A test device and method for studying the influence of internal flow on vortex-induced vibration of a marine riser

Abstract

The application discloses a kind of test device and method for studying the influence of internal flow on marine riser vortex-induced vibration, and relates to the technical field of ocean engineering, including trailer, water pump, water tank, fixed structure, pipeline system, marine riser model and force exerting system, the two ends of the marine riser model are fixed in the bottom of the trailer by the fixed structure, the water pump and the water tank are located on the trailer, and the force exerting system is located on the fixed structure;Among them, the trailer drives the marine riser model to move at a constant speed in the towing tank, the water pump provides internal flow for the marine riser model through the water tank and the pipeline system, and the force exerting system provides tension for the marine riser model.The test device designed by the application can conveniently, stably and safely provide internal flow for the marine riser model, can apply stable tension to the end of the marine riser model, can be dragged horizontally to immerse the whole marine riser model in water, thereby significantly increasing the effective length, and providing a reference for studying the internal flow effect in marine riser vortex-induced vibration.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, and in particular to an experimental apparatus and method for studying the influence of internal currents on the vortex-induced vibration of marine risers. Background Technology

[0002] Offshore risers are pipeline structures used to transport seabed resources such as oil, natural gas, and minerals to floating platforms or ships. If an offshore riser is damaged, the transported oil and gas resources will leak, and improper handling will cause incalculable economic losses and serious environmental pollution. Therefore, the safety of offshore risers is of paramount importance. Vortex-induced vibration is one of the main causes of fatigue damage in offshore risers, and the prediction of vortex-induced vibration and the estimation of its resulting damage are important factors that need to be considered during the design process of offshore risers.

[0003] In reality, the interior of a marine riser is filled with internal currents, but current studies on vortex-induced vibration (vortex-induced vibration) of marine risers typically neglect the influence of these internal currents. These internal currents exert internal forces on the marine riser structure, and the coupling of these effects with vortex-induced vibration makes the dynamic response of the marine riser more complex. Furthermore, the internal current effects vary depending on the composition, density, and velocity of the internal current. Therefore, it is necessary to consider the internal current effects when studying the vortex-induced vibration characteristics of marine risers.

[0004] Experimental methods are an important means of studying the characteristics of vortex-induced vibration of marine risers. They can directly measure the vortex-induced vibration response of marine riser models and provide references for numerical and theoretical methods, thereby guiding engineering practice. Currently, there are very few vortex-induced vibration tests of marine risers that consider internal flow effects. Existing related tests are usually carried out in circulating water tanks, with the marine riser model placed vertically and partially submerged in water. The effective length is relatively short, and there is usually only one pipe, which cannot divide the pressure and limits the range of internal flow variation.

[0005] Therefore, those skilled in the art are dedicated to developing an experimental apparatus and method for studying the influence of internal currents on the vortex-induced vibration of marine risers. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide an internal flow safely and stably for the marine riser model, so that the entire marine riser model can be submerged in water for testing.

[0007] To achieve the above objectives, the present invention provides an experimental apparatus for studying the influence of inflow on vortex-induced vibration of a marine riser, comprising a trailer, a water pump, a water tank, a fixed structure, a piping system, a marine riser model, and a force application system. The fixed structure secures both ends of the marine riser model to the bottom of the trailer. The water pump and the water tank are located on the trailer, and the force application system is located on the fixed structure. The trailer drives the marine riser model to move at a constant speed in a towed pool. The water pump provides inflow to the marine riser model through the water tank and the piping system, and the force application system provides tension to the marine riser model.

[0008] Further, the fixing structure includes a supporting longitudinal beam, a longitudinal beam hanger, a trailer hanger connector, a longitudinal beam vertical plate connector, a left upper bent plate, a left lower bent plate, a spoiler, a right vertical plate, and a right sleeve; wherein, the longitudinal beam hanger is fixed to the supporting longitudinal beam, the longitudinal beam hanger is fixed to the trailer via the trailer hanger connector, the supporting longitudinal beam is fixed to the left upper bent plate via the longitudinal beam vertical plate connector, the bent surfaces of the left upper bent plate and the left lower bent plate are stacked and fixed, the supporting longitudinal beam is fixed to the right vertical plate via the longitudinal beam vertical plate connector, the right sleeve is fixed to the right vertical plate, and the spoiler includes two parts, left and right, which are respectively fixed to the bottom of the left lower bent plate and the right vertical plate.

