A vibration damping device for riser vortex-induced vibration and a design method for the vibration damping device.

Abstract

This application provides a device for reducing and suppressing vortex-induced vibration in a riser and a design method for such a device. The device includes multiple sets of basic vibration-suppressing units, which are installed parallel to each other on the riser along its height. Each set of basic units includes a first sleeve, multiple dampers, multiple second sleeves, and multiple additional mass rods. The first sleeve is fitted onto the riser. One end of each damper is connected to the first sleeve at intervals along its circumference, and the other end is connected to a corresponding second sleeve. The second sleeve is fitted onto a corresponding additional mass rod. This device not only has a significant energy-dissipating and vibration-reducing effect but also interferes with the flow field to suppress the shedding of vortices from the riser wake, thus reducing vortex-induced vibration in the riser and providing a dual effect of vibration reduction and suppression.

Description

Technical Field

[0001] This application relates to the field of marine facilities, and in particular to a riser vortex-induced vibration reduction and damping device and a design method for the device. Background Technology

[0002] Deep-sea oil and gas extraction systems consist of three parts: subsea pipelines, riser systems, and floating structures. The riser connects the floating structure and subsea oil wells to transport oil and gas, and is a key piece of equipment for deep-sea oil exploration and development. Under the influence of marine environmental loads such as wind, waves, and currents, the floating structure connected to the riser experiences frequent movement. Simultaneously, risers operating in deep-sea environments are also frequently subjected to ocean current loads. These factors can induce vortex-induced vibration (VEM) in the riser. The large amplitude and multi-mode involvement of VEM make it a major factor leading to riser fatigue damage, seriously threatening the safety of deep-sea oil and gas extraction. Therefore, developing riser VEM damping devices is an important measure to ensure the safe operation of risers.

[0003] The mechanism of riser vortex-induced vibration induced by background ocean currents is relatively well understood. It is generated by alternating vortices falling off in the riser wake. Therefore, current research mostly focuses on designing vibration suppression devices to reduce this type of vortex-induced vibration based on controlling the flow field. These devices interfere with the flow field and suppress vortex shedding by changing the structural shape or installing auxiliary devices. Therefore, existing devices only have the single function of suppressing vortex shedding. The more widely used vibration suppression devices include fairings, spiral plates, and control rods. Although fairings can guide the wake of the riser well, they must be placed behind the object being flowed around. However, the direction of ocean currents is unpredictable, making it difficult to determine the rear of the riser, which limits the practical engineering application of fairings. Spiral plates that spiral upwards around the riser can not only roughen the surface of the riser but also have no requirements on the direction of the incoming flow and adjust the flow around the riser surface to a certain extent. However, spiral plates cannot always suppress the vibration of the object being flowed around. At certain flow velocities, they can increase the flow resistance and excite more vibration modes. Arranging small control cylinders around a flowing object can disrupt the flow field and suppress vibrations to some extent. However, only by arranging control rods at specific angles can they effectively suppress vortex-induced vibrations of the riser; in some angles, they can even enhance vortex-induced vibrations. Furthermore, control rods may increase the average lift coefficient. To overcome these limitations, improved devices based on these vibration suppression mechanisms have been invented, such as staggered helical tubes and rotating control rods. However, these devices suffer from drawbacks such as complex design, difficult manufacturing, difficulty in standardization, high cost, and even the requirement for external power. Their biggest limitation is that they cannot be applied to damping vortex-induced vibrations of risers induced by the motion of floating structures. Summary of the Invention

[0004] One of the purposes of this application is to provide a riser vortex-induced vibration reduction and damping device and a design method for the device, so as to solve the problem of poor vibration reduction effect of riser vortex-induced vibration induced by motion in existing marine floating structures.

[0005] The technical solution of this application is:

[0006] A riser vortex-induced vibration reduction and damping device and its design method are disclosed. The device comprises multiple sets of basic vibration reduction units, which are installed parallel to each other on the riser along its height direction. Each set of basic vibration reduction units includes a first sleeve, multiple dampers, multiple second sleeves, and multiple additional mass rods. The first sleeve is fitted onto the riser. One end of each damper is connected to the first sleeve at intervals along its circumference, and the other end is connected to a corresponding second sleeve. The second sleeve is fitted onto a corresponding additional mass rod.

