A vortex-induced vibration test device and method for marine umbilical cable

Abstract

The present invention belongs to the technical field of fluid mechanics research, and relates to a device and method for fluid mechanics testing. A marine umbilical cable vortex-induced vibration test device, comprising: a top tension application system and a fixing system; the fixing system comprises a bracket; an angle and height adjustment device is provided on the bracket, and the top tension application system is installed on the angle and height adjustment device. The device and method of the present invention have the following beneficial effects: vortex-induced vibration tests of umbilical cables at different inclination angles can be realized; the fixing system has no effect on the flow field, thereby ensuring the accuracy of the applied flow field; the tension application is more accurate and more stable, thereby avoiding the top movement of the model from distorting the experimental data.

Description

Technical Field

[0001] The invention belongs to the technical field of fluid mechanics research, and relates to a device and method for fluid mechanics testing. Background Art

[0002] As an important auxiliary connection system for the development of marine oil and gas resources, the umbilical cable provides cable power, optical fiber signals and medium transmission for the underwater production system. The marine umbilical cable is in a very complex and harsh environment. Due to the long and thin characteristics of the umbilical cable itself and the lack of intermediate support, the vortices that periodically fall off on both sides of the umbilical cable under the action of certain ocean currents produce periodic forces, causing the umbilical cable to produce vortex-induced vibrations in the transverse and downstream directions, making the umbilical cable prone to fatigue damage, which in turn causes damage to the optical fiber inside the umbilical cable, resulting in communication interruption, seriously threatening the safe production of the entire oil and gas industry, and causing huge economic losses.

[0003] In the prior art, invention patent CN208937285U discloses a vortex-induced vibration test device for marine umbilical cables. Although the test device can accurately apply and read the value of top tension, the device can only be applied to vertical cables and cannot simulate the influence of the angle between the marine cable and the incoming flow direction on vortex-induced vibration under real working conditions. In addition, the weight plate, weights, and nylon rope used to apply top tension in the test device are suspended in the air, and the top tension application process is easily disturbed by the external environment, and the top tension application process has high environmental requirements.

[0004] Umbilical cables are available in two forms: bonded and non-bonded. Both numerical and experimental studies of non-bonded umbilical cables are difficult. At present, the overall analysis of umbilical cables is generally simplified into a bonded type through numerical simulation, without considering the influence of internal friction. In addition, the structural axis is not completely perpendicular to the incoming flow in actual engineering, and the influence of the angle between the marine cable and the incoming flow on the vortex-induced vibration is not very clear. Therefore, the experimental simulation of non-bonded umbilical cables and bonded umbilical cables and the study of vortex-induced vibration of inclined flexible cylinders are of great significance. In the process of experimental simulation, it is necessary to accurately apply different pre-tensions to the umbilical cable model under a specific boundary connection method to conduct research in different aspects. Summary of the invention

[0005] In order to solve the problems existing in the prior art in the vortex-induced vibration test research of umbilical cables, the present invention provides a vortex-induced vibration test device and method for marine umbilical cables.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a marine umbilical cable vortex-induced vibration test device, comprising: a top tension application system and a fixing system; the fixing system comprises a bracket; an angle and height adjustment device is provided on the bracket, and the top tension application system is installed on the angle and height adjustment device.

[0007] The angle and height adjustment device includes a base platform, a top platform, at least one angle adjustment platform, and a support leg connecting the top platform and the angle adjustment platform, the support leg is fixed on the bracket, and its height is adjusted by a plurality of vertically arranged fixing holes provided on the bracket; a downwardly curved arc is provided in the middle of the angle adjustment platform, and a plurality of angle adjustment holes are provided on the arc.

[0008] The top tension application system includes a tension winch, a steel wire rope connected to the tension winch, a fixed pulley fixed above the top platform and a limiting pulley below, and a long screw; the steel wire rope passes around the fixed pulley, passes through the limiting pulley, and is connected to the long screw passing through the angle adjustment hole; the long screw is fixed to both sides of the angle adjustment platform through nuts.

[0009] The arc has the center of the limiting pulley as the center and the distance between the center of the limiting pulley and the angle adjustment platform as the radius.

