The invention relates to a vortex-reducing device and method.

Background of the invention

Many buildings and other constructions can be subjected to high a aerodynamic load due to for instance airflow around these buildings and constructions.

High chimneys, for instance, can be provided with so called "helical strakes" or "vortex shredders" in order to reduce vortices behind these chimneys in order to reduce vortex induced vibration (VIV). The phenomenon is mostly present in structures with a circular cross section. However, these helical strakes also have a significant drawback - they induce massive increases in drag and side forces that have significant structural implications for the chimney.

More recently, The Erasmusbaig in Rotterdam suffered from swinging of its stay cables due to the wind. Special dampers needed to be installed to solve this problem.

CN104265193 according to its (translated) abstract describes "The invention relates to the technical field of ocean engineering, in particular to a device and a method for restraining a vortex-induced vibration of a cylindrical staictural object. The device comprises a fixed disc and a plurality of spiral tubes, wherein the fixed disc coats and is fixed outside the cylindrical structural object; the plurality of spiral tubes respectively penetrate through the fixed disc, and are spirally arranged in the axial direction of the cylindrical structural object; and gaps for passing through ocean currents are formed between the spiral tubes and the outer wall of the cylindrical structural object. The device realizes the disturbance of fluid flowing fields in any direction through the spiral tubes so as to exert the restraining effect of the vortex- induced vibration; as the gaps are formed between the spiral tubes and the cylindrical staictural object, the choked flow area of the ocean currents can be effectively reduced, the drag force of the ocean currents to the cylindrical structural object and the whole device is reduced, the protection of the stability of the cylindrical structural object from two aspects of the vortex-induced vibration and bending stress fatigue is realized, and the service life of the device is prolonged."

US2002074133 according to its abstract describes "Apparatus and methods for suppressing vortex-induced vibrations (VIV) of aquatic elements of underwater structures. The system includes use of a sleeve positioned around at least a portion of an aquatic element and at least one strake positioned along at least a portion of the length of the aquatic member. The apparatus further comprises copper to suppress the growth of aquatic organisms."

For many constructions, there is no solution for the problem of aerodynamic load due to wind or motion.

Summary of the invention

A disadvantage of prior art is that no solution is provided for aerodynamic loads of structure parts.

Hence, it is an aspect of the invention to provide an alternative device for reducing or adjusting aerodynamic loads on structure parts. To that end, the invention provides a vortex-reducing device for deducing the aerodynamic forces of airflows on an elongated structure part having a longitudinal axis, said vortex-reducing device comprising a series of rings for mounting around said elongated structure part, each ring having a height, an inner periphery for clamping around said elongated staicture part, and comprising at least two indents at an angle with respect to said longitudinal axis and which said angle having a predefined relation to said inner periphery for holding wires in a predefined spiralling way on the elongated structure part.

In an embodiment, the indents with angle a helps applying the wires at the right angle, and securing the wires at the right pitch. Furthermore, the devices may additionally provide a means for mounting other functional parts, like lighting elements.

It was found that at relatively low Reynolds numbers, it proved to reduce vibration introduced by vortex shedding on structural parts due to disturbance of the Von Karman vortex street in the flows of air.

In an embodiment, the angle is such that said spiralling wires have a pitch of 6- 13 times an inner diameter of said rings. In a particular embodiment, the pitch is 9-1 1 times the inner diameter of the rings. In an embodiment, said indents are at an angle of 32°-12°. In a particular embodiment, the angle is determined with respect a line that is parallel to the axis of the devices.

In an embodiment, the indents have a size for holding a wire having a diameter of between 0.07-0.13 times the inner diameter of said rings. In particular the diameter is 0.08-0.11 times the inner diameter of said rings.

In an embodiment, the rings are mounted at a pre-set distance from one another for holding said wires spiralling at said angle, said pre-set distance having a predefined relation with respect to said inner periphery.

In an embodiment, the rings are arranged for holding at least three wires functionally spiralling. In an embodiment, said at least three wires are held spiralling in a functionally parallel manner, forming functionally a multiple helix.

