Device and method for controlling vertical vibration of semi-submersible platform by rotational inertia damper

Abstract

The present invention discloses a device and method for controlling the vertical vibration of a semi-submersible platform by a rotational inertia damper. The device of the present invention includes a semi-submersible platform system, a mooring system, a rotational inertia damper system, and a water tank test system; the rotational inertia damper system is used to control the vertical vibration of the semi-submersible platform system; the mooring system prevents the semi-submersible platform system from shifting during the test; the water tank test system is used to verify and test the effectiveness of the rotational inertia damper system in controlling the vertical vibration of the semi-submersible platform system. The present invention cleverly uses a ball screw to convert the vertical linear motion of the semi-submersible platform system into the high-speed rotation of a rotating tube, thereby driving the rotation of a damping plate, providing a significant damping effect for the semi-submersible platform system; determining the rule that the vertical vibration natural frequency of the semi-submersible platform falls within the wave frequency range, ensuring resonance in the vertical direction between the two, and achieving the same or better control effect as that of a fixed / tuned vertical vibration plate with a smaller physical mass.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration control, and particularly to a device and method for controlling the vertical vibration of a semi-submersible platform by a rotational inertia damper. Background Art

[0002] Among all energy types, marine energy has received increasing attention. To develop marine energy, researchers have designed and built various forms of buoyancy platforms, such as tension leg platforms (TLP), truss platforms, and semi-submersible platforms (SSP), etc. Among these platforms, the semi-submersible platform has gathered many advantages, such as a larger deck area and payload capacity, and thus has been the most widely used. However, due to problems such as a relatively shallow draft depth and large pontoons of the semi-submersible platform, excessive displacement may occur, especially vertical vibration, which reduces the platform production efficiency, endangers the structural integrity of the platform, and even directly affects the safety of relevant staff. Therefore, it is extremely necessary to improve the excessive vertical vibration problem of the semi-submersible platform. The most common method for controlling the vertical vibration of a semi-submersible platform is to rigidly install a fixed vertical vibration plate (FHP) at the bottom of the platform, aiming to increase the added mass and damping of the platform. Generally speaking, by introducing a fixed vertical vibration plate, the drag coefficient of the platform will be significantly increased. The fixed vertical vibration plate is divided into a solid type and a porous type. The solid plate generates higher damping at a larger Keulegan-Carpenter (KC) number, while the porous plate generates higher damping at an extremely low KC number. In addition to the traditional fixed vertical vibration plate, there is also a tuned vertical vibration plate (THP) to alleviate the vertical vibration problem of the semi-submersible platform. It is based on the concept of a tuned mass damper (TMD). The tuned mass damper is a well-known control system that has been widely used to reduce the structural vibration caused by various vibration sources. Different from the rigid connection in the fixed vertical vibration plate, the tuned vertical vibration plate is connected to the semi-submersible platform in parallel through a connection system. Based on this, the vibration energy of the semi-submersible platform can be transferred to the tuned vertical vibration plate and then dissipated. However, the tuned vertical vibration plate generally requires a larger plate size to achieve a larger mass ratio between the vertical vibration plate and the semi-submersible platform, so as to obtain excellent control performance. This will lead to corresponding cost increases and installation difficulties, making it difficult for the tuned vertical vibration plate to be widely used. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the present invention introduces an inertial device into the vibration control of an offshore platform under wave / wind loads. Specifically, a linkage system is formed by combining a rotational inertial damper system and a semi-submersible platform. A ball screw converts the vertical linear motion of the semi-submersible platform into the high-speed rotation of a rotating tube, thereby driving the rotation of a damping plate, and providing a significant damping effect to the semi-submersible platform by increasing the fluid resistance. A rule is determined that the vertical vibration natural frequency of the semi-submersible platform should fall within the wave frequency range to ensure resonance in the vertical direction between the two, and a control effect equivalent to or better than that of a fixed / tuned vertical vibration plate is achieved with a smaller physical mass. A non-linear mechanical model of the rotational inertial damper for the vertical vibration control level of the semi-submersible platform is proposed and verified by methods such as wave calibration, free vibration testing, regular wave and irregular wave testing.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The device for controlling the vertical vibration of a semi-submersible platform by the rotational inertial damper of the present invention includes a semi-submersible platform system, a mooring system, a rotational inertial damper system, and a water tank test system. The semi-submersible platform system is vertically connected to the rotational inertial damper system, and the rotational inertial damper system is located directly below the semi-submersible platform system; the rotational inertial damper system is used to control the vertical vibration of the semi-submersible platform system; the mooring system provides support for the fixation of the semi-submersible platform system and the rotational inertial damper system to prevent the semi-submersible platform system from shifting during the test. The semi-submersible platform system, the rotational inertial damper system, and the mooring system are placed inside the water tank test system; the water tank test system is used to test and verify the effectiveness of the rotational inertial damper system in controlling the vertical vibration of the semi-submersible platform system.