[0009] Furthermore, the contact area between the bending surface of the upper left bending plate and the bending surface of the lower left bending plate is adjustable.

[0010] Furthermore, the spoiler is circular, and its center is aligned with the axis of the marine riser model.

[0011] Furthermore, the pipeline system includes a left-side tee of the riser model, a right-side tee of the riser model, a pumping pipe, an outlet pipe, a branch pipe, a left-end pipe of the riser model, a right-end pipe of the riser model, a circulation pipe, a main valve, a branch valve, a left-side tee of the branch, a right-side tee of the branch, and a flow meter; wherein, the water tank, the pumping pipe, the pump, the outlet pipe, the left-end pipe of the riser model, the marine riser model, the right-end pipe of the riser model, and the circulation pipe are sequentially connected to form the main pipeline of the pipeline system; the water tank, the pumping pipe, the pump, the outlet pipe, the branch pipe, and the circulation pipe are sequentially connected to form the branch pipeline of the pipeline system; the left-side tee of the riser model, the right-side tee of the riser model, the left-side tee of the branch, and the right-side tee of the branch provide adapters for the nodes of the pipeline system; the main valve and the branch valve control the flow rate of the main pipeline and the branch pipeline of the pipeline system, respectively; the flow meter monitors the flow rate of the main pipeline of the pipeline system.

[0012] Furthermore, the force application system includes a linear motor, a hook, an inner sleeve pulley, an upper sleeve pulley, a wire rope, a spring, a right-side slider, a force sensor, a universal joint, and an adjusting nut; wherein, the linear motor is fixed to the right-side vertical plate, the hook is fixed to the slider of the linear motor, and the marine riser model, the right-side tee of the riser model, the universal joint, the adjusting nut, the force sensor, and the right-side slider are connected in sequence; the left end of the spring is fixed to the right-side slider, the right end of the spring is fixed to one end of the wire rope, and the other end of the wire rope is fixed to the hook after passing through the inner sleeve pulley and the upper sleeve pulley.

[0013] Furthermore, the marine riser model includes a silicone tube, a strain gauge, and a heat shrink tubing; wherein the strain gauge is attached to the outer surface of the silicone tube, the heat shrink tubing is sleeved on the outer surface of the silicone tube, and the heat shrink tubing is heated to fit tightly against the silicone tube and the strain gauge.

[0014] Furthermore, the silicone tube can be replaced with a metal tube, plastic tube, or rubber tube.

[0015] Furthermore, the fluid flowing into the silicone tube can be any one of water, other liquids, gases, or mixtures.

[0016] On the other hand, the present invention provides an experimental method for studying the influence of internal current on vortex-induced vibration of a marine riser. The method utilizes the experimental apparatus for studying the influence of internal current on vortex-induced vibration of a marine riser, and includes the following steps:

[0017] Step 1: Install the experimental device and the marine riser model;

[0018] Step 2: Change the tension of the marine riser model using the linear motor and the adjusting nut, and monitor the real-time tension using the force sensor. Stop adjusting when the actual tension is equal to and stable with the tension required for the test.

[0019] Step 3: Open the main valve and the branch valve to power on the water pump until the internal flow fills the pipeline and the flow meter reading stabilizes.

[0020] Step 4: If the current internal flow rate is greater than the flow rate required for the test conditions, reduce the main valve to decrease the internal flow rate of the marine riser model until the flow meter reading is equal to and stable with the flow rate required for the test conditions; if the current internal flow rate is less than the flow rate required for the test conditions, reduce the branch valve to increase the internal flow rate of the marine riser model until the flow meter reading is equal to and stable with the flow rate required for the test conditions.

[0021] Step 5: Collect real-time strain and real-time force of the marine riser model using the strain gauge and the force sensor;

[0022] Step 6: Transmit the data collected by the strain gauge and the force sensor to the computer and store it through a dynamic signal acquisition device;

[0023] Step 7: Process and analyze the stored strain and force data to obtain the influence law of internal flow on the vortex-induced vibration of the marine riser.