In an embodiment, the ring has a functionally circular inner periphery, in particular said ring having an inner surface functionally defining a circle cylinder portion.

In an embodiment, the rings have an inner diameter of between 20 and 250 mm. In an embodiment, the rings comprises an alignment identification for aligning said rings with one another.

In an embodiment, the rings are moulded, in particular moulded from a polymer material.

In an embodiment, the rings are made of relatively light weight material to reduce the influence on the natural vibration of the structure. Such materials may comprise polymer material. Alternatively or in combination, such materials may comprise metals like aluminium, magnesium, or mixtures thereof. Alternatively, composite materials may be used, or for instance foamed material. Alternatively, a design optimizing wall thicknesses and reinforcement ribs may also reduce weight.

In an embodiment, least part of said rings comprise a lighting element, in particular at least part of said rings comprise a housing for a said lighting element.

In an embodiment, the vortex-reducing device further comprises a power line connecting said rings, in particular wherein said rings comprise a clamp for holding said power line, with said clamp providing said alignment identification. The invention further pertains to a vortex-reducing assembly comprising a series of said vortex-reducing devices, and wires for holding in a predefined spiralling way on the elongated structure part.

In an embodiment, the elongated structure part is part of a structure, the devices comprising at least one lighting element, and said assembly further comprising a control device that is functionally coupled to the lighting elements of the devices.

In an embodiment, the control device comprises one or more images, the positions of the lighting elements on said structure, and a data processor for running a computer program which, when running on said data processor calculates a lighting element illumination setting for the lighting elements using said positions of said lighting elements such that the lighting elements together provide the visual illusion of the image.

In an embodiment, the control device comprises a series of images and a time frame, thus representing a motion picture part, and said computer program when running calculates a time series of lighting element illumination settings for the lighting elements using said positions of said lighting elements such that the lighting elements together provide a visual illusion of said motion picture part.

In an embodiment, the assembly further comprises a measuring device for measuring a motion of said structure, with said measuring device functionally coupled with said control device for providing motion data to said control device, and wherein said computer program, when running on said data processor calculates a dynamic position for the lighting elements using said motion data, and calculates said lighting element illumination settings using said dynamic positions for providing said visual illusion of said motion picture part.

The measuring device may, in an example of a rotating Ferris wheel, provide a rotational speed. From the rotational speed, the computer program in an embodiment calculates for each lighting element its speed (or a displacement vector). Thus, for each lighting elements a dynamic position with respect to a fixed observer may be calculated. It may even be possible to take into account the effect of vibrations in the staicture or staictural part. These measuring devices are as such known to a skilled person. It can comprise a displacement sensor, like a rotational speed sensor. In addition or in stead, a vibration sensor may be used that measures vibration in the structural part. Form the vibration data from such a vibration sensor, a dynamic position for the lighting elements may be calculated using their position on the structural part and the vibration data or rotational speed data.

The lighting elements thus in fact provide pixels in a pixel matrix, allowing an image to be projected. The pixels in an embodiment have a dynamic position in the image frame or matrix. For instance, a position of the lighting elements as a function of time with respect to a fixed observer can be calculated. Thus, in a matrix, dynamic pixels are provided. The control device controls an illumination setting for the lighting elements. This allows controlling light color, light intensity, and timing of these values. The control device may comprise a memory for holding one or more images. In an embodiment, the memory can further hold motion data from the measuring device.

It may be possible to use the wires (the helical wires) for providing power to the lighting devices.

The control device may comprise a PLC, a computer device, a series of coupled computer devices or distributed computer devices. These devices may be functionally coupled for instance via a remote, wired or wireless coupling. The control device may be functionally coupled to the lighting elements and to the measuring device via a wireless or wired coupling.

The invention further relates to a method for reducing aerodynamic forces of airflows on elongated structure parts, in particular on cables and tubes, more in particular having a diameter of between 40 and 250 mm, wherein said vortex-reducing device according to any one of the preceding claims is mounted on an elongated structural part, holding said wires spiralling about said elongated structural part.

