JPH0319839B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drift prevention device for marine structures.

Drifting forces such as wave drift force act on marine structures floating on the sea surface, so unless some measure is taken, the structures will drift on the sea surface. Maintaining the position of marine structures (preventing them from drifting) has traditionally been carried out using mooring lines, thrusters, etc., but in order to overcome large drifting forces and hold structures in a fixed position, mooring lines and Drifting prevention devices such as thrusters need to be large and strong.

An object of the present invention is to provide a device that can prevent marine structures from drifting by utilizing thrust acting on hydrofoils placed in waves.

A drift prevention device according to the present invention includes a wing support member attached to a marine structure so that at least a portion thereof is submerged in water, and a hydrofoil attached substantially horizontally to the underwater portion of the wing support member, The hydrofoil and the wing support member are mounted so that the hydrofoil can be adjusted in orientation, vertically moved, and rotated about a substantially horizontal axis to change the angle of attack.

The direction of the hydrofoil is adjusted so that it faces the drifting force, that is, the direction from the trailing edge to the leading edge of the wing is opposite to the direction of the drifting force, but normally, since the wave drifting force is large, The direction of the hydrofoil will be adjusted so that it faces the direction of wave travel. A hydrofoil placed almost horizontally in waves generates a thrust from the trailing edge of the wing toward the leading edge, and in particular, a hydrofoil placed facing the direction of wave propagation generates a thrust force that moves in the direction of wave propagation. It is known that thrust in the opposite direction is generated. (Refer to Japanese Patent Application Laid-Open No. 58-30893). Therefore, by adjusting the direction of the hydrofoil to oppose the drifting force, a thrust in the opposite direction to the drifting force is generated, and this thrust is used to cancel out part or all of the drifting force. Can be done.

Adjustment of the orientation of the hydrofoil can be achieved, for example, by attaching the wing support member to the marine structure so as to allow rotation about a substantially vertical axis, or by attaching the hydrofoil to a structure capable of rotation about a substantially vertical axis. It can be attached to the wing support member. Furthermore, although it is desirable that the direction of the hydrofoil be adjusted automatically in accordance with changes in the direction of travel of waves, it may also be done manually.

Hydrofoils can move vertically (heaving) and rotate around a substantially horizontal axis (pitching) to change the angle of attack relative to offshore structures.
It is expected that waves will generate more effective thrust.
To enable heaving and pitting of a hydrofoil, for example, the hydrofoil is fixed to a wing support member, and the wing support member has an elastic structure that allows vertical movement of the fixed portion of the hydrofoil and rotation about a substantially horizontal axis. Alternatively, a nearly vertical rod-shaped wing support member may be elastically supported on the marine structure to enable vertical movement, and the hydrofoil may be elastically supported by the wing support member to enable pitching. .

According to the present invention, as described above, it is possible to use thrust acting on hydrofoils placed in waves to partially or completely cancel the drifting force, thereby preventing marine structures from drifting. . Therefore, when a mooring line is used, for example, the marine structure can be reliably held in a fixed position without having to make it very strong, and the mooring line may become unnecessary in some cases. In particular, in deep sea areas, where mooring lines cannot be used, conventionally one had to rely on thrusters, but by using the device of this invention, thrusters can be downsized or eliminated, resulting in significant energy savings. You can expect good results.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment in which the present invention is applied to a semi-submersible marine structure 1. FIG. A vertical rotation shaft 2 is provided at the lower part of the structure 1 and coincident with its center line, and the lower part of this shaft 2 projects downward from the structure 1. The center of a wing support member 3, which is substantially U-shaped with a wide width when viewed from the side, is fixed to the lower end of the rotating shaft 2. The lower surface of the center of the arc of a semicircular hydrofoil 4 centered on the rotating shaft 2 is fixed to one end of the wing supporting member 3, and the lower surface of the center of the arc of a semicircular hydrofoil 4 centered on the rotating shaft 2 is fixed to one end of the wing supporting member 3; The central lower surface of the arc of the balancing member 5 having a radius is fixed. The wings 4 and the balancing member 5 are arranged horizontally on one circumference slightly below the sea level 6 and surround the structure 1 .
The cross section of the wing 4 has an airfoil shape, and the outer peripheral edge is a wing leading edge 7,
The inner peripheral edge is the trailing edge 8 of the blade. The cross section of the balancing member 5 is non-airfoil-shaped, for example elliptical. The wing support member 3 has appropriate elasticity, and its hydrofoil fixing portion 9 can move in the vertical direction and rotate around the horizontal axis in the vertical direction in FIG. be. Then, by rotating and stopping the rotating shaft 2 by appropriate means, the blades 4 and the balancing member 5 are attached to the structure 1.
rotates around and is fixed in any orientation.

In the marine structure 1 described above, the orientation of the hydrofoils 4 can be adjusted appropriately depending on the direction of wave propagation and the direction and amount of deviation from the set position of the structure 1, but usually the wave drifting force is large. Therefore, adjust it so that it faces the direction of travel of the waves. For example, if a wave is traveling in the direction shown by arrow A in FIG. Adjust. In this way, a thrust force in the direction opposite to the direction of wave propagation is generated in the blade 4, and a part or all of the drifting force is canceled by this thrust force. In addition, since the wing support member 3 has appropriate elasticity, heaving and pitting occur in the wing 4 due to waves, which can be expected to generate more effective thrust. Therefore, if the shape, dimensions, etc. of the hydrofoil 4 are appropriately selected, it is possible to prevent the marine structure 1 from drifting and to securely hold it in a fixed position without using retaining cables or thrusters. can. Furthermore, even if mooring lines and thrusters are necessary, there is no need to make them large and strong as in the past.