[0024] In a preferred embodiment of the present invention, the present invention has the following technical effects compared with the prior art:

[0025] The experimental setup of this invention is installed at the bottom of a trailer and conducted in a towing tank. The trailer tows the setup at a constant speed to simulate a uniform external flow field. The entire marine riser model is submerged in water, significantly increasing its effective length. A water pump draws water from a tank and returns it to the tank via a pipeline system, forming a loop. Only water from the tank needs to be supplied, without affecting the water flow in the towing tank, thus greatly reducing costs. In addition to the main pipeline (the marine riser model), the pipeline system includes a branch pipeline. Both the main and branch pipelines have valves to control the internal flow rate. The branch pipeline acts as a pressure divider, reducing the requirements for pipeline strength and improving experimental safety. Furthermore, the experimental setup proposed in this invention is easy to install and disassemble, highly adaptable, and readily applicable.

[0026] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the test apparatus according to a preferred embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the left-side fixing structure of a preferred embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the right-side fixing structure of a preferred embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the overall piping system according to a preferred embodiment of the present invention;

[0031] Figure 5 This is a partial schematic diagram of a piping system according to a preferred embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the right end structure of a preferred embodiment of the present invention.

[0033] Wherein: 1-Trailer; 2-Water pump; 3-Water tank; 4-Supporting longitudinal beam; 5-Longitudinal beam hanger; 6-Trailer hanger connector; 7-Longitudinal beam vertical plate connector; 8-Left upper bending plate; 9-Left lower bending plate; 10-Spoiler; 11-Right vertical plate; 12-Linear motor; 13-Hook; 14-Right sleeve; 15-Inner pulley of sleeve; 16-Upper pulley of sleeve; 17-Wire rope; 18-Spring; 19-Right slider; 20-Force transmitter Sensor; 21-Adjustable pitch nut; 22-Universal joint; 23-Marine riser model; 24-Riser model left tee; 25-Riser model right tee; 26-Pumping pipe; 27-Outlet pipe; 28-Branch pipe; 29-Riser model left end pipe; 30-Riser model right end pipe; 31-Circulation pipe; 32-Main valve; 33-Branch valve; 34-Branch left tee; 35-Branch right tee; 36-Flow meter. Detailed Implementation

[0034] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0035] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0036] like Figure 1 As shown in the figure, an experimental device for studying the influence of internal flow on vortex-induced vibration of a marine riser provided by an embodiment of the present invention includes a trailer 1, a water pump 2, a water tank 3, a fixed structure, a piping system, a marine riser model 23, and a force application system. The fixed structure fixes both ends of the marine riser model 23 to the bottom of the trailer 1. The water pump 2 and the water tank 3 are located on the trailer 1, and the force application system is located on the fixed structure. The trailer drives the marine riser model 23 to move at a constant speed in the towing pool. The water pump 2 provides internal flow to the marine riser model 23 through the water tank 3 and the piping system, and the force application system provides tension to the marine riser model 23.

[0037] like Figure 2 , Figure 3As shown, the fixed structure includes a supporting longitudinal beam 4, a longitudinal beam hanger 5, a hanger trailer connector 6, a longitudinal beam vertical plate connector 7, a left upper bending plate 8, a left lower bending plate 9, a spoiler 10, a right vertical plate 11, and a right sleeve 14. The longitudinal beam hanger 5 is fixed on the supporting longitudinal beam 4. The longitudinal beam hanger 5 is fixed to the trailer 1 through the hanger trailer connector 6. The supporting longitudinal beam 4 is fixed to the left upper bent plate 8 through the longitudinal beam vertical plate connector 7. The bent surface of the left upper bent plate 8 and the bent surface of the left lower bent plate 9 are stacked and fixed. The contact area between the bent surface of the left upper bent plate 8 and the bent surface of the left lower bent plate 9 is adjustable. The supporting longitudinal beam 4 is fixed to the right vertical plate 11 through the longitudinal beam vertical plate connector 7. The right sleeve 14 is fixed on the right vertical plate 11. The spoiler 10 includes two pieces, left and right. The spoiler 10 is fixed to the bottom of the left lower bent plate 9 and the right vertical plate 11 respectively. The spoiler 10 is circular, and its center is aligned with the axis of the marine riser model 23.

