JPS5961606A - Flow-formation type floating breakwater dam - Google Patents

Abstract

PURPOSE:To raise the efficiency of wave breaking of a flow-formation type floating breakwater dam by a method in which a structure is made up of faces with openings or apertures through which the sea water can pass in such a way that the amount of the sea water passing through the openings of apertures becomes greater in a fixed direction but becomes smaller in the opposite direction. CONSTITUTION:A structure is made up of pipes 1, 3 and 6 and semi-circular pillars 2 and 4 through which the sea water can pass. The structure is almost fully filled with water during the operating period in such a way as to keep the dry side 7 and the draft 8 at given levels. When tidal wave (a) collides on the structure, the water particles energetically pass through the apertures between the semi-circular pillars 2, and thereby the inside space is filled with vigorous eddy to raise the water level and water is discharged through the semi-circular pillars 4 and the pipes 6. Most of tidal wave energy is thus consumed and dissipated by eddy formation and wave breakage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a high wave-dissipating effect, the mooring device is much simpler than other general methods, and it converts a considerable part of the wave energy into a flow in a fixed direction. This relates to a floating wave bank that has the function of creating a flow.

Many types of floating wave breakers have been announced both domestically and internationally, and there are many types of wave-dissipating mechanisms, and many are designed to combine several of these mechanisms to achieve their wave-dissipating function.

However, there has been no attempt to generate current using wave energy.

Most existing formats reduce transmitted waves (i.e., dissipate) by reflecting the waves, but if the floating body moves with the waves, no reflection occurs, and therefore dissipation occurs. Since there is nothing to do, we need some means.

Tightening the mooring lines is one method, but it is dangerous because excessive force is applied during stormy weather. It is certainly one way to carry huge amounts of mass, but it is not economically viable.

Therefore, many devices try to alleviate the fluctuating force of waves and reduce the movement by using so-called phase difference reflection in some form, but as long as phase is used, in actual sea areas with irregular waves, regular waves It is difficult to achieve wave dissipation as in the water tank experiment, but there are many methods that attempt to dissipate wave energy by using 1° wave breaking, vortex creation, mass resistance, etc. However, most of them rely heavily on reflexes, and are forced to move by the fluid force exerted on the part responsible for buoyancy.

The motion of the floating body itself also generates waves. It is not impossible to effectively eliminate waves by matching the amplitude and phase of the incident wave, and there are models that use this method, but it is difficult to demonstrate its effectiveness in actual sea areas with irregular waves. Not a fool, but
Assuming motion, it is inevitable that the mooring system will be strained, and since the length of the unit cannot be increased, a series of troublesome problems arise, such as gaps between the units, complications in the mooring system, and collisions between units. ,.

The above is a simple criticism of all existing models, but the point is,
None of them have been able to effectively reduce motion, and all of them leave concerns about the mooring system.

When evaluating floating breakwaters as a sea area control technology, that is, a technology for expanding the use of sea areas and promoting the conservation and improvement of the environment, it is important to note that they not only have a wave-dissipating function, but also have the ability to flow even in areas with no current if there are waves. If the mooring system can be created, its value will be doubled1.Also, as mentioned in the previous section, all existing methods allow movement, and those that attempt to suppress it to some extent place an excessive burden on the mooring system, and in any case However, there remain concerns about mooring. Therefore, I searched for a format that actively reduced the amount of exercise.

The purpose of the present invention is to develop a highly practical system with the above two basic goals and all other related considerations. In order to achieve the above object, the present invention consists of a part or most of the structure having a surface with openings or gaps through which seawater passes, and by changing the shape of the surroundings of these openings or gaps or by special deposits. , a flow creation method that increases the amount of seawater passing in one direction and decreases it in the opposite direction, creating a flow in a fixed direction from the reciprocating movement of seawater caused by waves as a whole, and plays the role of wave dissipation. The aim is to provide a floating breakwater.

An example of carrying out the present invention will be described below with reference to the drawings. 4. FIG. 1 shows a typical cross section, and FIG. 2 is a front view showing a small portion in the longitudinal direction.

In the figure, 1 and 3 are watertight pipes, and all or part of 3 has a structure that allows water to be poured.During operation, almost all of the pipes are filled with water to maintain the freeboard (7) and draft (8) at predetermined levels. The vertical plane is a semicircular cylinder shown at 2 and 4, rounded toward the waves. Among the semicircular cylinders 2 and 4, only one 6 is a complete pipe, but this is because when all the water is drained in 3, the position of 6 becomes the water line, and 6 has a water line area and maintains stability. It is for. 5 is a frame structure to maintain the cross-sectional shape, and diagonal members connecting diagonals appropriately are also effective. 3. This frame structure may be watertight or non-watertight as appropriate.

Next, the function of this floating wavebank against waves will be explained. Third
The figure shows the flow creation function most clearly, and 9 is a very simple flap valve.

Figure 4 shows the motion of water particles due to waves.When the water depth is deeper than 1/2 of the wavelength, the wave is called a deep sea wave.The motion of n1 water particles is circular, but as the water depth becomes shallower, it gradually changes. ,
It will draw a long ellipse horizontally.

In the case of deep-sea waves, the amplitude of the circular motion gradually decreases as the water depth increases in proportion to eKZ. Note that K is the wave number 2π
/L, L is the wavelength, and Z is the distance in the vertical axis direction, with the upper side being taken as a plus.

Now, when a wave hits the structure in Figure 3, if the water particles move in the right direction (in the positive direction of X) on the diagram, the valve +
When the valve is opened and the valve is about to move to the left, the valve closes, and by repeating this process, the water will flow to the right. .

Although the structure shown in FIG. 3 shows an extreme example, the structure shown in FIG. 1 can also be expected to generate a considerable amount of flow.

