Systems, methods and configurations for suppressing rotor sail vibrations

Abstract

A vibration damping system (100) for a rotor sail (104, 200) is disclosed. The vibration damping system includes a support structure (108) having a first end (108A), a second end (108B), and a height (H) defined by the first and second ends, and a vibration damping unit (112, 204) attached to the support structure. The support structure is disposed within the rotor sail's rotating cylinder (110), and its second end is coupled to the rotor sail's base (106) to support the rotating cylinder. The distance from the first end to the vibration damping unit is between 0 and 30% of the support structure's height. The vibration damping unit suppresses vibrations of the rotor sail, allowing the rotating cylinder to operate at operating frequencies above the rotor sail's natural frequency.

Description

[Technical Field]

[0001] The disclosure of this application (hereinafter referred to as the present disclosure) relates to a vibration damping system for a rotor sail. The disclosure also relates to a method for damping vibration of a rotor sail. The disclosure also relates to a structure for damping vibration of a rotor sail.

[0002] With global interest in reducing dependence on fossil fuels and improving energy efficiency, rotating cylinders are being used as auxiliary propulsion systems for ships. These rotating cylinders are typically Flettner rotors. Flettner rotors offer clean propulsion technology and are configured to power ships using wind power. Typically, a Flettner rotor is a cylinder with disc-shaped end plates that rotates along its longitudinal axis as air passes through it. The Magnus effect generates aerodynamic forces in a direction nearly perpendicular (usually between 100° and 110°) to both the longitudinal axis and the direction of the airflow. Today, rotor sails, consisting of one or more Flettner rotors in an upright position, are used. The rotors are rotated by the ship's electrical system, acting like sails to propel the ship using wind power.

[0003] The larger the rotor sail, the more thrust it generates. In particular, increasing the length of the rotor sail is the easiest way to increase the amount of thrust it generates. Higher parts of a rotor sail experience higher wind speeds than lower parts. This is because wind speed increases as a function of height above ground or sea level. However, increasing the rotor sail's height increases its aspect ratio, making it slender. This slenderness equates to a lower natural frequency of the rotor sail. This creates operational limitations because the rotor sail's operating speed (in revolutions per minute) may reach or exceed the same frequency, creating a risk of resonance. Furthermore, the lower natural frequency caused by an increased aspect ratio can lead to problems with vortex shedding. Traditionally, rotor sails are designed to operate in a region where there is no risk of inducing resonance (vibration at the natural frequency). However, the structure and foundations of conventional rotor sails are stiff and heavy.

[0004] For these reasons, a need exists to overcome the aforementioned drawbacks associated with conventional rotor sails.

[0005] The present disclosure seeks to provide a vibration damping system for a rotor sail. The present disclosure also seeks to provide a method for suppressing vibrations of a rotor sail. The present disclosure also relates to an arrangement for a vibration damping system for a rotor sail. It is an object of the present disclosure to provide a solution that at least partially overcomes the problems encountered in the prior art.

[0006] Viewed in one respect, one embodiment of the present disclosure provides a vibration damping system for a rotor sail, the vibration damping system comprising: a support structure having a first end, a second end, and a predetermined height defined by the first end and the second end, the support structure being disposed within a rotation cylinder of the rotor sail, the second end being coupled to a base of the rotor sail to support the rotation cylinder; the vibration damping system further comprises one or more vibration damping units mounted on the support structure, the distance from the first end to the vibration damping units being between 0 and 30% of the predetermined height of the support structure; The one or more vibration damping units suppress vibration of the rotor sail and enable the rotating cylinder to operate so that the frequency of vibration caused by the operation of the rotating cylinder is equal to or greater than the natural frequency of the rotor sail.

