TWIN-FIN FAIRING

Abstract

A fairing (1) for improving fluid flow around a circular-cylindrical object comprises a first fairing-element (11) and a second fairing-element (12), which are releasable relative to one another. The fairing-elements are easy to manufacture, compactly stackable, and easy to install around the object. In installed condition, the first fairing-element and the second fairing-element are mutually connected in circumferential direction of the fairing, while forming a twin-fin fairing, which reduces vortex-induced vibrations around the object, while providing favourable flow resistance, and without performing galloping motions.

Claims

1. Twin-fin fairing for improving fluid flow around a circular-cylindrical object, wherein the fairing has an operation condition in which: the fairing is installed around said circular-cylindrical object and, under influence of said fluid flow, is reciprocally rotatable relative to the object about the longitudinal direction of the object, the circumferential direction and the longitudinal direction of the circular-cylindrical object are defining a corresponding circumferential direction of the fairing and a corresponding longitudinal direction of the fairing, respectively, and the fairing comprises, along at least one subrange of its overall-range in its longitudinal direction, and as seen in perpendicular cross-section relative to its longitudinal direction, at least one U-shaped portion, respectively, which according to the curvature of its U-shape envelopes the object in the circumferential direction of the fairing, and wherein the fairing comprises a first fin and a second fin, which are formed by the at least one U-shaped portion, and which are protruding in a free-ending manner relative to the object, according to the two free-ending legs, respectively, of said U-shape, and which make the fairing rotate according to said reciprocal rotatability under influence of said fluid flow, characterized in that the fairing comprises a first fairing-element and a second fairing-element, which are releasable relative to one another, and wherein said operation condition of the fairing requires an assembled condition of the first fairing-element and the second fairing-element, in which assembled condition the first fairing-element and the second fairing-element are mutually connected in the circumferential direction of the fairing, and wherein the first fairing-element and the second fairing-element are comprising the first fin and the second fin, respectively.

2. Twin-fin fairing according to claim 1, wherein, as seen in said operation condition, the fairing comprises along at least one second subrange of its overall-range in its longitudinal direction, and as seen in perpendicular cross-section relative to its longitudinal direction, at least one O-shaped portion, respectively, which according to the curvature of its O-shape envelopes the object in the circumferential direction of the fairing.

3. Twin-fin fairing according to claim 2, wherein the first fin and the second fin are absent in the at least one second subrange.

4. Twin-fin fairing according to claim 1, wherein the first fairing-element and the second fairing-element are mutually identical.

5. Twin-fin fairing according to claim 4, wherein, as seen in said assembled condition, the fairing is rotational symmetrical in the sense of a 180 degrees rotation of the complete fairing about a mathematical rotation axis which is perpendicular to said longitudinal direction of the fairing.

6. Twin-fin fairing according to claim 5, wherein the first fairing-element comprises a first interlocking structure integrally manufactured therewith, which, for forming said assembled condition, can interlock, in a manner determined by said being rotational symmetrical, with a second interlocking structure of the second fairing-element, which second interlocking structure is identical to the first interlocking structure because the second fairing-element is identical to the first fairing-element.

7. Twin-fin fairing according to claim 6, wherein the first interlocking structure comprises at least one first interlocking pin and at least one first interlocking edge, which at least one first interlocking pin and at least one first interlocking edge are identical to at least one second interlocking pin and at least one second interlocking edge of the second interlocking structure, respectively, and wherein, as seen in said assembled condition: the at least one first interlocking edge catches in a hingeable manner around the at least one second interlocking pin, respectively, the at least one second interlocking edge catches in a hingeable manner around the at least one first interlocking pin, respectively, and the at least one first interlocking pin and the at least one second interlocking pin are mutually in-line according to a hinge line, which corresponds to said hingeable manners, which hinge line is parallel to the longitudinal direction of the fairing, and which hinge line is extending in said operation condition at a side of the fairing facing away from the free ends of the first fin and the second fin, and about which hinge line the first fairing-element and the second fairing-element are hingeable relative to one another.

8. Twin-fin fairing according to claim 1 any one of the preceding claims, wherein the first fairing-element is made of plastic and/or wherein the second fairing-element is made of plastic.

Description

[0030] In the following, the invention is further elucidated with reference to some non-limiting embodiments and with reference to the schematic figures in the attached drawing.

[0031] FIG. 1 shows, in perspective view, an example of an embodiment of a first fairing-element of a twin-fin fairing according to the invention.

