CN110792398B

CN110792398B - Device for inhibiting vortex-induced vibration of marine riser

Info

Publication number: CN110792398B
Application number: CN201911063751.7A
Authority: CN
Inventors: 倪问池; 唐明昊; 胡琦凡; 张旭; 张蔚
Original assignee: Hohai University HHU
Current assignee: Hohai University HHU
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2021-09-28
Anticipated expiration: 2039-11-04
Also published as: CN110792398A

Abstract

The invention discloses a device for inhibiting vortex-induced vibration of a marine riser, which belongs to the technical field of marine engineering and comprises a hoop, a support fixed on a marine floating body and a vibration damping mechanism capable of providing resistance; the clamp is installed in the ocean riser outside, the one end of damping mechanism is fixed in the support, the other end is just right the clamp and with there is the interval between the clamp. The vortex-induced vibration suppression device is simple in structure, convenient to install and good in vortex-induced vibration suppression effect.

Description

Device for inhibiting vortex-induced vibration of marine riser

Technical Field

The invention belongs to the technical field of ocean engineering, and particularly relates to a device for inhibiting vortex-induced vibration of an ocean riser.

Background

The riser is a key part in a marine resource development system, and in an actual working environment, the riser generates vortex-induced vibration under the action of flow load, so that fatigue or structural damage is caused, and therefore the riser must be restrained. The riser connects the seabed to the surface floating structure and may be displaced with the floating structure in addition to being subjected to hydrodynamic forces. Thus, the damping mount must allow some displacement of the riser top while suppressing riser vortex induced vibration. The existing device for inhibiting the vortex-induced vibration of the stand pipe generally adopts a linear spring structure, and has poor inhibition effect on the vortex-induced vibration.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a device for inhibiting vortex-induced vibration of a marine riser, which is simple in structure, convenient to install and good in vortex-induced vibration inhibiting effect.

The invention provides the following technical scheme:

a device for inhibiting vortex-induced vibration of a marine riser comprises a hoop, a support fixed on a marine floating body and a damping mechanism capable of providing resistance; the clamp is installed in the ocean riser outside, the one end of damping mechanism is fixed in the support, the other end is just right the clamp and with there is the interval between the clamp.

Preferably, the damping mechanism comprises an outer cylinder body, a piston rod and a buffer spring; one end of the outer cylinder body is fixed on the support, the other end of the outer cylinder body is sealed by an end cover, and an inner pipe and a buffer pipe which are connected are arranged in the outer cylinder body; the piston rod penetrates through the end cover and the inner tube, one end of the piston rod is connected with a shoulder support positioned outside the outer cylinder body, and the other end of the piston rod is connected with a piston positioned in the buffer tube; and a buffer spring is arranged in the buffer tube, and two ends of the buffer spring are respectively connected with the piston and the bottom of the buffer tube.

Preferably, the vibration reduction mechanism further comprises a bearing, the bearing is sleeved outside the piston rod and fixed on the inner tube, and the bearing is a linear ball bearing.

Preferably, the cross-sectional shape of the shoulder rest is circular arc.

Preferably, the initial distance between the shoulder support and the marine riser is 0.6-0.7 times the diameter of the marine riser.

Preferably, the marine riser further comprises a linear spring, two ends of the linear spring are respectively connected with the clamp and the support, and the linear spring in an initial state is perpendicular to the marine riser.

Preferably, the average resistance provided by the vibration damping mechanism is 2-3 times of the average elastic force provided by the linear spring.

Preferably, the clamp comprises two semicircular metal rings, one ends of the two metal rings are connected, and the other ends of the two metal rings are fixed through fastening bolts.

Preferably, a layer of rubber gasket is arranged between the clamp and the marine riser.

Compared with the prior art, the invention has the beneficial effects that:

(1) the hoop is arranged outside the marine riser, the vibration reduction mechanism provides resistance for the displaced marine riser to influence the resonance state of the marine riser, so that the vibration frequency of the marine riser is separated from the resonance frequency to inhibit the amplitude of the marine riser, the vortex-induced vibration is inhibited, and the marine riser can be protected from being damaged by the vibration reduction mechanism;

(2) the distance between the vibration reduction mechanism and the clamp exists, and the vibration reduction mechanism can act on the marine riser only when the displacement of the marine riser exceeds a limit value, so that the actual requirement that the marine riser generates certain displacement can be met;

(3) the device provided by the invention has the advantages of simple structure, low manufacturing cost and convenience in installation.

Drawings

FIG. 1 is a schematic front view of the internal structure of the present invention;

FIG. 2 is a schematic view of the internal structure of the damping mechanism;

FIG. 3 is a schematic top view of the internal structure of the present invention;

labeled as: 1. clamping a hoop; 2. a linear spring; 3. a support; 4. fastening a bolt; 5. an outer cylinder body; 6. a piston; 7. a piston rod; 8. carrying out shoulder rest; 9. a bearing; 10. a buffer spring; 11. a liner; 12. an inner tube; 13. an end cap; 14. a buffer tube; 15. a marine riser.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

It should be noted that in the description of the present invention, the terms "upper", "lower", "inside", "outside", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention but do not require that the present invention must be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

As shown in fig. 1, the device for suppressing the vortex-induced vibration of the marine riser comprises a hoop 1, a support 3 and a damping mechanism capable of providing resistance; the support 3 is fixed on the ocean floating body through a welding method, the hoop 1 is installed outside the ocean riser 15, one end of the vibration reduction mechanism is fixed on the support 3, and the other end of the vibration reduction mechanism is opposite to the hoop 1 and has a distance with the hoop 1.