[0007] Viewed another way, an embodiment of the present disclosure provides a method for suppressing vibration of a rotor sail, the method comprising: providing one or more vibration damping units; Mounting the one or more vibration damping units on a support structure such that a distance from the first end to the vibration damping unit is between 0 and 30% of the predetermined height of the support structure; suppressing vibrations of the rotor sail so as to allow the rotating cylinder to operate such that the frequency of vibrations caused by the operation of the rotating cylinder is equal to or greater than the natural frequency of the rotor sail; Includes.

[0008] SUMMARY OF THE INVENTION Embodiments of the present disclosure substantially eliminate or at least partially address the aforementioned problems in the prior art and enable efficient vibration damping of rotor sails.

[0009] Further aspects, advantages, features and objects of the present disclosure will become apparent from the accompanying drawings and detailed description of illustrative embodiments, taken in conjunction with the appended claims.

[0010] It will also be appreciated that features of the present disclosure can be combined in various combinations without departing from the scope defined by the appended claims. [Brief explanation of the drawings]

[0011] The foregoing summary, as well as the following detailed description of exemplary embodiments, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the disclosure, exemplary configurations of the disclosure are shown in the drawings. However, the disclosure is not limited to the particular methods and apparatus disclosed therein. Also, the drawings are not to scale. Similar elements are designated by the same numerals wherever possible. Embodiments of the present disclosure will now be described, by way of example, with reference to the following drawings: [Figure 1] 1 is a schematic diagram of a vibration damping system disposed on a vessel, the vibration damping system being for a rotor sail, according to one embodiment of the present disclosure; FIG. [Figure 2] FIG. 1 is a schematic diagram of a rotor sail according to one embodiment of the present disclosure. [Figure 3] 1 illustrates steps of a method for suppressing vibrations of a rotor sail, according to one embodiment of the present disclosure. In the accompanying drawings, underlined numbers are used to represent the item at or adjacent to the number. Numbers without underlines are associated with the item identified by the line extending from them. When a number is not underlined and is accompanied by an arrow, the number is used to identify the general item the arrow points to. Detailed Description of the Embodiments

[0012] The following detailed description illustrates embodiments of the present disclosure and how they may be practiced. Although several forms for carrying out the present disclosure have been disclosed, those skilled in the art will recognize that other forms for carrying out the present disclosure are also possible.

[0013] Viewed in one respect, one embodiment of the present disclosure provides a vibration damping system for a rotor sail, the vibration damping system comprising: a support structure having a first end, a second end, and a predetermined height defined by the first end and the second end, the support structure being disposed within a rotation cylinder of the rotor sail, the second end being coupled to a base of the rotor sail to support the rotation cylinder; the vibration damping system further comprises one or more vibration damping units mounted on the support structure, the distance from the first end to the vibration damping units being between 0 and 30% of the predetermined height of the support structure; The one or more vibration damping units suppress vibration of the rotor sail and enable the rotating cylinder to operate so that the frequency of vibration caused by the operation of the rotating cylinder is equal to or greater than the natural frequency of the rotor sail.

[0014] Viewed another way, an embodiment of the present disclosure provides a method for suppressing vibration of a rotor sail, the method comprising: providing one or more vibration damping units; Mounting the one or more vibration damping units on a support structure such that a distance from the first end to the vibration damping unit is between 0 and 30% of the predetermined height of the support structure; suppressing vibrations of the rotor sail to allow the rotating cylinder to operate such that a frequency of vibrations caused by operation of the rotating cylinder is equal to or greater than a natural frequency of the rotor sail; Includes.

[0015] The present disclosure provides a vibration damping system for a rotor sail and a method for damping vibrations of the rotor sail. The system is configured to damp vibrations of the rotor sail. Typically, the system comprises one or more vibration damping units attached to a support structure of the rotor sail. Advantageously, the vibration damping system provides significant cost savings by enabling efficient use of wind power to propel a vessel, thereby increasing fuel efficiency, reducing greenhouse gas emissions, and making the vessel more environmentally friendly. A rotor sail using the vibration damping system can effectively stabilize the vessel in high winds, allowing it to safely navigate rough waters.

