A test device for simulating the dynamic response of marine tow cables under tugboat swaying towing conditions

Abstract

This invention discloses a test device for simulating the dynamic response of a marine towed cable under swaying towing conditions, relating to the interdisciplinary research fields of fluid mechanics and structural mechanics. Its features include a planar motion module, a towed cable suspension module, a connecting module, and a towed cable model. The planar motion module is connected to the connecting module, which includes a first universal joint, capable of moving the first universal joint in the X and Z directions. The towed cable suspension module includes a second universal joint, which can adjust and fix the position of the second universal joint in the X and Z directions. The towed cable model is connected to the first and second universal joints. This invention can realize dynamic response tests of marine towed cables under different swaying periods and amplitudes without affecting the flow field around the towed cable during the test. The test device can be disassembled into smaller components for easy transportation and installation.

Description

Technical Field

[0001] This invention relates to the field of interdisciplinary research in fluid mechanics and structural mechanics, and in particular to a test device for simulating the dynamic response of a marine tow cable under tugboat swaying and towing conditions. Background Technology

[0002] Marine seismic exploration systems are crucial for detecting seabed resources. They consist of three parts: the exploration vessel, the marine towed cable, and the underwater towed body. The marine towed cable, as an important auxiliary connection system, provides power to the underwater towed body and transmits the signals acquired by the underwater towed body back to the exploration vessel. During operation, the marine towed cable operates in a harsh environment, subjected to complex fluid forces, tugboat swaying forces, and its own weight. Due to its high aspect ratio and low stiffness, the marine towed cable experiences periodically varying lift on both sides under the influence of ocean currents, causing large-amplitude vortex-induced vibrations. This affects the acquisition efficiency of the towed system and the fatigue damage to the towed cable. Simultaneously, due to wave action, the exploration vessel experiences heave and sway motions. The towed cable, affected by the tugboat's swaying, generates wave-induced vibrations. The coupling of wave-induced vibrations and vortex-induced vibrations can trigger even more severe responses, causing greater damage to the towed system. Therefore, conducting relevant towed cable flow-induced vibration tests and studying the mechanisms of wave-induced vibrations and vortex-induced vibrations is essential.

[0003] Due to different working requirements, tow cables will exhibit different equilibrium configurations, and the corresponding flow fields will also change. The most significant feature is that the axis of the tow cable is at a certain angle to the direction of the flow field. The fluid component along the axis of the tow cable will affect the vortex-induced vibration of the tow cable. If the swaying effect of the tugboat is also taken into account, the response will be more complex and the mechanism is still unclear. Therefore, it is of great significance to carry out dynamic response tests of tow cables that take into account the swaying of the tugboat. With the existing technology and test conditions, it is not practical to carry out full-scale tests, which are costly, require large sites, and have high requirements for measurement equipment. It is more feasible to carry out corresponding model tests, but at the same time, the following problems will be encountered: (1) The exploration vessel is expensive to build, and when wave action is considered, it is difficult for the ship model to reach a stable dynamic equilibrium state, which affects the measurement effect. Moreover, the effect of waves on the ship model is difficult to quantify and difficult to conduct systematic research; (2) During towing, the fluid load on the tow body will be coupled with the vortex-induced vibration of the tow cable, making it difficult for the tow body to stabilize and difficult to detect the response of the tow cable under pure vortex-induced vibration. In the prior art, utility model patent CN210953321U discloses a marine umbilical cable vortex-induced vibration test device. Although this test device can simulate the influence of different angles between the marine cable and the direction of the incoming current on vortex-induced vibration, it cannot simulate the influence of tugboat swaying on the cable's vortex-induced vibration and wave-induced vibration.

[0004] Therefore, those skilled in the art are dedicated to developing a marine towline dynamic response test device that can simulate the effects of tugboat swaying on cable vortex-induced vibration and wave-induced vibration. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to simulate the influence of tugboat swaying on cable vortex-induced vibration and wave-induced vibration in a marine towline dynamic response test device.

[0006] To achieve the above objectives, the present invention provides a test device for simulating the dynamic response of a marine towline under tugboat swaying and towing conditions. The device comprises a planar motion module, a towline suspension module, a connecting module, and a towline model. The planar motion module is fixed to a trailer and connected to the connecting module. The connecting module includes a first universal joint, which the planar motion module can drive to move in the X and Z directions. The towline suspension module includes a second universal joint, which can adjust and fix the position of the second universal joint in the X and Z directions. The towline model is connected to the first and second universal joints.

