JPS61175199A - Reduction of drifting wave forces against oceanic structure - Google Patents

Abstract

PURPOSE:To reduce drifting wave forces exerted on a floating oceanic structure having non-wing profile cross section by arranging fins on a side opposite to that attacked by the waves. CONSTITUTION:Fins 5 and fins 6 are attached respectively in the center of a surface 3A of a lower hull 3 attached by the waves 4 and in the center of a surface 3B of a lower hull 3 opposite to the surface 3A so that both groups of fins can be swung. The fins 5 on the side 3A attacked by the waves 4 are postured downward while the fins 6 on the opposite side are retained horizontally with plurality of fixing cables 7. When the waves 4 attack in the direction shown with arrows, turbulent seawater flow generated at trailing edges of the fins 6 due to vertical movements of both waves 4 and a semi-submerged rig 1 flows to the left, generating, as a reaction, thrusts exerting on the lower hulls 3 in the direction opposite to that of the attacking waves 4. These thrusts offset the drifting wave forces exerted on columns 2 and lower hulls 3.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for reducing wave drifting forces acting on marine structures.

BACKGROUND OF THE INVENTION Objects floating in the ocean (semi-subrigs, buoys, etc.) are swept away by wind, waves, and currents, so mooring chains and thrusters have traditionally been used to counteract this. and,
Recently, in order to further improve this, a proposal has been made to add airfoil-shaped objects to the floating body and use the thrust of the vibrating blades to reduce the wave drifting force.

Problems to be Solved by the Invention However, when adding an airfoil to a floating body as described above, there is a problem in that the equipment becomes complicated and it is not easy to apply it to existing marine structures.

An object of the present invention is to provide a method for reducing the wave drifting force acting on marine structures, which solves the above-mentioned problems.

Means for Solving the Problems In order to solve the above problems, the present invention provides a method for reducing the wave drifting force acting on marine structures by connecting the surface of the non-airfoil-shaped structure floating in the ocean to the side where the waves attack. The fins provided on the opposite surface reduce the wave drifting force acting on the non-airfoil structure.

In other words, the method of the present invention attempts to approximate an airfoil-shaped object as a whole by adding fins to a non-airfoil structure, thereby generating thrust similar to that of an airfoil-shaped object.

Example An embodiment of the present invention will be described below based on the drawings.

In Figures 1 and 2, (1) is a semi-subrig,
(2) is the column, (3) is the lower hull (main floating body) installed at the lower end of the column (2), and now the wave (4) is moving between the column (2) and the lower hull (main floating body) in the direction shown by the arrow in the figure. ). (5) (6) is the lower hull (3)
The fins are rotatably attached to the center of the surface (3A) on the side where the wave (4) attacks and the center of the surface (3B) on the opposite side. The fins (5) on the side surface (3A) are in a hanging position (retracted position), and the fins (6) on the opposite side (3B) are held in a horizontal position by multiple fixing wires (cheno) (7). has been done. The lengths of the fins (5) and (6) in the left-right (longitudinal) direction are set as long as possible to fully demonstrate the effects described below, and in Figure 1, the length is the length spanning the length of the parallel section of the lower hull (3). It is provided. On the other hand, fin (5)
The length of (6) in the front-rear (width) direction is set to approximately 20% to 100% of the width of the lower hull (3).

With this configuration, when the wave (4) attacks in the direction of the arrow, the vertical movement of the wave (4) and the vertical movement of the semi-subrig (1) causes the vortex coming out from the rear end of the fin (6) to move to the left side (lower side). ), and as a reaction, a thrust is generated in the lower hull (3) in a direction opposite (opposite) to the direction of the wave (4). Therefore, this thrust acts in the direction of the wave drifting force C wave acting on the column (2) and lower hull (3) ().
This will cancel out the On the other hand, when the wave (4) attacks from the opposite side, the fish (6) is kept in a hanging position and the fin (5) on the opposite side is kept in a horizontal position with a fixed wire (7). As a result, similar effects can be obtained.

