Forced oscillation hydrodynamic experiment device for covering buoyancy block rigid riser

Abstract

The invention discloses a forced oscillation hydrodynamic experiment device for covering a buoyancy block rigid riser, which comprises an actuation module, a physical quantity sensing module, a rigid riser and a buoyancy block model, and is characterized in that the physical quantity sensing module is mounted on an actuation control module, the rigid riser is mounted on the physical quantity sensing module, the buoyancy block model is mounted on the rigid riser, and the buoyancy block model is mounted on the rigid riser. Therefore, the motion response of the rigid riser and the hydrodynamic load of the rigid riser can be measured in real time. The high-Reynolds-number forced oscillation experiment can be carried out on the rigid cylinder covered with the buoyancy block, the hydrodynamic coefficient of the rigid cylinder covered with the buoyancy block in a high-Reynolds-number flow field is obtained, and then a hydrodynamic coefficient library used for forecasting is established. The experimental device is simple in structure and easy to build and disassemble, meanwhile, the rigid stand pipe model is easy to disassemble, other stand pipe accessory structures can be replaced, and the experimental mode is flexible.

Description

Technical Field

[0001] This invention relates to the technical field of marine engineering pool experimental devices, and in particular to a forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block. Background Technology

[0002] As the exploitation of offshore oil and gas resources gradually moves into deeper waters, the length of marine pipelines has reached over a kilometer. Studies have shown that catenary systems are suitable for risers operating in deep-water oilfields. The catenary system offers advantages such as simple structure, convenient construction, low cost, no need for tension compensation, and high adaptability to buoyancy. However, with increasing water depth, the length and weight of the riser increase accordingly. This results in significant tension at the top suspension point, increasing the requirements for the tensioner. Furthermore, fatigue damage at the riser contact point is substantial in harsh environments or when the top platform experiences severe movement. To address these issues, installing buoyancy blocks on the riser or adopting a gentle wave-shaped layout can effectively solve these problems.

[0003] Marine risers are cylindrical, multi-scale structures with length-to-diameter ratios of several thousand. Under the influence of ocean currents, they undergo significant vortex-induced vibration, which is one of the main causes of fatigue damage or even destruction of risers. Therefore, the response prediction of vortex-induced vibration of marine risers has always been a hot research topic in academia and engineering.

[0004] The semi-empirical frequency domain prediction method commonly used in industry today is developed based on the hydrodynamic coefficient database established by experiments on forced oscillations of exposed rigid cylinders at low Reynolds numbers. However, in practical applications, studies have shown that installing buoyancy blocks can reduce fatigue damage to risers caused by vortex-induced vibrations. However, most current experimental studies on risers with buoyancy blocks and other attachments are scaled-down tests, which are less effective in low Reynolds number flow fields (10⁻¹⁰). 4 The Reynolds number is on the order of Reynolds, but in real marine environments, the Reynolds number of the flow field around the riser often reaches 10. 5 Magnitude. Studies have shown that differences in Reynolds number lead to significant differences in the amplitude of vortex-induced vibration response in risers. Before entering the supercritical region, the amplitude of vortex-induced vibration increases with increasing Reynolds number, resulting in more severe fatigue damage to marine risers than under low Reynolds number flow. Therefore, high Reynolds number hydrodynamic tests are necessary. Furthermore, when risers have appendages such as buoyancy blocks, spiral plates, or marine organisms, their hydrodynamic shape changes significantly, which has a significant impact on the vortex-induced vibration response. Therefore, relevant experiments are needed to study this further.

[0005] Therefore, there is an urgent need for a forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block. Summary of the Invention

[0006] This invention provides a forced oscillation hydrodynamic experimental device for a rigid cylinder covered with a buoyancy block. It can conduct high Reynolds number forced oscillation experiments on a rigid cylinder covered with a buoyancy block, obtain the hydrodynamic coefficients of the rigid cylinder covered with a buoyancy block under a high Reynolds number flow field, and then establish a hydrodynamic coefficient database for prediction.

[0007] This invention provides a forced oscillation hydrodynamic experimental device for covering a rigid riser with a buoyancy block, comprising an actuation module, a physical quantity sensing module, a rigid riser, and a buoyancy block model. The physical quantity sensing module is mounted on the actuation control module, the rigid riser is mounted on the physical quantity sensing module, and the buoyancy block model is mounted on the rigid riser, so as to realize real-time measurement of the motion response of the rigid riser and the hydrodynamic load on the rigid riser.