[0038] like Figure 4 , Figure 5 As shown, the piping system includes a left-side tee 24 of the riser model, a right-side tee 25 of the riser model, a pumping pipe 26, an outlet pipe 27, a branch pipe 28, a left-end pipe 29 of the riser model, a right-end pipe 30 of the riser model, a circulation pipe 31, a main valve 32, a branch valve 33, a left-side tee 34 of the branch, a right-side tee 35 of the branch, and a flow meter 36; wherein, the water tank 3, the pumping pipe 26, the water pump 2, the outlet pipe 27, the left-end pipe 29 of the riser model, the marine riser model 23, and the right-end pipe 35 of the riser model are all part of the pipeline system. End pipe 30 and circulation pipe 31 are connected in sequence to form the main pipeline of the pipeline system; water tank 3, pumping pipe 26, water pump 2, outlet pipe 27, branch pipe 28 and circulation pipe 31 are connected in sequence to form the branch pipeline of the pipeline system; left tee 24 of the riser model, right tee 25 of the riser model, left tee 34 of the branch pipeline and right tee 35 of the branch pipeline provide adapters for the nodes of the pipeline system; main pipeline valve 32 and branch pipeline valve 33 control the flow of the main pipeline and branch pipeline of the pipeline system respectively; flow meter 36 monitors the flow of the main pipeline of the pipeline system.

[0039] like Figure 1 , Figure 3 , Figure 6As shown, the force application system includes a linear motor 12, a hook 13, an inner sleeve pulley 15, an upper sleeve pulley 16, a steel wire rope 17, a spring 18, a right-side slider 19, a force sensor 20, and an adjusting nut 21. The linear motor 12 is fixed to the right-side vertical plate 11, and the hook 13 is fixed to the slider of the linear motor 12. The marine riser model 23, the right-side tee 25 of the riser model, the universal joint 22, the adjusting nut 21, the force sensor 20, and the right-side slider 19 are connected sequentially. The left end of the spring 18 is fixed to the right-side slider 19, and the right end of the spring 18 is fixed to one end of the steel wire rope 17. After passing through the inner sleeve pulley 15 and the upper sleeve pulley 16, the other end of the steel wire rope 17 is fixed to the hook 13.

[0040] The marine riser model 23 includes a silicone tube, a strain gauge, and a heat-shrink tubing. The strain gauge is attached to the outer surface of the silicone tube, and the heat-shrink tubing is fitted onto the outer surface of the silicone tube, and after heating, it adheres tightly to the silicone tube and the strain gauge. Preferably, the silicone tube can be replaced with a metal tube, a plastic tube, or a rubber tube. The fluid flowing inside the silicone tube can be any one of water, other liquids, gases, or mixtures.

[0041] The vortex-induced vibration test device for marine risers proposed in this invention, which considers the influence of internal flow, overcomes the shortcomings of existing technologies that consider internal flow effects, such as short effective length of marine riser models, lack of pressure division, and limited range of internal flow variation. The test device is installed at the bottom of a trailer and conducted in a towing tank. The trailer tows the test device at a constant speed to simulate a uniform external flow field, and the entire marine riser model is submerged in water, significantly increasing its effective length. The contact area of ​​the upper and lower left bending plates is adjustable, allowing the test device to adapt to marine riser models of different lengths. An adjusting nut can adjust the distance between the universal joint and the force sensor. A linear motor controls the tension of the marine riser model by changing the spring length. The adjusting nut and the linear motor work together to achieve coarse and fine adjustment of the tension of the marine riser model, thereby providing the required tension for the test accurately and stably. In addition to the main pipeline of the marine riser model, the piping system also includes a branch pipeline. Both the main and branch pipelines have valves to control the internal flow rate. The branch pipeline acts as a pressure divider, reducing the requirements for pipeline strength, improving experimental safety, and increasing the adjustment range of the main pipeline's internal flow rate. This allows for a safe and stable supply of the required internal flow rate to the marine riser model. Water is pumped from the tank and returned to the tank via the piping system, forming a circulation loop. Only the water in the tank needs to be supplied, without affecting the water flow in the towing pool, significantly reducing costs. Furthermore, the experimental device proposed in this invention is easy to install and disassemble, highly adaptable, and readily applicable.

