A device and method for multiphase flow monitoring and flexible riser flow-induced vibration testing

Abstract

The present application relates to a kind of multiphase flow monitoring and flexible riser flow-induced vibration testing device and method, device is by gas-liquid multiphase flow supply system, mixed transport system, riser vibration test system, flow monitoring system, backflow transport system and data acquisition system composition.By adjusting gas path valve and liquid path valve, form the gas-liquid two-phase flow of different flow pattern, adjust the inclination angle of the inclination of the inclination pipe by adjusting the inclination of the inclination board, adjust the vertical height of flexible riser model by adjusting the slippage support plate.By flow pattern probe, pressure sensor, tension sensor, high-speed camera comprehensive obtains the multiphase flow information inside flexible riser model and the displacement of flexible riser model flow-induced vibration under different working conditions, provides experimental data for the revelation of flexible riser vibration mechanism.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of research on the vibration characteristics of the marine riser under the coupling action of the internal multiphase flow and the internal and external flow, and particularly relates to a device and method for monitoring multiphase flow and testing flow-induced vibration of a flexible riser. BACKGROUND

[0002] With the development of offshore oil and gas exploration into deep sea, more and more marine risers are put into use. Common riser forms include catenary type and slow wave type, and with the increase of the length-diameter ratio of the riser, its flexibility is further highlighted. In order to save the cost of oil and gas exploration, offshore oil and gas is usually lifted to the offshore platform in the form of mixed transportation. Due to the undulation of the terrain and the change of the mixed transportation flow, different flow patterns of gas-liquid two-phase flow often appear in the pipeline, and the pressure, density and other parameters change in space and time in the pipeline, causing pulsating fluid force and easily exciting the vibration response of the riser. The vibration of the flexible riser structure in turn affects the gas-liquid two-phase flow in the pipeline, changes the force of the fluid acting on the riser, and presents a complex fluid-structure coupling response. The marine flexible riser is served in this complex fluid-structure coupling environment for a long time, which is easy to deform and cause fatigue damage, shorten the service life, and even cause fatigue failure, leading to oil and gas leakage, not only causing huge economic losses, but also causing irreversible disastrous damage to the environment. In order to reduce the damage of the two-phase internal flow to the riser during oil and gas mixed transportation, it is necessary to deeply analyze the mechanism of this fluid-structure coupling vibration response. However, the current research mainly focuses on the vortex-induced vibration response of the flexible riser under the action of the external flow, and there is less research on the two-phase internal flow-induced vibration of the curved flexible riser, especially lacking experimental research data. Therefore, it is urgent to design a device and method for monitoring multiphase flow and testing flow-induced vibration of a flexible riser to explore the gas-liquid two-phase flow characteristics and the fluid-structure coupling response mechanism in the flexible riser. SUMMARY

[0003] In order to solve the problems proposed in the background art, the purpose of the present application is to provide a device and method for monitoring multiphase flow and testing flow-induced vibration of a flexible riser.

[0004] In order to achieve the above-mentioned purpose, the device of the present application adopts the following technical scheme:

[0005] The device for monitoring and testing the flow-induced vibration of a flexible riser comprises a gas-liquid multiphase flow supply system, a mixed transportation system, a riser vibration testing system, a flow monitoring system, a backflow transportation system and a data acquisition system. The gas-liquid multiphase flow supply system mainly comprises a liquid supply module and a gas supply module. The liquid supply module comprises a water supply tank, a submersible pump, an electromagnetic turbine flowmeter and liquid valves. The water in the water supply tank is dyed black to track the gas-liquid interface. The water level in the water supply tank is higher than the working submersible pump. The submersible pump pumps the water in the water supply tank to the liquid pipeline. The liquid flow in the liquid pipeline is adjusted by the liquid valves. The liquid flow is measured by the electromagnetic turbine flowmeter and then enters the mixing tee. The gas supply part is sequentially connected by a gas pump, a buffer tank, gas valves and a gas flowmeter. The gas pump pumps the compressed air into the buffer tank for pressure stabilization. Then the gas is measured by the gas flowmeter and then transported to the mixing tee. The gas valves are used to control the gas flow.

[0006] The mixed transportation system mainly comprises a horizontal pipe transportation module and a variable-inclination downward pipe transportation module. The horizontal pipe transportation module comprises a horizontal lifting platform, a folding lifter and a horizontal straight pipe. The horizontal straight pipe is fixed in the middle line of the horizontal lifting platform surface along the flow direction. The horizontal lifting platform is fixedly installed on the folding lifter. According to the experimental requirements, the height of the horizontal lifting platform is changed by manually adjusting the folding lifter, so that the horizontal lifting platform is flush with the highest end of the downward plate. The variable-inclination downward pipe transportation module comprises a downward pipe, a downward plate, an inclination adjustment scale, an inclination adjustment wheel and a hinge. The downward pipe is fixed on the top surface of the downward plate along the flow direction. The downward plate has a downward flat plate and a downward wavy plate. One of them is selected according to the requirements to carry out the experiment. The downward plate is installed in the hinge fixing groove between the rectangular water tank and the downward plate through the hinge near one end of the rectangular water tank. The other end of the downward plate can move up and down. The inclination adjustment wheel and the inclination adjustment scale are installed on the bottom surface of the downward plate at a position 2 / 3 away from the hinge installation end. According to the scale on the inclination adjustment scale, the inclination of the downward plate is changed by rotating the inclination adjustment wheel, so as to change the downward angle of the downward pipe. The length of the horizontal straight pipe is 200 times of the inner diameter of the horizontal straight pipe, so as to ensure uniform mixing of the gas-liquid two-phase flow.