3 and 4 show the second embodiment, and the first embodiment
As in the embodiment, a vertical rotation shaft 11 is provided at the bottom of the semi-submersible marine structure 10. This axis 11
The center of the elongated horizontal plate 12 is fixed to the lower end of the
The centers of a pair of wing support members 13 similar to those in the first embodiment are fixed at right angles to both ends of this plate 12, respectively. A straight hydrofoil 14 is held horizontally between one end of a pair of wing support members 13,
A linear balancing member 15 is held horizontally between the opposite ends. The rest is the same as in the first embodiment, and the same parts are given the same reference numerals.

FIGS. 5 and 6 show a third embodiment, in which structures 1 are attached to the upper four corners of a marine structure 16 having a rectangular planar shape.
An arm 17 extending horizontally above the sea surface 6 outside of 6
is fixed, and a linear hydrofoil 18 is horizontally attached to the tip of each arm 17 via a vertical rod-shaped wing support member 19 to enable heaving and pitting. A swivel base 20 is provided on the arm 17, and the swivel base 20 can be rotated about a vertical axis and fixed at any position by suitable means. The wing support member 19 vertically passes through the arm 17 and the swivel base 20 and can move vertically with respect to these and rotate with respect to the arm 17, but is configured so that it cannot rotate with respect to the swivel base 20. It's getting old. A spring receiver 21 whose tip extends above the wing support member 19 is fixed to the swivel base 20, and both ends of a spring 22 are fixed to this tip and the wing support member 19. Wing support member 19
The lower part of the blade 18 is submerged below the sea surface 6, and a portion of the wing 18 near the leading edge 23 is rotatably attached to the lower end via a horizontal pin 24. Wing support member 19
A horizontal auxiliary member 25 is fixed to the lower part of the blade 18 , and a spring 27 is provided between the tip of the auxiliary member 25 and a portion of the wing 18 near the trailing edge 26 . In this way, the hydrofoil 18 is rotatably and elastically supported by the wing support member 19 by the pin 24 and the spring 27, and the wing support member 19 is movable in the vertical direction by the arm 17 by the spring 22. Being elastically supported, the hydrofoil 18 is normally held in a fixed position slightly below sea level 6, but is capable of heaving and pitching with waves.

In the marine structure 16 described above, for example, when waves advance in the direction shown by arrow B in FIG. When the waves advance in the direction shown by arrow C, the orientation of the four wings 18 is adjusted as shown by chain lines in the figure. Note that the direction of the hydrofoil 18 is adjusted by rotating the swivel base 20 and rotating the wing support member 19.

Figure 7 shows how this invention can be applied to a semi-submersible offshore structure 28.
A fourth embodiment applied to
Two straight hydrofoils 32 are arranged horizontally. Similar to the third embodiment, this hydrofoil 32 is attached to the lower surface of the center of the upper body 30 so as to be able to adjust its direction and perform heaving and pitching. The rest is the same as in the third embodiment, and the same parts are given the same reference numerals.

[Brief explanation of the drawing]

1 is a vertical sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view along the line shown in FIG. 1, FIG. 3 is a vertical sectional view showing a second embodiment, and FIG. 5 is a plan view showing the third embodiment, FIG. 6 is an enlarged sectional view along line 5, and FIG.
The figure is a side view showing the fourth embodiment. 1, 10, 16, 28...Ocean structure, 2, 1
1... Rotating shaft, 3, 13, 19... Wing support member,
4, 14, 18, 32...Hydrofoil, 6...Sea surface,
9...Hydrofoil fixing part, 22, 27...Spring, 2
4...Pin.

Claims (1)

[Scope of Claims] 1. A wing support member attached to a marine structure so that at least a portion thereof is submerged in water, and a hydrofoil attached substantially horizontally to the underwater portion of the wing support member, Drifting of a marine structure characterized in that the hydrofoil and the wing support member are attached so as to allow adjustment of the wing orientation, vertical movement and rotation about a substantially horizontal axis to change the angle of attack. Prevention device. 2. A hydrofoil is fixed to a hydrofoil support member, the wing support member is attached to a marine structure so as to rotate around a substantially vertical axis to adjust the orientation of the hydrofoil, and the wing support member is attached to a hydrofoil fixing part. It has elasticity that allows vertical movement and rotation around a substantially horizontal axis,
2. The drift prevention device for a marine structure according to claim 1, wherein the hydrofoil is capable of vertical movement and rotation about a substantially horizontal axis to change the angle of attack. 3. The wing support member is a nearly vertical rod-shaped member that is elastically supported by the offshore structure so that it can move vertically, and the wing support member is elastically supported by the marine structure so that the wing support member can rotate around a roughly horizontal axis that changes the angle of attack. Claim 1, wherein the hydrofoil is elastically supported by a member and is attached to a marine structure so that the wing support member rotates about a substantially vertical axis to adjust the orientation of the hydrofoil. Drifting prevention device for marine structures described in .