[0032] FIG. 2 shows, in perspective view, an example of an embodiment of a twin-fin fairing according to the invention, which twin-fin fairing comprises the first fairing-element of FIG. 1, and wherein the second fairing-element of the shown twin-fin fairing is identical to the first fairing-element, and wherein the first interlocking structure of the first fairing-element has been brought in partial interlocking with the second interlocking structure of the second fairing-element.

[0033] FIG. 3 shows the situation of FIG. 2 in another perspective view.

[0034] FIG. 4 shows the twin-fin fairing of FIG. 2 again in perspective view, however, wherein this time the first interlocking structure and the second interlocking structure have been brought in full interlocking, whereby the assembled condition of the fairing is formed, and, more specifically, wherein the operation condition of the fairing is formed in which the fairing is installed around a circular-cylindrical object.

[0035] FIG. 5 shows the situation of FIG. 4 in a cross-section, which is taken within said at least one first subrange perpendicularly to the longitudinal direction of the fairing, and in which cross-section there is occurring said U-shape of said U-shaped portion of the fairing.

[0036] FIG. 6 shows the situation of FIG. 4 in a cross-section, which is taken within said at least one second subrange perpendicularly to the longitudinal direction of the fairing, and in which cross-section there is occurring said O-shape of said O-shaped portion of the fairing.

[0037] FIG. 7 shows, in perspective view, two specimens of the first fairing-element of FIG. 1 in a compactly stacked condition.

[0038] FIG. 8 shows the situation of FIG. 7 in an upside-down orientation.

[0039] A number of the reference signs used in FIGS. 1-8 are referring to the abovementioned parts and aspects of the invention, in the following manner.

TABLE-US-00001 1 (twin-fin) fairing C circumferential direction of the fairing L longitudinal direction of the fairing 2 circular-cylindrical object 3A, 3B, 3C U-shaped portion 4A, 4B, 4C, 4D O-shaped portion 11 first fairing-element 12 second fairing-element 21 first fin 22 second fin 31A, 31B, 31C first subrange 32A, 32B, 32C, 32D second subrange 41 first interlocking pin 42 first interlocking edge

[0040] FIG. 4 shows that the overall-range in the longitudinal direction L of the fairing 1 comprises the three first subranges 31A, 31B, 31C and the four second subranges 32A, 32B, 32C, 32D.

[0041] In the three first subranges 31A, 31B, 31C the fairing 1 comprises the three U-shaped portions 3A, 3B, 3C, respectively. The U-shape of the U-shaped portion 3A is clearly seen in FIG. 5. This FIG. 5 shows a cross-section of the fairing 1, taken within the first subrange 31A at the location of a rib 7 of the fairing 1 (the rib 7 is indicated in FIGS. 4, 5 and 8).

[0042] FIG. 4 furthermore shows that the first fin 21 of the fairing 1 comprises the shown three first fin portions 21A, 21B, 21C, and that the second fin 22 of the fairing 1 comprises the shown three second fin portions 22A, 22B, 22C. The three first fin portions 21A, 21B, 21C are formed by the three U-shaped portions 3A, 3B, 3C, respectively. Also the three second fin portions 22A, 22B, 22C are formed by the three U-shaped portions 3A, 3B, 3C, respectively.

[0043] In the four second subranges 32A, 32B, 32C, 32D the fairing 1 comprises the four O-shaped portions 4A, 4B, 4C, 4D, respectively. The O-shape of the O-shaped portion 4B is clearly seen in FIG. 6. This FIG. 6 shows a cross-section of the fairing 1, taken exactly in the middle of the second subrange 32B.

[0044] Furthermore, the fairing 1 comprises in each of the four second subranges 32A, 32B, 32C, 32D each time two attachment strips, protruding from the O-shaped portion concerned, of which each time a first attachment strip 51 is part of the first fairing-element 11, and a second attachment strip 52 is part of the second fairing-element 12 (see FIG. 6). Each of the attachment strips 51, 52 is provided with an interlocking projection 43, an interlocking passageway 44, and a nutted bolt fixation passageway 53 (also see FIG. 1).

[0045] From the figures it can be derived that, in the operation condition of the fairing 1 (see FIGS. 4, 5, 6), in each of the four second subranges 32A, 32B, 32C, 32D each time an interlocking projection 43 and an interlocking passageway 44 of the first fairing-element 11 are interlocking with an interlocking passageway 44 and an interlocking projection 43, respectively, of the second fairing-element 11, while then each time a nutted fixation bolt 54 (see FIG. 6) can be extending through the interconnected nutted bolt fixation passageways 53 of the first fairing-element 11 and the second fairing-element 12, in order to firmly attach the first fairing-element 11 and the second fairing-element 12 to one another.

