Patent ID: 6959958

Claim:
An apparatus for reducing the fluid-dynamic base drag of a bluff body ( 20 ) moving through a fluid ( 21 ) and creating, at the rear of the body, a low pressure wake having an outer wake perimeter, which bluff body ( 20 ) has a substantially flat rear base surface ( 25 ), a pair of opposed side surfaces ( 22 A and 22 B), and opposed top and bottom surfaces all joined with said rear base surface at side, top and bottom trailing edges ( 24 ), respectively, so as to form a box container ( 30 ), said apparatus comprising: V shaped vortex generators in a linear array ( 40 ) ahead of the trailing edges ( 24 ) of said bluff body ( 20 ) for generating counter rotating stream-wise vortices ( 27 ) in a fluid boundary layer ( 23 ) passing generally along said bluff body and creating from said layer separated shear surfaces ( 26 ) which turn sharply inward aft of said trailing edges ( 24 ); boattail plates ( 50 ) inset and affixed a distance ( 18 ) from the top and side trailing edges ( 24 ); and rear edges on said boattail plates ( 50 ) sized to intercept the separated shear surfaces ( 26 ) at the outer perimeter of the low pressure wake, thereby providing maximum fluid-dynamic base drag reduction for said body.