| 摘要 |
A supersonic wing in turning the airstream downward to generate increased pressure on its underside also increases the air density. The energy of this compression field is normally diverted away from the wing downward towards the ground in the supersonic wave system, coalescing into a strong shock wave which dissipates most of this energy into heat, with a small residual reaching the ground and causing the sonic boom. My copending application No. 342,151, filed Mar. 16, 1973, disclosed the use of an expanding jet under a concave downward wing to transform this compression energy into vorticity. The present continuation-in-part application provides a wing section which concentrates most of the concave downward curvature of the wing underside in a short interaction region to generate the compression near its leading edge, corresponding to the short expansion region of the underexpanded jet. This correlation of the density change locations generates in adjacent regions both (1) equal magnitude and opposite sign Coriolis reaction forces due to the contrasting changes in angular momentum of the underwing streams as they are turned downward by the wing, providing a mechanism to feed energy into the transformation process, and (2) opposing sign perturbation velocities on the interface between the upper compressing stream and the lower expanding stream, thus invoking viscous forces to spin the fluid elements into an ordered form of vorticity about spanwise axes. The energy transformed into vorticity then proceeds aft with the flow under the wing, where its upwash adds to the streamwise velocity to comprise an upward inclined flow, producing an increased pressure on the undersurface enabling the wing to operate at a lesser angle with reduced drag. Residual energy unrecovered into useful work is retained as vorticity in the flow stream at the aircraft altitude, where it will eventually decay into heat, precluding its transport towards the ground to generate a sonic boom.
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