[0007] As one technical solution of this application, the spacing between adjacent dampers is the same.

[0008] As one technical solution of this application, the damper includes a first base plate, a second base plate, and at least one wire rope loop; the first base plate is welded to the first sleeve; the second base plate is welded to the second sleeve; one end of the wire rope loop is connected to the first base plate, and the other end is connected to the second base plate.

[0009] As one technical solution of this application, at least one first connecting hole is provided on the first base plate, and at least one second connecting hole is provided on the second base plate; the first connecting hole and the second connecting hole are on the same straight line; one end of the wire rope loop is connected to the first base plate through the first connecting hole, and the other end is connected to the second base plate through the second connecting hole.

[0010] A method for designing a vibration damping device, used to design the above-mentioned riser vortex-induced vibration damping device, includes the following steps:

[0011] Step 1: Based on the riser's geometric parameters and the background ocean currents of the service environment, perform vibration analysis on the riser for which vortex-induced vibration control is to be performed.

[0012] Step 2: Determine the installation range of the riser vortex-induced vibration reduction and damping device according to the vibration reduction and damping requirements of the riser.

[0013] Step 3: Determine the mass ratio of the total mass of the additional mass rod in the riser vortex-induced vibration damping device to the mass of the riser within a unit length range, and calculate the optimal damping ratio and optimal frequency of the riser vortex-induced vibration damping device.

[0014] Step 4: Based on the requirements of the disturbance flow field, determine the installation position of the vibration damping basic unit and the number of additional mass rods in each vibration damping basic unit, and determine the arrangement of the vibration damping basic units;

[0015] Step 5: Select and design the number and arrangement of the dampers;

[0016] Step 6: Calculate and analyze the vortex-induced vibration response of the riser equipped with the riser vortex-induced vibration reduction and damping device.

[0017] The beneficial effects of this application are:

[0018] The riser vortex-induced vibration reduction and suppression device and its design method disclosed in this application mainly consist of a damper and an additional mass rod deployed outside the riser. The damper is made of stainless steel wire rope loops, and damping and stiffness are provided by the dry friction generated between the intertwined wires through configuration changes of the wire rope loops. Furthermore, the damper connects the additional mass rod to the riser, and the inertial force generated by the vibration of the additional mass rod dissipates some energy, reducing the energy transmitted to cause riser vibration. Simultaneously, the presence of the damper and the additional mass rod can also interfere with the flow field, playing a certain role in suppressing riser vortex-induced vibration. Therefore, this device not only interferes with the flow field but also has energy-dissipating and vibration-reducing effects, simultaneously reducing riser vortex-induced vibration induced by floating structures and ocean currents. It is unaffected by complex ocean currents, requires no external power source, has good durability, and exhibits stable vibration suppression effects, showing promising prospects for practical engineering applications. Furthermore, this device addresses the structural aspects while also controlling the flow field. Therefore, it not only disrupts the flow field but also dissipates energy and reduces vibration over a wide frequency band and large amplitude range, significantly reducing riser vortex-induced vibration caused by any excitation. It is unaffected by any unknown ocean current directionality, providing multi-layered protection for the riser. Even when the flow field disruption function is ineffective, the stable energy dissipation and vibration reduction function still ensures the riser's resilience. Moreover, the device is easy to install, simple to maintain, and cost-effective. Because the damper provides damping through dry friction, the wire rope material has low stress levels and good fatigue resistance during operation, and can still perform well in energy dissipation and vibration reduction under extreme environments, providing a certain degree of protection for the riser. In addition, the device allows adjustment of the number of wire rope turns, spacing, and the mass and distribution of the additional mass rod according to the actual riser service environment and conditions, thereby achieving optimal reduction of riser vortex-induced vibration. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the riser vortex-induced vibration reduction and damping device and the design method of the device provided in the embodiments of this application;

[0021] Figure 2 A schematic diagram of a damper provided in an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the first angle of the damper provided in an embodiment of this application;

[0023] Figure 4 This is a schematic diagram of the second angle of the damper provided in an embodiment of this application;

[0024] Figure 5 This is a cross-sectional view of a wire rope loop provided in an embodiment of this application.

