Vibration damping devices for marine risers and submarine cables

Abstract

This utility model belongs to the technical field of marine oil and gas and power development equipment, and discloses a vibration damping device for marine risers and submarine cables. The device includes a damping cylinder, a positioning component, a support rod, a sleeve half-ring, bolt holes, and bolts. The damping cylinder is rigidly connected to the sleeve half-ring via the support rod and consists of two symmetrical half-cylinder structures, which are bolted together and fitted around the marine riser or submarine cable. The positioning component can be quickly installed and removed, providing reliable axial positioning for the vibration damping device. This utility model achieves efficient vibration reduction based on the synergistic mechanism of added mass efficiency and hydrodynamic damping energy dissipation. It has a simple structure, convenient and diverse installation methods, and is unaffected by ocean current direction or component attitude, making it widely applicable to vibration control of marine pipelines.

Description

Technical Field

[0001] This utility model belongs to the field of marine oil and gas and power development equipment technology, specifically a vibration reduction device for marine risers and submarine cables. Background Technology

[0002] Submarine risers and cables are core infrastructure for offshore oil and gas development, offshore wind power, and marine observation. Their service environments cover vertical, inclined, and even near-horizontal deployments, and they are constantly exposed to complex ocean currents, making them highly susceptible to vibrations caused by ocean currents. These vibrations accelerate the accumulation of fatigue damage to components, significantly shortening their service life. In severe cases, they can lead to major accidents such as component fracture, media leakage, and power and signal outages, causing huge economic losses and serious marine ecological risks.

[0003] Currently, fairing devices used for vibration control of marine risers and submarine cables require installation along the axial direction of the component. Both are constructed simultaneously with the lowering of the component, making it difficult to conveniently add them to in-service components and adapting to the vibration reduction needs throughout the entire lifecycle of marine risers and submarine cables. Existing fairing devices mostly rely on rectification and vortex breaking / elimination to prevent the formation of regular vortices. Their vibration reduction effect is highly dependent on the matching degree between the incoming flow direction and the device's attitude; changes in the flow field can significantly reduce their vibration reduction performance, resulting in limited effectiveness. Furthermore, existing fairing devices are mostly designed for vertically deployed marine risers, exhibiting poor adaptability to inclined or near-horizontal deployments. They are also mostly fixed-diameter designs, lacking versatility for components of different specifications, severely limiting their applicability. Therefore, they have shortcomings in terms of structural form, installation method, robustness, and applicable conditions.

[0004] Therefore, there is an urgent need to develop a vibration damping device for marine risers and submarine cables that is easy to install and maintain, has stable vibration reduction performance, and can be adapted to all scenarios and working conditions, in order to make up for the many shortcomings of existing technologies. Utility Model Content

[0005] This utility model addresses the problems of existing vibration damping devices for marine risers and submarine cables, such as a single vibration damping mechanism, poor installation adaptability, difficulty in adding in-service components, and insufficient reliability under complex working conditions. It provides a vibration damping device that features composite energy consumption, convenient installation, stable vibration reduction, and adaptability to all scenarios and all life cycles.

[0006] The technical solution of this utility model:

[0007] A vibration damping device for marine risers and submarine cables includes a vibration damping cylinder 1, a positioning component 2, a support rod 3, a sleeve half-ring 4, bolt holes 5, and bolts 6. The vibration damping cylinder 1 consists of two symmetrical half-cylinder structures. The two sleeve half-rings 4 are locked together by the bolt holes 5 and bolts 6 to form a ring that can accommodate the marine riser and submarine cable. The inner diameter of the ring is larger than the outer diameter of the marine riser and submarine cable. The inner wall of the vibration damping cylinder 1 is rigidly connected to the ring formed by the two sleeve half-rings 4 through the support rod 3. The positioning component 2 is clamped and fixed to the outer wall of the marine riser and submarine cable to provide axial positioning for the vibration damping device.

[0008] The vibration damping cylinder 1 has a structure with through openings at both the top and bottom, and the interior is an open cavity. The through openings at both the top and bottom allow the interior of the vibration damping cylinder 1 to be connected to the external seawater.

[0009] The vibration damping cylinder 1 has a continuous wave-shaped variable cross-section arc (not limited to circular arc) thin-walled structure along the axial direction. Its lateral outer edge dimension is 3-5 times the diameter of the marine riser or submarine cable to be protected, and its axial height is 1-2m.