When a wave hits the structure shown in Figure 1 from the left, the water particles become semi-cylindrical 2
It slips through the gap between them, and the space inside is filled with intense darkness. The water level rises and water is discharged to the right from between the semicircular column 4 and the vibro 0 on the right side.

When the trough of the wave comes to the left wall 2 to 6 in Figure 41, the water in the internal space tries to escape from between 2 and 6, but this leftward flow is not smoother and the flow rate is smaller than the rightward flow described above. . Eventually, the crest of the next wave will come and the inflow will begin. In this way, a flow to the right is created. Most of the wave energy is dissipated by eddies and wave breaking.

In a structure with a cross section like that shown in Figure 1, when the horizontal component of the wave fluctuating force is the largest, water passes relatively easily between the semicircular cylinders, and in some areas near the surface, waves break. Therefore, the external force received is considerably reduced.

Because the overall external shape is large, the additional mass for the movement of the structure is large; and the overall length is long enough to prevent the entire structure from riding a single wave in irregular waves at the actual sea surface, and averaging is performed. As a result, the movement displacement of the structure is extremely small.

Therefore, mooring can reasonably ensure safety.

Long lengths are generally avoided because they are subjected to large bending and torsion moments under the worst-case conditions of waves, that is, when waves with long wavelengths are incident on a structure from an oblique or right angle direction. There is.

This structural method has a smaller freeboard and fewer structures near the water line (such as the purge type (compared to C, the difference is obvious)
Therefore, the bending moment.

The torsional moment will not become excessive.

Furthermore, the overall depth, height, freeboard (7) + draft (8) is relatively large, and a large number of longitudinal pipes 1.3 are arranged on the top and bottom surfaces, making it very easy to design in terms of strength.

Structures with large external shapes like this are built and towed.

Construction methods such as construction and installation are one of the major issues, but towing is easy if the waterline at the time of towing is planned in advance and the stability calculations at that position are done in advance, as shown in 6 of Figure 1.

(9) During installation, pour the required amount of water into the pipe 3 on the bottom to submerge it to the specified state. This transient state tends to become unstable, but sinking in parallel is rather dangerous, so it is necessary to tilt it once to the left or right. These are problems that can be verified through sufficient calculations.

Up until now, we have considered structures in two dimensions, but when we consider them as a three-dimensional problem, that is, the problem of placement relative to the sea surface, it is also possible to make choices such as where to force the flow to be discharged. .

That is, the mouth of the flow can be concentrated by making part of the surface on the rear side flat with respect to the waves, or by changing the density of the gaps between the semicircular cylinders.

Note that the 2 or 40 semi-cylinder shown in Figure 1 is 2/40 in Figure 5.
, 4/, various modifications are possible.

What is difficult to predict on paper with this structure is the clogging of gaps due to biofouling and the increase in weight, but for the former, it is necessary to levitate the entire body at any time using Fig. You can also deal with this problem by increasing (10) or decreasing the amount of water. Note that there is a degree of freedom equal to the 6th place tfidf.

As described above, one practical example of the present invention has been described.According to the present invention, the freeboard is small and the buoyancy is mainly reduced by using a longitudinal pipe that also serves as a strength material (wave dissipating body). Since the stress can also be reduced, the length of the l unit can be made sufficiently long (for example, 200 to 300 m), so that the wave force can be averaged and the movement can be reduced.

Also from a constructional point of view, the large external dimensions result in a large additional mass even if the substance of the structural material is small, which also reduces the movement. Therefore, it is easy to moor and ensure safety.

As described above, the present invention is highly safe and economical, and has the function of creating a current even in a sea area where there is no current, making it an extremely practical floating breakwater.

[Brief explanation of drawings]

The drawings show an example of the implementation of the present invention, and FIGS. 1 and 2 are cross-sectional views and partial sectional views for explaining the device, FIG. 3 is an explanatory view of the operation, and FIG. 4 is an illustration of water particles. FIG. 5 is a cross-sectional view showing two examples of modification of the main part. The symbols in the drawings indicate the following members, respectively. 1: Pipe 2: Semi-cylinder 3: Pipe 4: Semi-cylinder 5: Frame structure 6: Pipe 7: Freeboard 8: Draft 9: Flap valve 10: Motion of water particles Patent applicant
Marine Science and Technology Center

Claims (1)

[Claims] 1. Part or most of the structure has a surface with openings or gaps through which river water can pass, and the shape of the surroundings of these openings or gaps, or special deposits, allow seawater to pass through. By making the passing acid larger in one direction and smaller in the opposite direction, the overall effect was to create a flow in a fixed direction from the reciprocating movement of seawater caused by waves, and to play the role of wave dissipation! Features a floating wave bank. 2. A hollow floating wavebank with a rectangular or trapezoidal cross-sectional shape, with most of the structure or wave-dissipating body concentrated on the four sides, with at least a part of the vertical or near-vertical surface having directional transmission. Flow creation method 3 according to claim 1, characterized in that by having a structure having a wave-dissipating function, it is possible to create a flow by using wave energy even in a sea area where there is no current. The structure having a rectangular or trapezoidal cross-sectional shape and forming the upper surface is a pipe with a honeycomb structure,
The structure that forms the bottom is a pipe with a watertight structure that can partly be filled with water, and the structures that form the front and back surfaces of the waves are semi-cylindrical in shape to allow the flow from the waves to flow easily and suppress the flow in the opposite direction. 1. A flow-type floating wavebank according to claim 1, characterized in that: 4. Of the structures that form the front and rear surfaces against the waves in Section 3, install one completely watertight pipe in each part of the same height near the bottom 1, so that when the bottom pipe is completely drained, the water will not leak. 2. The flow-type floating wavebank according to claim 1, characterized in that a line is secured.