[0042] In another embodiment of the present invention, an experimental method for studying the influence of internal current on vortex-induced vibration of a marine riser is provided. This method utilizes the aforementioned experimental apparatus and includes the following steps:

[0043] Step 1: Install the experimental setup and the marine riser model 23;

[0044] Step 2: Change the tension of the marine riser model 23 by using the linear motor 12 and the adjusting nut 21, and monitor the real-time tension by using the force sensor 20. Stop adjusting when the actual tension is equal to and stable with the tension required for the test.

[0045] Step 3: Open the main valve 32 and the branch valve 33 to power on the water pump 2 and continue until the internal flow fills the pipeline and the flow meter 36 reading stabilizes.

[0046] Step 4: If the current internal flow rate is greater than the flow rate required for the test conditions, reduce the main valve 32 to decrease the internal flow rate of the marine riser model 23 until the flow meter 36 reading is equal to and stable with the flow rate required for the test conditions; if the current internal flow rate is less than the flow rate required for the test conditions, reduce the branch valve 33 to increase the internal flow rate of the marine riser model 23 until the flow meter 36 reading is equal to and stable with the flow rate required for the test conditions.

[0047] Step 5: Collect real-time strain and real-time force of the marine riser model 23 using strain gauges and force sensors 20;

[0048] Step 6: Transmit the data collected by the strain gauge and force sensor 20 to the computer and store it through the dynamic signal acquisition instrument;

[0049] Step 7: Process and analyze the stored strain and force data to obtain the influence law of internal flow on the vortex-induced vibration of the marine riser.

[0050] The present invention will now be described in detail with reference to preferred embodiments.

[0051] Example 1

[0052] like Figure 1 As shown, this embodiment provides an experimental apparatus for studying the influence of internal flow on the vortex-induced vibration of a marine riser, including a trailer 1, a water pump 2, a water tank 3, a fixed structure, a piping system, a marine riser model 23, and a force application system. The fixed structure secures both ends of the marine riser model 23 to the bottom of the trailer 1. The trailer 1 moves the marine riser model 23 at a constant speed in a towed pool to simulate a uniform external flow field. The water pump 2 and the water tank 3 are located on the trailer 1. The water pump 2 provides a specified flow rate of internal flow to the marine riser model 23 through the water tank 3 and the piping system. The force application system is located on the fixed structure. The force application system provides a specified tension to the marine riser model 23.

[0053] like Figure 1 , 2As shown in Figure 3, the fixed structure includes a supporting longitudinal beam 4, a longitudinal beam hanger 5, a trailer hanger connector 6, a longitudinal beam vertical plate connector 7, a left upper bent plate 8, a left lower bent plate 9, a spoiler 10, a right vertical plate 11, and a right sleeve 14. There are two supporting longitudinal beams 4, arranged parallel to each other and located in the same horizontal plane. Two longitudinal beam hangers 5 are fixed to each supporting longitudinal beam 4. The longitudinal beam hangers 5 are bolted structures, with their tops fixed to the trailer hanger connector 6. The trailer hanger connector 6 is a combination of thick plates, thin plates, screws, and nuts, which can clamp and fix the panel of the bottom component of the trailer 1 to it. The bottom of the longitudinal beam hanger 5 is inserted into the supporting longitudinal beam 4 and fixed to it with nuts; the vertical height of the supporting longitudinal beam 4 can be freely adjusted according to the insertion depth. The left supporting longitudinal beam 4 is fixed to the left upper bent plate 8 via the longitudinal beam vertical plate connector 7. The longitudinal beam and vertical plate connector 7 is a combination of plates and bolts. The bolts are inserted into the top panel of the left upper bent plate and nuts are used to fix the left supporting longitudinal beam 4 and the left upper bent plate 8. The bent surfaces of the left upper bent plate 8 and the left lower bent plate 9 are stacked. The bent surface of the left upper bent plate 8 has two grooves, and the bent surface of the left lower bent plate 9 has several holes. Several screws pass through the holes and grooves and nuts are used to fix the left upper bent plate 8 and the left lower bent plate 9. The contact area between the two is adjustable, so that the test device can be used for marine riser models 23 of different lengths. The right supporting longitudinal beam 4 and the right vertical plate 11 are fixed by the longitudinal beam and vertical plate connector 7 in the same way as the left structure. Two circular baffles 10 are fixed to the bottom of the left lower bent plate 9 and the right vertical plate 11, respectively, to reduce the interference of the flow field generated by the movement of the fixed structure during the test on the vortex-induced vibration of the marine riser model 23. The center of the baffle 10 is aligned with the axis of the marine riser model 23. The right sleeve 14 is fixed to the outside of the right vertical plate 11, and the center of the cross section of the right sleeve 14 is also aligned with the axis of the marine riser model 23.

