Experimental device for vortex-induced vibration of a riser with bidirectional shear step constant and oscillatory flow

Abstract

The present invention provides a bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device, comprising: a base module; a rotating gear, the outer layer and inner side of which are respectively constrained and limited by an outer boundary elastic constraint module and an inner boundary elastic constraint module; a deep-sea riser model, the two ends of which are connected to the two ends of the rotating gear by a tensioner module and a rigid fixing module respectively; a pipe cover module, which is equipped with a circular pipe baffle, and the circular pipe baffle is mounted on the end of the deep-sea riser model; a power module, which provides power for the rotation of the rotating gear; a host computer module, which issues action instructions and then commands the power module to operate; a measurement module, whose signals are connected to the deep-sea riser model, a first three-force sensor, a second three-force sensor, and the host computer module. The present invention can accurately simulate both steady bidirectional shear step flow and bidirectional shear step oscillating flow field, and the device is simple, easy to install, runs smoothly, does not cause meshing jamming, and has good structural stability.

Description

Technical Field

[0001] The invention relates to the technical field of marine engineering, in particular to a bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device. Background Art

[0002] Internal waves are a typical severe sea condition prevalent in density-stratified oceans. They are characterized by large amplitude, long duration, and nonlinearity. These waves generate a unique bidirectional shear flow field. Furthermore, driven by platform motion, offshore risers are subject to time-varying oscillating flow fields in opposite directions along their lengths, known as bidirectional shear oscillatory flow fields. Because offshore risers span air and seawater, they are inevitably subject to step flow fields. This complex bidirectional shear step flow and bidirectional shear step oscillatory flow can not only cause severe shearing effects on deep-sea pipelines downstream, but can also induce highly complex vortex-induced vibrations (VIVs) downstream and across the flow. VIVs refer to the alternating discharge of vortices on either side of a columnar structure under the influence of water flow, generating periodic pulsating forces. When these pulsating forces approach a natural frequency of the columnar structure, they induce significant VIVs (Vortex-Induced Vibrations). VIVs are a key factor in fatigue damage to offshore risers. Currently, there is a lack of mechanistic understanding of the vortex-induced vibration (VIV) phenomenon in marine risers under such complex flow fields. Therefore, the development of an experimental setup for VIV in risers under bidirectional shear step constant and oscillating flow is crucial for studying VIV in risers under bidirectional shear step flow and bidirectional shear step oscillating flow.

[0003] Currently, domestic and international academic and engineering communities primarily rely on experimental methods to study the vortex-induced vibration phenomenon of marine risers. However, experimental technology for vortex-induced vibration of deep-sea risers under the action of bidirectional shear step flow and bidirectional shear step oscillating flow fields is very limited. Among previous experimental devices, patent document CN105547623A published in 2015 provides a tension leg vortex-induced vibration test device under bidirectional shear flow and bidirectional step shear flow. This experimental device has the following problems:

[0004] 1. The tension leg vortex-induced vibration experimental platform device for simulating bidirectional shear flow and bidirectional step shear flow is relatively complex and bulky, inconvenient to install, and requires a large motor power.

[0005] 2. The tension leg vortex-induced vibration experimental platform device for simulating bidirectional shear flow and bidirectional step shear flow is unstable and its natural frequency easily falls within the significant frequency range of vortex-induced vibration, causing resonance and affecting the accuracy of the experiment.

[0006] 3. The cantilever of the tension leg vortex-induced vibration test platform for simulating bidirectional shear flow and bidirectional step shear flow is very long, which poses a risk of structural instability;

[0007] 4. The cantilever structure of the tension leg vortex-induced vibration experimental platform that simulates bidirectional shear flow and bidirectional step shear flow will disrupt the flow field during the operation of the device, making the flow field created less than ideal and clean, affecting the test results.

[0008] 5. The tension leg vortex-induced vibration experimental platform device that simulates bidirectional shear flow and bidirectional step shear flow cannot simulate bidirectional oscillating time-varying flow fields.

[0009] In view of the above defects, it is urgent to design a new experimental device to meet the needs of the experiment. Summary of the Invention

[0010] In view of the defects in the prior art, the purpose of the present invention is to provide a bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device.