[0007] Furthermore, the planar motion module includes two lead screw modules and a profile. The two lead screw modules include an X-direction lead screw module and a Z-direction lead screw module. The X-direction lead screw module is fixed to the trailer by the profile, and the Z-direction lead screw module is mounted on the slider of the X-direction lead screw module.

[0008] Furthermore, the connection module also includes a connecting rod and a six-component force meter. The upper end of the connecting rod is connected to the slider of the Z-direction lead screw module, and the lower end of the connecting rod is connected to the upper end of the six-component force meter.

[0009] Furthermore, the first universal joint is connected to the lower end of the six-component force meter, and the towing cable model is connected to the lower end of the first universal joint.

[0010] Furthermore, the upper end of the connecting rod is connected to the slider of the Z-direction lead screw module by screws.

[0011] Furthermore, the towing cable suspension module also includes a tripod and a first square steel plate. The tripod is fixed to the railing of the trailer, and the first square steel plate is mounted on the tripod via a connecting steel plate. The first square steel plate can move back and forth on the tripod and be fixed in place.

[0012] Furthermore, the tow cable suspension module also includes optical shafts and a second square steel plate. Both the first and second square steel plates are provided with four round holes and two light-reducing holes. There are four optical shafts. The optical shafts pass through the four round holes of the first square steel plate and enter the water. The underwater ends of the optical shafts pass through the four round holes of the second square steel plate. The second square steel plate can move up and down on the optical shafts and be fixed. The second universal joint is installed on the second square steel plate.

[0013] Furthermore, the optical axis is connected and fixed to the first square steel plate and the second square steel plate by an optical axis fixing ring, and the first square steel plate is connected to the tripod by a screw.

[0014] Furthermore, the first universal joint and the second universal joint are made of aluminum alloy.

[0015] Furthermore, it also includes a control module connected to the planar motion module. The control module is programmed using PLC language and can control the planar motion module to generate motion in the X and Z directions.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. This device can be disassembled into smaller parts for easy transportation and installation. The device consists of five modules: a cable suspension module, a planar motion module, a connection module, a control module, and a cable model. Each module is independent and can be disassembled into several steel plates and profiles, resulting in high rigidity and low mass.

[0018] 2. This device does not affect the flow field around the tow cable. The planar motion module and the connecting module are on the water, while the four optical axes and a square steel plate of the tow cable suspension module are underwater. The distance between the optical axes and the tow cable is greater than 20D (D is the diameter of the tow cable), and will not affect the flow field around the tow cable.

[0019] 3. It can perform dynamic response tests of marine towed cables under different oscillation periods and amplitudes. In the test, the motion amplitude and period of the lead screw modules in the X and Z directions are controlled to simulate the effects of different waves.

[0020] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0021] Figure 1 This is a front view of a simulated marine towline dynamic response test device under tugboat swaying towing, according to a preferred embodiment of the present invention.

[0022] Figure 2This is a front view of the tow cable suspension system of a marine tow cable dynamic response test device for simulating tugboat rocking and towing, according to a preferred embodiment of the present invention.

[0023] Figure 3 This is a side view of the tow cable suspension system of a marine tow cable dynamic response test device for simulating tugboat rocking and towing, according to a preferred embodiment of the present invention.

[0024] Figure 4 This is a front view of the planar motion mechanism of a simulated marine towline dynamic response test device under tugboat swaying and towing, according to a preferred embodiment of the present invention.

[0025] Figure 5 This is a side view of the planar motion mechanism of a test device for simulating the dynamic response of an ocean tow cable under tugboat swaying and towing, according to a preferred embodiment of the present invention.

[0026] Figure 6 This is a front view of the connection system of a simulated marine towline dynamic response test device under tugboat swaying towing, according to a preferred embodiment of the present invention.

[0027] Among them, 1-X-direction lead screw module, 2-Z-direction lead screw module, 3-connecting rod, 4-six-component force meter, 5-first universal joint, 6-1500mm×80mm×80mm×5mm profile, 7-triangle frame, 8-optical axis, 9-first square steel plate, 10-1000mm×80mm×80mm×5mm profile, 11-second universal joint, 12-second square steel plate, 13-towing cable model. Detailed Implementation

[0028] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0029] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0030] The technical solution adopted by this invention to solve its technical problem is as follows: a test device for simulating the dynamic response of a marine tow cable under swaying towing conditions, comprising: a planar motion module, a tow cable suspension module, a connection module, a control module, and a tow cable model; the planar motion module includes two lead screw modules mounted on the trailer; the tow cable suspension module includes a tripod mounted on the trailer railing; the connection module is mounted on the planar motion module and connected to the tow cable model at its lower end; the control module is programmed using PLC language to control the motion of the planar motion module.