[0006] Further, the semi-submersible platform system includes a working deck, a buoyancy tank, and connecting columns; the upper ends of the connecting columns are connected to the working deck, and the lower ends are connected to the buoyancy tank. The working deck provides an operating space; the buoyancy tank provides a stable lifting force for the semi-submersible platform system.

[0007] Furthermore, the rotational inertia damper system includes an upper support plate, an upper spherical hinge, an upper fixing groove, a tension sensor I, a connecting pipe I, a rotational damping plate, a rotating pipe, a radial bearing, an outer cylinder, a ball screw, a connecting pipe II, a lower spherical hinge, a lower fixing groove, and a lower support plate; the semi-submersible platform system is fixedly placed on the upper surface of the upper support plate; the upper fixing groove is fixedly connected to the upper support plate; the upper end of the connecting pipe I is hinged to the upper fixing groove through the upper spherical hinge; the lower end of the connecting pipe I is fixedly connected to the ball screw; the ball screw is placed inside the rotating pipe; the ball screw is in rigid contact with the inner wall of the rotating pipe; the rotational damping plate is fixed to the rotating pipe; the rotation of the ball screw drives the rotation of the rotating pipe and the rotational damping plate; the tension sensor I is fixed on the connecting pipe I; the tension sensor I is used to measure the tension level of the connecting pipe I; the rotating pipe is placed inside the outer cylinder; the rotating pipe is fixedly connected to the outer cylinder through the radial bearing; the outer cylinder serves to protect the rotational inertia damper system; the upper end of the connecting pipe II is fixedly connected to the outer cylinder; the lower end of the connecting pipe II is hinged to the lower fixing groove through the lower spherical hinge; the lower fixing groove is fixedly connected to the lower support plate.

[0008] Furthermore, the mooring system includes a fixed vertical pole, a shirker, a tension sensor II, a spring, a V-shaped fixed pulley, an elastic rope, and a fixing bolt. The shirker, the tension sensor II, and the spring are vertically fixed to the elastic rope in sequence from top to bottom; the shirker changes the tension level in the elastic rope; the tension sensor II tests and records the tension value of the elastic rope; the spring serves as a buffer; the elastic rope bypasses the V-shaped fixed pulley; the V-shaped fixed pulley changes the direction of the elastic rope; the fixed vertical pole plays a role in support and stability; one end of the elastic rope is fixed to the fixed vertical pole, and the other end of the elastic rope is wound around the fixing bolt. The fixing bolt is fixedly connected to the four corners of the upper support plate, and the upper support plate is fixedly connected to the lower end of the buoyancy tank through the fixing bolt.

[0009] Furthermore, the water tank test system includes a water tank, a wave sensor I, a wave sensor II, and an optical camera; the semi-submersible platform system is placed in the middle of the water tank, and the wave sensor I and the wave sensor II are respectively arranged in front of and behind the semi-submersible platform system; the wave sensor I and the wave sensor II obtain the period, frequency, and wave height data of the oncoming waves; the optical camera is arranged on the side of the semi-submersible platform system, that is, between the side wall of the water tank and the semi-submersible platform system; the optical camera obtains the six-degree-of-freedom change information of the semi-submersible platform system; the wave sensor I, the wave sensor II, and the optical camera are fixed to the bottom bed of the water tank and are not connected to other components; the lower support plate of the rotational inertia damper system is fixedly connected to the bottom bed of the water tank; the fixed vertical pole and the V-shaped fixed pulley of the mooring system are fixedly connected to the bottom bed of the water tank and are close to the side wall of the water tank.

[0010] Furthermore, the specific dimensions of the semi-submersible platform system are determined according to the dimensions of the water tank and the scaling ratios of the working deck, the buoyancy tank, and the connecting columns.

[0011] Furthermore, the semi-submersible platform system is made of rigid materials and regarded as a rigid body with six degrees of freedom. The semi-submersible platform system is placed on the longitudinal axis of the water tank to reduce the influence of reflected waves during the water tank experiment. The incident direction of the waves in the water tank should be along the longitudinal direction of the water tank to ensure that the angle between the incident direction of the waves and the semi-submersible platform system is 0°.