[0016] Throughout this disclosure, the term "vibration damping system" refers to a system configured to suppress oscillatory motion within a rotor sail. Typically, rotor sails utilize wind to provide auxiliary propulsion for marine vessels. In some embodiments, the vessels may include cargo ships, passenger ships, liners, and the like. The vibration damping system is configured to prevent vibration-related motion, such as vibration or wobble, from being induced within the rotor sail due to the frequency of vibrations induced by operation and the natural frequency of the rotor sail. Typically, the frequency of vibrations induced by operation of a rotor sail (operating frequency) is the rotational speed at which the rotor sail is used or intended to be used. For rotor sails in particular, this frequency is the number of revolutions of the rotor sail per unit of time (revolutions per minute, revolutions per second, or 1 / s = Hz). The natural frequency of a rotor sail is a characteristic of the rotor sail that is determined by its physical properties and boundary conditions. Specifically, the natural frequency, also known as the resonant frequency, is the frequency at which the rotor sail naturally vibrates in the absence of a driving force. The natural frequency of a rotor sail is determined by its mass, stiffness, and damping characteristics. Vibration is when the rotor sail vibrates back and forth around a fixed point or axis. Vibration is a periodic motion that repeats itself over time with a constant period and amplitude. Vibration includes frequency, amplitude, phase, and damping. Frequency is the number of oscillations per unit time (1 / sec, Hz). The amplitude of vibration is the maximum displacement of the rotor sail from its equilibrium position. The phase of vibration is the position of the rotor sail during the vibration period. Vibration damping is the rate at which the amplitude of vibration decreases over time.

[0017] Typically, the operating frequency is the frequency at which a vibration control system is designed to operate. This is the frequency at which the system or device performs its intended function. For example, the frequency at which a rotor sail is designed to rotate to generate thrust is the operating frequency.

[0018] The damping system is configured to control the motion of the rotor sail by creating motion that opposes the natural frequency of the rotor sail to prevent the frequency of vibration of the rotor sail from falling within the natural frequency range. In some embodiments, the damping system is designed to reduce or suppress motion or vibration. The damping system can be used to control vibrations to reduce or eliminate unwanted vibrations that may affect the performance or operation of the system. Beneficially, the damping unit is configured to protect the structural integrity of the rotor sail.

[0019] Rotor sails are typically configured to provide auxiliary power to ships. They include a rotating cylinder mounted on the ship's deck. For example, when the ship is sailing, wind flows over the rotor sail, generating lift and forward thrust to propel the ship. Rotor sails are often used in combination with conventional propulsion systems, such as engines or sails, to increase the ship's efficiency and reduce fuel consumption. Rotor sails are particularly useful for ships sailing in areas with strong, steady winds, such as on long voyages or certain trade routes.

[0020] In some embodiments, multiple rotor sails may be installed on a vessel to improve the propulsion performance of the vessel. The multiple rotor sails installed on the vessel may have different natural frequencies due to different structural stiffness at the installation locations of each of the multiple rotor sails. The foundations for installing each of the multiple rotor sails may be different due to space limitations or the support structures (e.g., stiffeners) below the foundations may be different. In some embodiments, each rotor sail is installed on the vessel at a different length, which results in each rotor sail having a different natural frequency.

[0021] As used herein, the term "support structure" refers to an elongated, vertical structure used to hold a rotor sail in place on a vessel. In some embodiments, the support structure is fabricated from a metal or alloy, a composite material, a fiber, a ceramic, a plastic material, and / or a combination thereof. Typically, the support structure has a first end, a second end opposite the first end, and a predetermined height between the first end and the second end. The second end of the support structure is connected to the foundation of the vessel to provide stability for the rotor sail. As used herein, the term "rotating cylinder" refers to an elongated, vertical structure that rotates around the support structure. In some embodiments, the rotating cylinder is fabricated from a metal, a non-metal, a composite material, a ceramic, and a combination thereof. The rotating cylinder is mounted to be located outside the rotor sail support structure and rotates about its longitudinal axis driven by wind passing over the rotor sail. The rotating cylinder is rotatably attached to the first end of the support structure. The rotation of the rotating cylinder generates lift and drag, and the generated lift acts as a thrust to push the vessel, aiding in its navigation. In some embodiments, the rotating cylinder is equipped with an automatic control system that allows the vessel's crew to automatically adjust the rotation speed (rpm) of the rotating cylinder based on wind speed and direction to optimize the amount of lift generated.

