Floating device supporting an offshore wind turbine, and corresponding floating wind turbine unit
A floating device for supporting an offshore wind turbine, comprising a central floating pillar for fixedly receiving a tower of the wind turbine, at least three peripheral floaters, and one leg per floater, each leg extending in a longitudinal direction that runs radially in relation to the central pillar; each leg has a proximal end that is secured to the central pillar, and a distal end that is secured to the floater; the legs include an outer tubular element, which extends in the longitudinal direction of the leg and has a curved cross-section perpendicularly to the longitudinal direction, and an inner tubular element, which extends in the longitudinal direction of the leg and has a polygonal cross-section perpendicularly to the longitudinal direction, the polygonal cross-section being inscribed in the curved cross-section. The invention also relates to a floating wind turbine unit comprising the device and a wind turbine.
1. A floating device for supporting an offshore wind turbine, comprising:
a central floating pillar arranged for fixedly receiving a tower of the offshore wind turbine;
at least three peripheral floaters, each of the at least three peripheral floaters including at least one leg, each leg extending in a radial longitudinal direction in relation to the central floating pillar and comprising a proximal end secured to the central floating pillar and a distal end secured to a respective peripheral floater of the at least three peripheral floaters;
wherein each leg further comprises:
an outer tubular element in extending along the radial longitudinal direction having a curved cross-section perpendicular to the radial longitudinal direction, and
an inner tubular element extending along the radial longitudinal direction having a polygonal cross-section perpendicular to the radial longitudinal direction, the polygonal cross-section being inscribed in the curved cross-section of the outer tubular element.
2. The floating device of claim 1 , further comprising at least one connection member positioned between each pair of adjacent legs, each connection member comprising a first end and a second end secured in proximity to the respective distal ends of each pair of adjacent legs.
3. The floating device of claim 1 , wherein the legs extend horizontally with respect to a gravitational frame of reference.
4. The floating device of claim 1 , wherein the at least three peripheral floaters are symmetrically positioned around the central floating pillar.
5. The floating device of claim 1 , wherein the central floating pillar comprises a securing member comprising structure defining a hollow volume for receiving a tower of the offshore wind turbine, the hollow volume being cylindrical or truncated in such a way as to hug the shape an outer dimension of the tower.
6. The floating device of claim 1 , wherein the central floating pillar comprises a polygonal cross-section having a number of sides, wherein the number of sides is equal to double the number of legs, and wherein the legs are respectively secured to non-adjacent sides of the polygonal cross-section.
7. The floating device of claim 1 , wherein the at least three peripheral floaters comprise a truncated lower portion with a vertical axis and a cylindrical upper portion with a vertical axis.
8. The floating device according to any of claim 1 , wherein the floating device is made, at least partially, of reinforced concrete.
9. The floating device of claim 1 , wherein the floating device comprises portions made of steel.
10. A floating wind turbine unit, comprising:
a floating device according to claim 1 , and
the offshore wind turbine.