[0012] Furthermore, the mooring system includes four elastic ropes, and the angle between each elastic rope is 90°.

[0013] Furthermore, the shirker on the mooring system can slightly adjust the initial length of the elastic rope when necessary to ensure the stability of the semi-submersible platform system. The V-shaped pulley minimizes the additional friction from the pulley, so the friction loss here can be ignored during the test experiment.

[0014] The rotational inertia damper system and the semi-submersible platform system form a linkage system. The ball screw of the rotational inertia damper system converts the vertical linear motion of the semi-submersible platform system into the high-speed rotation of the rotating tube, thereby driving the rotation of the rotating damping plate. The rotation of the rotating damping plate enhances the local turbulence level and increases the fluid resistance to provide a significant damping effect for the semi-submersible platform system, achieving the same or even better control effect as the fixed / tuned vertical vibration plate with a smaller physical mass.

[0015] The method for the rotational inertia damper to control the vertical vibration of the semi-submersible platform system of the present invention includes the following steps:

[0016] S1. Prepare the structural components: Fix the optical camera, wave sensor I, wave sensor II, fixed vertical rod, and lower support plate on the bottom bed of the water tank; fix the lower fixed groove on the lower support plate; hinge the lower ball joint of the rotational inertia damper system to the lower fixed groove; connect the semi-submersible platform system to the rotational inertia damper system through the upper ball joint, upper support plate, and upper fixed groove; connect the fixed vertical rod and the semi-submersible platform system through an elastic rope; arrange the shirker, tension sensor II, and spring on the elastic rope; turn on the optical camera, wave sensor I, wave sensor II, tension sensor I, tension sensor II, and shirker; slightly adjust the initial length of the elastic rope to ensure the stability of the semi-submersible platform system.

[0017] S2. Free vibration test: Release a uniform and constant water flow in the water tank. Tension sensor I obtains the time series of the tension value under the stable flow field conditions, and performs Fourier spectrum analysis on the time series of the tension value to determine the natural period frequency of the semi-submersible platform system.

[0018] S3, Wave Calibration: Use an external wave maker to generate regular waves. Wave sensor I and wave sensor II obtain wave height data, and tension sensor II obtains period data. Compare the obtained data with the settings of the external wave maker to ensure the accuracy of the generated waves;

[0019] S4, Regular Wave Test: Generate regular waves. The variables of the regular waves are wave height and frequency. At least 2 types of wave heights and at least 5 types of frequencies should be designed for the regular waves; Wave sensor I, wave sensor II, tension sensor I, tension sensor II, and the optical camera synchronously obtain a data set;

[0020] S5, Irregular Wave Test: Generate irregular waves. The generation of irregular waves needs to satisfy formula (1):

[0021]

[0022] where S(ω) is the power spectral density (PSD) function;

[0023] H s is the significant wave height;

[0024] ω is the wave frequency;

[0025] ω0 is the peak frequency;

[0026] γ w is the peak factor;

[0027] τ is the shape parameter;

[0028]

[0029] Wave sensor I, wave sensor II, tension sensor I, tension sensor II, and the optical camera synchronously obtain a data set;

[0030] S6, Propose a Nonlinear Mechanical Model: Specifically, propose and establish a nonlinear mechanical model such as formulas (2)-(4),

[0031]

[0032]

[0033]

[0034] where F is the resistance exerted by the rotational inertia damper on the semi-submersible platform system;

[0035] N is the number of rotational damping plates;

[0036] m e is the inertial force;

[0037] m iis the equivalent mass caused by the original structural mass and moment of inertia;

[0038] is the relative acceleration;

[0039] is the relative velocity;

[0040] c e is the damping coefficient;

[0041] f c is the Coulomb friction coefficient;

[0042] c v is the viscous friction coefficient;

[0043] sgn is the signum function;

[0044] η is the conversion efficiency of the ball screw;

[0045] L is the lead of the ball screw;

[0046] ρ is the density of water;

[0047] c m is the inertia coefficient;

[0048] ρ s is the density of the rotational damping plate;

[0049] l tp is the width of the rotational damping plate;

[0050] t tp is the thickness of the rotational damping plate;

[0051] c d is the drag coefficient;

[0052] R1 is the outer diameter of the rotational damping plate;

[0053] R0 is the inner diameter of the rotational damping plate;

[0054] S7, verify the nonlinear mechanical model: Use the synchronous data sets of Wave Sensor I, Wave Sensor II, Tension Sensor I, Tension Sensor II, and the optical camera obtained by S4 and S5 to verify the nonlinear mechanical model, that is, formulas (2) to (4).