[0022] The second end of the support structure is coupled to the vessel's foundation, which provides support and stability to the support structure. Typically, the foundation is secured to the vessel's deck and is designed to withstand the loads and forces imposed on the support structure by wind and rotation of the rotating cylinder. The foundation is also configured to accommodate vibration loads as well as other non-vibration loads, such as loads resulting from vessel motion (e.g., rolling), green sea loads on the rotor sail, etc. In some embodiments, the foundation includes a base plate secured to the vessel's deck. In some embodiments, the foundation also includes one or more stiffeners extending downward to provide additional support. Preferably, the one or more stiffeners are bolted or welded to the base plate and the support structure.

[0023] The term "vibration damping unit" as used herein refers to a unit configured to dissipate or attenuate the amplitude of vibrations. Typically, one or more vibration damping units are configured to absorb kinetic energy generated during operation of the rotor sail. In this regard, the one or more vibration damping units are configured to absorb vibrations resulting from the rotor sail's natural frequency. The one or more vibration damping units reduce the amplitude of the vibratory motion and help stabilize the vibration damping system. In some embodiments, the one or more vibration damping units are selected from, but not limited to, shock absorbers, viscous dampers, dashpots, etc. In effect, the vibration damping units dissipate vibrations by converting the vibration-related motion into kinetic energy. Furthermore, the vibration damping units change the effective weight of the support structure, thereby changing its natural frequency and the natural frequency of the rotor sail. The one or more vibration damping units are mounted on the support structure. The distance from the first end to the vibration damping units is between 0 and 30% of the height (H) of the support structure. For example, if the support structure is 10 meters high, the damping units may be positioned between 0 and 3 meters from the first end toward the second end. When the rotor sail is in use, the damping units may be positioned between 7 and 10 meters above the foundation (or deck). Alternatively, the damping units may be positioned between 5, 10, 15, 20, 25%, and 10, 15, 20, 25, and 30% of the height H from the first end toward the second end.

[0024] In some embodiments, the support structure height (H) is in the range of 50% to 100% of the rotor sail height. The support structure height is a specific, pre-set height for the support structure. In some embodiments, the pre-set height of the support structure is in the range of 60, 70, 80, 90, 100% to 50, 60, 70, 80, 90%. In some embodiments, each of the one or more damping units comprises the following elements: Mounting structure. One or more isolators or springs coupled to the mounting structure. One or more weight elements coupled to said one or more isolators or springs.

