| 摘要 |
A casing (202,204), such as for a gas turbine engine (200), surrounds a fluid stream and has an unbounded fluid flowing over its external surface (212), in a downstream direction. The external surface (212) has formed therein alternating, adjoining troughs (214) and ridges (216) extending in the downstream direction to the trailing edge (210) of the casing (202,204), such that the casing (202,204) has a wave-like shape at its trailing edge (210). This construction reduces and can even eliminate boattail drag on the external surface of casings (202,204) by delaying or eliminating the onset of two-dimensional boundary layer separation. Shorter length casings with greater convex curvature may be used with less drag penalty. |