[0055] Furthermore, in step S4, the frequency range of the regular wave includes the vertical vibration natural period frequency of the semi-submersible platform system to ensure resonance between the wave and the semi-submersible platform system in the vertical direction.

[0056] Furthermore, in step S5, the average frequency range of the irregular waves includes the vertical vibration natural period frequency of the semi-submersible platform system to ensure resonance between the irregular waves and the semi-submersible platform system in the vertical direction.

[0057] Advantages of the present invention:

[0058] 1. The device of the present invention has a clever structure, good integrity, and low device cost.

[0059] 2. Cleverly utilize the ball screw to convert the vertical linear motion of the semi-submersible platform system into the high-speed rotation of the rotating tube, thereby driving the rotation of the damping plate, and increasing the fluid resistance by enhancing the local turbulence level to provide a significant damping effect for the semi-submersible platform system.

[0060] 3. Determine the rule that the vertical vibration natural frequency of the semi-submersible platform system should fall within the wave frequency range to ensure resonance between the two in the vertical direction, so as to achieve the same or better control effect as the fixed / tuned vertical vibration plate with a smaller physical mass.

[0061] 4. Propose a non-linear mechanical model for the vertical vibration control level of the semi-submersible platform system by the rotational inertia damper, and verify it through wave calibration, free vibration testing, regular wave and irregular wave methods. Description of the drawings

[0062] Figure 1 is the front view of the invention device;

[0063] Figure 2 is the top view of the invention device;

[0064] Figure 3 is the flow chart of the invention method.

[0065] In the figure: 1. Working deck, 2. Buoyancy tank, 3. Connecting column, 4. Upper support plate, 5. Fixed bolt, 6. Upper spherical hinge, 7. Upper fixed groove, 8. Tension sensor I, 9. Connecting pipe I, 10. Rotating damping plate, 11. Rotating tube, 12. Radial bearing, 13. Outer cylinder, 14. Ball screw, 15. Connecting pipe II, 16. Lower spherical hinge, 17. Lower fixed groove, 18. Lower support plate, 19. Fixed vertical rod, 20. Shrinker, 21. Tension sensor II, 22. Spring, 23. V-shaped fixed pulley, 24. Elastic rope, 25. Water tank, 26. Wave sensor I, 27. Wave sensor II, 28. Optical camera. Detailed implementation manners

[0066] The present invention will be further described below with reference to the drawings.

[0067] As Figure 1 、 Figure 2As shown in the figure, the device for controlling the vertical vibration of a semi-submersible platform system by a rotational inertia damper of the present invention includes a semi-submersible platform system, a mooring system, a rotational inertia damper system, and a water tank test system.

[0068] The semi-submersible platform system is vertically connected to the rotational inertia damper system, that is, the rotational inertia damper system is located directly below the semi-submersible platform system; the rotational inertia damper system is used to control the vertical vibration of the semi-submersible platform system; the mooring system provides support for the fixation of the semi-submersible platform system and the rotational inertia damper system to prevent the semi-submersible platform system from shifting during the test. The semi-submersible platform system, the rotational inertia damper system, and the mooring system are located inside the water tank test system; the water tank test system is used to test and verify the effectiveness of the rotational inertia damper system in controlling the vertical vibration of the semi-submersible platform system.

[0069] The semi-submersible platform system includes a working deck 1, a buoyancy tank 2, and a connecting column 3. The upper end of the connecting column 3 is connected to the working deck 1, and the lower end is connected to the buoyancy tank 2. The working deck 1 provides an operating space; the buoyancy tank 2 provides a stable lifting force for the semi-submersible platform system.

[0070] The rotational inertia damper system includes an upper support plate 4, an upper spherical hinge 6, an upper fixing groove 7, a tension sensor I 8, a connecting pipe I 9, a rotational damping plate 10, a rotating pipe 11, a radial bearing 12, an outer cylinder 13, a ball screw 14, a connecting pipe II 15, a lower spherical hinge 16, a lower fixing groove 17, and a lower support plate 18. The semi-submersible platform system is fixedly placed above the upper support plate 4; the upper fixing groove 7 is fixedly connected to the upper support plate 4; the upper end of the connecting pipe I 9 is hinged to the upper fixing groove 7 through the upper spherical hinge 6; the lower end of the connecting pipe I 9 is fixedly connected to the ball screw 14; the ball screw 14 is placed inside the rotating pipe 11; the ball screw 14 is in rigid contact with the inner wall of the rotating pipe 11; the rotational damping plate 10 is fixed to the rotating pipe 11; the rotation of the ball screw 14 drives the rotation of the rotating pipe 11 and the rotational damping plate 10; the tension sensor I 8 is fixed to the connecting pipe I 9; the tension sensor I 8 is used to measure the tension level of the connecting pipe I 9; the rotating pipe 11 is placed inside the outer cylinder 13; the rotating pipe 11 is fixedly connected to the outer cylinder 13 through the radial bearing 12; the outer cylinder 13 plays a role in protecting the rotational inertia damper system; the upper end of the connecting pipe II 15 is fixedly connected to the outer cylinder 13; the lower end of the connecting pipe II 15 is hinged to the lower fixing groove 17 through the lower spherical hinge 16; the lower fixing groove 17 is fixedly connected to the lower support plate 18.