The devices can also comprise molded metal parts, for instance molded parts from steel in case high impact resistance is required.

The invention further pertains to a lighting assembly for mounting on an elongated staicture part of a structure, said assembly a line comprising lighting elements spaced apart on said line, and a series of devices for mounting on said elongated structure part and holding said line on said structure part, said devices comprising a ring for mounting around said structural part and said rings comprising a housing for a said lighting element. The lighting assembly allows using a structure as a basis fir projecting an image, a series of images, or even motion pictures or movies.

In an embodiment of said lighting assembly, said lighting assembly further comprising a control device that is functionally coupled to the lighting elements of the devices, wherein said control device comprises one or more images, the positions of the lighting elements on said structure, and a data processor for running a computer program which, when running on said data processor, calculates a lighting element illumination setting for the lighting elements such that the lighting elements together provide the visual illusion of the image.

The terms "upstream" and "downstream" relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the first light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is "upstream", and a third position within the beam of light further away from the light generating means is "downstream".

The term "substantially" herein, such as in "substantially consists", will be understood by the person skilled in the art. The term "substantially" may also include embodiments with "entirely", "completely", "all", etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term "substantially" may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term "comprise" includes also embodiments wherein the term "comprises" means "consists of.

The term "functionally" will be understood by, and be clear to, a person skilled in the art. The term "substantially" as well as "functionally" may also include embodiments with "entirely", "completely", "all", etc. Hence, in embodiments the adjective functionally may also be removed. When used, for instance in "functionally parallel", a skilled person will understand that the adjective "functionally" includes the term substantially as explained above. Functionally in particular is to be understood to include a configuration of features that allows these features to function as if the adjective "functionally" was not present. The term "functionally" is intended to cover variations in the feature to which it refers, and which variations are such that in the functional use of the feature, possibly in combination with other features it relates to in the invention, that combination of features is able to operate or function. For instance, if an antenna is functionally coupled or functionally connected to a communication device, received electromagnetic signals that are receives by the antenna can be used by the communication device. The word "functionally" as for instance used in "functionally parallel" is used to cover exactly parallel, but also the embodiments that are covered by the word "substantially" explained above. For instance, "functionally parallel" relates to embodiments that in operation function as if the parts are for instance parallel. This covers embodiments for which it is clear to a skilled person that it operates within its intended field of use as if it were parallel.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices or apparatus herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the device or apparatus claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention further applies to an apparatus or device comprising one or more of the characterising features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterising features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications. Brief description of the drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Figure 1 a perspective view of embodiments of the device holding wires on a tube end;

Figure 2 a side view of figure 1;

Figure 3 a cross section as indicated in figure 2;

Figure 4 a perspective view of an embodiment of the device shown in figure 1 in detail;

Figure 5 the device of figure 4 in exploded view;

Figure 6 the rear part of the device of figure 5;

Figure 7 an alternative device, also shown in figures 1 and 2, detailed and in perspective view;

Figure 8 the device of figure 7 in top view;

Figure 9 the device of figure 8 in cross section as indicated.

The drawings are not necessarily on scale.

Description of preferred embodiments

Figure 1 shows a perspective view of embodiments of the device 3, 4 holding wires 5 a cylindrical part, here on a tube end 2. Figure 2 shows a side view of figure 1, and figure 3 a cross section as indicated in figure 3.

In this embodiment, the devices 3, 4 are mounted on an elongated structure part 2, here a tube end that may be part of a larger construction. Alternatively, the large structure part 2 may also be another cylindrical part. Often, such a cylindrical part will be circle-cylindrical. For instance, such a part can be a cable, for instance a steel wire cable. These parts in general have a circular cross section. In larger constaictions, these elongated construction parts may suffer from high aerodynamic loads. In particular, elongated constaiction parts that have a functionally circular cross section, as shown in the cross section indicated in figure 2 and depicted in figure 3, may suffer from this. In windy conditions, vortexes may form behind these structural parts. When these vortices have a frequency which is close to the structural frequency (or eigenfrequency) of the structural part, the structural part may come into resonance.