[0025] In this regard, the term "mounting structure" as used herein refers to a structure that provides a means for mounting vibration damping units and provides stability. The mounting structure for the vibration damping units is configured to hold or secure one or more vibration damping units to prevent the one or more vibration damping units from collapsing or falling. In some embodiments, the mounting structure can be fabricated from materials such as, but not limited to, metals, non-metals, alloys, composites, or any combination thereof. As used herein, the term "isolator or spring" refers to a device configured to isolate a vibration damping system from external forces or vibrations. Typically, one or more isolators or springs are used to reduce the transmission of forces or vibrations between different components of a vibration damping system. Preferably, one or more isolators or springs are elastic parts or mechanisms disposed on the mounting structure that can absorb, store, or release energy through changes in properties. The one or more isolators or springs are coupled to the mounting structure using fasteners, interlocks, welding, adhesives, magnetic couplings, snap fits, or the like. In some embodiments, the one or more isolators or springs are made of metal, i.e., copper, iron, beryllium, titanium, etc. Metal alloys include, for example, stainless steel, carbon steel, chrome silicon (an alloy of chromium and silicon), chrome vanadium (an alloy of chromium and vanadium), Elgiloy (an alloy of cobalt, chromium, and nickel), phosphor bronze, brass, etc. The one or more isolators or springs can be made of rubber, plastic (e.g., a plastic composite), polyphenylene sulfide, acrylonitrile butadiene styrene (ABS), nylon, acrylic, polyamide-imide (PAI), etc. In some embodiments, the one or more isolators or springs are made of composite materials, fibers, etc. In some embodiments, the one or more isolators or springs are viscous dampers (e.g., non-Newtonian fluid dampers, Newtonian fluid dampers), gas dampers, etc.Because the one or more isolators or springs are designed to undergo large deflections during use, the materials of construction must also have a wide elastic range to damp vibrations during use. The rotor sail can begin to vibrate due to external vibrations (such as wind, tides, or the ship's machinery, e.g., propeller blade passing frequencies) or internal vibrations (such as the movement of the rotor sail). The one or more weight elements prevent the rotor sail from inducing vibrations. (Rotor sail vibrations can significantly reduce the lifespan of a vibration damping system.) Optionally, if the one or more weight elements are not placed on the rotor sail, the rotor sail is not rotating, and the ship's vibrations are close to the rotor sail's natural frequency, the rotor sail will begin to resonate. When vibrations occur in the rotor sail, the one or more weight elements resist the force and generate a counterforce according to Newton's first law of inertia. This reaction force is conducted to the support structure through the one or more isolators or springs and the support structure. The one or more vibration damping units are attached to the support structure using a mounting structure for the vibration damping units. This attachment can be done using screws, bolts, welding, or fasteners. The vibration damping units can be provided as a package "ready" for installation. Without a mounting structure, the springs or isolators must be directly coupled to the support structure, complicating installation.

[0026] In some embodiments, the one or more vibration damping units further comprise a protective cover. The protective cover is configured to retain the mounting structure, the one or more isolators or springs, and the one or more weight elements. In this regard, the term "protective cover" as used herein refers to a protective layer configured to at least partially or completely surround the one or more vibration damping units. The protective cover encases the mounting structure, the one or more isolators or springs, and the one or more weight elements. In some embodiments, the protective cover prevents environmental factors from affecting the mounting structure, the one or more isolators or springs, and the one or more weight elements. In some embodiments, the protective cover may be implemented to have a substantially cubic or rectangular shape. Alternatively, the protective cover may be implemented to have any polygonal shape. The protective cover also reduces the risk of accidents during rotor sail maintenance because potentially movable weight elements are isolated from maintenance personnel.

[0027] In some embodiments, the one or more vibration control units are mounted on the support structure in either a stacked or side-by-side configuration. In some embodiments, the one or more vibration control units are mounted on the support structure in a stacked configuration, i.e., the one or more vibration control units are stacked on top of each other. The stacked arrangement of the one or more vibration control units forms layers, with each layer of the one or more vibration control units configured to provide damping to the rotor sail. In some embodiments, the one or more vibration control units are mounted on the support structure side-by-side with each other, allowing the rotor sail to be tuned to operate over a wider frequency range and above the operating frequency by adding or removing vibration control units.

[0028] The one or more damping units are adjustable, allowing the one or more damping units to be altered for placement in a particular location. The arrangement of the one or more damping units attached to the support structure in a stacked or side-by-side manner allows the one or more damping units to be evenly spaced around the circumference of the support structure to distribute loads evenly.