[0071] The mooring system includes a fixed vertical pole 19, a retractor 20, a tension sensor II 21, a spring 22, a V-shaped fixed pulley 23, an elastic rope 24, and a fixed bolt 5. The retractor 20, the tension sensor II 21, and the spring 22 are vertically fixed to the elastic rope 24 in sequence from top to bottom; the retractor 20 changes the tension level in the elastic rope 24; the tension sensor II 21 measures and records the tension value of the elastic rope 24; the spring 22 plays a buffering role; the elastic rope 24 bypasses the V-shaped fixed pulley 23; the V-shaped fixed pulley 23 changes the direction of the elastic rope 24; the fixed vertical pole 19 plays a role in support and stability; one end of the elastic rope 24 is fixed to the fixed vertical pole 19, and the other end of the elastic rope 24 is wound around the fixed bolt 5, and the fixed bolt 5 is fixedly connected to the four corners of the upper support plate 4.

[0072] The water tank test system includes a water tank 25, a wave sensor I 26, a wave sensor II 27, and an optical camera 28; the semi-submersible platform system is placed in the middle of the water tank 25, and the wave sensor I 26 and the wave sensor II 27 are respectively arranged in front of and behind the semi-submersible platform system; the wave sensor I 26 and the wave sensor II 27 obtain the period, frequency, and wave height data of the oncoming waves; the optical camera 28 is arranged on the side of the semi-submersible platform system, that is, between the side wall of the water tank 25 and the semi-submersible platform system; the optical camera 28 obtains the six-degree-of-freedom change information of the semi-submersible platform system; the wave sensor I 26, the wave sensor II 27, and the optical camera 28 are fixed to the bottom bed of the water tank 25 and are not connected to other components; the lower support plate 18 of the rotational inertia damper system is fixedly connected to the bottom bed of the water tank 25; the fixed vertical pole 19 and the V-shaped fixed pulley 23 of the mooring system are fixedly connected to the bottom bed of the water tank 25 and are close to the side wall of the water tank 25.

[0073] The specific size of the semi-submersible platform system is determined according to the size of the water tank and the scaling ratios of the working deck 1, the buoyancy tank 2, and the connecting columns 3.

[0074] The semi-submersible platform system is made of a rigid material and is regarded as a rigid body with six degrees of freedom; the semi-submersible platform system is placed on the longitudinal axis of the water tank 25 to reduce the influence of reflected waves during the experiment of the water tank 25; the incident direction of the waves in the water tank 25 needs to be along the longitudinal direction of the water tank 25 to ensure that the angle between the wave incident direction and the semi-submersible platform system is 0°.

[0075] The mooring system includes four elastic ropes 24, and the angle between each elastic rope 24 is 90°.

[0076] The retractor 20 on the mooring system can slightly adjust the initial length of the elastic rope 24 when necessary to ensure the stability of the semi-submersible platform system; the V-shaped pulley 23 minimizes the additional friction from the pulley, so the friction loss here can be ignored during the test experiment.

[0077] The rotational inertia damper system and the semi-submersible platform system form a linkage system. The ball screw 14 of the rotational inertia damper system converts the vertical linear motion of the semi-submersible platform system into the high-speed rotation of the rotating tube 11, thereby driving the rotation of the rotating damping plate 10; the rotation of the rotating damping plate 10 enhances the local turbulence level and increases the fluid resistance to provide a significant damping effect for the semi-submersible platform system, achieving the same or even better control effect as that of a fixed / tuned vertical vibration plate with a smaller physical mass.

