초록 ▼

An airfoil-shaped body has a relatively thin trailing edge with a series of alternating, adjoining, downstream extending troughs and ridges in its suction surface which form wave-like surface undulations terminating at the trailing edge. The ridges in the suction surface form corresponding troughs i

An airfoil-shaped body has a relatively thin trailing edge with a series of alternating, adjoining, downstream extending troughs and ridges in its suction surface which form wave-like surface undulations terminating at the trailing edge. The ridges in the suction surface form corresponding troughs in the pressure surface near the trailing edge; and the troughs in the suction surface form corresponding ridges near the trailing edge of the pressure surface. The resulting airfoil-shaped body has a trailing edge with a wave-like shape. The trough and ridge construction delays or prevents two-dimensional boundary layer separation without creating an undesirable drag penalty.

대표청구항 ▼

In an airfoil shaped body having a thin trailing edge, a trailing edge region, and a pressure and a suction surface terminating at said trailing edge, and adapted to be disposed in a fluid moving downstream relative thereto at a selected operating angle of attack A which would normally result in flo

In an airfoil shaped body having a thin trailing edge, a trailing edge region, and a pressure and a suction surface terminating at said trailing edge, and adapted to be disposed in a fluid moving downstream relative thereto at a selected operating angle of attack A which would normally result in flow separation from said suction surface, means for preventing or delaying such separation from occurring on said suction surface at such angle of attack comprising: a plurality of alternating, adjacent troughs and ridges in said suction surface extending to said trailing edge generally along streamlines of the bulk fluid flow adjacent to the suction surface and initiating at a point upstream of any separation, but no further upstream from said trailing edge than 75% of the mean chord length of the airfoil cross section, wherein said troughs and ridges in said suction surface form, respectively, ridges and troughs in said pressure surface at least in said trailing edge region, and said thin trailing edge is wave shaped, wherein the trough contour and size along its length is selected such that streamwise two-dimensional boundary layer separation on the surface of the troughs and ridges is eliminated over substantially the full length of said troughs at said selected operating angle, said troughs and ridges being generally “U”-shaped in cross section perpendicular to their length, and blending smoothly with each other, the peak-to-peak wave amplitude M of said troughs and ridges increasing from zero at their upstream ends to a maximum amplitude at the trailing edge which is substantially greater than the 99% boundary layer thickness measured immediately upstream of said troughs, and wherein the bottom of each trough forms an angle with the adjacent bulk fluid flow direction within a range which avoids two-dimensional boundary layer separation within substantially the full length of said troughs at said angle of attack A, and wherein at the trailing edge the distance W between adjacent ridge peaks is between 0.5 and 4.0 times M.