[0007] The riser vibration test system mainly consists of a flexible riser model, a rectangular water tank, a movable background plate, a tension sensor, a front high-speed camera and a top high-speed camera. The flexible riser model has two types of catenary and slack wave, and one of them is selected for the experiment according to the experimental requirements. The catenary flexible riser model is freely suspended in the rectangular water tank, while the slack wave flexible riser model is provided with four buoyancy blocks at the middle position of the flexible riser model along the axial direction to provide buoyancy for the flexible riser model, so that the flexible riser model assumes the shape of a slack wave in still water. Since the buoyancy blocks cannot be used to provide buoyancy for the flexible riser model in air, the flow-induced vibration experiment of the slack wave flexible riser model cannot be carried out in air. The surface of the flexible riser model is uniformly coated with black marker points along the axial direction, and the width of the black marker points is equal to the outer diameter of the flexible riser model. The bottom of the flexible riser model is connected with the downward inclined pipe and fixed to the bottom of the right side plate of the rectangular water tank, and the top of the flexible riser model is fixed to the fixed block of the left side wall of the rectangular water tank through a four-way pipe. The four sides and the bottom of the rectangular water tank are closed by rectangular organic glass plates, and the top of the rectangular water tank is open. The thickness of the bottom organic glass plate is equal to the thickness of the downward inclined plate. The front side plate of the rectangular water tank is marked with a scale near the side of the bottom end of the flexible riser model, which provides a scale reference for the vibration test. The flexible riser model passes through the circular hole in the middle of the bottom of the right side plate of the rectangular water tank and is fixed therein, and the left side plate near the top of the flexible riser model is nested with a slidable support plate and a side fixed plate. The side fixed plate is a hollow double-layer organic glass structure, and the gap between the two layers is wider than the thickness of the slidable support plate. The slidable support plate is embedded in the side fixed plate, and the height of the slidable support plate can be adjusted by the fixed tightening device installed outside the side fixed plate. The top of the slidable support plate is welded with a fixed block with a circular hole, which is used to fix the four-way pipe at the top of the flexible riser model. The tension sensor is installed on the fixed block to monitor the tension at the top of the flexible riser model. The movable background plate is made of white opaque PVC plate, and its height and width are equal to the height and width of the inner space of the rectangular water tank. A slide rail perpendicular to the back plate is welded on the upper and lower edges of the left and right side plates of the rectangular water tank, respectively. The slide rail is close to the back plate and its length is equal to half of the distance between the front and back side plates of the rectangular water tank. The four corners of the movable background plate are installed with slide blocks, which are installed on the slide rails to move the movable background plate along the slide rails. The front high-speed camera is perpendicular to the bending plane of the flexible riser model, and is used to capture the details of the multiphase flow inside the flexible riser model and the vibration displacement in the horizontal and vertical directions of the bending plane of the flexible riser model. The top high-speed camera is installed on the top high-speed camera support frame obliquely above the flexible riser model, and is used to capture the vibration displacement perpendicular to the bending plane of the flexible riser model. The top high-speed camera corner instrument is installed on the middle position of the horizontal bar above the top high-speed camera support frame, and the shooting angle of the top high-speed camera can be adjusted by rotating the top high-speed camera corner instrument and adjusting the height of the top high-speed camera support frame.

[0008] The flow monitoring system mainly consists of flow pattern probes and pressure sensors. The flow pattern probes are installed at the fixed positions of the bottom and top of the flexible riser model to monitor the flow pattern, liquid holdup and other flow characteristics at the bottom and top of the flexible riser model. The pressure sensors are also installed at the fixed positions of the bottom and top of the flexible riser model to monitor the fluctuating pressure at the bottom and top of the flexible riser model, respectively.

[0009] The reflux conveying system includes a gas-liquid separation funnel and a liquid reflux pipe. The gas-liquid separation funnel is installed directly below the top outlet of the flexible riser model. The liquid reflux pipe is a PVC pipe, the top of which is connected to the bottom of the gas-liquid separation funnel, vertically extends to the bottom of the fixed platform, and then is connected to the water supply tank horizontally along the bottom of the fixed platform. The gas-liquid two-phase flow flowing out of the top of the riser is separated in the gas-liquid separation funnel, the gas is discharged into the air, and the liquid flows back to the water supply tank through the liquid reflux pipe for repeated use.