[0010] The angle adjustment holes are symmetrically distributed on the arc with the vertical axis where the center of the circle is located as the axis.

[0011] The angle between the line connecting the angle adjustment hole and the center of the circle and the vertical axis is 0-45°.

[0012] The angle and height adjustment device also includes a base platform, and the base platform is provided with a slide groove, and bolts are installed in the slide groove.

[0013] The present invention also provides a method for testing vortex-induced vibration of a marine umbilical cable, comprising:

[0014] According to the inclination angle of the umbilical cable model required for the test, pass the long screw through the corresponding angle adjustment hole;

[0015] Tighten the bottom end of the umbilical cable model to the base platform with bolts through a universal hinge.

[0016] The top of the umbilical cable model is connected to the tension meter through a universal hinge, and the tension meter is connected to a long screw;

[0017] The tension is applied by the tension capstan, and the tension is fine-tuned by the nuts at the upper and lower ends of the long screw until the requirements of the vortex-induced vibration test are met.

[0018] The umbilical cable model is a non-bonded umbilical cable model or a bonded umbilical cable model.

[0019] The umbilical cable model adopts the form of inserting copper strands into an organic glass tube, wherein the organic glass tube and the copper strands of the non-bonded umbilical cable model are in natural contact and can produce relative slip; in the bonded umbilical cable model, the outside of the copper strands is bonded and fixed to the inner wall of the organic glass tube by an adhesive.

[0020] Compared with the prior art, the marine umbilical cable vortex-induced vibration test device and method of the present invention have the following beneficial effects:

[0021] (1) The umbilical cable model is more consistent with the actual structure

[0022] The model uses copper wire to simulate the internal structural functional units of the umbilical cable and spirally winds it at a certain helical angle, which is closer to the contact mode of the actual internal structural units of the umbilical cable.

[0023] (2) The test model takes into account the friction between the internal structural unit and the external protective layer.

[0024] By bonding the copper strands and the plexiglass tube and using natural contact, the two conditions of no friction and internal friction of the umbilical cable were simulated to make the experimental data more complete.

[0025] (3) The fixing system is small in size and light in weight, making it easy to transport and install.

[0026] The fixing system consists of three separate parts, namely the base platform, the bracket and the angle and height adjustment device, all of which are made of square steel, with high rigidity and light weight. The bracket is fixed to the two side walls of the sink with G-shaped clamps to increase the stability of the system.

[0027] (4) The fixed system has no effect on the flow field, ensuring the accuracy of the applied flow field

[0028] The fixing system has only a base platform in the underwater part, and the bracket and angle and height adjustment devices are all located above the water tank. The fixing system does not affect the water flow in the water tank, thereby ensuring the accuracy of the applied flow field.

[0029] (5) Vortex-induced vibration test of umbilical cables at different inclination angles can be realized

[0030] During the test, the tilt angle of the umbilical cable model was adjusted by adjusting the distance between the bracket and the angle and height adjustment device and the position of the universal hinge fixed on the slide.

[0031] (6) Tension is applied more accurately and stably, avoiding the distortion of experimental data caused by the movement of the top of the model

[0032] Connect the tensiometer directly to the umbilical cable model, and you can directly see the top tension applied to the umbilical cable model. Apply the required tension through the tension capstan and fixed pulley, and then fine-tune it through the adjustment nut on the long screw, so that the tension application is more accurate and stable, and the tension application accuracy has strong adaptability to the test environment. The upper and lower arc-segment platforms limit the horizontal shaking of the top of the umbilical cable model, and the nuts above and below the platform constrain the movement of the top of the umbilical cable along the direction of the long screw, avoiding the influence of the movement of the top of the umbilical cable on the experimental data during the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 2 is a front view of a vortex-induced vibration test device for a marine umbilical cable according to an embodiment of the present invention;

[0034] Figure 2 2 is a right side view of a vortex-induced vibration test device for a marine umbilical cable according to an embodiment of the present invention;

[0035] Figure 3 yes Figure 1 The front view of the middle bracket;

[0036] Figure 4 is a top view of the bracket;

