AERODYNAMIC-CONTROL COUPLED OPTIMIZATION DESIGN METHOD FOR MORPHING AEROSPACE VEHICLES

Autonomous round-trip flight of aerospace vehicles, which requires traversing the atmosphere and near space with full-mission autonomy, is an important technical approach for developing reusable and low-cost space transportation systems. To address the strong nonlinear aerodynamic effects induced by morphing during wide-speed-range flight, as well as the stability and controllability issues caused by the high coupling between aerodynamic and control characteristics, this paper proposes an aerodynamic-control coupled optimization design method for morphing aerospace vehicles oriented to morphing strategy design. In the conceptual design stage, the multidisciplinary design optimization concept is introduced to conduct a unified evaluation of aerodynamic and control performance, thereby enabling the optimal selection of coordinated multi-component morphing strategies. Taking a simplified X-33 configuration as the study object, the wing dihedral angle, wingtip deflection, and wing twist angle are selected as combined morphing design variables. The optimization is carried out at three representative flight conditions, Ma = 0.6 , Ma = 2.5 , and Ma = 5 , corresponding to the subsonic autonomous takeoff-and-landing segment, the supersonic cross-regime acceleration segment, and the key hypersonic reentry segment, respectively. The non-dominated sorting genetic algorithm II (NSGA-II) is employed, with drag reduction, settling-time reduction, and gain-margin enhancement as the optimization objectives. The optimization results show that the optimal morphing strategies exhibit speed-adaptive characteristics under different flight conditions: under subsonic and supersonic conditions, they are mainly characterized by upward wing and wingtip deflections accompanied by downward wing twist, whereas under hypersonic conditions, they shift to a combination of reduced wing dihedral angle, slight upward wingtip deflection, and downward wing twist. Under subsonic and supersonic conditions, the drag coefficient is reduced by about 16% and 12%, respectively, the settling time is shortened by about 3% and 24%, respectively, and the gain margin is increased by about 14% and 5%, respectively; under hypersonic conditions, the lift-to-drag ratio is increased by about 1.92%, while the settling time and gain margin are slightly improved. These results indicate that the proposed method can achieve a coordinated trade-off among morphing strategy, aerodynamic performance, and longitudinal control performance over a wide speed range, providing a useful reference for morphing strategy design and aerodynamic-control collaborative optimization of morphing aerospace vehicles in autonomous round-trip missions.