[0010] The data acquisition system consists of a data acquisition terminal and a synchronous trigger. The acquisition lines of the pressure sensors, the flow pattern probes, the tension sensors, the front high-speed camera and the overhead high-speed camera are connected to the synchronous trigger, which is then connected to the data acquisition terminal. When the test starts, all the monitoring devices are started simultaneously by the synchronous trigger, and the real-time synchronous acquisition of data is realized.

[0011] The test device for multiphase flow monitoring and flexible riser flow-induced vibration provides a test method for multiphase flow monitoring and flexible riser flow-induced vibration. The liquid in the water supply tank is dyed black, the gas pump is started, the gas supply is adjusted by adjusting the gas valve, and the gas flow is measured by the gas flow meter. Then the submersible pump is started, the liquid supply is adjusted by adjusting the liquid valve, and the liquid flow is measured by the electromagnetic turbine flow meter. The gas and liquid are mixed in the mixing tee, the gas flow and liquid flow are adjusted by adjusting the gas valve and liquid valve, different gas-liquid ratios are achieved, and different flow patterns of the gas-liquid two-phase flow are formed, and then the mixed gas-liquid two-phase flow passes through the horizontal section and then enters the downward section. The downward plate has a downward flat plate and a downward wave plate, which respectively simulate flat and undulating seabeds. During the experiment, one of them is selected for testing as needed. By adjusting the inclination of the adjusting wheel, the inclination angle of the downward plate and the inclination angle of the downward pipe can be changed, so as to test the influence of different inclination angles on the flow pattern of the gas-liquid two-phase flow in the pipe. When the gas-liquid two-phase flow flows through the flexible riser model, the flexible riser model will generate vibration, the horizontal and vertical bending plane vibration displacement of the flexible riser model and the gas-liquid two-phase flow details in the pipe are monitored by the front high-speed camera and the overhead high-speed camera, the pressure fluctuation at the inlet and outlet of the flexible riser model is monitored by the pressure sensors at the top and bottom of the flexible riser model, the flow pattern and instantaneous cross-sectional liquid holdup in the flexible riser model are monitored by the flow pattern probe, and at the same time, the instantaneous tension change of the flexible riser model is monitored by the tension sensor at the top. During monitoring, all monitoring data are monitored in real time by starting the synchronous trigger. When there is no water in the rectangular water tank, the flow-induced vibration response of the catenary flexible riser model in air can be tested. When the rectangular water tank is filled with water, the flow-induced vibration response of the catenary flexible riser model and the mild wave flexible riser model in water can be tested. According to the experimental requirements, one of them is selected for testing. The gas-liquid flow conditions remain unchanged, the movable background plate is moved forward, and the flexible riser model can be fixed on the movable background plate as a whole, so as to test the change of the gas-liquid two-phase flow characteristics in the fixed flexible riser model. The flow characteristics in the fixed flexible riser model are compared with the flow characteristics in the vibrating flexible riser model, and the influence of vibration on the gas-liquid two-phase flow in the flexible riser model is analyzed. By changing the height of the slidable support plate on the left side of the rectangular water tank, the height of the flexible riser model is adjusted, the flow-induced vibration test of the flexible riser model with different vertical heights is realized, and the influence of the vertical height of the flexible riser model on the vibration response of the flexible riser is analyzed. Therefore, the test device for multiphase flow monitoring and flexible riser flow-induced vibration can be used to test the flow-induced vibration response of the catenary flexible riser model and the mild wave flexible riser model under different flexible riser vertical heights, different external fluid environments and different downward conditions.

[0012] The present application has the following advantages due to the use of the above technical solutions:

[0013] 1. The flexible riser model of the device can be fixed as a whole by the movable background plate, realizing the comparison of multiphase flow in the vibrating riser and the fixed riser;

[0014] 2. The vertical height of the flexible riser model of the device can be adjusted by the slidable support plate on the left side of the rectangular water tank, realizing the multiphase flow monitoring and the flow-induced vibration test of the riser in the flexible riser model with different vertical heights;

[0015] 3. The inclination angle of the downward inclined pipe of the device can be changed by adjusting the included angle of the downward inclined plate, and different forms of downward inclined plate can be replaced, realizing the multiphase flow monitoring and the flow-induced vibration test of the riser in the flexible riser model under different downward inclined conditions;

[0016] 4. The synchronous trigger of the device synchronously triggers the pressure sensor, the flow pattern probe, the tension sensor, the front high-speed camera and the overhead high-speed camera, so that the collected data are one-to-one corresponding in time sequence, which provides guarantee for revealing the flow-induced vibration mechanism of the flexible riser model. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a three-dimensional structure schematic diagram of the device;

[0018] Figure 2 It is a movable background plate structure schematic diagram of the device;

[0019] Figure 3 It is a detachable variable-inclination downward inclined plate structure schematic diagram of the device;

[0020] Figure 4 It is a detachable test riser structure schematic diagram of the device;

[0021] Figure 5 It is a riser height lifting plate structure schematic diagram of the device;

[0022] Figure 6 It is a horizontal lifting platform structure schematic diagram of the device;