[0054] like Figure 1 , 4As shown in Figure 5, the pipeline system includes a left-side tee 24 of the riser model, a right-side tee 25 of the riser model, a pumping pipe 26, an outlet pipe 27, a branch pipe 28, a left-end pipe 29 of the riser model, a right-end pipe 30 of the riser model, a circulation pipe 31, a main valve 32, a branch valve 33, a left-side tee 34 of the branch, a right-side tee 35 of the branch, and a flow meter 36, etc. The pipeline system includes two pipelines: a main pipeline and a branch pipeline. Sufficient water is filled into the water tank 3. One end of the pumping pipe 26 is inserted into the water tank 3, and the other end is connected to the inlet of the water pump 2. One end of the outlet pipe 27 is connected to the outlet of the water pump 2, and the other end is connected to the left-side tee 24 of the branch. The other two openings of the left-side tee 24 of the branch are connected to the branch pipe 28 and the left-end pipe 29 of the riser model, respectively. The other end of the left-end pipe 29 of the riser model is connected to the left-side tee 24 of the riser model. Regarding the other two openings of the left tee 24 of the riser model: one is plugged with a stopper to prevent water from entering, and then inserted into and fixed to the left universal joint 22. The other end of the left universal joint 22 is fixed to the left lower bending plate 9; the other is connected to the left end of the marine riser model 23. The right end of the marine riser model 23 is connected to the right tee 25 of the riser model. The other two openings of the right tee 25 of the riser model are connected to the right universal joint 22 and the right end pipe 30 of the riser model, respectively. The other end of the right end pipe 30 of the riser model is connected to the right tee 35 of the branch road. The other two openings of the right tee 35 of the branch road are connected to the branch pipe 28 and the circulation pipe 31, respectively. The other end of the circulation pipe 31 is inserted into the water tank 3, forming a pipe circulation system. After the water is pumped out of the water tank 3 by the water pump 2, it passes through the main road of the marine riser model 23 and the branch road of the branch pipe 28, and finally returns to the water tank. The water is recycled without the need for replenishment and will not affect the water flow in the towing pool. A main flow valve 32 is installed in pipe 29 at the left end of the riser model, which can control the flow rate of the main flow. A branch flow valve 33 is installed in pipe 28, which can control the flow rate of the branch flow. A flow meter 36 is installed in pipe 30 at the right end of the riser model, which can display the real-time flow rate of the main flow.

[0055] like Figure 1 , 3As shown in Figure 6, the force application system includes a linear motor 12, a hook 13, an inner pulley 15 in the sleeve, an upper pulley 16 in the sleeve, a wire rope 17, a spring 18, a right-side slider 19, a force sensor 20, and an adjusting nut 21. The linear motor 12 is fixed to the outside of the right-side vertical plate 11. The hook 13 is fixed to the slider of the linear motor 12. The slider of the linear motor 12 can move along the track of the linear motor 12 and be fixed in a designated position. The right end of the marine riser model 23 is connected to the left end of the right-side tee 25 of the riser model. The right end of the right-side tee 25 of the riser model is plugged with a plug to prevent water from entering and then connected to the left end of the right-side universal joint 22. The right end of the right-side universal joint 22 is fixed to the left end of the adjusting nut 21. The right end of the adjusting nut 21 is fixed to the left end of the force sensor 20. The right end of the force sensor 20 is fixed to the right-side slider 19. The right-side slider 19 partially extends into the right-side sleeve 14 and is fixed to the left end of the spring 18. The right end of spring 18 is fixed to wire rope 17. Inner sleeve pulley 15 and upper sleeve pulley 16 are fixed inside and at the top of right sleeve 14, respectively. Wire rope 17 passes through inner sleeve pulley 15 and upper sleeve pulley 16 in sequence, then extends vertically upwards, with its end fixed to hook 13. Adjusting nut 21 adjusts the distance between right universal joint 22 and force sensor 20, while linear motor 12 adjusts the length of spring 18. Together, they provide the specified tension to marine riser model 23.