The device 3, 4 comprises a ring-shaped band that is clamped around the elongated staicture part 2. In figures 1 and 2, several devices 3, 4 are mounted around the elongated structure part 2. There are two embodiments of the device 3, 4 shown in the drawings. These embodiments will be discussed in more detail later when discussing figures 3-6 and figures 7-9.

The devices and assembly of the devices and the wires as shown in the current drawings also have design features that can be part of a protection through a design or design patent.

The devices 3, 4 are mounted at a set mutual distance Dl and hold several lines or wires 5 in place in a spiralling manner about the elongated structure part 2. In general, there will be at least three wires. In order to effectively function to reduce aerodynamic loads, and in particular reduce vortices, the thickness (indicated H) of the lines 5 and the pitch P are carefully selected with respect to the size of the cross section D of the elongated structure part 2, and which relates to the inner periphery 8 of the devices 3, 4. Thus, the lines 5 form several helices around the elongated structure part 2. The wires 5 are held functionally parallel with respect to one another, as can be seen in figure 2.

In order to hold the lines 5 at the right pitch, the devices 3, 4 have indents or grooves 9 that are at a predefined angle a with respect to a line L that is parallel to the axis of the devices 3, 4 or the longitudinal axis of the elongated structure part 2. Furthermore, in order to clampingly hold the wires or lines 5, the size of the grooves or indents are adapted to the size of the lines 5. The angle a is indicated in figures 5/6 for device 3 and in figures 7/9 for device 4.

The device is shown in two different, exemplary embodiments. In a first embodiment, device 3 is further detailed in figures 3-6, and in a second embodiment device 4 is further illustrated in figures 7-9.

The device 3, 4 provides a ring around the elongated structure part 2, and has grooves or indents 9 for holding the line or wire 5 in place.

For the first embodiment, in figure 4 a perspective view is shown, in figure 5 an exploded view, and in figure 6 the rear part of the device of figure 5 is shown in detail. In the first embodiment, the device 3 is provided with a casing 6 for holding a lighting element. Often, such a lighting element will be a Light Emitting Diode (LED), or similar light emitting device. The casing has a lid 12 that may have a window or even a lens. Here, the lid is attached via screws, making it relatively easy to apply and dismount. Alternatively, a snap coupling may be used. The casing 6 comprises grooves 13 for allowing a power line 7 to enter and leave the casing 6 of device 3. In figures 1, the power line 7 is at regular interspaces provided with lighting elements. These regular interspaces comply with the positions of casings of the device 3 of the first embodiment longitudinally along the elongated structure part 2.

A second, relatively more simplified embodiment of the device is shown in figures 7-9.

In figure 7 the second embodiment that is also shown in figures 1 and 2 is shown more detailed and in perspective view. In figure 8 the embodiment of figure 7 is depicted in top view, and in figure 9, the device of figure 8 is depicted in cross section as indicated.

The second embodiment of the device 4 provides a ring with an inner ring surface 8. The device 4 has an inner diameter D that usually is just a little smaller than the perimeter of the elongated structure part 2 in order to allow it to be firmly clamped on the elongated structure, just like the first embodiment device 3. The grooves or indents 9 are here in fact parts of the ring that bulge out radially outward. These are dimensioned for clamping or holding the wire or line 5 firmly. The groove 9 is here substantially cylindrical with an axis that is at an angle a with respect to a line parallel to the axis of the device 4. The angle a depends on the inner perimeter of the device.

