Abstract:
The folding wing can achieve both high-density carriage and excellent aerodynamic performance for the aircraft. However, during high-speed flight, protruding components such as the folding axis can induce complex shock wave interactions, leading to extra drag and aerodynamic heating effects. In this paper, numerical simulations are conducted on an axisymmetric aircraft with folding-tail under high-speed conditions with Mach numbers Ma = 5,7 and angle of attack α = 0°,15°, focusing on the distribution of the flow field and surface heat flux around the aircraft. It is discovered that near the leading edge of the folded fin, there exists a
complex shock wave/boundary layer interaction phenomenon involving the oblique shock from the fin's leading edge, the bow-shaped shock at the folding axis head, and interactions with the boundary layer. This results in extremely high heat flux density of the magnitude of 10 MW/m2 near the intersection of the head of the folding axis and the leading edge of the folding wing. I To avoid this complex shock interference phenomenon while preserving the rotational inertia characteristics of the tail fin about the folding axis, the folding axis is shifted along the x-direction to eliminate the concave region. This arrangement decouples the bow shock at the folding axis head from the oblique shock at the leading edge of the tail wing, reducing the multi-shock/boundary layer interference to a single shock/boundary layer interaction. This optimization effectively reduces the peak heat flux density at the head of upwind folding axis to 1.9 MW/m2 and 6.0 MW/m2 at Mach numbers 5 and 7, respectively, when α = 15°. It also decreases the upwind wing's drag by approximately 10%, yielding overall aircraft drag reduction ranging from 0.66% to 1.86%.