[0025] Icons: 1-Riser; 2-First Sleeve; 3-Additional Mass Bar; 4-Second Sleeve; 5-Damper; 6-First Base Plate; 7-Wire Rope Loop; 8-Second Base Plate. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this application, it should be noted that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only used to facilitate the description of this application and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] Furthermore, in this application, unless otherwise expressly specified and limited, "above or below" the first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Moreover, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0033] Example:

[0034] Please refer to Figure 1 (Refer to) Figures 2 to 5This application provides a riser vortex-induced vibration reduction and suppression device, which has a simple structure, reliable performance, and convenient installation. It can cope with any incoming flow direction and can simultaneously reduce the motion of the floating platform and suppress the vortex-induced vibration of the riser 1 induced by ocean currents. It is a novel riser vortex-induced vibration reduction and suppression device and its design method with dual functions of interfering with the flow field and energy dissipation and vibration reduction. It mainly includes multiple sets of vibration reduction and suppression basic units, which are installed parallel to each other on the riser 1 along the height direction. Each set of vibration reduction and suppression basic units includes a first sleeve 2, multiple dampers 5, multiple second sleeves 4, and multiple additional mass rods 3. The first sleeve 2 is sleeved on the riser 1. One end of each of the multiple dampers 5 is connected to the first sleeve 2 at intervals along the circumference of the first sleeve 2, and the other end is connected to the corresponding second sleeve 4. At the same time, the second sleeve 4 is sleeved on the corresponding additional mass rod 3. This device, by arranging additional mass rods 3 around the riser 1 and connecting them with dampers 5, achieves energy dissipation and vibration reduction by providing damping and stiffness with the additional mass rods 3 providing inertial force. It is unaffected by ocean current direction and can simultaneously reduce vortex-induced vibration of the riser 1 caused by background ocean currents and the movement of the floating platform. Based on meeting energy dissipation and vibration reduction requirements, this device can further reduce vortex-induced vibration of the riser 1 caused by background ocean currents by adjusting the distance between the additional mass rods 3 and the riser 1 and their surrounding arrangement, while also controlling ocean currents to suppress vortex shedding. Furthermore, due to its energy dissipation and vibration reduction function, in addition to reducing vortex-induced vibration of the riser 1, it also has a certain vibration reduction effect on vibrations caused by other factors, providing some protection for the riser 1 even in extreme situations such as submarine earthquakes.

[0035] It should be noted that, based on the requirements of the disturbed flow field, the number and arrangement of the additional mass rods 3 in the vibration damping basic unit are determined; the optimal damping ratio and optimal frequency in the vibration damping basic unit are determined based on the theory of tuned mass dampers, and the damper 5 is selected accordingly; furthermore, the damper 5 in the vibration damping basic unit needs to meet characteristics such as corrosion resistance, maintenance-free operation, and good fatigue resistance, including but not limited to the wire rope damper in this embodiment. In addition, the spacing between adjacent vibration damping basic units can be the same or different, and their arrangement can be designed differently according to actual environmental requirements. The optimal arrangement can be selected based on the needs of the disturbed flow field. The spacing between adjacent dampers 5 can be the same or different, and their arrangement can be designed differently according to actual environmental requirements. The optimal arrangement can be selected based on the needs of the disturbed flow field.

[0036] Furthermore, each damper 5 includes a first base plate 6, a second base plate 8, and at least one wire rope loop 7; the first base plate 6 is welded to the first sleeve 2; the second base plate 8 is welded to the second sleeve 4; one end of the wire rope loop 7 is connected to the first base plate 6, and the other end is connected to the second base plate 8. This device has a simple structure, is easy to implement, and is easy to install. Since the damper 5 is made of stainless steel wire, and the additional mass rod 3 only provides sufficient mass, materials that meet the requirements of the marine environment are sufficient, thus the device cost is also low. The number and spacing of the wire rope loops 7, as well as the mass and distribution of the additional mass rod 3, can be adjusted according to the actual service environment and conditions of the riser 1 to achieve the optimal effect of reducing the vortex-induced vibration of the riser 1.