As shown in fig. 2, the damping mechanism includes an outer cylinder 5, a piston rod 7, and a damper spring 10; one end of the external cylinder body 5 is fixed on the support 3, the other end is sealed by an end cover 13, and an inner pipe 12 and a buffer pipe 14 which are connected are arranged inside the external cylinder body 5; the piston rod 7 penetrates through the end cover 13 and the inner tube 12, one end of the piston rod 7 is connected with a shoulder support 8 positioned outside the outer cylinder body 5, and the other end of the piston rod 7 is connected with a piston 6 positioned in a buffer tube 14; a buffer spring 10 is arranged in the buffer tube 14, and two ends of the buffer spring 10 are respectively connected with the piston 6 and the bottom of the buffer tube 14.

As shown in fig. 2, the damping mechanism further includes a bearing 9, the bearing 9 is sleeved outside the piston rod 7 and fixed on the inner tube 12, the bearing 9 is a linear ball bearing, and the bearing 9 can reduce friction between the piston rod 7 and the wall of the inner tube 12. The cross-sectional shape of the shoulder rest 8 is circular arc, preventing the clip 1 from being damaged when colliding with the shoulder rest 8. The initial distance between the shoulder support 8 and the marine riser 15 is 0.6-0.7 times of the diameter of the marine riser 15, and the distance can produce the best vortex-induced vibration suppression effect.

As shown in fig. 1, the device for suppressing marine riser vortex-induced vibration according to this embodiment further includes a linear spring 2, which is made of stainless steel, two ends of the linear spring 2 are respectively connected to the clamp 1 and the support 3, the linear spring 2 in an initial state is perpendicular to the marine riser 15, and when the marine riser 15 displaces, the linear spring 2 can provide elastic restoring force. The average resistance provided by the vibration damping mechanism is 2-3 times of the average elastic force provided by the linear spring 2, and the optimal vortex-induced vibration suppression effect can be generated under the condition.

As shown in fig. 3, the clamp 2 comprises two semicircular metal rings, one ends of the two metal rings are connected, and the other ends of the two metal rings are fixed by the fastening bolt 4, so that the tightness of the fastening bolt 4 can be adjusted according to the diameter of the marine riser 15. A layer of rubber gasket 11 is arranged between the hoop 1 and the marine riser 15, so that the marine riser 15 is protected from being damaged, and meanwhile, the installation firmness of the hoop 1 can be improved.

The parameters of the linear spring 2 and the damping mechanism are determined according to the actual marine riser and the environmental load, the components are machined, the initial distance between the shoulder rest 8 and the marine riser 15 is calculated, and then the installation is performed. Firstly welding a support 3 on an ocean floating body, then fixing a hoop 1 outside an ocean riser through a fastening nut 4, clamping a gasket 11 between the hoop 1 and the ocean riser, and correspondingly installing the hoop 1 and the support 3; then, welding and fixing one end of an outer cylinder body 5 of the vibration damping mechanism on the support 3, and enabling the shoulder support 8 to be opposite to the hoop 1; and finally, welding two ends of the linear spring 2 on the clamp 1 and the support 3 respectively to complete installation and simplify operation.

After the device is installed, when the marine riser 15 generates vortex-induced vibration and the amplitude is larger than a certain value, the marine riser 15 drives the hoop 1 to be in contact with the shoulder support 8, the shoulder support 8 pushes the piston rod 7 and the piston 6 to move towards the support 3, the buffer spring 10 is compressed, asymmetric resistance is applied to the marine riser 15 which vibrates at the natural frequency, the motion track of the marine riser 15 and the symmetry of a wake field are damaged, the wake field form of the marine riser is changed, the resonance state of the marine riser is further influenced, the vibration frequency of the marine riser is separated from the resonance frequency, and the purpose of restraining the riser vortex-induced vibration is finally achieved.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims

1. A device for inhibiting vortex-induced vibration of a marine riser is characterized by comprising a hoop, a support fixed on a marine floating body and a damping mechanism capable of providing resistance; the hoop is arranged outside the marine riser, one end of the vibration reduction mechanism is fixed on the support, and the other end of the vibration reduction mechanism is opposite to the hoop and has a distance with the hoop;

the vibration reduction mechanism comprises an outer cylinder body, a piston rod and a buffer spring; one end of the outer cylinder body is fixed on the support, the other end of the outer cylinder body is sealed by an end cover, and an inner pipe and a buffer pipe which are connected are arranged in the outer cylinder body; the piston rod penetrates through the end cover and the inner tube, one end of the piston rod is connected with a shoulder support positioned outside the outer cylinder body, and the other end of the piston rod is connected with a piston positioned in the buffer tube; a buffer spring is arranged in the buffer tube, and two ends of the buffer spring are respectively connected with the piston and the bottom of the buffer tube;

the initial distance between the shoulder support and the marine riser is 0.6-0.7 times of the diameter of the marine riser;

the marine riser clamp comprises a hoop, a support and a linear spring, wherein the hoop is arranged on the marine riser, the support is arranged on the marine riser, the linear spring is arranged on the marine riser, and the hoop is connected with the support;

the average resistance provided by the vibration reduction mechanism is 2-3 times of the average elastic force provided by the linear spring.

2. The device for suppressing marine riser vortex-induced vibrations of claim 1, wherein the damping mechanism further comprises a bearing, the bearing being sleeved outside the piston rod and fixed to the inner tube, the bearing being a linear ball bearing.

3. An apparatus for suppressing marine riser vortex induced vibrations according to claim 1, characterised in that the cross-sectional shape of the shoulder rest is circular arc.

4. A device for suppressing marine riser vortex induced vibrations as claimed in claim 1, wherein the clamp comprises two semi-circular metal rings connected at one end and secured at the other end by a fastening bolt.

5. An apparatus for suppressing marine riser vortex induced vibrations as claimed in claim 1, wherein a layer of rubber material is provided between the clamp and the marine riser.