[0031] Two lead screw modules control the movement in the X and Z directions respectively; the X-direction lead screw module is fixed to the trailer by five profiles, 12 fixed steel plates, 24 screws and 48 nuts; the Z-direction lead screw module is installed on the slider of the X-direction lead screw module; the X-direction lead screw module can move back and forth with a maximum amplitude of 50cm; the Z-direction lead screw module can move up and down with a maximum amplitude of 80cm.

[0032] The tow cable suspension module includes a tripod, four optical shafts, two square steel plates, eight fixing steel plates, 16 optical shaft fixing rings, a connecting steel plate, 20 screws, and 40 nuts. The tripod is fixed to the trailer railing via the fixing steel plates. The first square steel plate is mounted on the tripod via the connecting steel plates. Both the first and second square steel plates have four round holes and two light-reducing holes. The four optical shafts are 2.7m long and pass through the four round holes of the first square steel plate to reach underwater. The second square steel plate is installed at the underwater end of the optical shaft. The optical shaft fixing rings are used to connect and fix the optical shaft to the two square steel plates. The first square steel plate mounted on the tripod can move back and forth, with a movement distance of 0-1m. The second square steel plate mounted on the underwater optical shaft can move up and down, with a movement distance of 0-1.5m.

[0033] The connection module includes a connecting rod, a six-component force gauge, and a first universal joint; the connecting rod is connected to the slider of the Z-direction lead screw module by screws; the upper end of the six-component force gauge is connected to the connecting rod, and the lower end is connected to the first universal joint; the first universal joint is made of aluminum alloy, and its lower end is connected to the towing cable model.

[0034] The planar motion module and the connecting module are on the water, while the four optical axes of the tow cable suspension module and the second square steel plate are underwater. The distance between the optical axes and the tow cable is greater than 20D (D is the diameter of the tow cable), so it will not affect the flow field around the tow cable.

[0035] The embodiment provided by this invention is: a test device for simulating the dynamic response of an ocean towline under tugboat swaying towing conditions, the structure of which is as follows. Figure 1As shown, the system includes: an X-direction lead screw module 1, a Z-direction lead screw module 2, a connecting rod 3, a six-component force meter 4, a first universal joint 5, a 1500mm×80mm×80mm×5mm profile 6, a tripod 7, an optical axis 8, a first square steel plate 9, a 1000mm×80mm×80mm×5mm profile 10, a second universal joint 11, a second square steel plate 12, and a towing cable model 13. Specifically, the X-direction lead screw module 1, Z-direction lead screw module 2, 1500mm×80mm×80mm×5mm profile 6, and 1000mm×80mm×80mm×5mm profile 10 form a planar motion module; the connecting rod 3 and the six-component force meter 4 form a connecting module; and the second universal joint 11, the tripod 7, the optical axis 8, the first square steel plate 9, and the second square steel plate 12 form a towing cable suspension module.

[0036] like Figure 2 and Figure 3 As shown, the planar motion module consists of two lead screw modules and five profiles. The lead screw modules include two in the X and Z directions. The X-direction lead screw module 1 is connected to the trailer through a 1500mm×80mm×80mm×5mm profile 6 and a 1000mm×80mm×80mm×5mm profile 10. The Z-direction lead screw module 2 is mounted on the slider of the X-direction lead screw module 1. The movement of the slider of the X-direction lead screw module 1 causes the tow cable model 13 to produce a swaying motion, and the movement of the slider of the Z-direction lead screw module 2 causes the tow cable model 13 to produce a heaving motion.

[0037] like Figure 4 and Figure 5 As shown, the tow cable suspension module consists of four optical shafts 8, a tripod 7, a first square steel plate 9, and a second square steel plate 12. The tripod 7 is suspended from the trailer railing. The first square steel plate 9 is connected to the bottom crossbeam of the tripod 7 via a connecting plate. The first square steel plate 9 has light-reducing holes and four optical shaft holes. The connecting plate can move back and forth on the crossbeam to control the forward and backward position of the tow cable model 13. The optical shafts 8 are inserted underwater through the optical shaft holes. The connection between the optical shafts 8 and the first square steel plate 9 is secured by an optical shaft fixing ring. The underwater end of the optical shafts 8 is connected to the second square steel plate 12 via the optical shaft fixing ring. A second universal joint 11 is installed on the second square steel plate 12 for connection with the tow cable model 13. The position of the optical shaft fixing ring can be adjusted up and down to control the towing depth.