[0023] Among them: 1. Flexible riser model; 101. Catenary flexible riser model; 102. Wave-type flexible riser model; 2. Black marker point; 3. Downward-sloping pipe; 4. Horizontal straight pipe; 5. Mixing tee; 6. Electromagnetic turbine flow meter; 7. Liquid valve; 8. Submersible pump; 9. Water supply tank; 10. Gas flow meter; 11. Gas valve; 12. Buffer tank; 13. Air pump; 14. Rectangular water tank; 15. Fixing block; 16. Sliding support plate; 17. Side fixing plate; 18. Fixing tightener; 19. Movable background plate; 20. Slide rail; 21. Slider; 22. Gas-liquid separation funnel; 2 3. Liquid reflux pipe; 24. Fixed platform; 25. Hinge fixing groove; 26. Hinge; 27. Downward tilting plate; 2701. Downward tilting flat plate; 2702. Downward tilting wave plate; 28. Tilt angle adjustment scale; 29. ​​Tilt angle adjustment wheel; 30. Horizontal lifting platform; 31. Folding lifting device; 32. High-speed camera support frame for overhead view; 33. High-speed camera angle measuring device for overhead view; 34. High-speed camera for overhead view; 35. High-speed camera for frontal view; 36. Pressure sensor; 37. Flow pattern probe; 38. Tension sensor; 39. Four-way pipe; 40. Synchronous trigger; 41. Data acquisition terminal; 42. Buoyancy block. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, a multiphase flow monitoring and flexible riser flow-induced vibration testing device consists of a gas-liquid multiphase flow supply system, a mixing and conveying system, a riser vibration testing system, a flow monitoring system, a return conveying system, and a data acquisition system. The gas-liquid multiphase flow supply system mainly consists of two modules: a liquid supply module and a gas supply module. The liquid supply module includes a water tank 9, a submersible pump 8, an electromagnetic turbine flow meter 6, and a liquid valve 7. The water in the water tank 9 is dyed black to track the gas-liquid interface. The water level in the water tank 9 overflows the operating submersible pump 8, which pumps the water from the water tank 9 to the liquid pipeline. The liquid flow rate in the liquid pipeline is regulated by the liquid valve 7. The liquid flow rate is measured by the electromagnetic turbine flow meter 6 and then enters the mixing tee 5. The gas supply section consists of an air pump 13, a buffer tank 12, a gas valve 11, and a gas flow meter 10 connected in sequence. The air pump 13 compresses the air and pumps it into the buffer tank 12 for pressure stabilization. Then, the gas is metered by the gas flow meter 10 and delivered to the mixing tee 5. The gas valve 11 is used to control the gas flow rate.

[0026] like Figure 1 , Figure 3As shown, the mixed transport system mainly consists of horizontal pipe transport module and variable-inclination downward inclined pipe 3 transport module. The horizontal pipe transport module includes horizontal lifting platform 30, folding lifter 31 and horizontal straight pipe 4, the horizontal straight pipe 4 is fixed on the center line of the horizontal lifting platform 30 in the flow direction, and the horizontal lifting platform 30 is fixedly installed on the folding lifter. According to the experimental needs, the height of the horizontal lifting platform 30 is changed by manually adjusting the folding lifter, so that the horizontal lifting platform 30 is flush with the highest end of the downward inclined plate 27. The variable-inclination downward inclined pipe 3 transport module includes downward inclined pipe 3, downward inclined plate 27, inclination adjustment scale 28, inclination adjustment rotating wheel 29 and hinge 26, wherein the downward inclined pipe 3 is fixed on the center line of the top surface of the downward inclined plate 27 in the flow direction, the downward inclined plate 27 has two types of downward inclined flat plate 2701 and downward inclined wavy plate 2702, and one of them is selected according to the needs to carry out the experiment. The end of the downward inclined plate 27 close to the rectangular water tank 14 is installed in the hinge fixed slot 25 between the rectangular water tank 14 and the downward inclined plate 27 through the hinge 26, and the other end of the downward inclined plate 27 can move up and down. The inclination adjustment rotating wheel 29 and the inclination adjustment scale 28 are installed on the bottom surface of the downward inclined plate 27 at a position 2 / 3 away from the hinge 26 installation end, according to the scale on the inclination adjustment scale 28, the inclination of the downward inclined plate 27 is changed by rotating the inclination adjustment rotating wheel 29, so as to change the downward inclination of the downward inclined pipe 3. The length of the horizontal straight pipe 4 is 200 times of the inner diameter of the horizontal straight pipe 4, so as to ensure the uniform mixing of gas-liquid two-phase flow.

