Unsteady aerodynamic characteristics of a flying wing aircraft with variable-sweep morphing

In this paper, numerical simulation method was used to solve the unsteady aerodynamic characteristics of a flying wing aircraft with variable-sweep morphing, and the influences of the shear morphing rate, angle of attack, and Mach number on the unsteady aerodynamic characteristics were analyzed. The results indicate that the best flight performance of the aircraft can be achieved by adjusting the wing sweep angle under various flight conditions. The unsteady aerodynamic coefficients exhibit dynamic hysteresis loops relative to the corresponding static-state data in the varying sweep process. Due to the influence of additional velocity effect and hysteresis effect, the surface pressure and shear stress distribution of the aircraft during the sweep forward and backward processes are significantly different from the static state, especially near the wingtip. As the shear morphing rate increases, the influences of the unsteady effects become more pronounced. The dynamic deviation of aerodynamic coefficients and the areas of hysteresis loops are approximately proportional to the shear morphing rate. As the angle of attack increases, flow separation occurs on the upper surface of the wing, intensifying the hysteresis effects of the flow structures. As the Mach number increases, the wing's sweep morphing influences the shock position and strength. This work provides a reference for the aerodynamic optimization and dynamic control strategy of variable configuration aircraft in a wide speed range.