[0011] According to the present invention, a bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device is provided, comprising:

[0012] A base module equipped with a support bearing;

[0013] The bottom of the rotary gear is rotatably matched with the support bearing and the outer layer and the inner side are respectively constrained by the outer boundary elastic constraint module and the inner boundary elastic constraint module;

[0014] A deep-sea riser model, with both ends connected to the two ends of the slewing gear through a tensioner module and a rigid fixing module respectively and passing through the center of the slewing gear;

[0015] A pipe cover module is provided with a round pipe baffle cover, and the round pipe baffle cover is sleeved on the end of the deep-sea riser model;

[0016] A power module, providing power for the rotation of the rotary gear;

[0017] The host computer module issues action instructions to command the power module to act. The action instructions can be set to match different experimental scenarios;

[0018] The measurement module is signal-connected to the deep-sea riser model, the first three-force sensor of the tensioner module, the second three-force sensor of the rigid fixing module, and the host computer module.

[0019] Preferably, the plurality of inner boundary elastic constraint modules arranged in a ring form radial limitations on the inner side surface of the rotating gear, and the plurality of outer boundary elastic constraint modules arranged in a ring form radial limitations on the outer side surface of the rotating gear.

[0020] Preferably, the outer boundary elastic constraint module is flexibly rotated with the outer side surface of the rotating gear, and the inner boundary elastic constraint module is flexibly rotated with the inner side surface of the rotating gear.

[0021] Preferably, the deep-sea riser model comprises a central pipe, a plurality of fiber Bragg grating strain strings adhered to the surface of the central pipe, and a heat shrink tube wrapped around the fiber Bragg grating strain strings and the outside of the central pipe.

[0022] Preferably, the tensioner module adopts elastic tensioning.

[0023] Preferably, the tensioner module includes a first clamp, a first universal joint, a first three-force sensor, a first slider, a first linear rail, a long-axis screw, a screw adapter flange, a bottom fixed adapter flange, a first spring, a top plate and a top screw. One end of the deep-sea riser model is connected to the first clamp; the first clamp is connected to one end of the first universal joint; the other end of the first universal joint is connected to the first three-force sensor; the first three-force sensor is connected to one end of the long-axis screw; the long-axis screw is connected to the first slider through the screw adapter flange, and the first slider is slidably matched with the first linear rail; the first linear rail is detachably connected to the bottom fixed adapter flange; the top screw presses one end of the first spring through the top plate, and the other end of the first spring is in contact with the bottom fixed adapter flange; the elastic force of the first spring reacts on the top plate, thereby elastically stretching and tensioning the stretched deep-sea riser model.

[0024] Preferably, the power module drives the rotary gear to rotate by means of a driving wheel and a belt.

[0025] Preferably, the host computer module can control the power module to operate at different flow rates or set sinusoidal oscillation times of different amplitudes and frequencies.

[0026] Preferably, the measurement module includes a fiber Bragg grating demodulator, an IO module, a storage module, a wireless module and a receiving module. The fiber Bragg grating demodulator demodulates the vibration strain signal from the strain gauge in the fiber Bragg grating strain string. The IO module converts the analog signal of the three-force sensor into a digital signal. The vibration strain signal and the digital signal are synchronously stored by the storage module. The wireless module sends the stored data to the receiving module to complete the dynamic strain and force response measurement. The receiving module is connected to the host computer module.

[0027] Preferably, a circular tube flow shield is mounted on the end of the deep-sea riser model so as to shield the deep-sea riser model of a set length from the flow field.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention can accurately simulate both steady bidirectional shear step flow and bidirectional shear step oscillation flow field by adopting a rotating gear in conjunction with a rotating device of a deep-sea riser model. The flow field oscillation parameters are easy to adjust, the natural frequency of the device is greatly different from the significant period of vortex-induced vibration, and no resonance phenomenon occurs. There are no auxiliary structures on the inner side of the rotating gear of the device, the flow field is clean and ideal, the experimental device is simple and easy to install, and runs smoothly without meshing jamming. The structural stability is good, and the structural instability caused by the excessively long cantilever of traditional experimental technology will not occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0031] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0032] Figure 2 Schematic diagram of the tensioner module.

[0033] Figure 3 It is a structural diagram of the rigid fixed module.

[0034] Figure 4 This is a structural diagram of the inner boundary elastic constraint module.