[0008] The forced oscillation hydrodynamic experimental device for covering the rigid riser of the buoyancy block, preferably, includes an actuation module comprising an actuation track, a vertical truss, a horizontal truss, a servo motor, a connecting shaft bearing, and a connecting shaft. The vertical truss is installed on both sides of the horizontal truss, the actuation track is installed on the vertical truss, the servo motor and the connecting shaft bearing are provided on the horizontal truss, the connecting shaft and the connecting shaft bearing are distributed on both sides of the servo motor, the connecting shaft is connected to the servo motor through a first coupling, and the connecting shaft passes through the connecting shaft bearing, the connecting shaft is connected to the actuation track through a second coupling, and a slider is provided on the actuation track, the slider being connected to the physical quantity sensing module.

[0009] The forced oscillation hydrodynamic experimental device for covering the rigid riser of the buoyancy block, preferably, includes a physical quantity sensing module comprising a slider connecting plate, a three-component force sensor, a flow baffle, and a model connector. The slider connecting plate is connected to the slider, the three-component force sensor is mounted on the slider connecting plate, the flow baffle is connected to the slider connecting plate by bolts, the flow baffle has an opening in the middle, the three-component force sensor passes through the opening and is connected to the model connector by bolts, and the model connector is connected to the rigid riser.

[0010] The forced oscillation hydrodynamic experimental device for covering the rigid riser of the buoyancy block is preferably a hollow tube, with the model connector inserted into the hollow cavity of the rigid riser, and both ends of the rigid riser connected to the three-part force sensors mounted on the slider connecting plate by bolts through the model connector.

[0011] The forced oscillation hydrodynamic experimental device for covering the rigid riser of the buoyancy block is preferably provided in that the buoyancy block model includes multiple buoyancy block models and multiple cable ties. The multiple buoyancy block models are arranged on the rigid riser, and the outer surface of the buoyancy block model is provided with a cable tie groove along the circumferential direction. The cable tie groove is provided with the cable tie.

[0012] The forced oscillation hydrodynamic experimental device for covering the rigid riser of the buoyancy block, preferably, includes a first hemispherical module and a second hemispherical module. The first hemispherical module and the second hemispherical module are provided with a central groove. After the first hemispherical module and the second hemispherical module are fastened together, the central groove is aligned. The central groove accommodates the rigid riser to pass through. The outer surfaces of the first hemispherical module and the second hemispherical module are provided with the tie groove along the circumferential direction.

[0013] The beneficial effects are: This invention can conduct forced oscillation experiments on rigid risers with buoyancy blocks. It has a simple structure and is easy to build. This invention can be erected and fixed on the bottom of a marine engineering pool (the pool must have active flow generation capability) for experiments, or it can be fixed and mounted on a pool trailer by welding or other methods for towing experiments, making it flexible in use.

[0014] In addition to covering the buoyancy block model, the rigid riser of this invention can also be fitted with other riser accessories, such as suppression devices, roughness simulation devices, spiral plates, etc. Stainless steel cable ties can be used to bind other riser accessories to the surface of the riser model, making model replacement convenient and facilitating various experiments.

[0015] Compared to traditional small-scale experimental devices, this invention features a larger model scale, enabling high Reynolds number hydrodynamic experiments and providing a more realistic and reliable marine environment, thus yielding more accurate and reliable experimental data. After the experiment, hydrodynamic coefficients of the rigid cylinder covering the buoyancy block under specific Reynolds number flow fields can be obtained through data analysis of drag and lift time histories, such as the average drag coefficient, excitation force coefficient, and additional mass force coefficient during vibration. This allows for the establishment of a hydrodynamic coefficient database for prediction. The experimental device has a simple structure, is easy to assemble and disassemble, and the rigid riser model is easily disassembled and can be replaced with other riser accessories, offering flexible experimental methods. Attached Figure Description

[0016] Figure 1 This is a perspective view of the present invention; Figure 2 This is a structural diagram of the actuation module; Figure 3-1 This is a schematic diagram of the physical quantity sensing module; Figure 3-2 This is a schematic diagram of the slider connecting plate. Figure 4 This is a structural schematic diagram of a rigid riser; Figure 5 This is a structural schematic diagram of the buoyancy block model; Figure 6 This is a schematic diagram of the implementation process of this experimental setup.

[0017] In the picture: 11. Actuation module; 12. Physical quantity sensing module; 13. Rigid riser; 14. Buoyancy block model; 21. Actuation track; 22. Vertical truss; 23. Horizontal truss; 24. Servo motor; 25. Connecting shaft bearing; 26. Connecting shaft; 27. Slider; 31. Slider connecting plate; 32. Three-part force sensor; 33. Baffle plate; 34. Model connector; 511. First hemisphere module; 512. Second hemisphere module; 52. Cable tie groove; 53. Central groove. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first," "second," etc., to define components is merely for the convenience of distinguishing the aforementioned components; unless otherwise stated, these terms have no special meaning and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" 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 invention based on the specific circumstances.