[0027] As Figure 1 , Figure 2 , Figure 4 , Figure 5As shown, the riser vibration test system mainly consists of flexible riser model 1, rectangular water tank 14, movable background plate 19, tension sensor 38, front high-speed camera 35 and overhead high-speed camera 34. Flexible riser model 1 has two types of catenary and slack wave, and one of them is selected according to the experimental needs. Among them, the catenary flexible riser model 101 is freely suspended in the rectangular water tank 14, while the slack wave flexible riser model 102 is arranged with four buoyancy blocks 42 at the middle position of the flexible riser model 1 along the axial direction, providing buoyancy for the flexible riser model 1, so that it presents the shape of the slack wave in still water. Because the buoyancy block 42 cannot provide buoyancy for the flexible riser model 1 in the air, the flow-induced vibration experiment of the slack wave flexible riser model 102 cannot be carried out in the air. The surface of the flexible riser model 1 is uniformly coated with black marker points 2 along the axial direction, and the width of the black marker points 2 is equal to the outer diameter of the flexible riser model 1. The bottom of the flexible riser model 1 is connected with the downward inclined pipe 3 and fixed to the bottom of the right side plate of the rectangular water tank 14, and the top of the flexible riser model 1 is fixed to the fixed block 15 on the left side wall of the rectangular water tank 14 through the four-way pipe 39. The four sides and the bottom of the rectangular water tank 14 are closed by rectangular organic glass plates, and the top of the rectangular water tank 14 is open. The thickness of the bottom organic glass plate is equal to the thickness of the downward inclined plate 27. The front side plate of the rectangular water tank 14 is marked with a scale near the side of the bottom end of the flexible riser model 1, which provides a scale reference for vibration test. The flexible riser model 1 passes through the circular hole in the middle of the bottom of the right side plate of the rectangular water tank 14 and is fixed therein, and the left side plate near the top of the flexible riser model 1 is nested with the slidable support plate 16 and the side fixed plate 17. The side fixed plate 17 is a hollow double-layer organic glass structure, and the gap width between the two is greater than the thickness of the slidable support plate 16. The slidable support plate 16 is embedded in the side fixed plate 17, and the height of the slidable support plate 16 is adjusted by the fixed tightening device 18 installed outside the side fixed plate 17. The top of the slidable support plate 16 is welded with a fixed block 15 with a circular hole, which is used to fix the four-way pipe 39 at the top of the flexible riser model 1, and the tension sensor 38 is installed on the fixed block 15 to monitor the tension at the top of the flexible riser model 1. The movable background plate 19 is made of white opaque PVC plate, and its height and width are equal to the height and width of the inner space of the rectangular water tank 14. A slide rail 20 perpendicular to the back plate is welded on the upper and lower edges of the left and right side plates of the rectangular water tank 14, respectively, and the slide rail 20 is tightly attached to the back plate and its length is equal to half the distance between the front and back side plates of the rectangular water tank 14. The four corners of the movable background plate 19 are respectively installed with slide blocks 21, which are installed on the slide rails 20, so that the movable background plate 19 moves forward and backward along the slide rails 20.The front-view high-speed camera 35 is directly opposite the curved plane of the flexible riser model 1, and is used to capture the multiphase flow details inside the flexible riser model 1 and the vibration displacement in the horizontal and vertical directions of the curved plane of the flexible riser model 1; the overhead high-speed camera 34 is installed on the overhead high-speed camera support frame 32 obliquely above the flexible riser model 1, and is used to capture the vibration displacement perpendicular to the curved plane of the flexible riser model 1. The overhead high-speed camera corner instrument 33 is installed at the middle position of the horizontal rod above the overhead high-speed camera support frame 32, and the shooting angle of the overhead high-speed camera 34 is adjusted by rotating the overhead high-speed camera corner instrument 33 and adjusting the height of the overhead high-speed camera support frame 32.

[0028] As shown in Figure 1 , the flow monitoring system mainly consists of a flow pattern probe 37 and a pressure sensor 36. The flow pattern probe 37 is installed at the fixed positions at the bottom and top of the flexible riser model 1, and is used to monitor the flow pattern, liquid holdup and other flow characteristics at the bottom and top of the flexible riser model 1. The pressure sensor 36 is also installed at the fixed positions at the bottom and top of the flexible riser model 1, and is used to monitor the pulsating pressure at the bottom and top of the flexible riser model 1, respectively.

[0029] As shown in Figure 1 , the backflow conveying system includes a gas-liquid separation funnel 22 and a liquid backflow pipe 23. The gas-liquid separation funnel 22 is installed directly below the top outflow port of the flexible riser model 1, and the liquid backflow pipe 23 is a PVC pipe, the top of which is connected to the bottom of the gas-liquid separation funnel 22, vertically extends to the bottom of the fixed platform 24, and then is connected horizontally along the bottom of the fixed platform 24 to the water supply tank 9. The gas-liquid two-phase flow discharged from the top of the riser is separated in the gas-liquid separation funnel 22, the gas is discharged into the air, and the liquid flows back to the water supply tank 9 through the liquid backflow pipe 23 for repeated use.

[0030] As shown in Figure 1 , the data acquisition system consists of a data acquisition terminal 41 and a synchronous trigger 40, and the acquisition lines of the pressure sensor 36, the flow pattern probe 37, the tension sensor 38, the front-view high-speed camera 35 and the overhead high-speed camera 34 are all connected to the synchronous trigger 40, and then are connected to the data acquisition terminal 41. When the test starts, all the monitoring devices are started simultaneously by the synchronous trigger 40, and the real-time synchronous acquisition of data is realized.