[0035] Figure 5 This is a structural diagram of the outer boundary elastic constraint module.

[0036] Figure 6 Schematic diagram of the three-dimensional structure of the power module.

[0037] Figure 7 Schematic diagram of the three-dimensional structure of the base module.

[0038] Figure 8 Schematic diagram of the three-dimensional structure of the pipe cover module.

[0039] Figure 9 This is a schematic diagram of the host computer module.

[0040] Figure 10 Schematic diagram of the three-dimensional structure of the deep-sea riser model.

[0041] Figure 11 This is a block diagram of the measurement module.

[0042] Figure 12 This is a schematic diagram of the structure of the rotary gear.

[0043] Figure 13 It is a structural diagram of the driving wheel.

[0044] Figure 14 Schematic diagram of the structure of a metal wire flexible belt.

[0045] The figure shows:

[0046] Rotating gear 1

[0047] Base module 2

[0048] Outer Boundary Elastic Constraint Module 3

[0049] Inner boundary elastic constraint module 4

[0050] Deep Sea Riser Model 5

[0051] Pipe cover module 6

[0052] Tensioner module 7

[0053] Rigid fixing module 8

[0054] Metal wire flexible belt 9

[0055] Outer boundary elastic driving wheel 10

[0056] Power module 11

[0057] Host computer module 12 measurement module 13

[0058] First spring 14

[0059] Long axis screw 15

[0060] Top screw 16

[0061] Top sheet 17

[0062] Bottom fixed adapter flange 18 screw adapter flange 19 first three-point force sensor 20

[0063] First clamp 21

[0064] First universal joint 22

[0065] First linear track 23

[0066] First slider 24

[0067] Second clamp 25

[0068] Second universal joint 26

[0069] Second three-force sensor 27 base fixing flange 28 inner top flange block 29 inner top bearing 30 inner boundary constraint bolt 31 second spring 32

[0070] Second slider 33

[0071] Second linear rail 34 First base flange 35 External top bearing 36 External boundary restraining bolt 37 Third spring 38 Downward pressing flange block 39 Servo motor 40

[0072] Reducer 41

[0073] Support structure 42

[0074] and the second base flange 43

[0075] First bearing seat 44

[0076] Optical axis 45

[0077] Support base 46

[0078] Second bearing base 47

[0079] Support bearing 48

[0080] Third base flange 49

[0081] Transfer fixing block 50

[0082] Round tube baffle 51

[0083] Industrial computer 52

[0084] Motion Controller 53

[0085] Drive 54

[0086] Heat shrink tubing 55

[0087] Fiber Bragg Grating Strain 56

[0088] Center pipe 57

[0089] Fiber Bragg grating interrogator 58

[0090] IO module 59

[0091] Storage module 60

[0092] Wireless module 61

[0093] Receiving module 62 DETAILED DESCRIPTION

[0094] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0095] Example 1:

[0096] The present invention provides a bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device for simulating bidirectional shear step flow and bidirectional shear step oscillating flow field, comprising a rotary gear 1, a base module 2, a deep-sea riser model 5, a pipe cover module 6, a power module 11, a host computer module 12 and a measurement module 13. The base module 2 is provided with a support bearing 48; the bottom of the rotary gear 1 is rotatably matched with the support bearing 48, and the outer layer and the inner side are respectively constrained by the outer boundary elastic constraint module 3 and the inner boundary elastic constraint module 4; the two ends of the deep-sea riser model 5 are respectively connected to the two ends of the rotary gear 1 by a tensioner module 7 and a rigid fixing module 8 and pass through the center of the rotary gear 1; the pipe cover module 6 is provided with a support bearing 48; the bottom of the rotary gear 1 is rotatably matched with the support bearing 48, and the outer layer and the inner side are respectively constrained by the outer boundary elastic constraint module 3 and the inner boundary elastic constraint module 4; the two ends of the deep-sea riser model 5 are respectively connected to the two ends of the rotary gear 1 by a tensioner module 7 and a rigid fixing module 8 and pass through the center of the rotary gear 1; A circular tube baffle 51 is provided, which is mounted on the end of the deep-sea riser model 5; the power module 11 provides power for the rotation of the slewing gear 1; the host computer module 12 issues action instructions to command the power module 11 to act, and the action instructions can be set to match different experimental scenarios; the measurement module 13 is connected to the deep-sea riser model 5, the first three-force sensor 20 of the tensioner module 7, the second three-force sensor 27 of the rigid fixing module 8, and the host computer module 12. The measurement module 13 converts and / or demodulates the signals collected by the deep-sea riser model 5, the first three-force sensor 20, and the second three-force sensor 27, and stores them and finally transmits them to the host computer module 12.