[0078] As Figure 3 shown, the method for controlling the vertical vibration of the semi-submersible platform system by the rotational inertia damper of the present invention includes the following steps:

[0079] S1. Prepare the structural components: Assemble the components of the connection device structure, and fix the optical camera 28, wave sensor I 26, wave sensor II 27, fixed vertical rod 19, and lower support plate 18 on the bottom bed of the water tank 25; fix the lower fixing groove 17 on the lower support plate 18; hinge the lower ball hinge 16 of the rotational inertia damper system to the lower fixing groove 17; connect the semi-submersible platform system to the rotational inertia damper system through the upper ball hinge 6, upper support plate 4, and upper fixing groove 7; connect the fixed vertical rod 19 and the semi-submersible platform system through the elastic rope 24; arrange the retractor 20, tension sensor II 21, and spring 22 on the elastic rope 24; turn on the optical camera 28, wave sensor I 26, wave sensor II 27, tension sensor I 8, tension sensor II 21, and retractor 20; slightly adjust the initial length of the elastic rope 24 to ensure the stability of the semi-submersible platform system.

[0080] S2. Free vibration test: Release a uniform and constant water flow in the water tank 25. The tension sensor I 8 obtains the time series of the tension value under the stable flow field condition, and performs Fourier spectrum analysis on the time series of the tension value to determine the natural period frequency of the semi-submersible platform system.

[0081] S3. Wave calibration: Use an external wave maker to generate regular waves. The wave sensors I 26 and II 27 obtain the wave height data, and the tension sensor II 21 obtains the period data. Compare the obtained data with the settings of the external wave maker to ensure the accuracy of the generated waves.

[0082] S4. Regular wave test: Generate regular waves. The variables of the regular waves are wave height and frequency. At least two kinds of wave heights and at least five kinds of frequencies should be designed for the regular waves; in order to better prove the control effect, it is required that the vertical vibration natural period frequency of the semi-submersible platform system should fall within the selected frequency range of the regular waves to ensure resonance in the vertical direction between the waves and the semi-submersible platform system. The wave sensors I 26, II 27, tension sensor I 8, tension sensor II 21, and optical camera 28 synchronously obtain the data set.

[0083] S5, Irregular wave test: Generate irregular waves, and the generation of irregular waves shall satisfy formula (1):

[0084]

[0085] wherein, S(ω) is the power spectral density (PSD) function;

[0086] H s is the significant wave height;

[0087] ω is the wave frequency;

[0088] ω0 is the crest frequency;

[0089] γ w is the peak factor;

[0090] τ is the shape parameter;

[0091]

[0092] To better prove the control effect, it is required that the vertical vibration natural period frequency of the semi-submersible platform system should fall within the average frequency range of the irregular waves to ensure resonance between the irregular waves and the semi-submersible platform system in the vertical direction. The wave sensor I 26, wave sensor II 27, tension sensor I 8, tension sensor II 21, and optical camera 28 synchronously acquire the data set.

[0093] S6, Propose a nonlinear mechanical model: The present invention proposes and establishes a nonlinear mechanical model as shown in formulas (2)-(4),

[0094]

[0095]

[0096]

[0097] wherein, F is the resistance applied by the rotational inertia damper to the semi-submersible platform system;

[0098] N is the number of rotational damping plates 10;

[0099] m e is the inertial force;

[0100] m i is the equivalent mass caused by the original structure mass and moment of inertia;

[0101] is the relative acceleration;

[0102] is the relative velocity;

[0103] c e is the damping coefficient;

[0104] f c is the Coulomb friction coefficient;

[0105] c v is the viscous friction coefficient;

[0106] sgn is the signum function;

[0107] η is the conversion efficiency of the ball screw 14;

[0108] L is the lead of the ball screw 14;

[0109] ρ is the density of water;

[0110] c m is the inertia coefficient;

[0111] ρ s is the density of the rotating damping plate 10;

[0112] l tp is the width of the rotating damping plate 10;

[0113] t tp is the thickness of the rotating damping plate 10;

[0114] c d is the drag coefficient;

[0115] R1 is the outer diameter of the rotating damping plate 10;

[0116] R0 is the inner diameter of the rotating damping plate 10.

[0117] S7, verify the nonlinear mechanical model: Use the synchronous data sets of the wave sensor I 26, wave sensor II 27, tension sensor I 8, tension sensor II 21, and optical camera 28 obtained by S4 and S5 to verify the nonlinear mechanical model proposed by the present invention, that is, formulas (2) to (4).

[0118] In the description of the present invention, it should be understood that the terms regarding the orientation or positional relationship based on the figures shown are only for the purpose of facilitating the simplified description of the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention.