[0031] The multiphase flow monitoring and flexible riser flow-induced vibration testing device provides a multiphase flow monitoring and flexible riser flow-induced vibration testing method. The liquid in the water supply tank 9 is dyed black, the gas pump 13 is started, the gas valve 11 is adjusted to supply gas, and the gas flow is measured by the gas flow meter. Then the submersible pump 8 is started, the liquid supply valve 7 is adjusted, the liquid flow is measured by the electromagnetic turbine flow meter 6. The gas and liquid are mixed in the mixing tee 5, the gas flow and liquid flow are adjusted by adjusting the gas valve 11 and the liquid valve 7 to achieve different gas-liquid ratios, thereby forming different flow patterns of gas-liquid two-phase flow, and the mixed gas-liquid two-phase flow passes through the horizontal section and then enters the downward section. The downward plate 27 has two types of downward flat plate 2701 and downward wave plate 2702, which simulate flat and undulating seabed respectively. During the experiment, one of them is selected for testing as needed. By adjusting the inclination of the rotating wheel 29, the inclination angle of the downward plate 27 can be changed, and thus the inclination angle of the downward pipe 3 can be changed, so as to test the influence of different inclination angles on the gas-liquid two-phase flow pattern in the pipe. When the gas-liquid two-phase flow passes through the flexible riser model 1, it will excite the flexible riser model 1 to vibrate, the horizontal and vertical bending plane vibration displacement of the flexible riser model 1 and the gas-liquid two-phase flow details in the pipe are monitored by the front high-speed camera 35 and the overhead high-speed camera 34 synchronously, the pressure fluctuation at the inlet and outlet of the flexible riser model 1 is monitored by the pressure sensor 36 at the top and bottom of the flexible riser model 1, the flow pattern and instantaneous cross-sectional liquid holdup in the flexible riser model 1 are monitored by the flow pattern probe 37, at the same time, the instantaneous tension change of the flexible riser model 1 is monitored by the tension sensor 38 at the top, during the monitoring, the real-time synchronous monitoring of all monitoring data is realized by starting the synchronous trigger 40. When there is no water in the rectangular water tank 14, the flow-induced vibration response of the catenary flexible riser model 1 in air can be tested, when the rectangular water tank 14 is filled with water, the flow-induced vibration response of the catenary flexible riser model 101 and the mild wave flexible riser model 102 in water can be tested, according to the experimental needs, one of them is selected for testing. Keep the gas-liquid flow conditions unchanged, move the movable background plate 19 forward, the flexible riser model 1 can be fixed on the movable background plate as a whole, so as to test the change of gas-liquid two-phase flow characteristics in the fixed flexible riser model 1, compare the flow characteristics in the fixed flexible riser model 1 with those in the vibrating flexible riser model 1, and analyze the influence of vibration on the gas-liquid two-phase flow in the flexible riser model 1. By changing the height of the slidable support plate 16 on the left side of the rectangular water tank 14, the height of the flexible riser model 1 is adjusted, the flow-induced vibration testing of the flexible riser model 1 with different vertical heights is realized, and the influence of the vertical height of the flexible riser model 1 on the flexible riser vibration response is analyzed. Therefore, the multiphase flow monitoring and flexible riser flow-induced vibration testing device can be used to test the flow-induced vibration response of the catenary flexible riser model 101 and the mild wave flexible riser model 102 under different flexible riser vertical heights, different external fluid environments and different downward conditions.