[0097] Specifically, there are multiple inner and outer elastic constraint modules 4 and 3, each of which is arranged in a ring and radially limits the inner side surface of the rotating gear 1. Multiple outer elastic constraint modules 3 are arranged in a ring and radially limit the outer side surface of the rotating gear 1. The inner and outer elastic constraint modules 4 and 3 achieve horizontal positioning of the rotating gear 1. It should be noted that the flexible rotational engagement of the outer and inner elastic constraint modules 3 with the outer side surface of the rotating gear 1, and the flexible rotational engagement of the inner and outer elastic constraint modules 4 with the inner side surface of the rotating gear 1, significantly reduces the assembly precision requirements for the rotating gear 1 and reduces the cost of the equipment.

[0098] The power module 11 of the present invention drives the rotary gear 1 to rotate by means of a driving wheel and a belt. The tensioner module 7 adopts elastic tensioning.

[0099] Example 2:

[0100] This embodiment is a preferred example of Embodiment 1.

[0101] like Figure 1As shown, this embodiment provides a bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device capable of simulating bidirectional shear step flow and bidirectional shear step oscillating flow field, comprising a rotary gear 1, a base module 2, an outer boundary elastic constraint module 3, an inner boundary elastic constraint module 4, a deep-sea riser model 5, a pipe cover module 6, a tensioner module 7, a rigid fixing module 8, a metal wire flexible belt 9, an outer boundary elastic driving wheel 10, a power module 11, a host computer module 12, and a measurement module 13, wherein both ends of the deep-sea riser model 5 are respectively connected to the tensioner The tightening module 7 and the rigid fixing module 8 are connected and then bolted to the rotating gear 1. The deep-sea riser model 5 passes through the center of the rotating gear 1. The rotating gear 1 is fixed to the base module 2 via the inner boundary elastic constraint module 4 and the outer boundary elastic constraint module 3. The base module 2 is bolted to the false bottom of the offshore water tank. The upper computer module 12 can control the power module 11 to operate at different flow rates or set sinusoidal oscillation time history with different amplitudes and frequencies. The power module 11 drives the driving pulley 10 via the flexible metal belt 9, which drives the rotating gear 1. The pipe cover module 6 is fixed to the rotating gear 1, shielding the flow field of the deep-sea riser model 5 of a set length. The measurement module 13 measures and records the vortex-induced vibration response signal of the deep-sea riser, ultimately simulating the bidirectional shear step and bidirectional shear step oscillation flow field experienced by the deep-sea riser model 5 and collecting experimental deep-sea riser vortex-induced vibration response data.

[0102] The entire experimental device operates in a deep-water tank of an ocean engineering project. The bottom of the experimental device is fixed to the lifting false bottom of the ocean engineering tank by bolts through the base module 2.

[0103] like Figure 2As shown, the tensioner module 7 includes a first clamp 21, a first universal joint 22, a first three-force sensor 20, a first slider 24, a first linear rail 23, a long-axis screw 15, a screw adapter flange 19, a bottom fixed adapter flange 18, a first spring 14, a top plate 17 and a top screw 16. One end of the deep-sea riser model 5 is connected to the first clamp 21 by bolt clamping; the first clamp 21 is connected to one end of the first universal joint 22 through a flange end plate; the other end of the first universal joint 22 is bolted to the first three-force sensor 20 through a flange; the first three-force sensor 20 is connected to one end of the long-axis screw 15 through a flange bolt; the long-axis screw 15 is bolted to the first slider 24 through a screw adapter flange 19, and the first slider 24 slides with the first linear track 23; the first linear track 23 is connected to the bottom fixed adapter flange 18 by bolts; the top screw 16 presses one end of the first spring 14 through the top plate 17, and the other end of the first spring 14 is in contact with the bottom fixed adapter flange 18; the elastic force of the first spring 14 reacts on the top plate 17, thereby causing the stretched deep-sea riser model 5 to be elastically stretched and tensioned. The deep-sea riser model 5 of the present invention adopts elastic tensioning to effectively prevent the deep-sea riser model 5 from deforming during the experiment, thereby causing the axial tension to be excessively amplified, thereby interfering with the experimental results.