[0010] The vibration damping device is fitted onto the exterior of the marine riser and submarine cable. Axial positioning is achieved by clamping and fixing the positioning component 2 to the outer wall, preventing significant displacement of the vibration damping device along the axial direction of the marine riser and submarine cable. The weight of the vibration damping device is greater than its buoyancy. The inner cavity of the vibration damping cylinder 1 is filled with seawater, and the inner diameter of the sleeve half-ring 4 is not less than the outer diameter of the marine riser and submarine cable. In a static state, the interaction force between the vibration damping device and the marine riser and submarine cable is negligible. When the vibration amplitude of the marine riser and submarine cable is small, the vibration damping device has no significant effect. When the vibration amplitude of the marine riser and submarine cable is large, the outer wall collides with the sleeve half-ring 4, causing the vibration damping device to vibrate synchronously. The inertial force of the vibration damping cylinder 1 and the seawater inside the cylinder will generate motion resistance on the marine riser and submarine cable, ultimately achieving the vibration damping effect.

[0011] When the inner diameter of the sleeve half-ring 4 is equal to the outer diameter of the marine riser and submarine cable, it is equivalent to the vibration damping device being fixed to the marine riser and submarine cable and moving in complete synchronization. This is equivalent to providing additional mass to the marine riser and submarine cable. If other conditions remain unchanged, the amplitude will usually be reduced, but the effect may not be very obvious. In addition, the vibration frequency of the marine riser and submarine cable will be reduced, resulting in a lower flow velocity for vortex-induced vibration. This solution is usually not adopted.

[0012] The vibration damping device is flexible and adaptable to various working conditions. When the marine riser and submarine cable are excited by ocean currents, they cause the vibration damping cylinder (1) to vibrate. On the one hand, the vibration damping cylinder (1) generates resistance to the marine riser and submarine cable by accelerating the movement of the seawater inside the vibration damping cylinder (1). On the other hand, the vibration damping energy is dissipated by the water resistance generated by the relative movement between the outer wall of the vibration damping cylinder (1) and the seawater. The dual mechanisms work together to achieve efficient vibration damping. The vibration damping performance of the device is not affected by changes in the direction of ocean currents and is adaptable to any vertical, horizontal, or inclined posture of the marine riser and submarine cable.

[0013] The vibration damper 1 comprises two symmetrical semi-cylindrical structures. The cylinder body has a continuous wave-shaped variable cross-section arc-shaped thin-walled structure along the axial direction, which can prevent the vibration damper 1 from generating periodic vortex-induced forces due to ocean current excitation, and achieve higher structural stiffness through the spatial continuous wave-shaped variable cross-section arc-shaped thin-walled structure. The vibration damper 1 can be made of lightweight materials such as aluminum and foam. Together with the support rod 3, the sleeve half-ring 4, and the bolts 6, its overall weight is greater than its buoyancy, and the difference is balanced by the positioning component 2.

[0014] The size and number of vibration damping cylinders 1 are not limited and can be flexibly adjusted according to project needs, taking into account the convenience of manufacturing, transportation and installation. The maximum outer edge size of a single vibration damping cylinder 1 is 3-5 times the diameter of the marine riser or submarine cable to be protected, and the axial height is 1-2m. Multiple sets can be connected in series along the axial direction of the marine riser or submarine cable. The two ends of the vibration damping cylinder 1 do not need to be sealed, the structure is simple and basically does not affect the vibration damping effect.

[0015] The positioning component 2 is used to axially limit the vibration damping device. Its material, size, quantity, and construction are not limited, but it has sufficient load-bearing capacity, locking reliability, and ease of installation and removal. Alternatively, the sleeve half-ring 4 can be directly tightened onto the outer wall of the marine riser or submarine cable to rigidly fix the vibration damping device to the marine riser or submarine cable. In this case, no additional positioning component 2 is required, but the vibration damping effect may be affected.

[0016] The support rod 3 is used to connect the vibration damping cylinder 1 and the sleeve half ring 4. The three have sufficient strength, rigidity and stability. The material, size, quantity and connection method of the support rod 3 are not limited.

[0017] The sleeve half-ring 4 has at least two layers along the axial direction of the marine riser and submarine cable, and its inner diameter is larger than the outer diameter of the marine riser and submarine cable. Its material, size, quantity and form are not limited.

[0018] The bolt holes 5 are usually located at both ends of the sleeve half ring 4, and their diameter, number, and position are not limited.

[0019] The bolt 6 matches the bolt hole 5 to ensure sufficient strength, and its material and size are not limited.

[0020] The connection method of the sleeve half ring 4 is not limited to bolt connection; other convenient and reliable connection methods are also acceptable.