Claims

1. A multiphase flow monitoring and flexible riser flow-induced vibration testing device is composed of a gas-liquid multiphase flow supply system, a mixed transport system, a riser vibration testing system, a flow pattern monitoring system, a backflow transport system and a data acquisition system, characterized in that: The gas-liquid multiphase flow supply system is mainly composed of two modules of liquid supply and gas supply. The liquid supply module includes a water supply tank (9), a submersible pump (8), an electromagnetic turbine flowmeter (6) and a liquid valve (7). The water in the water supply tank (9) is dyed black, the water level in the water supply tank (9) is higher than the working submersible pump (8), the submersible pump (8) pumps the water in the water supply tank (9) to the liquid pipeline, the liquid flow in the liquid pipeline is adjusted by the liquid valve (7), the liquid flow is measured by the electromagnetic turbine flowmeter (6), and then enters the mixing tee (5). The gas supply part is sequentially connected by a gas pump (13), a buffer tank (12), a gas valve (11) and a gas flowmeter (10). The gas pump (13) pumps the compressed air into the buffer tank (12) for pressure stabilization, and then the gas is measured by the gas flowmeter (10) and delivered to the mixing tee (5), wherein the gas valve (11) is used to control the flow of the gas. The mixed conveying system is mainly composed of a horizontal pipe conveying module and a variable-inclination downward inclined pipe (3) conveying module. The horizontal pipe conveying module includes a horizontal lifting platform (30), a folding lifter (31) and a horizontal straight pipe (4). The horizontal straight pipe (4) is fixed along the flow direction on the center line of the surface of the horizontal lifting platform (30), and the horizontal lifting platform (30) is fixedly installed on the folding lifter (31). The height of the horizontal lifting platform (30) is adjusted by manually adjusting the folding lifter (31) to make the horizontal lifting platform (30) flush with the highest end of the downward inclined plate (27). The variable-inclination downward inclined pipe (3) conveying module includes a downward inclined pipe (3), a downward inclined plate (27), an inclination adjustment scale (28), an inclination adjustment rotating wheel (29) and a hinge (26). The downward inclined pipe (3) is fixed along the flow direction on the center line of the top surface of the downward inclined plate (27). The downward inclined plate (27) has two types of downward inclined flat plate (2701) and downward inclined wavy plate (2702), and one of them is selected for experiment according to needs. The end of the downward inclined plate (27) close to the rectangular water tank (14) is installed in the hinge fixing groove (25) between the rectangular water tank (14) and the downward inclined plate (27) through the hinge (26), and the other end of the downward inclined plate (27) can move up and down. The inclination adjustment rotating wheel (29) and the inclination adjustment scale (28) are installed on the bottom surface of the downward inclined plate (27) at a position 2 / 3 away from the installation end of the hinge (26). According to the scale on the inclination adjustment scale (28), the inclination of the downward inclined flat plate (2701) is changed by rotating the inclination adjustment rotating wheel (29), so as to change the downward inclination of the downward inclined pipe (3). The standpipe vibration test system is mainly composed of a flexible standpipe model (1), a rectangular water tank (14), a movable background plate (19), a tension sensor (38), a front high-speed camera (35) and a top high-speed camera (34). The surface of the flexible standpipe model (1) is uniformly coated with black marker points (2) along the axial direction, and the width of the black marker points (2) is equal to the outer diameter of the flexible standpipe model (1).The bottom of the flexible riser model (1) is connected with the downward inclined pipe (3) and fixed to the bottom of the right side plate of the rectangular water tank (14), and the top of the flexible riser model (1) is fixed to the fixed block (15) of the left side wall of the rectangular water tank (14) through the four-way pipe (39); the periphery and the bottom of the rectangular water tank (14) are closed by the rectangular organic glass plate, and the top of the rectangular water tank (14) is open, the thickness of the bottom organic glass plate is equal to the thickness of the downward inclined plate (27); the front side plate of the rectangular water tank (14) is marked with a scale near the side of the bottom end of the flexible riser model (1), which provides a scale reference for vibration test; the flexible riser model (1) passes through the circular hole in the middle of the bottom of the right side plate of the rectangular water tank (14) and is fixed therein, and the left side plate near the top of the flexible riser model (1) is nested with the slidable support plate (16) and the side edge fixed plate (17), the top middle position of the slidable support plate (16) is welded with the fixed block (15) with a circular hole, which is used for fixing and connecting the four-way pipe (39) at the top of the flexible riser model (1), the tension sensor (38) is installed on the fixed block (15) and used for monitoring the tension at the top of the flexible riser model (1); the front high-speed camera (35) is opposite to the bending plane of the flexible riser model (1) and used for capturing the multiphase flow details inside the flexible riser model (1) and the vibration displacement in the horizontal and vertical directions in the bending plane of the flexible riser model (1); the overhead high-speed camera (34) is installed on the overhead high-speed camera support frame (32) obliquely above the flexible riser model (1) and used for capturing the vibration displacement perpendicular to the bending plane of the flexible riser model (1); the overhead high-speed camera corner instrument (33) is installed at the middle position of the horizontal rod above the overhead high-speed camera support frame (32), and the shooting angle of the overhead high-speed camera (34) is adjusted by rotating the overhead high-speed camera corner instrument (33) and adjusting the height of the overhead high-speed camera support frame (32); the flow monitoring system mainly consists of the flow pattern probe (37) and the pressure sensor (36); the flow pattern probe (37) is installed at the fixed positions of the bottom and the top of the flexible riser model (1) and used for monitoring the flow pattern, liquid holdup and other flow characteristics at the bottom and the top of the flexible riser model (1); the pressure sensor (36) is also installed at the fixed positions of the bottom and the top of the flexible riser model (1) and used for monitoring the pulsating pressure at the bottom and the top of the flexible riser model (1) respectively; the backflow conveying system includes the gas-liquid separation funnel (22) and the liquid backflow pipe (23), the gas-liquid separation funnel (22) is installed directly below the outlet at the top of the flexible riser model (1), the liquid backflow pipe (23) is a PVC pipe, the top of which is connected with the bottom of the gas-liquid separation funnel (22), vertically extends to the bottom of the fixed platform (24), and then horizontally connects to the water supply tank (9) along the bottom of the fixed platform (24); the gas-liquid two-phase flow out of the top of the riser is separated in the gas-liquid separation funnel (22), the gas is discharged into the air, and the liquid flows back to the water supply tank (9) through the liquid backflow pipe (23) for repeated use; the data acquisition system consists of the data acquisition terminal (41) and the synchronous trigger (40);The flexible riser model (1) has catenary type and slow wave type, wherein the catenary type flexible riser model (101) is freely suspended in the rectangular water tank (14), and the slow wave type flexible riser model (102) is provided with four buoyancy blocks (42) arranged at equal intervals along the axis at the middle position of the flexible riser model (1) to provide buoyancy for the flexible riser model (1), so that the flexible riser model (1) presents a slow wave type shape in still water; since the buoyancy blocks (42) cannot provide buoyancy for the flexible riser model (1) in the air, the flow-induced vibration experiment of the slow wave type flexible riser model (102) cannot be carried out in the air; the side fixed plate (17) is a hollow double-layer organic glass structure, the gap width between the middle is greater than the thickness of the slidable support plate (16), the slidable support plate (16) is embedded in the side fixed plate (17), and the height of the slidable support plate (16) is adjusted by the fixed screwing device (18) installed outside the side fixed plate (17); the movable background plate (19) is made of white opaque PVC plate, and the height and width are equal to the height and width of the inner space of the rectangular water tank (14); a slide rail (20) perpendicular to the back plate is welded on the upper and lower edges of the left and right side plates of the rectangular water tank (14) respectively, the slide rail (20) is close to the back plate and the length is equal to half of the distance between the front and back side plates of the rectangular water tank (14); the four top corners of the movable background plate (19) are respectively provided with slide blocks (21), the slide blocks (21) are installed on the slide rails (20), so that the movable background plate (19) moves forward and backward along the slide rails (20); the collection lines of the pressure sensor (36), the flow pattern probe (37), the tension sensor (38), the front high-speed camera (35) and the overhead high-speed camera (34) are connected to the synchronous trigger (40), and then connected to the data acquisition terminal (41); when the test starts, all the monitoring devices are started simultaneously by the synchronous trigger (40), so that the data is synchronously collected in real time.