[0104] like Figure 3 As shown, the rigid fixing module 8 includes a second clamp 25, a second universal joint 26, a second three-force sensor 27 and a base fixing flange 28. The other end of the deep-sea riser model 5 is connected to one end of the second clamp 25, the other end of the second clamp 25 is connected to one end of the second universal joint 26, and the other end of the second universal joint 26 is bolted to the second three-force sensor 27 and the base fixing flange 28 in sequence. The base fixing flange 28 is detachably fixed to the rotary gear 1 by bolts.

[0105] It should be noted that both ends of the deep-sea riser model 5 adopt a universal joint structure, on the one hand to simulate the larger boundary conditions, and on the other hand to prevent the riser from torsional deformation, which would cause deviation in the measurement point direction.

[0106] like Figure 4As shown, the inner boundary elastic constraint module 4 includes an inner top bearing 30, an inner top flange block 29, an inner boundary constraint bolt 31, a second spring 32, a second linear track 34, a second slider 33, and a first base flange 35. The inner boundary constraint bolt 31 is tightened to compress the second spring 32. The inner boundary constraint bolt 31 is connected to the inner top flange block 29, which is bolted to the second slider 33. The second slider 33 can move on the second linear track 34. The second linear track 34 is fixed to the first base flange 35 by bolts. The restoring force of the second spring 32 reacts on the inner top flange block 29, thereby causing the inner top bearing 30 to press against the slewing gear 1, limiting the radial inward movement of the slewing gear 1. The first base flange 35 is detachably fixed to the base module 2 by bolts.

[0107] like Figure 5 As shown, the outer boundary elastic constraint module 3 includes an outer top bearing 36, an outer boundary constraint bolt 37, a third spring 38 and a downward pressure flange block 39. The outer top bearing 36 is rigidly connected to the downward pressure flange block 39. The outer boundary constraint bolt 37 has a limiting head end and a threaded end. The threaded end of the outer boundary constraint bolt 37 passes through the downward pressure flange block 39 and is fixed to the base module 2. The third spring 38 is sleeved on the outer boundary constraint bolt 37 and is arranged between the limiting head end and the downward pressure flange block 39 and is compressed. The restoring force of the compressed third spring 38 reacts to the downward pressure flange block 39, thereby causing the outer top bearing 36 to press the rotating gear 1, thereby limiting the radial outward movement of the rotating gear 1.

[0108] Both the inner and outer sides of the rotary gear 1 are constrained by elastic constraint modules, which can effectively prevent the occurrence of vibration of the rotary gear when rotating due to processing errors, and also reduce the requirements for the processing accuracy of parts, which is conducive to reducing processing costs.

[0109] like Figure 6 As shown, the power module 11 includes a servo motor 40, a speed reducer 41, an optical shaft 45, a first bearing seat 44, a support structure 42, and a second base flange 43. The first bearing seat 44 is fixed to the support structure 42, which is bolted to the false bottom of the offshore tank via the second base flange 43. The optical shaft 45 is fixedly connected to the driving wheel 10 via a key. The servo motor 40 is driven and connected to the optical shaft 45 via the speed reducer 41. When the servo motor 40 rotates, it drives the driving wheel 10, which in turn drives the slewing gear 1, ultimately driving the deep-sea riser model 5.

[0110] like Figure 7As shown, base module 2 includes a support base 46, a support bearing 48, and a second bearing base 47. Support base 46 is fixed to the lifting false bottom of the marine engineering deep-water tank via high-strength bolts, thereby enabling the bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device to operate as a whole in the marine engineering deep-water tank. Support bearing 48 is rotatably mounted on second bearing base 47, which is bolted to support base 46. The top of support bearing 48 is in contact with the bottom surface of slewing gear 1. Rotation of slewing gear 1 drives support bearing 48, thereby reducing friction and ensuring smooth rotation of slewing gear 1. Support bearing 48 provides vertical support.