[0021] The weight of the vibration damping device is greater than its buoyancy. It can be installed at the designated section position of the marine riser and submarine cable in three typical ways, as follows: (1) Simultaneous installation with the marine riser and submarine cable: First, install the section fixing positioning part 2 above the water surface. Then, symmetrically wrap the two vibration damping cylinders 1 around the marine riser and submarine cable above the positioning part 2. Lock the device into a whole by passing the bolt 6 through the bolt hole 5 to complete the installation of the vibration damping device. Multiple sets of vibration damping devices can be installed section by section along the axial direction of the marine riser and submarine cable and then lowered to the design position as a whole. (2) Pre-installation and sinking installation above the water surface: First, install the section fixing positioning part 2 at the target section of the marine riser and submarine cable using underwater operation equipment. Then, install the vibration damping device on the marine riser and submarine cable above the water surface. Utilize the difference between the weight and buoyancy of the device to allow the vibration damping device to sink freely along the marine riser or submarine cable to the top of the positioning part 2. Then, set the positioning part 2 and lower the vibration damping device at different sections one by one. (3) Underwater full-condition installation: Vibration damping devices are installed on several sections of marine risers and submarine cables using underwater operating equipment.

[0022] The vibration reduction mechanism of this invention is a synergistic mechanism of the inertial reaction force of the vibration damping cylinder and seawater, and the damping energy dissipation of the vibration damping cylinder by water resistance: When the marine riser or submarine cable vibrates due to ocean current excitation, it first collides with the sleeve half-ring 4, causing the support rod 3 and the vibration damping cylinder 1 to vibrate synchronously. On the one hand, the seawater filling the inner cavity of the vibration damping cylinder 1 accelerates with the cylinder body, and the inertial force of the vibration damping cylinder 1 and the seawater in the inner cavity provides resistance to dissipate vibration energy for the marine riser and submarine cable. On the other hand, during the vibration of the vibration damping cylinder 1 with the components, the outer wall of the vibration damping cylinder 1 generates relative motion with the surrounding seawater, continuously dissipating vibration energy through negative work done by water resistance. The synergistic effect of the dual mechanisms can achieve a highly efficient vibration reduction effect. Since the cross-section of the vibration damping cylinder 1 is circular, its axis is basically parallel to the axis of the marine riser and submarine cable. Therefore, regardless of the flow direction or the vibration direction of the marine riser and submarine cable, the direction of motion of the vibration damping cylinder 1 is always the direction that can provide the maximum water resistance, and it will not produce any negative effects. Positioning component 2 can effectively prevent the vibration damping device from sliding along the axial direction. Regardless of whether the marine riser or submarine cable is laid vertically, inclined, or nearly horizontally, it can ensure that the vibration damping device is always in the preset high-incidence section of vortex-induced vibration, maintain a long-term stable and efficient vibration damping effect, and ensure the long-term service safety of the marine riser and submarine cable.

[0023] The beneficial effects of this utility model are: (1) The vibration reduction device is ingenious, simple in structure, convenient to install, diverse in form, economical and efficient, and adaptable to the entire life cycle of marine risers and submarine cables; (2) It integrates the dual vibration reduction mechanism of seawater added mass efficiency and hydrodynamic damping energy dissipation, which greatly improves the vibration energy dissipation efficiency; (3) The variable cross-section cylinder design not only greatly improves the overall stiffness of the thin-walled structure, but also avoids the occurrence of single-frequency vortex shedding; (4) The vibration reduction performance of the vibration reduction device is not affected by the change of ocean current direction, and is adaptable to any vertical, horizontal and inclined posture of marine risers and submarine cables, with a wide range of applicable scenarios. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall assembly of a marine riser and submarine cable vibration damping device;

[0025] Figure 2 This is a schematic diagram of a vibration damping cylinder structure.

[0026] In the diagram: 1. Vibration damper, 2. Positioning component, 3. Support rod, 4. Hoop half-ring, 5. Bolt hole, 6. Bolt. Detailed Implementation

[0027] The specific embodiments of this utility model are described in detail below with reference to the technical solution and accompanying drawings.

[0028] Based on the design parameters of the marine riser and submarine cable to be protected and the ocean current conditions of the service area, the size, quantity, installation position and specifications of the matching positioning parts are determined through theoretical analysis, experiments or simulation calculations. The vibration damping device is prefabricated in the factory as an integrated single-petal component, consisting of the vibration damping cylinder, support rod, sleeve half ring, bolt hole, and bolt.