[0037] Furthermore, at least one first connecting hole is provided on the first base plate 6, and at least one second connecting hole is provided on the second base plate 8; the first connecting hole and the second connecting hole are on the same straight line; one end of the wire rope loop 7 is connected to the first base plate 6 through the first connecting hole, and the other end is connected to the second base plate 8 through the second connecting hole.

[0038] It should be noted that in this embodiment, the number of first connecting holes and second connecting holes can be one; however, in other embodiments, multiple first connecting holes can be equally spaced at symmetrical positions on the first base plate 6, and multiple second connecting holes can be equally spaced at symmetrical positions on the second base plate 8. The distance between adjacent first connecting holes and the distance between adjacent second connecting holes can be adjusted according to actual conditions. The diameters of both the first and second connecting holes are slightly larger than the diameter of the wire rope loop 7, so that the wire rope loop 7 can pass through the first and second connecting holes. Holes are provided to connect the first base plate 6 and the second base plate 8, thereby forming an integral structure. Furthermore, the wire rope loops 7 are made of steel wires that meet the requirements and are wound together according to certain rules to provide damping. The number of wire rope loops 7 and the length of the wire rope can be calculated and adjusted according to the actual vibration reduction and suppression requirements of the riser 1. In addition, the first base plate 6 is welded to the first sleeve 2, and the second base plate 8 is welded to the second sleeve 4. The second sleeve 4 is fitted onto the additional mass rod 3 to make it a whole. The additional mass rod 3 is also calculated according to the vibration reduction and suppression requirements of the riser 1, and the arrangement is determined by considering the requirements of the interference flow field.

[0039] The damper 5 and the additional mass bar 3 can reduce the vortex-induced vibration of the riser 1 caused by ocean current excitation and floating platform motion in any direction of incoming flow. The damper 5 dissipates the vibration energy and the additional mass bar 3 reduces the vibration energy. The additional mass bar 3 surrounding the riser 1 also suppresses the shedding of wake vortices generated by ocean current in any direction of incoming flow, thereby reducing the vortex-induced vibration of the riser 1. The vortex-induced vibration response of the riser 1 under the combined excitation of background ocean current and floating platform motion can be calculated according to the form, length and connection method of the marine riser 1. The degree of reduction of the vortex-induced vibration response needs to be determined, as well as the number and length of the wire rope loops 7 of the damper 5, the mass, number and arrangement of the additional mass bar 3, and the number and arrangement of the required vibration damping devices are determined to achieve the best effect of reducing the vortex-induced vibration of the riser 1.

[0040] Furthermore, this embodiment also provides a design method for a vibration damping device, which is used to design a vibration damping device for vortex-induced vibration of a riser; the method mainly includes the following steps:

[0041] Step 1: Based on the geometric parameters of riser 1 and the background ocean currents of the service environment, conduct vibration analysis on riser 1, which is to be subject to vortex-induced vibration control.

[0042] Step 2: Determine the installation range of the vortex-induced vibration damping device for riser 1 based on the vibration reduction and suppression requirements of riser 1.

[0043] Step 3: Determine the mass ratio of the total mass of the additional mass rod 3 in the riser vortex-induced vibration damping device to the mass of the riser 1 within a unit length range, and calculate the optimal damping ratio and optimal frequency of the riser vortex-induced vibration damping device.

[0044] Step 4: Based on the requirements of the disturbance flow field, determine the installation position of the vibration reduction and damping basic unit and the number of additional mass rods 3 in each vibration reduction and damping basic unit, and determine the arrangement of the vibration reduction and damping basic units.

[0045] Step 5: Select and design damper 5;

[0046] Step 6: Calculate and analyze the vortex-induced vibration response of riser 1 equipped with a riser vortex-induced vibration reduction and damping device.