[0111] like Figure 8 As shown, the pipe cover module 6 includes a third base flange 49, an adapter fixing block 50, and a circular tube flow shield 51. The circular tube flow shield 51 is mounted on the end of the deep-sea riser model 5 and is arranged concentrically with the deep-sea riser model 5. The circular tube flow shield 51 can shield the deep-sea riser model 5 of a set length from the flow field. The circular tube flow shield 51 can be made of stainless steel or aluminum. The end of the circular tube flow shield 51 is welded to the adapter fixing block 50 as a whole. The adapter fixing block 50 is connected to the third base flange 49 by bolts, and the third base flange 49 is fixed to the rotary gear 1 by screws.

[0112] like Figure 9 As shown, the host computer module 12 includes an industrial control computer 52, a motion controller 53 and a driver 54. The operator inputs the steady speed or the oscillation speed amplitude and the oscillation speed frequency period at the edge of the bidirectional oscillating flow field into the industrial control computer 52. The working computer 52 issues a motion instruction to the motion controller 53. The motion controller 53 controls the driver 54 to drive the servo motor 40 to complete the set action according to the motion instruction.

[0113] like Figure 10 As shown, the deep-sea riser model 5 includes a central tube 57, a heat shrink tubing 55, and fiber Bragg grating (FBG) strain trains 56. Two pairs of FBG strain trains 56 are pre-embedded on the downstream and transverse surfaces of the central tube 57, respectively. The heat shrink tubing 55 wraps around the central tube 57 and the FBG strain trains 56. It should be noted that the downstream direction is along the flow direction, while the transverse direction is perpendicular to the flow direction. The downstream tube faces the flow field, with one strain train each placed in the forward and backward directions. The paired FBG strain trains 56 can be used to determine the bending strain by subtracting the strain-deformation relationship. The transverse principle is the same as the downstream principle.

[0114] like Figure 11As shown, the measurement module 13 includes a fiber Bragg grating demodulator 58, an I / O module 59, a storage module 60, a wireless module 61, and a receiving module 62. The fiber Bragg grating demodulator 58 demodulates the vibration strain signal from the strain gauges in the fiber Bragg grating strain string 56 pre-embedded on the surface of the central tube 57. The I / O module 59 converts the analog signal of the three-force sensor into a digital signal. Both signals are synchronously stored by the storage module 60. The wireless module 61 sends the stored data to the receiving module 62 to complete the dynamic strain and force response measurement. The receiving module 62 is preferably connected to the industrial control computer 52 of the host computer module 12.

[0115] like Figure 12 , 13, and 14 respectively show the rotary gear 1, the driving wheel 10, and the metal flexible belt 9. The driving wheel 10 is fixed to the optical axis 45 of the power module 11 and drives the rotary gear 1 to rotate through the metal flexible belt 9. In turn, it drives the deep-sea riser model 5 to rotate according to the set speed or oscillation instruction, forming a relative bidirectional shear step and a bidirectional shear step oscillating flow field with the surrounding water.

[0116] The production and installation process of this embodiment is as follows:

[0117] Before the formal experiment, the appropriate similarity criteria, model scale ratio, and experimental conditions were selected based on the actual dimensions of the deep-sea riser, the specific test conditions, the size of the laboratory deep-water tank, and the economic feasibility of the experiment. The appropriate materials and dimensions of each module were selected based on the strength and rigidity requirements of the experimental device under the experimental conditions. After the modules of the experimental device were fabricated, the detailed installation steps were as follows:

[0118] First, 20 independent base modules 2 are assembled and fixed on the steel lifting bottom of the laboratory pool to form a circle with a diameter of 8 meters, which is consistent with the diameter of the rotating gear 1.

[0119] Next, the rotating gear 1 is placed on the supporting base 46 , and 20 outer boundary elastic constraint modules 3 and 20 inner boundary elastic constraint modules 4 are installed to fix the rotating gear 1 .

[0120] Next, the support structure 42 of the power module 11 is mounted on the steel lifting false bottom of the pool via the second base flange 43. The first bearing seat 44, driving pulley 10, and optical axis 45 are assembled in sequence, followed by the reducer 41 and servo motor 40. The flexible wire belt 9 is tightly fitted into the grooves of the rotating gear 1 and the driving pulley 10, completing the power system connection.

