JPS6355209A - Fluid resistance-reducing structure - Google Patents

Abstract

PURPOSE:To reduce the resistance of fluid by attaching a long flexible filmy outer cylinder to a riser tube. CONSTITUTION:A plurality of flexible reinforcing rings 5 and openings 9 are provided for a long flexible filmy outer cylinder 4 attached to the periphery of a riser tube 1 erected under water. The attachment to the riser tube can thus be made easier, and when great flow rates of fluid acts on the riser tube, the resistance of the fluid of the outer cylinder 4 can be reduced because the shape of the horizontal cross section is deformed to a streamline form.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fluid resistance reduction structure that is attached to the outer periphery of a riser pipe or the like that stands up in water.

[Conventional technology]

As a fluid resistance reduction structure for a riser pipe consisting of a single pipe, for example, as shown in the perspective view of FIG.
Fairing 011, which is rotatable and has a streamlined horizontal cross-section, is attached to the outer circumference of 1.Furthermore, as a fluid resistance reduction structure for a multi-riser pipe consisting of a plurality of pipes, for example,
As shown in the factorial diagram, there has conventionally been a seven air ring 014 that is rotatable and has a streamlined horizontal cross section and is attached to the outer periphery of a cover ring 013 that surrounds a single multi-riser pipe 012.

However, such a structure has the following drawbacks.

(1) When the fairing 011 is attached to the flexible riser pipe 015, which requires relatively low bending rigidity, as shown in the side view of FIG. 5, its rigidity is increased.

(2) Fairing 014 is multi riser tube 01
If you attach it to 2, it will be difficult to sharpen it.

[Problem that the invention seeks to solve]

The present invention was proposed in view of these circumstances.
The overall objective is to provide a fluid resistance reduction structure that is easy to attach to riser pipes and does not impair their flexibility.

[Means for solving problems]

To this end, the present invention provides a fluid resistance reduction structure for an elongated flexible vertical member that extends vertically in the water, in which an elongated flexible membrane-like outer cylinder is loosely fitted onto the elongated flexible vertical member. a plurality of flexible reinforcing rings attached to the long flexible membrane-like outer cylinder at appropriate intervals in the longitudinal direction; It is characterized by comprising a plurality of openings that allow.

[For production]

(1) When a high flow velocity acts on a riser pipe or the like, the fluid resistance reduction structure allows the horizontal cross-sectional shape of the outer periphery of the riser pipe to deform into a streamlined shape.

(Even if the two-fluid resistance reduction structure is attached to a riser pipe, etc., the flexibility thereof will not be impaired.

(3) The fluid resistance reduction structure can be easily attached to riser pipes, etc.

〔Example〕

An embodiment in which the present invention is applied to a riser pipe will be described with reference to the drawings.
FIG.

In the above figure, 1 is a riser pipe that rises from the sea on a working deck 3 constructed above the water 1ffiWL of an offshore structure, and 4
is a flexible membrane-like outer cylinder fitted around the riser pipe 1,
The flexible membrane-like outer cylinder 4 is reinforced by a plurality of flexible reinforcing rings 5 installed at appropriate intervals in the axial direction, and in this embodiment, the material of the flexible membrane-like outer cylinder 4 is vinyl sheet, The material of the flexible reinforcing ring 5 is a rubber belt.

Reference numeral 6 denotes a plurality of hanging ropes that lock the upper end of the flexible membrane-like outer cylinder 4 to the tensioner 7 on the work deck 3 via an eye fitting 8 protruding from the upper part of the riser pipe 1; Flexible membrane outer cylinder 4
These are openings at the top and bottom that allow seawater to flow freely between the inside and outside of the tank.

In such a fluid resistance reduction structure, since the main body is composed of the flexible membrane-like outer cylinder 4, it is easy to attach to the riser pipe 1, and the flexibility of the riser pipe 1 is not impaired. There is no.

Furthermore, since the flexible membrane-like outer cylinder 4 is reinforced by a plurality of flexible reinforcing rings 5, it maintains its original cylindrical shape when there is no flow of seawater or when there is no water flow. However, when a large flow acts on it, as shown in Figure 2, it deforms into a streamlined shape with a small drag coefficient, reducing the fluid resistance acting on the riser pipe 1 and suppressing the generation of vortices. .

Note that instead of the openings 9, small openings for seawater circulation may be provided at appropriate intervals in the axial direction of the flexible membrane-like outer cylinder 4.

According to such a structure, the following effects can be achieved.

(1) Since it is easy to handle, it is possible to save labor when installing it on riser pipes, etc., and it can also be used for multi-riser pipes.

(2) Even if it is installed in a riser pipe, its flexibility will not be impaired, so it can also be used conveniently in a flexible riser pipe.

〔Effect of the invention〕

In short, according to the present invention, in an example of a structure for reducing fluid resistance of an elongated flexible vertical member extending vertically in water, the elongated flexible membrane is loosely extrapolated from the elongated flexible vertical member. a shaped outer cylinder;
A plurality of flexible reinforcing rings are attached to the long flexible membrane-like outer cylinder at appropriate intervals in the longitudinal direction, and a plurality of flexible reinforcing rings are installed on the long flexible membrane-like outer cylinder to allow water to flow in and out. The present invention is industrially extremely useful because it provides a fluid resistance reducing structure that can be easily attached to riser pipes and the like without impairing their flexibility. It is.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
It is a horizontal sectional view taken along the line ■-■ in the figure. FIG. 3 is a perspective view showing a known fairing for reducing fluid resistance in a riser pipe, FIG. 4 is a horizontal cross-sectional view showing a known fairing for reducing fluid resistance in a multi-riser pipe, and FIG. 5 is a known flexible riser fairing. It is a side view showing a tube. DESCRIPTION OF SYMBOLS 1... Riser pipe, 3... Working deck, 4... Flexible membrane outer cylinder, 5... Flexible reinforcing ring, 6... Suspension rope, 7
...Tensioner, 8...Eye hardware, 9...Opening. Sub-Agent Patent Attorney Masashi Tsukamoto Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] In a fluid resistance reduction structure for an elongated flexible vertical member extending vertically in water, an elongated flexible membrane-like outer cylinder loosely fitted onto the elongated flexible vertical member. a plurality of flexible reinforcing rings attached to the long flexible membrane-like outer cylinder at appropriate intervals in the longitudinal direction; A fluid resistance reduction structure characterized by comprising a plurality of openings that allow.