Aerodynamic optimization design of wing under the interaction of propeller slipstream

The propeller slipstream effects usually create large difference to the flow field around wings, nacelles and other parts of turboprop aircraft compared with no slipstream effect. Thus, the slipstream effects should be taken into account in aerodynamic design of wings, leading to better aerodynamic characteristics under real flying condition which includes slipstream effects. Propeller slipstream is simulated using multiple reference frames (MRF) quasi-steady method based on Reynolds-averaged Navier-Stokes equations. Free form deformation (FFD) technology is used for parameterization of wings. A grid deformation method based on radial basis functions (RBF) interpolation is embedded in optimization for rapid grid regeneration. After the aerodynamic data of wing samples is obtained, a Kriging surrogate model is trained with these original samples and iteratively improved with EI (Expected Improvement) through optimization. Combining random weighted particle swarm optimization (PSO) algorithm with aforementioned methods, the optimization system is established. The optimization design result of a certain turboprop aircraft using this optimization system indicates that the wing and nacelle of the optimized configuration have a drag reduction of 3.98 counts and lift-drag ratio increase by 3.325% in cruising state. Therefore, the numerical method and the optimization system used are practical and valuable for wing design under slipstream effects.