초록 ▼

A body adapted to move downstream through a fluid has a downstream extending smooth surface terminating at a blunt base. Extending transversely across the smooth surface and disposed upstream of the blunt base is a thin, downstream extending plate closely spaced from the smooth surface. At least the

A body adapted to move downstream through a fluid has a downstream extending smooth surface terminating at a blunt base. Extending transversely across the smooth surface and disposed upstream of the blunt base is a thin, downstream extending plate closely spaced from the smooth surface. At least the downstream end portion of the plate is convoluted such that its downstream end is wave shaped. The convolutions are designed to generate pairs of counterrotating vortices which delay boundary layer separation from the smooth surface and cause fluid to flow into the space immediately behind the blunt base, reducing base drag on the body. The device generates very little drag of its own.

대표청구항 ▼

A vortex generating plate-like wall member adapted to be disposed in a fluid moving downstream relative thereto, said member having oppositely facing flow surfaces extending in a first direction, an upstream edge transverse to said first direction and a downstream edge transverse to said first direc

A vortex generating plate-like wall member adapted to be disposed in a fluid moving downstream relative thereto, said member having oppositely facing flow surfaces extending in a first direction, an upstream edge transverse to said first direction and a downstream edge transverse to said first direction, at least one of said flow surfaces comprising a plurality of adjoining, alternating, U-shaped lobes and troughs extending in said first direction terminating at said downstream edge, and increasing in height and depth, respectively, in the downstream direction, whereby a downstream portion of said member is convoluted, the contour and dimensions of said troughs and lobes being selected to insure that during use each trough generates a pair of adjacent large-scale vortices downstream of said downstream edge, said pair of vortices generated by each trough rotating in opposite directions about respective axes extending in the first direction, wherein said wall member is adapted to be secured in closely spaced relation to a downstream extending exterior surface of a vehicle.