JPH04277213A - Wave calming body and wave calming device using the same - Google Patents

Abstract

PURPOSE:To calm effectively the propagation of surface waves hydrodynamically with a simple structure. CONSTITUTION:A wave calming body 10 floating on the surface 11 of the sea to intercept the propagation of surface waves is formed. The surface of the wave calming body opposed to the surface waves is curved to make the reflection of the surface waves difficult. Also, the opposite side surface is curved such that the surface waves getting over the wave calming body do not generate large turbulence due to the drop, but generate an action of effectively returning in the opposite direction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wave calming device for calming liquid waves.

0002

BACKGROUND OF THE INVENTION Conventional techniques of this type include the following. (1) There are a transparent type control structure disclosed in Japanese Patent Application Laid-Open No. 63-176511 and a sea area control structure with a transparent horizontal plate disclosed in Japanese Patent Application Laid-Open No. 63-93918. These structures are installed offshore from beaches to control huge waves and create calm waters.

(2) There is a wave dissipating device using high-pressure liquid disclosed in Japanese Patent Application Laid-Open No. 2-66203. The wave dissipating device is
A high-pressure fluid passage is disposed in the water around a floating structure placed on the water surface, a high-pressure fluid nozzle is provided upward in the high-pressure fluid passage, and the base end of the high-pressure fluid passage is connected to a pump.

0004

[Problem to be solved by the invention] Above (1) and (2)
Both have rigid structures that can absorb the force of waves, making them large and expensive to install. Furthermore, waves cannot be effectively suppressed due to the influence of reflected waves from structures.

The present invention has been made in view of the above-mentioned points, and provides a wave suppressing body that has a simple structure and can effectively suppress the propagation of surface waves hydrodynamically, and a wave suppressing body that uses the wave suppressing body. The purpose is to provide a wave calming device.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a wave calming body that floats on the liquid surface and blocks the propagation of surface waves, wherein the surface of the wave calming body facing the surface waves is It has a curved surface that makes it difficult for surface waves to be reflected, and the opposite surface has a curved shape that allows the surface waves that have passed through the wave suppressor to effectively return in the opposite direction without causing any major disturbance due to their fall. characterized by something.

[0007] Furthermore, the cross section of the wave suppressing body is a combination of a semi-ellipse obtained by cutting an ellipse with its short axis, and a semicircle having the same diameter as the short axis of the semi-ellipse, and the tip of the semi-ellipse is It is characterized by facing the direction of travel of surface waves.

[0008]

[Operation] Since the reflection from the wall surface of the wave suppressing body is for the vertical component of the traveling wave, if the angle between the wall surface and the horizontal plane is θ as shown in FIG. 12, the reflected component is sin θ.
is proportional to. Assuming minute oscillations in the potential flow,
Since the horizontal component is proportional to , it is sufficient to consider inclining the wall surface so as to suppress the reflection corresponding to the position of depth H.

When calculating a wall surface with such an inclination,
Let x be the horizontal coordinate measured from the position of depth H, and then

[0010] The cross section is a combination of a semi-ellipse obtained by cutting an ellipse along its short axis, and a semicircle with the same diameter as the short axis diameter of the semi-ellipse, and the tip of the semi-ellipse is opposed to the traveling direction of the surface wave. The long axis of the ellipse is tilted by 10° to 15° so that the tip is on the lower side.
The shape as shown in FIG. 2 closely approximates the shape described above.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of the wave suppressing body of the present invention. As illustrated, the cross section of the wave suppressing body 10 has a shape that is a combination of a semi-ellipse with a major axis radius 2R and a minor axis radius R, and a semicircle with a radius R. The relationship between the total length L of the cross section and the radius R is 3R≒L
It is.

As shown in FIG. 2, the wave suppressing body 10 having the above-mentioned cross-sectional shape has a semi-elliptical tip facing the direction of propagation of the surface wave, and the center of the semi-ellipse and semicircle of the cross-section of the wave suppressing body 10 is located in the stationary liquid. It is arranged 0.2 to 0.25 R below the surface 11, and the long axis of the semi-ellipse is inclined downward by 10° to 15° with respect to the liquid level 11. Hereinafter, the action of the wave suppressing body 10 to suppress surface waves will be explained.

As shown in FIG. 3, the strength of the surface wave of wavelength L (the magnitude of fluctuating pressure and velocity components) decreases rapidly as the depth from the water surface, ie, the water depth H increases. For example, assuming a potential flow and a small amplitude, it is proportional to . When H/L=0.75, it becomes. Therefore, when installing an obstacle of depth H,
The pressure fluctuations transmitted downstream beyond this area are reduced to about twice that of the upstream surface area.

However, depending on the shape of the obstacle, the fluctuating pressure caused by the reflection of the surface wave may be amplified. At that time, the attenuation of the propagating surface wave will be reduced by the amount of the amplification. Therefore, it is desirable that the shape of the obstacle does not cause noticeable wave reflection. Further, it is desirable that the shape of the downstream side of the obstacle is such that the surface wave that has overcome the obstacle returns to the liquid level without disturbing the liquid level.