[0121] Fourth, a deep-sea riser model 5 is fabricated. A central pipe 57 is fabricated using PPR material and copper cable composites. Four sets of fiber Bragg grating strain gauges 56 in the downstream and transverse directions are affixed to the surface of the central pipe 57. A heat shrink tubing 55 is then wrapped around the central pipe 57 to protect the four sets of fiber Bragg grating strain gauges 56.

[0122] Fifth, the first fixture 21, first universal joint 22, first three-force sensor 20, and long-axis screw 15 of the tensioner module 7 are assembled sequentially, completing the assembly of the tensioner module 7. The module is then secured to the rotary gear 1 via the base flange. The rigid fixing module 8 is then assembled with the second fixture 25, second universal joint 26, second three-force sensor 27, and base fixing flange 28, and secured radially opposite the rotary gear 1. The pipe cover module 6 is then concentrically placed around the deep-sea riser model 5, which is then secured between the tensioner module 7 and the rigid fixing module 8 using the clamps.

[0123] Sixth, the fiber Bragg grating strain string 56 of the deep-sea riser model 5 was connected to the fiber Bragg grating demodulator, and the three-force sensors installed at both ends of the deep-sea riser model 5 were connected to the IO module 59. The data was stored in the remote computer module 60 and transmitted to the receiving module 62 via the wireless module 61. The overall debugging and connection were successful, preparing for the formal experiment.

[0124] Seventh, connect the power module 11 to the host computer module 12, connect the servo motor 40 to the driver 54, connect the driver 54 to the motion controller 53, and embed the motion controller 53 into the PCI slot of the industrial computer 52. This completes the operation preparation of the host computer module 12.

[0125] Finally, after the overall installation of the experimental device is completed, the device is debugged. After debugging, the experimental device can be started according to the specific working conditions and experimental technical requirements, and the constant speed and oscillation motion instructions are input and set. Combined with the pipe cover module 6, it is used to simulate the bidirectional shear step flow and bidirectional shear step oscillation flow for testing.

[0126] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0127] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device, characterized in that: include: A base module (2) is provided with a support bearing (48); The bottom of the rotary gear (1) is in rotational engagement with the support bearing (48), and the outer side and the inner side are respectively constrained and limited by an outer boundary elastic constraint module (3) and an inner boundary elastic constraint module (4); A deep-sea riser model (5), both ends of which are connected to the two ends of the slewing gear (1) through a tensioner module (7) and a rigid fixing module (8) and pass through the center of the slewing gear (1); A pipe cover module (6) is provided with a circular pipe baffle cover (51), wherein the circular pipe baffle cover (51) is sleeved on the end of the deep-sea riser model (5); A power module (11) provides power for the rotation of the rotary gear (1); The host computer module (12) issues an action instruction to instruct the power module (11) to move, and the action instruction can be set to match different experimental scenarios; A measuring module (13) is signal-connected to the deep-sea riser model (5), the first three-force sensor (20) of the tensioner module (7), the second three-force sensor (27) of the rigid fixing module (8), and the host computer module (12); The plurality of inner boundary elastic constraint modules (4) arranged in an annular shape form radial limitations on the inner side surface of the rotary gear (1), and the plurality of outer boundary elastic constraint modules (3) arranged in an annular shape form radial limitations on the outer side surface of the rotary gear (1); The outer boundary elastic constraint module (3) is flexibly rotated with the outer side surface of the rotary gear (1), and the inner boundary elastic constraint module (4) is flexibly rotated with the inner side surface of the rotary gear (1); The inner boundary elastic constraint module (4) includes an inner top flange block (29), an inner top bearing (30), an inner boundary constraint bolt (31), a second spring (32), a second linear track (34), a second slider (33) and a first base flange (35), wherein the inner boundary constraint bolt (31) is tightened to compress the second spring (32), the inner boundary constraint bolt (31) is connected to the inner top flange block (29), the inner top flange block (29) is connected to the second slider (33), the second slider (33) can move on the second linear track (34), the second linear track (34) is fixed on the first base flange (35), the restoring force of the second spring (32) reacts on the inner top flange block (29) to make the inner top bearing (30) support the rotary gear (1), and limit the radial inward movement of the rotary gear (1), and the first base flange (35) is detachably fixed on the base module (2); The outer boundary elastic constraint module (3) includes an outer top bearing (36), an outer boundary constraint bolt (37), a third spring (38) and a downward pressure flange block (39), wherein the outer top bearing (36) is rigidly connected to the downward pressure flange block (39), the outer boundary constraint bolt (37) has a limiting head end and a threaded end, the threaded end of the outer boundary constraint bolt (37) passes through the downward pressure flange block (39) and is fixed to the base module (2), the third spring (38) is sleeved on the outer boundary constraint bolt (37) and is arranged between the limiting head end and the downward pressure flange block (39) to be compressed, and the restoring force of the compressed third spring (38) reacts to the downward pressure flange block (39), thereby causing the outer top bearing (36) to press the rotating gear (1), thereby limiting the radial outward movement of the rotating gear (1); The base module (2) includes a support base (46), a support bearing (48) and a second bearing base (47), wherein the support base (46) is fixedly arranged on a lifting false bottom of a deep-water tank of an ocean engineering project, and the support bearing (48) is rotatably arranged on the second bearing base (47), and the second bearing base (47) is fixed on the support base (46), and the top of the support bearing (48) is in contact with and connected to the lower bottom surface of the rotary gear (1).