[0037] Figure 5 is the left view (or right view) of the bracket;

[0038] Figure 6 It is a structural schematic diagram of the angle and height adjustment device;

[0039] Figure 7 This is a top view of the top platform;

[0040] Figure 8 is a top view of the angle adjustment platform;

[0041] Fig. 9 is a schematic diagram of the base platform;

[0042] Fig.10 is a schematic diagram of the chute cross section;

[0043] Fig.11 It is the main view of the bolt;

[0044] Fig.12 It is the right side view (or left side view) of the bolt;

[0045] Fig.13 This is a schematic diagram of the bolt being placed into the slide;

[0046] Fig.14 It is a top view of the limiting pulley;

[0047] Fig.15 yes Figure 1Partial detail diagram at point A in the middle;

[0048] Fig.16 This is a schematic diagram of the copper stranded wire structure inside the umbilical cable;

[0049] Fig.17 It is a schematic diagram of the cross section of the umbilical cable model, where a is a non-bonded type and b is a bonded type. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] The first embodiment provided by the present invention is: a marine umbilical cable vortex-induced vibration test device, the structure of the device is as follows Figure 1-2 As shown, it includes: tension winch 1, wire rope 2, fixed pulley 3, limit pulley 4, angle adjustment platform 5, long screw 6, universal hinge 9, bracket 11, top support platform 12, base platform 13 and support leg 14. Among them, tension winch 1 and wire rope 2, fixed pulley 3, limit pulley 4, long screw 6, nut 7, tension meter 8 constitute the tension applying system of this embodiment; angle adjustment platform 5, long screw 6, universal hinge 9, bracket 11, top support platform 12, base platform 13 and support leg 14 constitute the fixing system of this embodiment.

[0052] like Figure 3-5 As shown, the bracket 11 is welded by 8 square steel pipes, and the bottom frame is composed of 2 longer square steel pipes and 2 shorter square steel pipes, which are welded at the lower ends of four vertical square steel pipes, and the longer steel pipes extend out of the edge of the bracket on both sides. A number of through holes 16 are opened at equal intervals from top to bottom along the vertical steel pipes. In order to facilitate the connection between the bracket and the angle and distance adjustment device and the adjustment of the height between the two. The two longer square steel pipes of the bracket 11 are placed on the side walls of the sink at right angles to the water flow direction. The clamping part is clamped to the side wall of the sink with a G-shaped clamp to ensure the overall stability of the bracket during the test, further increase the overall rigidity of the test bracket, and meet the test requirements.

[0053] like Figure 6 As shown, the angle and height adjustment device includes a top support platform 12, an angle adjustment platform 5, a leg 14 and a base platform 13. The top support platform 12 and the angle adjustment platform 5 are welded to the leg 14. The leg 14 is composed of four directional steel pipes, and a fixing hole 15 is opened at the lower end. The top support platform 12 is a platform frame formed by welding square steel pipes.

[0054] In the tension applying system of this embodiment, the tension winch 1 is fixed on the truss support on the right side of the top support platform 12. The tension winch 1 is connected to the wire rope 2. The fixed pulley 3 and the limit pulley 4 are welded to the upper and lower sides of the middle support of the top support platform 12 respectively, and the wire rope 2 bypasses the fixed pulley 3 and passes through the inside of the limit pulley 4.

[0055] The angle adjustment platform 5 is a platform welded from square steel pipes, wherein there is a downwardly curved arc 19 in the middle of the platform. In this embodiment, the angle adjustment platform 5 has two layers, namely, a middle layer arc platform and a lower layer arc platform. The radius of the arcs of the two-layer platforms is the vertical distance of each arc from the center of the limiting pulley 4. Seven angle adjustment holes 20 are reserved on the arcs of the two-layer platforms. The angles of the line connecting the angle adjustment hole 20 and the center of the limiting pulley 4 with the vertical direction are 0°, left and right 15°, left and right 30°, and left and right 45°, respectively.

