Body provided with a superficial area adapted to reduce drag

Abstract

Body provided with a superficial area adapted to reduce drag when the body is moving relative to a gaseous or watery medium, comprising depressions in said superficial area, wherein the depressions have a greater length than width and are provided in the superficial area so as to collectively shape a curvature provided in a length direction of said depressions in the superficial area, and/or said depressions themselves are provided with a curvature in their length direction. The depressions are thus adapted to provide that a turbulent boundary layer of the gaseous or watery medium adjacent to the superficial area of the body is exposed to lateral excitation with reference to a movement direction of the body in the gaseous or watery medium or with reference to a flow direction of said turbulent boundary layer along said superficial area of the body. Said lateral excitation results in a reduction of drag.

Claims

1. A body provided with a superficial area adapted to reduce drag when the body is moving relative to a gaseous or watery medium, comprising depressions in said superficial area, wherein the depressions have a greater length than width and are provided in the superficial area so as to collectively shape a curvature provided in a length direction of said depressions in the superficial area, and/or said depressions themselves are provided with a curvature in their length direction, characterized in that the depressions are deprived of sharp edges in a transitional area wherein the depressions meet the superficial area, and that the depressions have a maximum depth (D) relative to the superficial area of 5% of the depressions' width so as to cause that in use a turbulent boundary layer of the gaseous or watery medium adjacent to the superficial area is exposed to lateral excitation with reference to a movement direction of the body relative to the gaseous or watery medium or with reference to a flow direction of said turbulent boundary layer along said superficial area of the body.

2. The body according to claim 1, characterized in that in the transitional area a radius r exists and that the depressions have a radius R, and that the radius r and the radius R are selected at values to satisfy the relation r>0,1*R.

3. The body according to claim 1, characterized in that there are multiple curvatures that are provided staggered, parallel or antiparallel with respect to each other in the superficial area.

4. The body according to claim 1, characterized in that the curvature or curvatures are wavy and comprising a shape of a sinus or cosines or suitable combinations thereof.

5. A method to reduce drag of a body moving relative to a gaseous or watery medium by providing the body with depressions in a superficial area of the body, comprising the step of providing the depressions with a greater length than width in the superficial area of the body so as to collectively shape a curvature in a length direction of said depressions in the superficial area, and/or providing that said depressions themselves have a curvature in their length direction, characterized by providing that the depressions are deprived of sharp edges in a transitional area wherein the depressions meet the superficial area, and providing that the depressions have a maximum depth (D) relative to the superficial area of 5% of the smallest of the depressions' width so as to cause that a turbulent boundary layer of the gaseous or watery medium adjacent to the superficial area of the body is exposed to lateral excitation with reference to a movement direction of the body relative to the gaseous or watery medium or with reference to a flow direction of said turbulent boundary layer along said superficial area of the body.

6. The method according to claim 5, characterized by providing that in the transitional area a radius r exists and that the depressions have a radius R, and that the radius r and the radius R are selected at values to satisfy the relation r>0,1*R.

7. The method according to claim 5, characterized by providing the superficial area with multiple curvatures in a staggered, parallel or antiparallel orientation with respect to each other.

8. The method according to claim 5, characterized by providing the curvature or curvatures with the shape of a sinus or cosines, or suitable combinations thereof.

9. Body according to claim 1, wherein, during use, vortices are prevented to form in the depressions.

10. Method according to claim 5, wherein, during use, vortices are prevented to form in the depressions.

Description

(1) The invention will hereinafter be further elucidated with reference to the drawing of some exemplary embodiments of a superficial area of a body embodied according to the invention, and not limiting as to the appended claims.

(2) In the drawing:

(3) FIGS. 1-6 show examples of curvatures in the surface area of a body according to the invention; and

(4) FIG. 7 shows a typical example of a cross-sectional view through one of the bodies shown in FIGS. 1-6.

(5) Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

(6) The provided examples in FIGS. 1-6 are based on the inventive thought to reduce drag of a moving body 1 relative to a gaseous or watery medium by providing the body 1 with depressions 2 in a superficial area 3 of the body 1, wherein the depressions 2 are adapted to provide that a turbulent boundary layer of the gaseous or watery medium adjacent to the superficial area 3 of the body 1 is exposed to lateral excitation with reference to a movement direction of the body 1 relative to the gaseous or watery medium orwhich is effectively the samewith reference to a flow direction (as indicated with the arrow 4) of said turbulent boundary layer along said superficial area 3 of the body 1.

(7) All embodiments in FIGS. 1-6 have in common that the depressions 2 have a greater length (which measures in the direction of arrow 4) than width (which measures in a direction transverse to the direction of arrow 4), and exhibit the feature that the depressions 2 in the superficial area 3 either collectively shape a curvature in the length direction of said depressions 2 in the superficial area 3 (as in the embodiments of FIGS. 1, 2, 3, 5 and 6), and/or that said depressions 2 themselves have a curvature in their length direction (as in the embodiment of FIG. 4).

(8) Further to increase effectivity of the drag reduction of the body 1 it is desirable that the superficial area 3 is provided with multiple curvatures in a staggered (FIGS. 4 and 5), parallel (FIGS. 1, 2, 3) or antiparallel (FIG. 6) orientation with respect to each other.

(9) In some embodiments it is beneficial that the curvature or curvatures are provided with the shape of a sinus or cosines, as is shown in the embodiments of FIGS. 1, 3 and 5.

(10) With reference to FIG. 7 it is pointed out that all depressions 2 in the bodies shown in FIGS. 1-6 have in common that the depressions 2 are deprived of sharp edges in a transitional area 5 wherein the depressions 2 meet the superficial area 3, and that the depressions 2 have a maximum depth D relative to be superficial area 3 of 5% of the smallest of the depressions' width W or length. For clarity the drawing of FIG. 7 is out of proportion so the actual measures in FIG. 7 need not exactly correspond to this feature. It is particularly the just mentioned feature elucidated with reference to FIG. 7 that causes that in use a turbulent boundary layer of the gaseous or watery medium adjacent to the superficial area 3 is exposed to lateral excitation with reference to a movement direction of the body 1 relative to the gaseous or watery medium or with reference to a flow direction 4 of said turbulent boundary layer along said superficial area of the body 1.

(11) Particularly with reference to the absence of sharp edges, it is found that best results are achieved when in the transitional area 5 a radius r exists and that the depressions 2 have a radius R, and that the radius r and the radius R are selected at values to satisfy the relation r>0,1*R.

(12) Although the invention has been discussed in the foregoing with reference to some exemplary embodiments of the features of the invention, the invention is not restricted to these particular embodiments which can be further varied in many ways without departing from the invention. The discussed exemplary embodiments shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiments are merely intended to explain the wording of the appended claims without intent to limit the claims to these exemplary embodiments. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using these exemplary embodiments.