An Integrated Optimization Method of Wingtip Stealth/Aerodynamic Using Surrogate-Based Method

Abstract

AbstractStealth/Aerodynamic optimization of the wingtip is an important supplementary research to improve the performance of flying wing UAVs. In this paper, relying on the surrogate model, the influence of different wingtip shapes on the stealth and aerodynamic performance of the aircraft is investigated, and the optimal wingtip design is realized. Firstly, the optimization objective is set to minimize the drag coefficient and the lateral average Radar Cross Section (RCS) under specific conditions. The sweep angle, the taper ratio, the dihedral angle and the twist angle of the wingtip are selected to be the optimization variables. Secondly, to analyze the stealth performance, the Large Element Physical Optics (LEPO) method and the Kriging model are exploited to evaluate the lateral average RCS. In order to reduce the computational cost of the aerodynamic optimization, a Co-Kriging model which combines the high-fidelity and the low-fidelity analysis is adopted. Specifically, the high-fidelity analysis adopts the Reynolds average Navier Stokes (RANS) method, while the low-fidelity analysis adopts the three-dimensional (3D) panel method. Finally, based on the above Kriging and Co-Kriging models, the non-dominated sequence genetic algorithm (NSGA-II) is used to comprehensively optimize the stealth/aerodynamic performance, and the optimal Pareto front of multi-objective optimization can be obtained. The simulation results show that compared with the baseline design, the wingtip optimization can reduce the lateral average RCS by 33 dBm2 and the drag coefficient by 6.03 counts, which brings stealth/aerodynamic gains for the flying wing UAV.KeywordsFlying wing UAVWingtipStealthAerodynamicNSGA-II