[0056] The function of the limit pulley 4 is to make the steel wire rope connected to the tension winch swing in a circular arc with a constant radius to adapt to umbilical cable tests at different angles. The structure of the limit pulley 4 is as follows: Fig.14 As shown, it consists of two parts, an external frame 41 and two internal rotating bearings 42. The external frame 41 is a "U"-shaped structure, and the two bearings are installed side by side in the cavity 43 inside the external frame 41. Both bearings 42 are variable diameter cylinders, and the diameter of the middle part along the axis of the cylinder is larger than the diameter of the two ends. There is a gap 44 between the middle parts of the two bearings, and the wire rope 2 connected to the tension winch bypasses the fixed pulley 3 and passes through the gap 44 in the middle of the limiting pulley 4. The limiting pulley 4 can better control the position of the wire rope and realize the unimpeded rotation of the bearing.

[0057] The long screw rod 6 passes through the angle adjustment holes 20 on the two platforms of the angle adjustment platform 5, and its upper and lower sides are respectively clamped and fixed with the arcs of the two platforms by nuts 7. The upper end of the long screw rod 6 is connected to the lower end of the wire rope 2, and the lower end of the long screw rod 6 is used to connect and fix the top of the umbilical cable model 10. By passing the long screw rod 6 through the angle adjustment holes 20 at different positions, the angle between the umbilical cable model 10 and the vertical axis can be adjusted.

[0058] Since the length of the long screw 6 is fixed, when the inclination angle of the umbilical cable model 10 is adjusted, as the long screw 6 is located in the angle adjustment hole 20 at different positions, the height of the long screw also changes. By adjusting it to be at a suitable height, the umbilical cable model, the long screw and the wire rope can be in a straight line. The height adjustment is achieved by connecting and fixing the fixing holes 15 on the legs 14 with the through holes 16 at different positions on the bracket 11.

[0059] In order to further cooperate with the angle and height adjustment device to achieve angle and height adjustment, the present embodiment further provides a base platform 13, such as Fig. 9 As shown, the base platform 13 is used to fix the bottom end of the umbilical cable model 10. A slide groove 17 is provided on the base platform 13, and a bolt 18 is provided in the slide groove. The cross section of the slide groove 17 is as shown in FIG. Fig.10 As shown, the chute structure is an "inverted T-shaped" structure that is narrow at the top and wide at the bottom. The narrower part at the top is the screw space, and the wider part at the bottom is the nut space. In order to prevent the bolt 18 from rotating in the chute 17 when the universal hinge 9 at the bottom of the umbilical cable model 10 is connected to the bolt 18, the bolt size is made according to the chute size, such as Fig.11 , 12 As shown, the nut of the bolt 18 is rectangular, the wide side of the nut is slightly smaller than the cross-sectional width of the slide slot 17, and the long side of the nut is larger than the cross-sectional width of the slide slot. Fig.13 As shown, the bolt 18 is placed in the slide groove 17 and connected with the universal hinge to effectively prevent the bolt from rotating during installation and testing.

[0060] In this embodiment, in order to limit the shaking of the long screw 6 in the horizontal direction, Fig.15 As shown, the long screw 6 passes through the angle adjustment holes of the arc segments of the two-layer platform in turn, and the long screw 6 is clamped and fixed with nuts 7 on the upper and lower sides of each layer of the platform, which not only limits the horizontal shaking of the long screw, but also limits the movement of the long screw along its own long axis, so that the application of the top tension of the umbilical cable model is both accurate and stable. A nut is also installed at the connection between the universal hinge 9 and the tension meter 8 and the connection between the tension meter 8 and the long screw 6, and the upper and lower nuts are tightened to prevent the tension meter and the universal hinge from rotating during the test and affecting the accuracy of the test data.

[0061] The use method and working principle of the marine umbilical cable vortex-induced vibration test device of this embodiment are as follows:

[0062] Before the test, in order to ensure that the slide groove of the base platform 13 and the arc segment of the angle adjustment platform 5 are in the same vertical plane, the approximate height is calculated first, and the four legs 14 of the angle and height adjustment device are placed on the four vertical steel pipes of the bracket 11 according to this height, and the fixing holes 15 and through holes 16 are fixed with screws or pins.

