Suppression element for vortex-induced vibrations

1. A suppression element ( 1 ) for vortex vibrations, comprising:

an envelope ( 2 ) for at least partly enveloping a tubular element ( 100 ), wherein the envelope is modular to form, in circumferential direction of the tubular element ( 100 ), with similar suppression elements a tube ( 101 , 102 ) which, in operation, at least partly envelops the tubular element, and wherein the suppression element ( 1 ) has, in a longitudinal direction (A) of the suppression element ( 1 ), a first longitudinal direction (A) end ( 10 ) and an opposing second longitudinal direction (A) end ( 11 );

at least one projection ( 3 ) pointing away from the envelope for reducing the formation of vortices on the downstream side of the tubular element ( 100 ), wherein the projection ( 3 ) extends in the longitudinal direction (A) and lies at an inclined angle to the longitudinal direction (A); and

a directing element ( 6 - 8 ) for positioning the suppression element ( 1 ) relative to another said suppression element such that the first end ( 10 ) of the suppression element ( 1 ) adjoins the second end ( 11 ) of said another suppression element;

characterized in that the projection ( 3 ) extends from a first longitudinal direction (A) projection end of the projection ( 3 ) near the first end ( 10 ) of the suppression element ( 1 ) to a second longitudinal direction (A) projection end of the projection ( 3 ) near the second end ( 11 ) of the suppression element ( 1 ), and in that the directing element ( 6 - 8 ) comprises means for positioning the projection ( 3 ) such that its first projection end adjoins a second projection end of a projection of said another suppression element, enabling the projections of several said suppression elements to be connected to each other, as a result of which an elongate continuous projection can be obtained.

2. The suppression element ( 1 ) according to claim 1 , further comprising: at least one spacer ( 4 a - 4 d ) for maintaining, in mounted condition, an interspace between the envelope ( 2 ) and the tubular element ( 100 ).

3. The suppression element ( 1 ) according to claim 1 , further comprising at least one passage ( 5 ) in the envelope ( 2 ).

4. The suppression element ( 1 ) according to claim 3 , wherein the passage ( 5 ) at least partly extends through the projection ( 3 ).

5. The suppression element ( 1 ) according to claim 3 , wherein the passage ( 5 ) also forms a passage for a connecting element ( 9 ).

6. The suppression element ( 1 ) according to claim 3 , wherein the passage ( 5 ) is at a transition between the envelope ( 2 ) and the projection ( 3 ).

7. The suppression element ( 1 ) according to claim 6 , wherein the surface of the projection ( 3 ) lies at an angle greater than or equal to 90 degrees to the surface of the envelope ( 2 ).

8. The suppression element ( 1 ) according to claim 6 , wherein the envelope ( 2 ) is unilaterally curved around a longitudinal direction (A) of the suppression element ( 1 ).

9. The suppression element ( 1 ) according to claim 8 , wherein the envelope ( 2 ), transverse to the longitudinal direction (A), is substantially in the form of a circular arc.

10. The suppression element ( 1 ) according to claim 9 , wherein the envelope ( 2 ), seen transverse to the longitudinal direction (A), forms a circular arc of 120 plus or minus up to 3 degrees.

11. The suppression element ( 1 ) according to claim 1 , wherein the suppression element ( 1 ) has one projection ( 3 ).

12. The suppression element ( 1 ) according to claim 1 , wherein the projection ( 3 ) has a triangular cross-section.

13. The suppression element ( 1 ) according to claim 1 , wherein the projection ( 3 ) is open on a side directed toward the envelope ( 2 ).

14. The suppression element ( 1 ) according to claim 1 , wherein an interior ( 22 ) of the envelope ( 2 ), which interior ( 22 ), in mounted condition, is directed toward the tubular element ( 100 ), has a form corresponding to an exterior ( 21 ) of the envelope ( 2 ), which exterior ( 21 ), in mounted condition, faces away from the tubular element ( 100 ).

15. The suppression element ( 1 ) according to claim 1 , wherein said element is manufactured from a material having a specific density lower than water.

16. The suppression element ( 1 ) according to claim 15 , wherein the material has a specific density ranging between 800 and 900 kg/cm 3 .

17. The suppression element ( 1 ) according to claim 1 , wherein the element is at least partly manufactured from a foamed plastic.

18. The suppression element ( 1 ) according to claim 1 , wherein the element is at least partly manufactured from reused plastic.

19. The suppression element ( 1 ) according to claim 1 , wherein the element is at least partly manufactured from polyethylene or polypropylene.

20. The suppression element ( 1 ) according claim 1 , further comprising an origin marking ( 12 ).

21. A construction kit for a suppression system, comprising at least two suppression elements ( 1 ) according to claim 1 .

22. A suppression system for vortex vibrations, comprising at least two suppression elements ( 1 ) according to claim 1 , which together form a tube, which, in operation, at least partly envelops a tubular element ( 100 ).

23. The suppression system for vortex vibrations according to claim 22 , further comprising: a flow element ( 5 ) for providing a fluid flow in the space between the tubular element ( 100 ) and the suppression elements ( 1 ).

24. An apparatus for extracting minerals, comprising a platform, which is located in or on a body of water, and at least one pipeline ( 100 ), which extends from the platform in the water, a part of the pipeline located in the water at least partly being enveloped by a suppression element ( 1 ) according to claim 1 .

25. A mold for manufacturing a suppression element ( 1 ) according to claim 1 , wherein the mold comprises interior walls defining a moulding space of the mold, which moulding space corresponds to the shape of the suppression element ( 1 ).