Boattail plates with non-rectangular geometries for reducing aerodynamic base drag of a bluff body in ground effect

An apparatus for reducing the aerodynamic base drag of a bluff body having a leading end, a trailing end, a top surface, a bottom surface opposing left and right side surfaces, and a base surface at the trailing end substantially normal to a longitudinal centerline of the bluff body, said base surface joined to the left side surface at a left trailing edge, to the right side surface at a right trailing edge, to the bottom surface at a bottom trailing edge, and to the top surface at a top trailing edge, said apparatus comprising:

• left and right vertical boattail plates orthogonally attached to the base surface of the bluff body and inwardly offset from the left and right trailing edges, respectively, and from the top trailing edge, to produce left and right vertical channels which generate, in a flowstream substantially parallel to the longitudinal centerline, respective left and right vertically-aligned vortical structures therein, said left and right vertical boattail plates having a non-rectangular geometry with a shorter plate width at top and bottom ends thereof than at the center to more quickly turn the flowstream around into the base surface at the top and bottom ends than at the center of the vertical boattail plate.

A vehicle attachment for reducing the aerodynamic base drag of a bluff body having a leading end, a trailing end, a top surface, a bottom surface, opposing left and right side surfaces, and a base surface at the trailing end substantially normal to a longitudinal centerline of the bluff body, said base surface joined to the left side surface at a left trailing edge, to the right side surface at a right trailing edge, to the bottom surface at a bottom trailing edge, and to the top surface at a top trailing edge, said apparatus comprising:

• left and right vertical boattail plates orthogonally connectable to the base surface of the bluff body so as to be inwardly offset from the left and right trailing edges, respectively, and from the top trailing edge, and produce left and right vertical channels which generate, in a flowstream substantially parallel to the longitudinal centerline, respective left and right vertically-aligned vortical structures therein, said left and right vertical boattail plates each having a plate width defined by a rear edge spaced from the base surface, with said plate width being shorter at top and bottom ends thereof than at the center to more quickly turn the flowstream around into the base surface at the top and bottom ends than at the center of the vertical boattail plate.