[0063] The bottom end of the umbilical cable model 10 is connected to the universal hinge 9. The universal hinge 9 is connected to the bolt 18 in the slide groove 17 of the base platform 13. The top end of the umbilical cable model 10 is connected to the tension meter 8 through the universal hinge 9, and the tension meter 8 is connected to the lower end of the long screw 6. The long screw 6 passes through the corresponding angle adjustment holes 20 on the two-layer platform arc 19 of the angle adjustment platform 5 in sequence according to the required angle and is connected to the lower end of the wire rope 2. The tension meter 8 is connected to the tension counter value display.

[0064] Use a laser calibration device to calibrate in the vertical direction, and adjust the height to ensure that the umbilical cable model 10, the lower section of the wire rope 2 and the arc section of the angle adjustment platform 5 are in the same vertical plane, and then use a G-shaped clamp to firmly fix the bracket 11 on the side walls of the water tank to prevent vibration. The base platform 5 is fixed to the bottom of the water tank.

[0065] During the test, the tension winch 1 is used to apply the required tension first, and then the nut 7 at the upper end of the long screw 6 is used for fine adjustment. The value displayed on the tension counter value display is the top tension applied to the upper end of the umbilical cable model during the test.

[0066] The friction between the wire rope and the fixed pulley and the tension winch and the shaking of the wire rope during the test will lead to inaccuracy in the application of pre-tension. This device uses a tensiometer to directly connect with the universal hinge at the upper end of the umbilical cable model to ensure the accuracy of tension application.

[0067] The second embodiment provided by the present invention is: a method for testing vortex-induced vibration of a marine umbilical cable, the method comprising the following specific steps:

[0068] (1) Making an umbilical cable model

[0069] The umbilical cable model of this embodiment consists of two parts: an internal copper strand and an external organic glass tube. In order to simulate the spiral twisted contact mode between the internal structural functional units of the umbilical cable, the umbilical cable model of this embodiment is made of seven copper wires twisted together. Fig.16 As shown, the middle copper wire and the outer six copper wires are twisted and contacted with the middle copper wire in a form of helix angle α=9° and pitch h=178.5mm, and processed by a professional twisting machine. The diameter of the copper stranded wire used in this embodiment is 9mm, and the outer diameter of the organic glass tube used is 19mm and the inner diameter is 9mm.

[0070] The copper wires are twisted spirally at the selected helix angle and pitch to make two copper strands. One copper strand is evenly coated with modified acrylic adhesive on the outside, and then placed in a processed organic glass tube and left to stand for 12 hours to make it firmly bonded; the other copper strand is directly placed in the processed organic glass tube to make two models of bonded umbilical cables and non-bonded umbilical cables, such as Fig.17 shown.

[0071] (2) Install the fixing system

[0072] Weld the four corners of the base platform to the bottom of the water tank, install the bracket, calculate the approximate height required for the angle and height adjustment device when the umbilical cable is tilted at a certain angle during the test, and put the four legs of the angle and height adjustment device on the four vertical steel pipes of the bracket. Use short screws or pins to pass through the through holes on the bracket and the fixing holes on the legs to firmly connect the two parts. Use a laser calibration device to calibrate in the vertical direction so that the center line of the slide and the center line of the arc section of the angle adjustment platform of the angle and height adjustment device are in the same vertical plane. After the calibration is completed, use a G-clamp to clamp the bracket to the side wall of the water tank. Install bolts in the slide of the base platform, connect the universal hinge to the bolts, and do not tighten them first to ensure that the bolts can slide along the slide.

[0073] (3) Install the model

[0074] According to the inclination angle of the umbilical cable model required for the test, the long screw is passed through the angle adjustment hole of a specific angle. The long screw is screwed with nuts on the upper and lower sides of the arc section of the two-layer platform in advance, but enough space must be left for the long screw to slide in the inclination direction. Then the tensiometer and the universal hinge are connected in sequence. The bottom end of the umbilical cable model is installed on the universal hinge below. The top of the umbilical cable model is connected to the universal hinge above by adjusting the position of the long screw, and the screws are gently tightened in four directions of the two universal hinges to prevent excessive force from causing damage to the bottom of the umbilical cable model. Straighten the connected umbilical cable model along the direction of the long screw, and finally tighten the universal hinge at the bottom of the umbilical cable and the bolts on the slide to prevent the bottom of the umbilical cable model from sliding. The model is installed.