[0119] In the present invention, unless otherwise clearly specified or limited, terms such as "arranged" and "connected" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0120] The above description is only the preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the content of the specification of the present invention, or directly or indirectly applied to the technical field of other related products, is included in the scope of patent protection of the present invention.

Claims

1. Device for controlling vertical vibration of semi-submersible platform by rotational inertia damper, characterized in that: It includes a semi-submersible platform system, a mooring system, a rotational inertia damper system, and a water tank test system; the semi-submersible platform system is vertically connected to the rotational inertia damper system, and the rotational inertia damper system is located directly below the semi-submersible platform system; the rotational inertia damper system is used to control the vertical vibration of the semi-submersible platform system; the mooring system is used to fix the semi-submersible platform system and the rotational inertia damper system to prevent the semi-submersible platform system from shifting during the test; the semi-submersible platform system, the rotational inertia damper system, and the mooring system are placed inside the water tank test system; the water tank test system is used to test and verify the effectiveness of the rotational inertia damper system in controlling the vertical vibration of the semi-submersible platform system; The semi-submersible platform system includes a working deck, a buoyancy tank, and connecting columns; the upper ends of the connecting columns are connected to the working deck, and the lower ends are connected to the buoyancy tank; the working deck provides an operating space; the buoyancy tank provides a stable lifting force for the semi-submersible platform system; The rotational inertia damper system includes an upper support plate, an upper spherical hinge, an upper fixed groove, a tension sensor I, a connecting pipe I, a rotational damping plate, a rotating pipe, a radial bearing, an outer cylinder, a ball screw, a connecting pipe II, a lower spherical hinge, a lower fixed groove, and a lower support plate; the semi-submersible platform system is fixedly placed above the upper support plate; the upper fixed groove is fixedly connected to the upper support plate; the upper end of the connecting pipe I is hinged to the upper fixed groove through the upper spherical hinge; the lower end of the connecting pipe I is fixedly connected to the ball screw; the ball screw is placed inside the rotating pipe; the ball screw is in rigid contact with the inner wall of the rotating pipe; the rotational damping plate is fixed to the rotating pipe; the rotation of the ball screw drives the rotation of the rotating pipe and the rotational damping plate; the tension sensor I is fixed to the connecting pipe I; the tension sensor I is used to measure the tension level of the connecting pipe I; the rotating pipe is placed inside the outer cylinder; the rotating pipe is fixedly connected to the outer cylinder through the radial bearing; the outer cylinder plays a role in protecting the rotational inertia damper system; the upper end of the connecting pipe II is fixedly connected to the outer cylinder; the lower end of the connecting pipe II is hinged to the lower fixed groove through the lower spherical hinge; the lower fixed groove is fixedly connected to the lower support plate; The mooring system includes fixed vertical poles, a shifter, a tension sensor II, a spring, a V-shaped fixed pulley, an elastic rope, and a fixing bolt; The shifter, the tension sensor II, and the spring are vertically fixed to the elastic rope in sequence from top to bottom; the shifter is used to change the tension level in the elastic rope; the tension sensor II is used to test and record the tension value of the elastic rope; the spring plays a buffering role; the elastic rope bypasses the V-shaped fixed pulley, and the V-shaped fixed pulley changes the direction of the elastic rope; the fixed vertical pole plays a role in support and stability; one end of the elastic rope is fixed to the fixed vertical pole, and the other end of the elastic rope is wound around the fixing bolt, and the fixing bolt is fixedly connected to the four corners of the upper support plate, and the upper support plate is fixedly connected to the lower end of the buoyancy tank through the fixing bolt; The described water tank test system includes a water tank, Wave Sensor I, Wave Sensor II, and an optical camera. The semi-submersible platform system is placed in the middle of the water tank. Wave Sensor I and Wave Sensor II are respectively arranged in front of and behind the semi-submersible platform system. Wave Sensor I and Wave Sensor II acquire the period, frequency, and wave height data of the oncoming waves. The optical camera is arranged on the side of the semi-submersible platform system, that is, between the side wall of the water tank and the semi-submersible platform system. The optical camera acquires the six-degree-of-freedom change information of the semi-submersible platform system. Wave Sensor I, Wave Sensor II, and the optical camera are fixed to the bottom bed of the water tank and are not connected to other components. The lower support plate of the rotational inertia damper system is fixedly connected to the bottom bed of the water tank. The fixed vertical pole and the V-shaped fixed pulley of the mooring system are fixedly connected to the bottom bed of the water tank and are close to the side wall of the water tank.

