kriging algorithm was further coupled with differential evolution which improved performance and allowed for finding the optimal geometrical structure with minimal computational expense. Examination of the results showed that an increasingly cambered and smooth curvature for the wing surfaces achieved better performance. Additionally, a higher number of blades also demonstrated similar effects.
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