[0075] (4) Apply top tension

[0076] Apply top tension through the tension winch, wire rope, fixed pulley and limit pulley. Connect the tension meter directly to the universal hinge at the top of the umbilical cable model. The reading on the tension counter value display is the top tension applied. Apply the approximate top tension required for the test by turning the handle of the tension winch and paying attention to the value on the tension counter value display, and fix the tension winch handle. Adjust the upper and lower nuts of the middle arc platform for fine-tuning. The tension increases when tightened and decreases when loosened. After the tension reading reaches the value required for the test, tighten the upper and lower nuts of the lower arc platform at the same time. When tightening, adjust back and forth several times to ensure that the tension reading does not change. At the same time, ensure that the long screw in the test cannot shake in both the horizontal and vertical directions to meet the vortex-induced vibration requirements.

Claims

1. A method for testing vortex-induced vibration of a marine umbilical cable, using a vortex-induced vibration test device for a marine umbilical cable, characterized in that: include: According to the inclination angle of the umbilical cable model required for the test, pass the long screw through the corresponding angle adjustment hole; Tighten and fix the bottom end of the umbilical cable model to the bolts in the slide slot of the base platform through the universal hinge; The top of the umbilical cable model is connected to a tension meter through a universal hinge, and the tension meter is connected to a long screw; The tension is applied by a tension winch, and the tension is fine-tuned by nuts at the upper and lower ends of the long screw until the vortex-induced vibration test requirements are met; the umbilical cable model is a non-bonded umbilical cable model or a bonded umbilical cable model; the umbilical cable model is in the form of a copper strand inserted into an organic glass tube, wherein the organic glass tube and the copper strand of the non-bonded umbilical cable model are in natural contact; The outer portion of the copper stranded wire of the bonding umbilical cable model is bonded and fixed to the inner wall of the organic glass tube by an adhesive; The marine umbilical cable vortex-induced vibration test device comprises: a top tension application system and a fixing system; the fixing system comprises a bracket; an angle and height adjustment device is provided on the bracket, and the top tension application system is installed on the angle and height adjustment device; the angle and height adjustment device comprises a top platform, at least one layer of angle adjustment platform, and a support leg connecting the top platform and the angle adjustment platform, the support leg is fixed on the bracket, and its height is adjusted by a plurality of vertically arranged fixing holes provided on the bracket; A downwardly curved arc is provided in the middle of the angle adjustment platform, and a plurality of angle adjustment holes are provided on the arc; the angle adjustment platform with the arc limits the shaking of the top end of the umbilical cable model in the horizontal direction.

2. The vortex-induced vibration test method for marine umbilical cable according to claim 1, characterized in that: The top tension application system includes a tension winch, a steel wire rope connected to the tension winch, a fixed pulley fixed above the top platform and a limiting pulley below, and a long screw; the steel wire rope passes around the fixed pulley, passes through the limiting pulley, and is connected to the long screw passing through the angle adjustment hole; the long screw is fixed to both sides of the angle adjustment platform through nuts.

3. The vortex-induced vibration test method for marine umbilical cable according to claim 1, characterized in that: The arc has the center of the limiting pulley as the center and the distance between the center of the limiting pulley and the angle adjustment platform as the radius.

4. The vortex-induced vibration test method for marine umbilical cable according to claim 1, characterized in that: The angle adjustment holes are symmetrically distributed on the arc with the vertical axis where the center of the circle is located as the axis.

5. The vortex-induced vibration test method for marine umbilical cable according to claim 1, characterized in that: The angle between the line connecting the angle adjustment hole and the center of the circle and the vertical axis is 0-45°.

6. The vortex-induced vibration test method of marine umbilical cable according to claim 1, characterized in that: The angle and height adjustment device also includes a base platform, and the base platform is provided with a slide groove, and bolts are installed in the slide groove.

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