2. The device for controlling the vertical vibration of a semi-submersible platform by a rotational inertia damper according to claim 1, characterized in that: The semi-submersible platform system is placed on the longitudinal axis of the water tank to reduce the influence of reflected waves during the water tank experiment. The incident direction of the waves in the water tank needs to be along the longitudinal direction of the water tank to ensure that the angle between the wave incident direction and the semi-submersible platform system is 0°.

3. The device for controlling the vertical vibration of a semi-submersible platform by a rotational inertia damper according to claim 1, characterized in that: The mooring system includes four elastic ropes, and the angle between each elastic rope is 90°.

4. A method for controlling the vertical vibration of a semi-submersible platform by using the rotational inertia damper device according to any one of claims 1 to 3, characterized in that: It includes the following steps: S1, Prepare the structural components: Fix the optical camera, Wave Sensor I, Wave Sensor II, fixed vertical pole, and lower support plate to the bottom bed of the water tank. The lower fixing groove is fixed on the lower support plate. The lower ball hinge of the rotational inertia damper system is hinged to the lower fixing groove. The semi-submersible platform system is connected to the rotational inertia damper system through the upper ball hinge, upper support plate, and upper fixing groove. Connect the fixed vertical pole and the semi-submersible platform system through elastic ropes. Install a retractor, Tension Sensor II, and spring on the elastic ropes. Turn on the optical camera, Wave Sensor I, Wave Sensor II, Tension Sensor I, Tension Sensor II, and retractor. Slightly adjust the initial length of the elastic ropes to ensure the stability of the semi-submersible platform system. S2, Free vibration test: Release a uniform and constant water flow in the water tank. Tension Sensor I acquires the time series of the tension values under the stable flow field conditions. Perform Fourier spectrum analysis on the time series of the tension values to determine the natural period frequency of the semi-submersible platform system. S3, Wave calibration: Use an external wave maker to generate regular waves. Wave Sensor I and Wave Sensor II acquire the wave height data, and Tension Sensor II acquires the period data. Compare the acquired data with the settings of the external wave maker to ensure the accuracy of the generated waves. S4, Regular wave test: Generate regular waves. The variables of the regular waves are wave height and frequency. At least 2 types of wave heights and at least 5 types of frequencies are designed for the regular waves. Wave Sensor I, Wave Sensor II, Tension Sensor I, Tension Sensor II, and the optical camera synchronously acquire the data set. S5, Irregular wave test: Generate irregular waves. The generation of irregular waves needs to satisfy formula (1): where S(ω) is the power spectral density (PSD) function; H s is the significant wave height; ω is the wave frequency; ω0 is the peak frequency; γ w is the peak factor; τ is the shape parameter; The wave sensor I, wave sensor II, tension sensor I, tension sensor II, and optical camera synchronously acquire a data set; S6. A non-linear mechanical model is proposed: specifically, a non-linear mechanical model as shown in formulas (2)-(4) is proposed and established. Among them, F is the resistance exerted by the rotational inertia damper on the semi-submersible platform system; N is the number of rotational damping plates; m e is the inertial force; m i is the equivalent mass caused by the original structural mass and moment of inertia; is the relative acceleration; is the relative speed; c e is the damping coefficient; f c is the Coulomb friction coefficient; c v is the coefficient of viscous friction; sgn is the signum function; η is the conversion efficiency of the ball screw; L is the lead of the ball screw; ρ is the density of water; c m is the inertia coefficient; ρ s is the density of the rotating damping plate; l tp is the width of the rotation damping plate; t tp is the thickness of the rotation damping plate; c d is the drag coefficient; R1 is the outer diameter of the rotational damping plate; R0 is the inner diameter of the rotational damping plate; S7. The non-linear mechanical model is verified: the non-linear mechanical model, namely formulas (2)-(4), is verified by using the synchronous data set of the wave sensor I, wave sensor II, tension sensor I, tension sensor II, and optical camera obtained in S4 and S5.

5. The method for controlling the vertical vibration of a semi-submersible platform by a rotational inertia damper according to claim 4, characterized in that: In step S4, the frequency range of the regular wave includes the vertical vibration natural period frequency of the semi-submersible platform system to ensure resonance occurs between the wave and the semi-submersible platform system in the vertical direction.

6. The method for controlling the vertical vibration of a semi-submersible platform by a rotational inertia damper according to claim 4, characterized in that: In step S5, the average frequency range of the irregular wave includes the vertical vibration natural period frequency of the semi-submersible platform system to ensure resonance occurs between the irregular wave and the semi-submersible platform system in the vertical direction.

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