[0056] like Figure 1 As shown, the marine riser model 23 includes silicone tubes, strain gauges, and heat shrink tubing. First, four parallel lines are drawn on the outer surface of the silicone tube, running from end to end and parallel to the tube's axis. The interval between adjacent lines corresponds to a 90-degree arc of the silicone tube's cross-section. Then, the cross-sectional positions of several silicone tubes to be observed in the experiment are determined, and strain gauges are attached to the intersections of each cross-section position and the four lines. After the strain gauges are attached, a waterproof material, such as adhesive glue or silicone rubber, is applied to their surface. After the waterproof material solidifies and stabilizes, the heat shrink tubing is fitted onto the outer surface of the silicone tube, and uniformly heated to ensure a tight seal between the heat shrink tubing, the silicone tube, and the strain gauges. Waterproof material should also be applied to the gaps between the heat shrink tubing and the silicone tube at the ends of the marine riser model 23 to prevent water from entering and affecting the strain gauges. During installation, two sets of the four lines are arranged, with two sets spaced apart. One set should be in the horizontal plane to measure strain in the downstream direction, and the other set should be in the vertical plane to measure strain in the cross-flow direction. During the experiment, the inside of the silicone tube will be filled with water pumped from the water tank 3 by the water pump 2.

[0057] During the vortex-induced vibration test of a marine riser with internal flow, the test apparatus and marine riser model 23 are first installed. Then, the tension of the marine riser model 23 is changed using a linear motor 12 and adjusting nut 21. The real-time tension is monitored by a force sensor 20 and adjusted until the actual tension equals and stabilizes with the required test tension. Next, the main valve 32 and branch valve 33 are fully opened, and the water pump 2 is energized to pump water until the pipeline is full and the flow meter 36 reading stabilizes. If the current internal flow rate is greater than the required flow rate for the test conditions, the main valve 32 is adjusted to reduce the internal flow rate of the marine riser model 23 until the flow meter 36 reading equals and stabilizes with the required flow rate for the test conditions. If the current internal flow rate is less than the required flow rate for the test conditions, the branch valve 33 is adjusted to increase the internal flow rate of the marine riser model 23 until the flow meter 36 reading equals and stabilizes with the required flow rate for the test conditions. When the main valve 32 is fully open and the branch valve 33 is fully closed, the stable reading of the flowmeter 36 represents the maximum internal flow rate of the marine riser model 23 achievable by the experimental setup. When the main valve 32 is fully closed and the branch valve 33 is fully open, the reading of the flowmeter 36 is 0, and the minimum internal flow rate of the marine riser model 23 is 0. During the experiment, the situation where both the main valve 32 and the branch valve 33 are fully closed should be avoided. After the internal flow rate of the marine riser model 23 meets the requirements and stabilizes, the trailer 1 moves the experimental setup at a constant speed to simulate a uniform external flow field. During the experiment, real-time strain and real-time force of the marine riser model 23 are collected using strain gauges and force sensors 20. The data collected by the strain gauges and force sensors 20 are transmitted to a computer and stored via a dynamic signal acquisition instrument. After the experiment, the stored strain and force data are processed and analyzed to reveal the influence of internal flow on the vortex-induced vibration of the marine riser, explore the mechanism behind the internal flow effect, and provide reference and guidance for practical marine engineering.

