Bodies with reduced base drag
AssigneeUnited Technologies Corporation
InventorsRobert W. Paterson, Michael J. Werle, Walter M. Presz, Jr.
Life of this patent
Estimating the term…
Abstract
A body adapted to move downstream through a fluid has a downstream extending smooth surface terminating at a blunt base. A plurality of adjacent U-shaped, downstream extending troughs in the smooth surface intersect the blunt base to form trough outlets. The troughs are appropriately spaced apart, sized and configured to flow full over their entire length and cause fluid to flow into the space immediately behind the blunt base, thereby reducing base drag on the body.
Claims38
An article adapted to be disposed in a fluid moving downstream relative thereto, said article having a first surface extending generally downstream, and a blunt end surface immediately downstream of an adjoining said first surface and facing generally downstream, a plurality of adjacent troughs formed in said first surface extending in an axial direction, which is the direction of the streamlines of the bulk fluid flow adjacent said surface in which said troughs are disposed, and continuing to said end surface to form a plurality of adjacent trough outlets in said end surface, each of said troughs including a pair of downstream extending sidewall surfaces which intersect said end surface to form side edges of said trough outlets, wherein a portion of the area of said blunt end surface extends laterally from each of said side edges of each of said plurality of trough outlets to the side edge of an adjacent trough outlet over the full length of each of said side edges, wherein said laterally extending area portion between each pair of adjacent trough outlets is at least one-fourth (1/4) of the downstream projected area of one of said adjacent trough outlets, wherein, in cross-section perpendicular to the downstream direction, lines tangent to each sidewall of said pair of trough sidewalls at their steepest point at said trough outlet are substantially parallel, wherein each of said troughs has an inlet and gradually increases from no depth at said inlet to its maximum depth, and wherein the contour and dimensions of said troughs and the size of said laterally extending area portions of said blunt end surface are such as to ensure that each trough flows full throughout its length and causes fluid to flow into the space immediately downstream of said blunt end surface to reduce base drag.
An article adapted to be disposed in a fluid moving downstream relative thereto, said article having a first surface extending generally downstream, and a blunt end surface immediately downstream of and adjoining said first surface and facing generally downstream, a plurality of adjacent troughs formed in said first surface extending in an axial direction, which is the direction of the streamlines of the bulk fluid flow adjacent said surface in which said troughs are disposed, and continuing to said end surface to form a plurality of adjacent trough outlets in said end surface, the sum of the downstream projected areas of said troughs outlets being no greater than about 30% of the downstream projected area of said blunt end surface, each of said troughs including a pair of downstream extending sidewall surfaces which intersect said end surface to form side edges of said trough outlets, wherein a portion of the area of said blunt end surface extends laterally from each of said side edges of each of said plurality of trough outlets to the side edge of an adjacent trough outlet over the full length of each of said side edges, wherein each of said troughs has an inlet and gradually increases from no depth at said inlet to its maximum depth, wherein the contour and dimensions of said troughs and the size of said laterally extending area portions of said blunt end surface are such as to ensure that each trough flows full throughout its length and causes fluid to flow into the space immediately downstream of said blunt end surface to reduce base drag.
A vehicle adapted to be disposed in a fluid moving downstream relative thereto, said vehicle having a blunt rear end surface and a first surface defining a first plurality of adjacent, downstream extending troughs, each of said troughs terminating at said rear end surface to form a plurality of spaced apart trough outlets in said end surface, each of said troughs including a pair of downstream extending sidewall surfaces which intersect said rear end surface to form side edges of said trough outlets, wherein in cross-section perpendicular to the downstream direction, lines tangent to each sidewall of each of said pair of trough sidewalls at their steepest point at said trough outlet are substantially parallel, wherein a first portion of the area of said rear end surface extends laterally from each of said side edges to the side edge of an adjacent trough outlet over the full length of each of said side edges, wherein the downstream projected area of the rear end surface disposed laterally between each pair of adjacent trough outlets of said first plurality of troughs is at least one-fourth (1/4) of the downstream projected area of one of said pair of adjacent trough outlets, wherein each of said troughs has an inlet and gradually increases from no depth at said inlet to its maximum depth, wherein the contour and dimensions of said troughs and the size of said first area portions are such as to ensure that each trough flows full throughout its length and causes fluid to flow into the space immediately downstream of said rear end surface to reduce base drag.
A vehicle adapted to be disposed in a fluid moving downstream relative thereto, said vehicle having a blunt rear end surface and a first surface defining a first plurality of adjacent, downstream extending troughs, each of said troughs terminating at said rear end surface to form a plurality of spaced apart trough outlets in said end surface, the sum of the downstream projected areas of all of said trough outlets being no greater than about 30% of the downstream projected area of said rear end surface, each of said troughs including a pair of downstream extending sidewall surfaces which intersect said rear end surfaces to form side edges of said trough outlets, wherein a first portion of the area of said rear end surface extends laterally from each of said side edges to the side edge of an adjacent trough outlet over the full length of each of said side edges, wherein each of said troughs has an inlet and gradually increases from no depth at said inlet to its maximum depth, wherein the contour and dimensions of said troughs and the size of said first area portions are such as to ensure that each trough flows full throughout its length and causes fluid to flow into the space immediately downstream of said rear end surface to reduce base drag.
Dependencies are inferred from the claim text.