In an embodiment, the vortex-reducing device is used to reduce vortices of elongated steel wire cables that have a diameter of about 84-86 mm. The rings in that embodiment have an inner perimeter that is about 0.3-0.6 mm smaller. In a particular embodiment, the vortex-reducing device is used to reduce vortices of elongated steel wire cables that have a diameter of about 85.67 mm. The rings in that embodiment have an inner perimeter of about 85.20 mm. The height of a ring is in that embodiment 25 mm. The diameter of the wires or lines H in that embodiment was selected about 8 mm. The hart-to-hart distance Dl of the rings in the embodiment is about 127 mm. The pitch of the wires about the steel cable in that embodiment is about 762 mm. The angle a is here about 19-20°. The embodiment is designed to have an as low as possible aerodynamic drag difference in comparison to a circular cross section without these embodiments installed.

The vortex-reducing device is in general used for a staicture part that has a diameter of between 50 - 250 mm. Usually as mentioned, the inner perimeter of the device will be a little smaller in order to allow proper clamping of the device around the structure part.

In general, as mentioned above, it was found that the line or wire 5 has a diameter of 0.07-0.13 times the diameter D of the elongated structure part. The line or wire 5 for use on a structure part having a diameter as details above extends a distance H of between 6 - 12 mm from the structure part, depending on the diameter of the structure part. In particular, as stated, the line or wire 5 has a diameter of 0.08-0.1 1 times the diameter D of the elongated structure part. Often, the line or wire will have a round or circular cross section. In such an embodiment, the wire or line for instance has a diameter of about 6 - 8 mm.

As stated before, the pitch is 6-13 times the main diameter of the structural part.

In an embodiment as mentioned before, for a diameter D of the elongated structure of about 86 mm, the pitch of the wire is about 762 mm, thus resulting in an angle a of between 19° - 20°.

The lighting element may comprise several lighting devices which together allow making a desires color by switching lighting devices on and/or off, or by changing their intensity. In fact, when the assembly when provided with lighting elements is mounted onto a structure, it is possible, using a control device for controlling the individual lighting elements, to create an image from the assembly of lighting elements. It may even be possible, using the control device, to control each individual lighting element in such a way that the set of lighting elements together operate as pixels in a display device, allowing even projection of moving images, allowing display of a movie or part of a movie.

In an embodiment, the assembly is provided on a moving structure, like a Ferris wheel. When mounted on a Ferris wheel, the assembly can for instance be mounted on the spokes of the Ferris wheel. Then the control device is coupled to a measuring device for measuring a motion of the structure, for instance with the Ferris wheel measuring the rotational speed, the control device may take the motion into account and control the lighting devices in such a way that it compensates for the motion of the structure. Thus, in the example the control device is functionally coupled to the measuring device and to the lighting elements. Using the measurement values of the measuring device the control device can control the lighting elements on the structure in such a way so as to compensate for the motion of the structure. The control device can control the lighting elements in such a way that the lighting elements together project the visual illusion of a still image despite the motion of structure, or project the visual illusion of a movie or moving image despite the motion of the staicture.

In an embodiment, the assembly comprises a series of devices 4 on one or more a structural parts of a structure, the devices provided with at least one lighting element, and a control device functionally coupled to the lighting elements of the devices. The control device provided with one or more images and with the positions of the lighting elements and with a data processor fur running a computer program which, when running on said data processor, calculates a lighting element illumination setting for the lighting elements such that the lighting elements together provide the visual illusion of the image. In an embodiment, the control device comprises a series of images and a time frame, thus representing a motion picture part, and said computer program when running calculates a time series of lighting element illumination settings for the lighting elements such that the lighting elements together provide a visual illusion of said motion picture part.

In an embodiment, the assembly further comprises a measuring device for measuring a motion of said staicture, with said measuring device functionally coupled with said control device for providing motion data to said control device, and wherein said computer program, when ainning on said data processor calculates a dynamic position for the lighting devices using said motion data, and calculates said lighting element illumination settings using said dynamic positions.

It will also be clear that the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. Starting from this disclosure, many more embodiments will be evident to a skilled person. These embodiments are within the scope of protection and the essence of this invention and are obvious combinations of prior art techniques and the disclosure of this patent.