[0058] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An experimental apparatus for investigating the effect of internal flow on vortex-induced vibration of a marine riser, characterized by, The marine riser model is moved at a constant speed in the towing tank by the trailer, and the water pump provides internal flow for the marine riser model through the water tank and the pipeline system, and the force applying system provides tension for the marine riser model. The fixed structure comprises a support longitudinal beam, a longitudinal beam hanger, a hanger trailer connecting piece, a longitudinal beam vertical plate connecting piece, a left upper bending plate, a left lower bending plate, a spoiler, a right vertical plate and a right sleeve; the longitudinal beam hanger is fixed on the support longitudinal beam, and the longitudinal beam hanger is fixed with the trailer through the hanger trailer connecting piece; the support longitudinal beam is fixed with the left upper bending plate through the longitudinal beam vertical plate connecting piece; the bending surface of the left upper bending plate is fixed with the bending surface of the left lower bending plate; the support longitudinal beam is fixed with the right vertical plate through the longitudinal beam vertical plate connecting piece; the right sleeve is fixed on the right vertical plate; the spoiler comprises two left and right pieces, and is fixed at the bottom of the left lower bending plate and the right vertical plate, respectively. The pipeline system comprises a riser model left side tee, a riser model right side tee, a water pumping pipeline, a water outlet pipeline, a branch pipeline, a riser model left end pipeline, a riser model right end pipeline, a circulation pipeline, a main road valve, a branch valve, a branch left side tee, a branch right side tee and a flow meter; the water tank, the water pumping pipeline, the water pump, the water outlet pipeline, the riser model left end pipeline, the marine riser model, the riser model right end pipeline and the circulation pipeline are connected in sequence to form a main road of the pipeline system; the water tank, the water pumping pipeline, the water pump, the water outlet pipeline, the branch pipeline and the circulation pipeline are connected in sequence to form a branch of the pipeline system; the riser model left side tee, the riser model right side tee, the branch left side tee and the branch right side tee provide adapters for nodes of the pipeline system; the main road valve and the branch valve control the flow of the main road of the pipeline system and the branch of the pipeline system, respectively; and the flow meter monitors the flow of the main road of the pipeline system.

2. The apparatus of claim 1, wherein, The contact area of the bending surface of the left upper bending plate with the bending surface of the left lower bending plate is adjustable.

3. The apparatus of claim 1, wherein, The spoiler is circular, and the center of the spoiler is aligned with the axis of the marine riser model.

4. The apparatus of claim 1, wherein, The force applying system comprises a linear motor, a hook, an inner sleeve pulley, an upper sleeve pulley, a steel wire rope, a spring, a right slide block, a force sensor, a universal joint and a distance adjusting nut; wherein the linear motor is fixed on the right vertical plate, the hook is fixed on the slide block of the linear motor, the marine riser model, the riser model right side tee joint, the universal joint, the distance adjusting nut, the force sensor and the right slide block are connected in sequence; the left end of the spring is fixed with the right slide block, the right end of the spring is fixed with one end of the steel wire rope, the steel wire rope passes through the inner sleeve pulley and the upper sleeve pulley and is fixed with the hook at the other end.

5. The apparatus of claim 4, wherein, The marine riser model comprises a silica gel pipe, a strain gauge and a heat shrink tube; wherein the strain gauge is attached to the outer surface of the silica gel pipe, and the heat shrink tube is sleeved on the outer surface of the silica gel pipe, and the heat shrink tube is tightly attached to the silica gel pipe and the strain gauge after being heated.

6. The apparatus of claim 5, wherein, The silica gel pipe can be replaced by a metal pipe, a plastic pipe or a rubber pipe.

7. The apparatus of claim 5, wherein, The inner flow of the silica gel pipe is any one of water, other liquid, gas or mixture.

8. A test method for investigating the effect of internal flow on vortex-induced vibration of a marine riser, characterized by, The method utilizes the device of any one of claims 5-7, and the test method comprises the following steps: Step 1, installing the test device and the marine riser model; Step 2, changing the tension of the marine riser model through the linear motor and the distance adjusting nut, and monitoring the real-time tension through the force sensor, and stopping adjusting when the actual tension is equal to and stable at the required tension of the test; Step 3, opening the main road valve and the branch valve, and making the water pump work under electricity, and waiting until the inner flow fills the pipeline and the flow meter reading is stable; Step 4, if the current inner flow is greater than the required flow of the test working condition, then the main road valve is adjusted to reduce the inner flow of the marine riser model, until the flow meter reading is equal to and stable at the required flow of the test working condition; if the current inner flow is less than the required flow of the test working condition, then the branch valve is adjusted to increase the inner flow of the marine riser model, until the flow meter reading is equal to and stable at the required flow of the test working condition; Step 5, collecting the real-time strain and real-time force of the marine riser model through the strain gauge and the force sensor; Step 6, transmitting the data collected by the strain gauge and the force sensor to the computer through the dynamic signal acquisition instrument and storing the data; Step 7, processing and analyzing the stored strain data and force data to obtain the influence law of the inner flow on the vortex-induced vibration of the marine riser.

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