Abstract:
Folding wings are increasingly being adopted to expand aircraft flight envelopes due to their capability to increase the lift-drag ratio and payload capacity. However, compared with traditional fixed-wing aircraft, this configuration not only inherits the aerodynamic heating problems associated with fixed wings but also introduces extra localized thermal disturbance during the wing deployment, imposing a severe challenge to thermal protection design. In this paper, we propose a method for simulating the unsteady aerodynamic heating of a simplified folding-wing aircraft model during wing deployment using dynamic overset grids. The unsteady aerodynamic heating environment during the deployment of the folding wing is numerically investigated using the newly developed unsteady method and the conventional quasi-steady method, focusing on the unsteady flow fields around a rotating folding wing and the variation trend of the aerodynamic heating during the deployment process as well as the dependence on the freestream condition. The heat flux distributions obtained by the two methods are generally consistent, but local distributions in heat flux arise from unsteady thermal effects: pronounced unsteady thermal effects manifest at both the wingtip and mid-span regions during the folding process. The thermal disturbances at the wingtip are related to the strong local linear velocity, while that at the mid-span is associated with time-varying wave interference and heat accumulation. The flight angle of attack has a more pronounced effect on the heat flux at the wing leading edge under large folding angle configurations; the difference in heat flux between angle of attack of -10° and 10° at the same location can reach 2055kW/m
2. As the flight Mach number decreases, the intensity of shock wave interference acting on the wing leading edge weakens, and the magnitude of fluctuations in the heat flux distribution at the wing leading edge correspondingly diminishes.