Flow body with low-friction surface structure

Abstract

The invention relates to a flow body with a surface that has a pyramidal elevation (1) in at least one location. The elevation (1) has a rhombic base here; a first diagonal (D1) of the rhombic base is aligned in the direction of flow (S) when the flow body is in use and it has a length ratio of between 5 and 8 with respect to the second diagonal (D2).

Claims

1. Flow body with a surface having a pyramidal elevation (1) in at least one location, said pyramidal elevation having a rhombic base, wherein a first diagonal (D1) of the rhombic base is aligned in the direction of flow (S) when the flow body is in use and said first diagonal has a length ratio of between 5 and 8 with respect to a second diagonal (D2), and wherein the surface of the pyramidal elevation (1) likewise has pyramidal elevations whose dimensions are, however, reduced to 1/10 to 1/100 compared to the dimensions of the first elevation on which they rest.

2. Flow body according to claim 1, characterized in that the height (H) of the elevation approximately corresponds to one-fourth of the diagonal length (D1) aligned in the direction of flow (S).

3. Flow body according to claim 1 having at least two pyramidal elevations (1) arranged directly behind one another in the direction of flow (S), wherein the height (H) of the elevation (1) arranged further downstream in the direction of flow (S) is only half as large as the elevation (1) that is upstream in the direction of flow (S).

4. Flow body according to claim 1, characterized in that the pyramidal elevation (1) or the pyramidal elevations are created by structuring the base material of the flow body.

5. Flow body according to claim 1, characterized in that the pyramidal elevation (1) or the pyramidal elevations are formed on a coating that is applied to the base material of the flow body.

6. Flow body according to claim 1, characterized in that the surface has at least 2 pyramidal elevations (1) arranged at an offset to one another and essentially orthogonal with respect to the direction of flow.

7. Flow body according to claim 6, characterized in that the elevations (1) are arranged along the leading edge.

8. Flow body according to claim 6, characterized in that the elevations (1) that are arranged at an offset to one another and essentially orthogonal with respect to the direction of flow (S) do in fact have the same length ratios of their diagonals (D1), (D2) but have a different overall length.

9. Flow body according to claim 3, characterized in that the diagonal lengths (D1), (D2) of an elevation (1) on the surface that is located in an area of greater flow velocity (51) are smaller than a second elevation arranged in an area with a lower flow velocity (S2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following are shown in the drawings:

(2) FIG. 1 shows a schematic top view of a pyramidal elevation,

(3) FIG. 2 shows a side view of a pyramidal elevation,

(4) FIG. 3 shows a sectional view in the direction of flow of an embodiment,

(5) FIG. 4 shows a top view of an elevation with further elevations similar to itself,

(6) FIG. 5 shows a top view of a further design form of the flow body with pyramidal elevations of different sizes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) A top view of a pyramidal elevation 1 on the surface of the flow body as per the invention is schematically shown in FIG. 1. The arrow S represents the direction of flow of the flow medium here that prevails on the surface of the flow body. It is evident from this that the elevation is arranged on the surface of the flow body in such a way that the diagonal D1 of the rhombic base of the pyramidal elevation that has the greater length in comparison to the second diagonal D2 of the base is aligned in the direction of flow S. The second diagonal D2 is therefore aligned orthogonally to the direction of flow S. The acute angle of the rhombic base of the pyramidal elevation 1 is preferably between 15 and 30 and is around 20 as shown here.

(8) FIG. 2 shows a side view of the pyramidal elevation 1 of the surface-structured flow body. As shown here, the pyramidal elevation 1 has a height h that corresponds to around one-fourth of the length of the diagonal D1 that is aligned lengthwise to the direction of flow S. The pyramidal elevation 1 shown here can have a length L of the diagonal D1 aligned in the direction of flow of between 3 nm and 30 mm, but preferably 300 nm.

(9) FIG. 3 shows a sectional view of the flow body in the direction of flow S. In accordance with the embodiment shown here, several pyramidal elevations 1, 1b, 1c are provided one behind the other in the direction of flow S that, as shown here, have the same diagonal lengths D1, D2 and the same lengths L1, L2 and L3; their heights h are halved, however, in the direction of flow S with each subsequent pyramidal elevation.

(10) FIG. 4 shows a pyramidal elevation 1 that has pyramidal elevations 1 on its four side areas F1, F2, F3 and F4 that are reduced by 1/100 to 1/10 vis-a-vis the pyramidal elevation 1 on which they rest. The smaller elevations that are shown in an enlarged fashion in a detailed view are geometrically self-similar to the pyramidal elevation 1 on which they rest.

(11) FIG. 5 shows a further embodiment of the invention in a schematic top view. Elevations 1 with different dimensions are provided here orthogonally to the direction of flow S that are, however, geometrically similar with respect to their rhombic bases. The dimensions are smaller in the areas 51 in which a greater flow velocity prevails on the flow body in the operating state than in areas S2 with a lower flow velocity over the surface of the body.

LIST OF REFERENCE NUMERALS

(12) 1 Elevation

(13) D1 Diagonal in the direction of flow

(14) D2 Diagonal orthogonal to the direction of flow

(15) S Direction of flow

(16) H Height der pyramidal elevation

(17) L Length der pyramidal elevation

(18) F1-F4 Side areas of the pyramidal elevation

(19) 1b, 1c Elevations behind one another in the direction of flow