[0038] like Figure 6As shown, the connecting module consists of a connecting rod 3, a force meter 4, and a first universal joint 5. The connecting rod 3 is connected to the slider of the Z-direction lead screw module 2. The lower end of the connecting rod 3 is connected to the force meter 4, and the lower end of the force meter 4 is equipped with the first universal joint 5. The lower end of the first universal joint 5 is equipped with the towing cable model 13. The force meter 4 can measure the force in six directions at the end of the towing cable model 13. The first universal joint 5 restricts the translation of the towing cable model 13 in the XYZ directions, allowing the towing cable to rotate in three directions.

[0039] The method of use and working principle of the simulated tugboat swaying towing marine towline dynamic response test device in this embodiment are as follows:

[0040] Before the test, in order to ensure that the tow cable model 13 is in a taut state, the approximate vertical and horizontal distances at both ends of the tow cable model 13 were calculated. The tow cable suspension module was adjusted to the corresponding position according to the distance. The first square steel plate 9 in the horizontal direction was fixed to the tripod 7 with screws, and the optical axis 8 was fixed with an optical axis fixing ring.

[0041] The connecting module is connected to the slider on the Z-direction lead screw module 2 of the planar motion module. The top end of the tow cable model 13 is connected to the first universal joint 5 of the connecting module, and the bottom end of the tow cable model 13 is connected to the second universal joint 11 of the tow cable suspension module. The six-component force meter 4 can measure the force at the top end of the tow cable model.

[0042] During the test, the trailer moves forward at a certain speed. The planar motion module is controlled by PLC language to move in both forward and vertical directions to simulate the swaying and heaving of a ship. The strain information of each position of the tow cable can be obtained through the strain acquisition device.

[0043] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A device for simulating the dynamic response of an ocean tow cable when towed by a tugboat oscillating in a seaway, characterized in that, The device comprises a plane motion module, a towline suspension module, a connecting module and a towline model; the plane motion module is fixed on a trailer, the plane motion module is connected with the connecting module, the connecting module comprises a first universal joint, the plane motion module can drive the first universal joint to move in X direction and Z direction; the towline suspension module comprises a second universal joint, the towline suspension module can adjust the position of the second universal joint in X direction and Z direction and fix it, the towline suspension module further comprises a tripod and a first square steel plate, the tripod is fixed on the rail of the trailer, the first square steel plate is installed on the tripod through a connecting steel plate, the first square steel plate can move and fix on the tripod, the towline suspension module further comprises an optical axis and a second square steel plate, four round holes and two lightening holes are arranged on the first square steel plate and the second square steel plate, the optical axis has four optical axes, the optical axes pass through the four round holes of the first square steel plate and enter the water, the underwater end of the optical axis passes through the four round holes of the second square steel plate, the second square steel plate can move and fix on the optical axis, the second universal joint is installed on the second square steel plate; the towline model is connected with the first universal joint and the second universal joint.

2. The device for simulating the dynamic response test of the ocean tow cable when the tugboat is oscillating towing according to claim 1, wherein, The plane motion module comprises two screw rod modules and a profile, the two screw rod modules comprise an X direction screw rod module and a Z direction screw rod module, the X direction screw rod module is fixed on the trailer through the profile, and the Z direction screw rod module is installed on the sliding block of the X direction screw rod module.

3. The device for simulating the dynamic response of a marine tow cable to the sway of a tugboat during towing at sea according to claim 2, characterized in that, The connecting module further comprises a connecting rod and a six-component force instrument, the upper end of the connecting rod is connected with the sliding block of the Z direction screw rod module, and the lower end of the connecting rod is connected with the upper end of the six-component force instrument.

4. The device for simulating the dynamic response of a marine tow cable to the sway of a tugboat during towing at sea according to claim 3, characterized in that, The first universal joint is connected with the lower end of the six-component force instrument, and the towline model is connected with the lower end of the first universal joint.

5. The device for simulating the dynamic response of a marine tow cable to the sway of a tugboat as claimed in claim 3, wherein, The upper end of the connecting rod is connected with the sliding block of the Z direction screw rod module through a screw.

6. The device for simulating the dynamic response of a marine tow cable to the sway of a tugboat according to claim 1, wherein, The optical axis, the first square steel plate and the second square steel plate are connected and fixed through an optical axis fixing ring, and the first square steel plate is connected with the tripod through a screw rod.

7. The device for simulating the dynamic response of a marine tow cable to the sway of a tugboat according to claim 1, wherein, The first universal joint and the second universal joint are made of aluminum alloy.

8. The device for simulating the dynamic response of a marine tow cable to the sway of a tugboat according to claim 1, wherein, The device further comprises a control module, the control module is connected with the plane motion module, the control module is programmed by using PLC language, and the control module can control the plane motion module to generate movement in X direction and Z direction.

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