The generation of thrust will be explained based on FIG. That is, as shown in fa) in Fig. 3, when an airfoil object αO is placed in water with waves (4), the wave particle movement and the vertical component of the movement of the airfoil object αO cause the wing trailing edge (IOA) to A vortex stronger than that at the leading edge of the wing (10B) is generated, and as a result, thrust is generated in the airfoil object αO. Therefore, as shown in FIG. 3(b), the present invention provides fins (
5) This is an attempt to approximately obtain the same effect as the airfoil-shaped object α0 by adding (6).

@4 FIGS. 2 and 5 show other embodiments. In the figure 2,
@ is a cylindrical floating buoy, such as a buoy.

It is used for data collection, etc. (To)α
4 is a rotation support groove in two stages, upper and lower, provided below the water surface on the outer circumferential surface of the buoy, and a horizontal fin α9 is fitted in the upper paper support groove (toward) so as to be slidable and rotatable; One side of the direction control plate αQ, which is provided so as to overlap from the center of the lower surface of the fin a9, is slidably and rotatably fitted to the lower ◎ rolling support hole α→. It is now assumed that wave (4) attacks floating buoy 4 in the direction shown by the arrow in the figure.

With this configuration, when the wave (4) attacks in the direction of the arrow, that is, when the direction of the wave (4) and the direction of the symmetry axis of the fin (toward) are different, first, the wave (4) is moved to the direction control plate α0. Since the force is applied unbalanced, the fin (to) 2 and the rotation control plate αe integrated therewith slide along the rotation support groove (to) α4, and the surface of the floating buoy @ on which the waves (4) strike It will naturally (or forcefully) fall onto the opposite side.

After the situation has calmed down, a thrust force is generated in the direction opposite to (opposite to) the direction of attack of the wave (4), as described in the previous embodiment.

Effects of the Invention According to the present invention, the present invention can be implemented by simply disposing fins on a non-airfoil structure, and the wave drifting force can be effectively reduced while the equipment is much simpler than the conventional method. Moreover, it is easy to apply to existing marine structures.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of a semi-subrig, FIG. 2 is a view taken along arrow A-A in FIG. 1, and FIG.
1(b) is a diagram explaining the principle, FIGS. 4 and 5 show other embodiments, FIG. 4 is a plan view of the floating buoy, and FIG. 5 is a side view of the same. (1)...Semi-subrig, (3)...Lower hull,
(3A)...The surface on the side where the waves attack, (3B)...The surface on the opposite side from the side where the waves attack, (4)...The waves, (
5) (6) αυ...Fin, @...Floating Buoy Agent Yoshihiro Morimoto Figure 2 Figure 5 Procedural Amendment (Restraint 1, Incident Indication 1985 Patent Application No. 17254 2)
, Title of the invention Method for reducing wave drifting forces acting on offshore structures 3, Person making the amendment - Relationship to the case Name of patent applicant (5u) Hitachi Zosen Corporation Telephone Osaka 06 (532) 4025 (Main) Name
(6808) Patent Attorney Delivery Hon Yoshihiro 5, Date of Notice of Reasons for Refusal (Delivery Date) Showa Year, Month, Day 6, Number of Inventions Increased by Amendment 7, Grasp of Detailed Explanation of the Invention in the Detailed Layer Subject to Amendment 8, Amendment Contents (1) @ Page 55, item 5, "Upper ◎ Rolling support groove" is corrected to "Upper rotation support groove."<2) On page m5, line 7, "lower ◎ rotation support groove" is corrected to "lower rotation/Xfj groove". (3) @Page 5, line 8, "Surikiri◎turn" is corrected to "Sliding rotation"O

Claims (1)

[Claims] 1. The wave drifting force acting on the non-airfoil structure floating in the ocean is reduced by fins arranged on the surface opposite to the side where waves attack the non-airfoil structure floating in the ocean. A method for reducing wave drifting forces acting on offshore structures.