[0029] Installation Method 1: Applicable to the construction and lowering phase of marine risers and submarine cables, involving operations entirely above the water surface without underwater construction. During the lowering of the marine riser or submarine cable, a pre-installed section fixing positioning component 2 is first installed above the water surface. Two vibration damping cylinders 1 are symmetrically wrapped around the perimeter of the marine riser or submarine cable above the positioning component 2, aligning with the bolt holes 5 of the sleeve half-ring 4, and locked with bolts 6, so that the device is connected as a whole and radially fitted into the limiting position of the positioning component 2 on the marine riser or submarine cable, completing the installation of a single set of vibration damping devices. Multiple sets of vibration damping devices can be installed segment by segment along the axial direction of the marine riser or submarine cable and then lowered to the design position as a whole.

[0030] Installation Method 2: Applicable to the later installation of vertical marine risers and submarine cables that have already been installed. First, fix the positioning component 2 at the designated installation section of the marine riser or submarine cable using underwater operating equipment. Above the water surface, symmetrically wrap the two vibration damping cylinders 1 around the outer perimeter of the above-water section of the marine riser or submarine cable, aligning the bolt holes 5 of the sleeve half-ring 4, and lock them with bolts 6, so that the vibration damping device is connected as a whole and radially fitted onto the marine riser or submarine cable. Utilizing the difference between the gravity of the vibration damping device and the buoyancy of the seawater, the vibration damping device is allowed to sink freely along the marine riser or submarine cable to the top of the positioning component 2, where the positioning component 2 completes the axial limitation, completing the installation of a single set of vibration damping devices. This process can be followed to fix the positioning component 2 and lower and install the vibration damping devices at different sections of the marine riser or submarine cable to complete the deployment of multiple sets of vibration damping devices.

[0031] Installation Method 3: Suitable for complex working conditions such as inclined or near-horizontal installations of marine risers and cables, and installations with entanglement on the outer wall. It can also be used for the later installation of in-service marine risers and cables. First, the positioning component 2 is fixed at the designated installation section of the marine riser or cable using underwater operating equipment. The prefabricated vibration damping device body is then transported to the underwater target position. Two vibration damping cylinders 1 are symmetrically wrapped around the perimeter of the marine riser or cable, aligning the bolt holes 5 of the sleeve half-ring 4, and locked with bolts 6. This connects the vibration damping device into a whole, radially fitted onto the marine riser or cable, and abuts against the top of the positioning component 2. The positioning component 2 completes the axial limiting, completing the installation of a single vibration damping device. Multiple sets of vibration damping devices can be installed at several designated sections of the marine riser or cable using this method.

[0032] The working process of this utility model is as follows: When the ocean current flows through the marine riser and submarine cable, the periodic flow of the fluid excites and induces transverse and longitudinal vibrations. First, it collides with the sleeve half-ring 4, causing the support rod 3 and the vibration damping cylinder 1 to vibrate synchronously. On one hand, the seawater filling the inner cavity of the vibration damping cylinder 1 accelerates synchronously with the cylinder body, generating significant inertial force, which reacts on the marine riser and submarine cable to dissipate vibration energy. On the other hand, during the vibration of the vibration damping cylinder 1 along with the marine riser and submarine cable, the outer wall of the vibration damping cylinder 1 moves relative to the surrounding seawater, forming water resistance to dissipate vibration energy. The synergistic effect of these two mechanisms achieves a highly efficient vibration reduction effect.

Claims

1. A vibration damping device for marine risers and submarine cables, characterized in that, The vibration damping device for marine risers and submarine cables includes a vibration damping cylinder (1), a positioning component (2), a support rod (3), a sleeve half-ring (4), bolt holes (5), and bolts (6). The vibration damping cylinder (1) consists of two symmetrical half-cylinder structures. The two sleeve half-rings (4) are locked together by the bolt holes (5) and bolts (6) to form a ring that can accommodate marine risers and submarine cables. The inner diameter of the ring is equal to or greater than the outer diameter of the marine riser and submarine cable. The inner wall of the vibration damping cylinder (1) is rigidly connected to the ring formed by the two sleeve half-rings (4) through the support rod (3). The positioning component (2) is clamped and fixed to the outer wall of the marine riser and submarine cable to provide axial positioning for the vibration damping device.

2. The vibration damping device for marine risers and submarine cables according to claim 1, characterized in that, The vibration damping cylinder (1) has a structure with open ends at both the top and bottom, and the interior is an open cavity. The open ends at both the top and bottom connect the interior of the vibration damping cylinder (1) with the external seawater.

3. The vibration damping device for marine risers and submarine cables according to claim 1, characterized in that, The vibration damping cylinder (1) has a continuous wave-shaped variable cross-section arc-shaped thin-walled structure along the axial direction. Its maximum axial outer diameter is 3-5 times the outer diameter of the marine riser and submarine cable to be protected, and its axial height is 1-2m.

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