[0047] In summary, the riser vortex-induced vibration reduction and suppression device and its design method of this application mainly consist of a damper 5 and an additional mass rod 3 arranged outside the riser 1. The damper 5 is made of stainless steel and provides damping and stiffness through the configuration change of the wire rope loops 7 and the dry friction generated between the intertwined wires. Furthermore, the damper 5 connects the additional mass rod 3 to the riser 1, and the vibration of the additional mass rod 3 generates inertial force to consume part of the energy, thereby reducing the energy transmitted to cause the riser 1 to vibrate. At the same time, the presence of the damper 5 and the additional mass rod 3 can also interfere with the flow field, playing a certain role in suppressing the vortex-induced vibration of the riser 1. Therefore, this device not only has the function of interfering with the flow field, but also has the function of energy consumption and vibration reduction. It can simultaneously reduce the vortex-induced vibration of the riser 1 induced by the floating structure and ocean currents, and is not affected by complex ocean currents. It does not require an external power source, has good durability, and has good stability in vibration suppression effect, showing good prospects for practical engineering applications. Furthermore, this device, designed from a structural perspective while also controlling the flow field, not only interferes with the flow field but also dissipates energy and reduces vibration over a wide frequency band and large amplitude range. This significantly reduces vortex-induced vibration of riser 1 caused by any excitation, and it is unaffected by any unknown ocean current directionality, providing multi-layered protection for riser 1. Even when the flow field interference function is ineffective, the stable energy dissipation and vibration reduction function still ensures the resilience of riser 1. Moreover, the device is easy to install, simple to maintain, and low in cost. Because the damper 5 provides damping through dry friction, the stress level of the wire rope material is low during operation, resulting in good fatigue resistance. It can still perform well in energy dissipation and vibration reduction under extreme environments, providing a certain degree of protection for riser 1. In addition, the device allows adjustment of the number of wire rope coils 7, spacing, and the mass and distribution of the additional mass rod 3 according to the actual service environment and conditions of riser 1, thereby achieving the optimal reduction of vortex-induced vibration of riser 1. Furthermore, the flexible connection allows the wire rope damping vibration reduction device to provide some protection for riser 1 even in extreme situations, reducing the degree and probability of riser 1 damage and improving its toughness. In addition, this device is very simple, easy to manufacture, and low in cost; therefore, it has excellent application prospects.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for designing a vibration damping device, used to design a vibration damping device for vortex-induced vibration of a riser, the riser vortex-induced vibration damping device comprising multiple sets of vibration damping basic units, the multiple sets of vibration damping basic units being installed parallel and spaced apart along the height direction of the riser, and each set of vibration damping basic units comprising a first sleeve, multiple dampers, multiple second sleeves, and multiple additional mass rods; the first sleeve being sleeved on the riser; one end of each of the multiple dampers being connected to the first sleeve at intervals along the circumference of the first sleeve, and the other end being connected to a corresponding second sleeve; the second sleeve being sleeved on a corresponding additional mass rod; each damper comprising a first base plate, a second base plate, and at least one wire rope loop; the first base plate being welded to the first sleeve; The second base plate is welded to the second sleeve; one end of the wire rope loop is connected to the first base plate, and the other end is connected to the second base plate; at least one first connecting hole is provided on the first base plate, and at least one second connecting hole is provided on the second base plate; the first connecting hole and the second connecting hole are on the same straight line; one end of the wire rope loop is connected to the first base plate through the first connecting hole, and the other end is connected to the second base plate through the second connecting hole; characterized in that, The method includes the following steps: Step 1: Based on the riser's geometric parameters and the background ocean currents of the service environment, perform vibration analysis on the riser for which vortex-induced vibration control is to be performed. Step 2: Determine the installation range of the riser vortex-induced vibration reduction and damping device according to the vibration reduction and damping requirements of the riser. Step 3: Determine the mass ratio of the total mass of the additional mass rod in the riser vortex-induced vibration damping device to the mass of the riser within a unit length range, and calculate the optimal damping ratio and optimal frequency of the riser vortex-induced vibration damping device. Step 4: Based on the requirements of the disturbance flow field, determine the installation position of the vibration damping basic unit and the number of additional mass rods in each vibration damping basic unit, and determine the arrangement of the vibration damping basic units; Step 5: Select and design the number and arrangement of the dampers; Step 6: Calculate and analyze the vortex-induced vibration response of the riser equipped with the riser vortex-induced vibration reduction and damping device.

2. The vibration damping device design method according to claim 1, characterized in that, The spacing between adjacent dampers is the same.

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