7 Flight Mystery and Aerodynamic Principles
489
Fig. 7.51 Typical wing profiles of Airbus aircraft
Fig. 7.52 A320 (supercritical wing)
the critical Mach number, starting from 5% chord length from the leading
edge, there is a uniform supersonic flow with almost no acceleration along
the upper surface. Thus, the supersonic Mach number before the shock wave
at the trailing edge is low, the shock intensity is weak, and the stretching
range is not large, the back pressure gradient after the shock wave is small,
the boundary is not easy to separate, thereby alleviating the drag divergence
phenomenon. (2) In order to compensate for the lack of lift in front section
of the upper airfoil, the lower airfoil near the trailing edge is made concave to
489
Fig. 7.51 Typical wing profiles of Airbus aircraft
Fig. 7.52 A320 (supercritical wing)
the critical Mach number, starting from 5% chord length from the leading
edge, there is a uniform supersonic flow with almost no acceleration along
the upper surface. Thus, the supersonic Mach number before the shock wave
at the trailing edge is low, the shock intensity is weak, and the stretching
range is not large, the back pressure gradient after the shock wave is small,
the boundary is not easy to separate, thereby alleviating the drag divergence
phenomenon. (2) In order to compensate for the lack of lift in front section
of the upper airfoil, the lower airfoil near the trailing edge is made concave to