[0029] In some embodiments, the one or more vibration damping units are mounted on an inner or outer surface of the support structure. In some embodiments, the one or more vibration damping units are mounted on an inner surface of the support structure. In some embodiments, the one or more vibration damping units are mounted on an outer surface of the support structure. Advantageously, one or more vibration damping units mounted on the outer surface of the support structure also serve to provide structural integrity to the support structure. One or more vibration damping units mounted on the inner surface of the support structure allow for easy access for maintenance and repair.

[0030] In some embodiments, the operating frequency of the rotor sail is in the range of 0 to 6 Hz, and the natural frequency of the rotor sail and each of the one or more damping units is in the range of 1 to 6 Hz. In some embodiments, the operating frequency of the rotor sail is in the range of 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 Hz to 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 Hz. In some embodiments, the natural frequency of the rotor sail is in the range of 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 5.5 Hz to 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 Hz. In some embodiments, the operating frequency of each of the one or more damping units is in the range from 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 Hz to 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 Hz.

[0031] In some embodiments, the one or more vibration damping units are configured to damp vibrations of the rotor sail in the x, y, and z directions. In some embodiments, the one or more vibration damping units are configured to damp vibrations of the rotor sail in the x direction. In some embodiments, the one or more vibration damping units are configured to damp vibrations of the rotor sail in the y direction. In some embodiments, the one or more vibration damping units are configured to damp vibrations of the rotor sail in the z direction. Typically, rotor sails are subjected to vibrations in the x, y, and z directions due to wind variability. To reduce this unwanted motion and increase the efficiency of the rotor sail, the one or more vibration damping units are used. These units are designed to absorb and dissipate vibration energy, effectively reducing the amplitude of the vibrations. The one or more vibration damping units are strategically attached to the surface of the support structure of the rotor sail and damp vibrations in the x, y, and z directions. This improves the stability and performance of the rotor sail, making it more efficient and reducing wear on the damping system. Such placement of the damping units also helps with load distribution, space and maintenance needs.

[0032] The present disclosure also relates to a method for suppressing vibrations of the rotor sail as described above. The various embodiments and variants disclosed above apply mutatis mutandis to the method for suppressing vibrations of the rotor sail.

[0033] According to one aspect, there is provided a rotor sail arranged on the deck of a vessel, the rotor sail being provided with a vibration damping system, the number of rotor sails being plural, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. Each vibration damping system in such an arrangement may be as described above.

[0034] In some embodiments, or alternatively, at least one of the stiffness of one or more isolators or springs, the position of the weight elements, or the mass of the weight elements of the vibration damping units of the vibration damping system is adjustable. Adjustments may be necessary to further reduce rotor sail vibrations. This provides a means to fine-tune the vibration damping system after installation and to calibrate the vibration damping system on an ad-hoc basis. In some embodiments, this adjustment may be made in real time, where the vibrations of the rotor sail are measured and adjustments are made based on the measurements to change the frequency of the vibrations.

[0035] In some embodiments, the damping system comprises two or more damping units, each damping unit being independently adjustable relative to the others, to take into account, for example, the heeling of the vessel (which may be caused by wind or uneven cargo loading).

[0036] For example, adjusting the stiffness of a spring or isolator can be done electrically. For example, in the case of a spring, this can be done by adjusting the spring constant using "smart materials" whose properties change when electricity is passed through the material. In the case of an isolator, it is also possible to electrically adjust the stiffness of the isolator (e.g., using electroactive materials such as electroactive polymers) to dampen rotor sail vibrations. The weight of the weight can also be adjustable. For example, the weight can be changed by making the weight a container that can be filled with a fluid such as water, and adjusting the amount of water. The center of gravity of the weight element can also be adjustable. For example, if the weight element is made up of many (small) weights, removing or adding the small weights can change the center of gravity of the weight element.

[0037] Also, in some embodiments, the position of the weighted element can be controlled, for example, if the weighted element is movably formed on a rail or guide, which can be moved hydraulically, pneumatically (using an actuator), or by other suitable means for moving the element (wherein the rail or the like is formed on the support structure or on the mounting structure in a longitudinal direction relative to the support structure).