[0021] This invention provides a forced oscillation hydrodynamic experimental device for a rigid riser covered with a buoyancy block. The device includes an actuation module, a physical quantity sensing module, a rigid riser, and a buoyancy block model. The physical quantity sensing module is mounted on the actuation control module, the rigid riser is mounted on the physical quantity sensing module, and the buoyancy block model is mounted on the rigid riser. This enables real-time measurement of the motion response and hydrodynamic load on the rigid riser. This invention can conduct high Reynolds number forced oscillation experiments on a rigid cylinder covered with a buoyancy block to obtain the hydrodynamic coefficients of the rigid cylinder under high Reynolds number flow fields, thereby establishing a hydrodynamic coefficient database for prediction. The experimental device has a simple structure, is easy to assemble and disassemble, and the rigid riser model is easily disassembled and can be replaced with other riser auxiliary structures, making the experimental method flexible.

[0022] The following section uses a forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block as an example to illustrate the entire technical process in detail.

[0023] Example 1 like Figure 1 , Figure 2 , Figure 3-1 , Figure 3-2 , Figures 4 to 5 As shown, a forced oscillation hydrodynamic experimental device for covering a rigid riser with a buoyancy block includes an actuation module 1, a physical quantity sensing module 12, a rigid riser 13, and a buoyancy block model 14. The physical quantity sensing module 12 is mounted on the actuation control module, the rigid riser 13 is mounted on the physical quantity sensing module 12, and the buoyancy block model 14 is mounted on the rigid riser 13 to realize real-time measurement of the motion response of the rigid riser 13 and the hydrodynamic load on the rigid riser 13.

[0024] like Figure 2 As shown, the actuation module 1 includes an actuation track 21, a vertical truss 22, a horizontal truss 23, a servo motor 24, a connecting shaft bearing 25, and a connecting shaft 26. The vertical truss 22 is installed on both sides of the horizontal truss 23, and the actuation track 21 is installed on the vertical truss 22. The horizontal truss 23 is provided with the servo motor 24 and the connecting shaft bearing 25. The connecting shaft 26 and the connecting shaft bearing 25 are distributed on both sides of the servo motor 24. The connecting shaft 26 is connected to the servo motor 24 through a first coupling, and the connecting shaft 26 passes through the connecting shaft bearing 25. The connecting shaft 26 is connected to the actuation track 21 through a second coupling. The actuation track 21 is provided with a slider 27, and the slider 27 is connected to the physical quantity sensing module 12.

[0025] The servo motor 24 connects the two actuation tracks 21 via the connecting shaft 26, ensuring synchronous movement of the two actuation tracks 21 during operation. The slider 27 is mounted on the actuation track 21 and can move along the track to support the test model. The connecting shaft bearing 25 is placed on the connecting shaft 26 to support the connecting shaft 26.

[0026] like Figure 3-1 and Figure 3-2 As shown, the physical quantity sensing module 12 includes a slider 27 connecting plate 31, a three-part force sensor 32, a baffle plate 33, and a model connector 34. The slider 27 connecting plate 31 is connected to the slider 27. The three-part force sensor 32 is installed on the slider 27 connecting plate 31. The baffle plate 33 is connected to the slider 27 connecting plate 31 by bolts. An opening is provided between the baffle plates 33. The three-part force sensor 32 passes through the opening and is connected to the model connector 34 by bolts. The model connector 34 is connected to the rigid riser 13.

[0027] like Figure 4 As shown, the rigid riser 13 is a hollow tube, and the model connector 34 is inserted into the hollow cavity of the rigid riser 13. The two ends of the rigid riser 13 are connected to the three-part force sensor 32 installed on the slider connecting plate 31 by bolts through the model connector 34.

[0028] In this model connector 34, the outer diameter of the protruding cylinder is the same as the inner diameter of the rigid riser 13 (it will be slightly smaller in actual processing to facilitate insertion). During the mating process, the protruding cylinder of the model connector 34 is inserted into the rigid riser 13.

[0029] like Figure 5 As shown, the buoyancy block model 14 includes multiple buoyancy block models 14 and multiple cable ties. The multiple buoyancy block models 14 are set on the rigid riser 13. The outer surface of the buoyancy block model 14 has a cable tie groove 52 along the circumferential direction, and the cable tie is provided on the cable tie groove 52. The number of buoyancy block models 14 installed is determined by the arrangement of buoyancy blocks in the actual project.