2. A method of multiphase flow monitoring and flexible riser VIV testing using the multiphase flow monitoring and flexible riser VIV testing apparatus of claim 1, characterized by: The liquid in the water supply tank (9) is dyed black, the air pump (13) is started, the air valve (11) is adjusted to supply air, and the air flow is measured by the air flow meter; then the submersible pump (8) is started, the liquid valve (7) is adjusted to supply liquid, and the liquid flow is measured by the electromagnetic turbine flow meter (6); the gas and liquid are mixed in the mixing tee (5), the gas flow and liquid flow are adjusted by adjusting the air valve (11) and the liquid valve (7), different gas-liquid ratios are realized, and different gas-liquid two-phase flow patterns are formed, the mixed gas-liquid two-phase flow passes through the horizontal section and then enters the downward section; the downward plate (27) has two types of downward flat plate (2701) and downward wave plate (2702), which simulate flat and undulating seabed respectively; during the experiment, one of them is selected for testing according to the needs; by adjusting the inclination angle of the runner (29), the inclination angle of the downward plate (27) can be changed, and then the inclination angle of the downward pipe (3) can be changed, so as to test the influence of different inclination angles on the gas-liquid two-phase flow pattern in the pipe; when the gas-liquid two-phase flow passes through the catenary type flexible riser model (1), it will excite the flexible riser model (1) to vibrate, the bending plane and vertical bending plane vibration displacement of the flexible riser model (1) and the gas-liquid two-phase flow details in the pipe are monitored synchronously by the front high-speed camera (35) and the overhead high-speed camera (34), the pressure fluctuation of the inlet and outlet of the flexible riser model (1) is monitored by the pressure sensor (36) at the top and bottom of the flexible riser model (1), the flow pattern and instantaneous cross-sectional liquid holdup in the flexible riser model (1) are monitored by the flow pattern probe (37), at the same time, the instantaneous tension change of the flexible riser model (1) is monitored by the tension sensor (38) at the top, during monitoring, all monitoring data are monitored in real time by starting the synchronous trigger (40); when there is no water in the rectangular tank (14), the flow-induced vibration response of the catenary type flexible riser model (101) in air can be tested, when the rectangular tank (14) is filled with water, the flow-induced vibration response of the catenary type flexible riser model (101) and the gentle wave type flexible riser model (102) in water can be tested, according to the experimental needs, one of them is selected for testing; keep the gas-liquid flow conditions unchanged, move the movable background plate (19) forward, the flexible riser model (1) can be fixed on the movable background plate (19) as a whole, so as to test the change of gas-liquid two-phase flow characteristics in the fixed flexible riser model (1), compare the flow characteristics in the fixed flexible riser model (1) with those in the vibrating flexible riser model (1), and analyze the influence of vibration on the gas-liquid two-phase flow in the flexible riser model (1); by changing the height of the slidable support plate (16) on the left side of the rectangular tank (14), the height of the flexible riser model (1) is adjusted, the flow-induced vibration test of the flexible riser model (1) with different vertical heights is realized, and the influence of the vertical height of the flexible riser model (1) on the vibration response of the flexible riser is analyzed.Therefore, the test device for monitoring multiphase flow and flow-induced vibration of flexible riser can be used to test the flow-induced vibration response of the catenary flexible riser model (101) and the lazy wave flexible riser model (102) under different flexible riser vertical heights, different external fluid environments, and different inclination conditions.

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