[0038] In some embodiments, sensors for measuring vibrations (i.e., frequency) are formed on the support structure, and the vibration information can be used to adjust the damping system by varying the spring characteristics (spring constant / stiffness), for example, using electrical means. Alternatively, the weight or position of the weights could be changed. In practice, the measured frequency can be compared with known resonant frequencies (natural frequencies) or desired operating frequencies. If there is an indication that the rotor sail is experiencing unwanted vibrations, a control signal can be provided to make the necessary adjustments.

[0039] In some embodiments, the springs or isolators or weight elements may be controlled and / or adjusted by wireless means. Operation, control and adjustment of the vibration damping units (springs, isolators, weight elements) may be cloud-based (e.g. using a cloud server). [Detailed description of the drawing]

[0040] Referring to FIG. 1 , a schematic diagram of a vibration damping system 100 disposed on a vessel 102 for a rotor sail 104 is shown, in accordance with one embodiment of the present disclosure. As shown, the vessel 102 is a vessel having a rotor sail 104. The rotor sail 104 is mounted on the vessel 102 by being attached to a foundation 106. The foundation 106 is attached to the deck of the vessel 102. As shown, the vibration damping system 100 has a support structure 108. The support structure 108 has a first end 108A and a second end 108B, and a height H of the support structure 108 is defined by the first end 108A and the second end 108B. That is, the height H is the distance between the first end and the second end.

[0041] As shown, the support structure 108 is disposed within the rotating cylinder 110 of the rotor sail 104, and the second end 108B is coupled to the base 106 of the rotor sail 104 to support the rotating cylinder 110. The rotating cylinder is rotatably supported (e.g., by a bearing) by the first end 108A of the support structure.

[0042] The vibration damping system 100 comprises one or more vibration damping units 112 mounted to the support structure 108. The one or more vibration damping units 112 may operate to suppress vibrations of the rotor sail 104 such that the rotating cylinder 110 can operate at an operating frequency that is higher than the natural frequency of the rotor sail 104.

[0043] One or more vibration damping units 112, 204 are attached to the support structure 108 near the first end 108A. The distance from the first end 108A to the vibration damping units is between 0 and 30% of the height (H) of the support structure. As shown, when the rotor sail is in use, the vibration damping units are at the top of the support structure.

[0044] Referring to FIG. 2, a schematic diagram of a rotor sail 200 according to an embodiment of the present disclosure is shown. As shown, a close-up view of a vibration damping unit 204 is also shown. The one or more vibration damping units include a base 206, one or more isolators or springs (a first isolator or spring is indicated by reference numeral 208A, and a second isolator or spring is indicated by reference numeral 208B) coupled to the base 206, and one or more weight elements (masses) 210 coupled to the one or more isolators or springs 208A, 208B. The one or more weight elements 210 are supported on the one or more isolators or springs 208A, 208B. The one or more vibration damping units further include a protective cover 212. The protective cover 212 is configured to hold the base 206 , one or more isolators or springs 208 A, 208 B, and one or more weight elements 210 .

[0045] Referring to FIG. 3 , steps of a method for suppressing vibrations of a rotor sail are shown, according to one embodiment of the present disclosure. In step 302, one or more vibration suppression units are provided. In step 304, the one or more vibration suppression units are attached to a first end of a support structure of the rotor sail (in some embodiments, a fixed distance from the first end). Here, a support structure having a predetermined height is disposed within the rotating cylinder of the rotor sail, and a second end of the support structure is coupled to a base of the rotor sail to support the rotating cylinder. In step 306, vibrations of the rotor sail are suppressed, allowing the rotating cylinder to operate at a rotational speed higher than the natural frequency of the rotor sail.

[0046] Steps 302, 304, and 306 are illustrative only, and other embodiments may be provided in which one or more steps are added, one or more steps are removed, or one or more steps are performed in a different order without departing from the scope of the claims herein.