[0030] The buoyancy block model 14 includes a first hemisphere module 511 and a second hemisphere module 512. The first hemisphere module 511 and the second hemisphere module 512 are provided with a central groove 53. After the first hemisphere module 511 and the second hemisphere module 512 are fastened together, the central groove 53 is aligned. The central groove 53 accommodates the rigid riser 13 to pass through. The outer surfaces of the first hemisphere module 511 and the second hemisphere module 512 are provided with a tie groove 52 along the circumferential direction.

[0031] The specific dimensions of the buoyancy block model 14 are determined by scaling down the actual buoyancy block dimensions studied using similarity criteria in marine engineering experiments.

[0032] Work process: like Figure 6 As shown, the forced oscillation hydrodynamic experimental device from Example 1 is vertically submerged in a water tank. The water tank itself has the ability to actively generate flow, eliminating the need for a trailer to passively generate flow. This simulates the experimental model's condition under flow conditions. Alternatively, it can be towed by a trailer fixed to the water tank using traditional methods such as welding. The control device inputs relevant motion commands to the servo motor 24, driving the rigid riser and buoyancy block model 14 to perform sinusoidal motion via the actuation module 11. Simultaneously, through active or passive flow generation, the rigid riser 13 and buoyancy block model 14 are placed in a uniform inflow for the experiment. The physical quantity sensing module 12 can measure in real time the resistance along the inflow direction and the lift perpendicular to the inflow direction of the rigid riser 13 and buoyancy block model 14 during the experiment. After the experiment, by analyzing the relevant data of resistance and lift time history, the hydrodynamic coefficients of the rigid riser 13 covering the buoyancy block model 14 under a specific Reynolds number flow field are obtained, such as the average resistance coefficient, excitation force coefficient, and additional mass force coefficient during vibration. This allows for the establishment of a hydrodynamic coefficient library for prediction. Example 2 Unlike Example 1, in addition to covering the buoyancy block model 14, the rigid riser 13 can also be fitted with other riser accessories, such as suppression devices, roughness simulation devices, spiral plates, etc. Stainless steel cable ties can be used to bind other riser accessories to the surface of the rigid riser 13, making model replacement convenient and facilitating various experiments.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block, characterized in that, It includes an actuation module, a physical quantity sensing module, a rigid riser, and a buoyancy block model. The physical quantity sensing module is installed on the actuation control module, the rigid riser is installed on the physical quantity sensing module, and the buoyancy block model is installed on the rigid riser, so as to realize real-time measurement of the motion response of the rigid riser and the water dynamic load on the rigid riser.

2. The forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block according to claim 1, characterized in that, The actuation module includes an actuation track, a vertical truss, a horizontal truss, a servo motor, a connecting shaft bearing, and a connecting shaft. The vertical truss is installed on both sides of the horizontal truss. The actuation track is installed on the vertical truss. The servo motor and the connecting shaft bearing are provided on the horizontal truss. The connecting shaft and the connecting shaft bearing are distributed on both sides of the servo motor. The connecting shaft is connected to the servo motor through a first coupling and passes through the connecting shaft bearing. The connecting shaft is connected to the actuation track through a second coupling. A slider is provided on the actuation track, and the slider is connected to the physical quantity sensing module.

3. The forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block according to claim 2, characterized in that, The physical quantity sensing module includes a slider connecting plate, a three-part force sensor, a baffle plate, and a model connector. The slider connecting plate is connected to the slider, and the three-part force sensor is installed on the slider connecting plate. The baffle plate is connected to the slider connecting plate by bolts. The baffle plate has an opening in the middle, and the three-part force sensor passes through the opening and is connected to the model connector by bolts. The model connector is connected to the rigid riser.

4. The forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block according to claim 3, characterized in that, The rigid riser is a hollow tube, and the model connector is inserted into the hollow cavity of the rigid riser. The two ends of the rigid riser are connected to the three-part force sensor installed on the slider connecting plate by bolts through the model connector.

5. The forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block according to claim 4, characterized in that, The buoyancy block model includes multiple buoyancy block models and multiple cable ties. The multiple buoyancy block models are set on the rigid riser. The outer surface of the buoyancy block model has a cable tie groove along the circumferential direction, and the cable tie is provided on the cable tie groove.

6. The forced oscillation hydrodynamic experimental device for covering a rigid riser of a buoyancy block according to claim 5, characterized in that, The buoyancy block model includes a first hemispherical module and a second hemispherical module. The first hemispherical module and the second hemispherical module are provided with a central groove. After the first hemispherical module and the second hemispherical module are fastened together, the central groove is aligned. The central groove accommodates the rigid riser to pass through. The outer surface of the first hemispherical module and the second hemispherical module is provided with the tie groove along the circumferential direction.

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