[0046] From the figures it can furthermore be derived that, in the operation condition of the fairing 1, two interlocking edges 42 of one of the two fairing-elements 11 and 12 are interlocking with two interlocking pins 41 of the other fairing-element, while at the same time two interlocking edges 42 of said other fairing-element are interlocking with two interlocking pins 41 of said one fairing-element.

[0047] Furthermore it is shown in the figures that the fairing 1 at both of its ends in the longitudinal direction L has flanges 5 (indicated in FIG. 4). With these flanges 5, the fairings 1 that are interconnected in the longitudinal direction L can abuttingly support one another, which support as desired can be a slidable support in the circumferential direction C, so that the thus interconnected fairings 1 can reciprocally rotate relative to one another in the circumferential direction C.

[0048] Also it is shown in the figures that the fairing 1 can have various ribs, for example the ribs which are parallel to the abovementioned rib 7, which rib 7 is indicated in FIGS. 4 and 8.

[0049] As mentioned above, the first fairing-element 11 and the second fairing-element 12 of the twin-fin fairing 1, shown in FIGS. 2-6, are mutually identical. More in particular, as seen in assembled condition (as shown in FIGS. 4-6), the fairing 1 is rotational symmetrical in the sense of a 180 degrees rotation of the complete fairing 1 about a mathematical rotation axis which is perpendicular to the longitudinal direction L of the fairing 1. In the shown example, said mathematical rotation axis is shown in FIG. 1, where it is indicated by the reference sign R. For understanding said rotational symmetry one can imagine that the first fairing-element 11, shown in FIG. 1, is rotated by 180 degrees about said mathematical rotation axis R. This 180 degrees rotation has been indicated in FIG. 1 by means of a curved arrow. Furthermore, one can imagine that the space, which the first fairing-element 11 would occupy directly after the imaginary performing of said 180 degrees rotation, is exactly occupied by a second fairing-element 12. The second fairing-element 12 then interlocks with all its interlocking means 41, 42, 43, 44 with the interlocking means 41, 42, 43, 44 of the first fairing-element 11. In fact, the first fairing-element 11 and the second fairing-element 12 are then forming the fairing 1 shown in FIGS. 4-6.

[0050] The shown example illustrates that said rotational symmetry offers sophisticated possibilities for obtaining effective interconnections of the two elements in the circumferential direction C of the fairing. For example, FIGS. 2 and 3 are showing a condition in which each interlocking edge 42 of the fairing 1 each time partly catches around an interlocking pin 41 of the fairing 1, co-operating therewith, while in these FIGS. 2 and 3 the interlocking projections 43 and interlocking passageways 44 of the fairing 1 have not yet been brought in interlocking condition. The lastmentioned interlocking conditions are easily obtainable by farthergoing mutual rotation of the two fairing-elements 11 and 12 around the interlocking pins 41, whereafter the two fairing-elements 11 and 12 can be firmly attached to one another by bringing nutted fixation bolts 54 (see FIG. 6) through the nutted bolt fixation passageways 53. Thus, the mutual fixation of the shown fairing-elements 11 and 12 is not only reliable, but also easy to realize.

[0051] It is remarked that the abovementioned examples of embodiments of the invention do not limit the invention, and that various alternatives are possible within the scope of the appended claims.

[0052] For example, in the present document U-shapedness is meant to refer to shapes, which substantially have the shape of the character U. Therefore, a U-shape has two free ending legs, which at their sides facing away from their free ends are interconnected by the bottom of the U-shape concerned. Various kinds of said bottom of the U-shape are possible, not only circular-arched shapes, but also various differently curved shapes, like for instance oval shapes. And also, for example, piecewise-linearly shaped U-shapes are possible and/or U-shapes which are formed by piecewise combinations of curved and linear shapes. Said legs of the U-shape can be mutually parallel, but also non-parallel, for example in that they are, in the direction of their free ends, mutually narrowing (as in the shown example) or mutually widening.

[0053] Likewise, in the present document O-shapedness is meant to refer to shapes, which substantially have the shape of the character O. Various kinds of O-shapes are possible, not only circles, but also various other peripheral shapes, like for example oval shapes. And, for example, also piecewise-linearly shaped O-shapes are possible and/or O-shapes which are formed by piecewise combinations of curved and linear shapes.

[0054] Furthermore, U-shapes and O-shapes in the sense of the present document can have local interruptions, such as is the case for example in FIGS. 5 and 6, where the fairing 1 nearby the interlocking pins 41 and the interlocking edges 42 has a narrow slit in the first fairing-element 11.

[0055] However, other variations or modifications are also possible. These and similar alternatives are deemed to fall within the scope of the invention as defined in the appended claims.