[0047] Modifications to the embodiments of the present disclosure described above can be made without departing from the scope defined by the appended claims. The terms "including," "comprising," "incorporating," "having," "being," and the like, used to describe and claim the present disclosure, are intended to be interpreted in a non-exclusive manner, i.e., allowing for the presence of items, parts, or components not expressly recited. The absence of a plurality of elements does not preclude the presence of a plurality of such elements.

Claims

1. 1. A rotor sail having a vibration damping system, the rotor sail having a rotating cylinder and the vibration damping system, the vibration damping system comprising: a support structure having a first end, a second end, and a predetermined height defined by the first end and the second end, the support structure being disposed within the rotation cylinder of the rotor sail, the second end being coupled to a base of the rotor sail to support the rotation cylinder; the vibration damping system further comprises one or more vibration damping units mounted on the support structure, the distance from the first end to the vibration damping units being between 0 and 30% of the predetermined height of the support structure; the one or more vibration suppression units suppress vibration of the rotor sail and enable the rotating cylinder to operate so that a frequency of vibration caused by operation of the rotating cylinder is equal to or greater than a natural frequency of the rotor sail. Vibration control system.

2. The rotor sail of claim 1 , wherein the predetermined height of the support structure is in the range of 50% to 100% of the height of the rotor sail.

3. Each of the one or more vibration damping units comprises: - mounting structure; one or more isolators or springs coupled to said mounting structure; one or more weight elements coupled to said one or more isolators or springs; 2. The rotor sail of claim 1, comprising:

4. 4. The rotor sail of claim 3, wherein the one or more vibration damping units further comprise a protective cover configured to retain the mounting structure, the one or more isolators or springs, and the one or more weight elements.

5. A rotor sail according to any one of claims 1 to 4, wherein the one or more vibration control units are attached to the support structure in either a stacked or side-by-side configuration.

6. A rotor sail according to any one of claims 1 to 5, wherein the one or more vibration control units are attached to an inner or outer surface of the support structure.

7. 2. The rotor sail of claim 1, wherein the operating frequency of the rotor sail is in the range of 0 to 6 Hz, and the natural frequency of the rotor sail and the operating frequency of each of the one or more damping units are in the range of 1 to 6 Hz.

8. 8. A rotor sail according to claim 1, wherein the one or more vibration damping units are configured to damp vibrations of the rotor sail in x, y and z directions.

9. 1. A method for suppressing vibrations of a rotor sail having a vibration damping system, the rotor sail having a rotating cylinder and the vibration damping system, the method comprising: a support structure having a first end, a second end, and a height defined by the first end and the second end; one or more vibration damping units; wherein the support structure is disposed within the rotation cylinder of the rotor sail and the second end is coupled to a base of the rotor sail to support the rotation cylinder, and the method further comprises: Mounting the one or more vibration damping units to a support structure such that a distance from the first end to the vibration damping unit is between 0 and 30% of the predetermined height of the support structure; suppressing vibrations of the rotor sail so as to operate the rotating cylinder such that the frequency of vibrations caused by operation of the rotating cylinder is equal to or greater than the natural frequency of the rotor sail; A method comprising:

10. 10. The method of claim 9, wherein the predetermined height of the support structure is in the range of 50% to 100% of the height of the rotor sail.

11. Each of the one or more vibration damping units comprises: - mounting structure; one or more isolators or springs coupled to said mounting structure; one or more weight elements coupled to said one or more isolators or springs; 11. The method of claim 9 or 10, comprising:

12. 12. The method of claim 9, wherein the operating frequency of the rotor sail is in the range of 0 to 6 Hz, and the natural frequency of the rotor sail and the operating frequency of each of the one or more damping units are in the range of 1 to 6 Hz.

13. A rotor sail according to any one of claims 1 to 8, wherein the vibration damping system comprises two or more vibration damping units, each independently adjustable relative to one another.

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