2. The bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device according to claim 1 is characterized in that: The deep-sea riser model (5) comprises a central pipe (57), a plurality of fiber grating strain strings (56) adhered to the surface of the central pipe (57), and a heat shrink tube (55) wrapped around the fiber grating strain strings (56) and the outside of the central pipe (57).

3. The bidirectional shear step constant and oscillating flow riser vortex-induced vibration experimental device according to claim 1 is characterized in that: The tensioner module (7) adopts elastic tensioning.

4. The bidirectional shear step constant and oscillatory flow riser vortex-induced vibration experimental device according to claim 1 is characterized in that: The tensioner module (7) comprises a first fixture (21), a first universal joint (22), a first three-force sensor (20), a first slider (24), a first linear track (23), a long-axis screw (15), a screw adapter flange (19), a bottom fixed adapter flange (18), a first spring (14), a top plate (17) and a top screw (16); one end of the deep-sea riser model (5) is connected to the first fixture (21); the first fixture (21) is connected to one end of the first universal joint (22); the other end of the first universal joint (22) is connected to the first three-force sensor (20); the first three-force sensor (20) is connected to the long-axis screw One end of the rod (15) is connected; the long-axis screw (15) is connected to the first slider (24) through the screw adapter flange (19), and the first slider (24) is slidably matched with the first linear track (23); the first linear track (23) is detachably connected to the bottom fixed adapter flange (18); the top screw (16) presses one end of the first spring (14) through the top plate (17), and the other end of the first spring (14) is in contact with and connected to the bottom fixed adapter flange (18); the elastic force of the first spring (14) reacts to the top plate (17), thereby causing the deep-sea riser model (5) to be elastically stretched and tensioned.

5. The bidirectional shear step constant and oscillatory flow riser vortex-induced vibration experimental device according to claim 1 is characterized in that: The power module (11) drives the rotary gear (1) to rotate by means of a driving wheel and a belt.

6. The bidirectional shear step constant and oscillatory flow riser vortex-induced vibration experimental device according to claim 1 is characterized in that: The host computer module (12) can control the power module (11) to operate according to different flow rates or set sinusoidal oscillation times of different amplitudes and frequencies.

7. The bidirectional shear step constant and oscillatory flow riser vortex-induced vibration experimental device according to claim 2, characterized in that: The measuring module (13) includes a fiber Bragg grating demodulator (58), an IO module (59), a storage module (60), a wireless module (61) and a receiving module (62). The fiber Bragg grating demodulator (58) demodulates the vibration strain signal from the strain gauge in the fiber Bragg grating strain string (56). The IO module (59) converts the analog signal of the three-force sensor into a digital signal. The vibration strain signal and the digital signal are synchronously stored by the storage module (60). The wireless module (61) sends the stored data to the receiving module (62) to complete the dynamic strain and force response measurement. The receiving module (62) is connected to the host computer module (12).

8. The bidirectional shear step constant and oscillatory flow riser vortex-induced vibration experimental device according to claim 1 is characterized in that: The end of the deep-sea riser model (5) is provided with a circular tube baffle (51), thereby being able to shield the deep-sea riser model (5) of a set length from being subjected to a flow field.

Images