Taking these points into consideration, an example of a wave suppressing body that is designed to effectively suppress the surface waves floating on the liquid surface and proceeding is a wave suppressing body with the cross-sectional shape shown in FIG. be.

As shown in FIG. 1, the sedative body has a cross section that is a combination of a semi-ellipse with a major axis radius of 2R and a minor axis radius R, and a semicircle with a radius of R. As shown in FIG. The tips of the wave suppressing body 10 are made to face the traveling direction of the surface waves, and the centers of the semi-ellipse and semicircle of the cross section of the wave suppressing body 10 are 0.2 to 0.0 mm away from the stationary liquid level 11.
An example of a case where the semi-ellipse is disposed below 25R and the long axis of the semi-ellipse is inclined downward by 10 degrees to 15 degrees with respect to the liquid level 11 will be explained as follows.

As shown in FIG. 4(a), even if the surface wave 11a overcomes the wave suppressing body 10, the surface of the wave suppressing body 10 facing the surface wave 11a is a curved surface that makes it difficult for the surface wave 11a to be reflected. No reflected waves are generated, and there is no propagation of surface waves due to reflected waves. In addition, the surface waves that have overcome the wave suppressor return along the wall surface under the calming body 10 and in the opposite direction to the traveling direction of the surface wave 11a as shown by arrow A due to the falling energy. Disturbance of the liquid level due to falling waves is also extremely small.

On the other hand, as shown in FIG. 4(b),
If the rear side of the wave calming body 10' is vertically steep,
The surface wave 11a that has overcome the wave calming body 10' becomes the wave calming body 1.
It will suddenly fall from the rear end of 0' to the liquid surface, causing the liquid surface to swell.

Further, as shown in FIG. 4(c), when the rear side of the wave suppressing body 10'' is a sloped surface, the wave suppressing body 1
The surface waves exceeding 0'' will go down this slope and propagate directly to the downstream side.

The wave suppressing body of the above embodiment has a shape that is a combination of a semi-ellipse with a major axis radius of 2R and a minor axis radius R, and a semicircle with a radius R. However, the wave calming body of the present invention is not limited thereto; wave reflection is unlikely to occur, and the downstream side of the obstacle allows the surface waves that have overcome the obstacle to flow through the wave calming body without disturbing the liquid surface. Any curved surface shape may be used as long as it returns to the direction opposite to the traveling direction of the surface waves at the bottom. Also,
Even if the cross-sectional shape is a combination of a semiellipse and a semicircle, the ratio of the major axis diameter to the minor axis diameter of this ellipse is not limited to the above example.

[0021] Furthermore, the liquid surface on which surface waves are to be suppressed using the wave suppressing body of the present invention is not limited to water surfaces such as sea surfaces and lake surfaces, but can be used to suppress surface waves of various liquids. Is possible.

FIG. 5 is a diagram showing a schematic configuration of a wave calming device using the wave calming body of the present invention. As shown in the figure, a guide plate 12 is provided on the downstream side of the wave suppressing body 10 to return the surface waves that have passed over the wave suppressing body 10 to the lower side of the wave suppressing body 10 and to the opposite side to the traveling direction of the surface waves. ing.

By providing the guide plate 12 on the downstream side of the wave suppressor 10 as described above, the surface waves 11a that have overcome the wave suppressor 10 are actively directed to the lower side of the wave suppressor 10 by the guide plate 12. Therefore, the liquid level 11' behind the guide plate 12, that is, on the downstream side, becomes flat.

FIG. 6 is a diagram showing a schematic configuration of a wave calming device using the wave calming body of the present invention, FIG. 5(a) is a plan view, and FIG.
(b) is an enlarged cross section taken along the line A-A in the same figure (a). As shown in the figure, this device places a wave calming body 10 in a predetermined range on the sea surface 20.
are arranged in an annular shape to calm waves that rush from outside the annular wave calming body 10, and the sea surface 21 surrounded by the wave calming body 10 is
is defined as a sea surface with no waves or calm waves.

As described above, the sea surface surrounded by the wave calming body 10 without waves or with calm waves can be used as a leisure facility such as a sea level pool. In addition, it can be used on the sea surface or in places where structures should be installed to avoid strong waves, such as undersea oil field platforms and underwater construction sites.

FIG. 7 is a diagram showing the case where the wave calming body of the present invention is used as an oil fence, and FIG. 7(a) is a plan view;
FIG. 7(b) is an enlarged sectional view taken along the line AA in FIG. 7(a). When oil spills onto the sea surface 30 from a tanker or the like, the sea surface 30' where the oil spills is surrounded by a wave calming body 10 shown in FIG. As a result, waves hitting from the outside of the wave calming body 10 are calmed, and the sea surface 30' surrounded by the wave calming body 10 becomes a calm sea surface, which makes it possible to prevent oil from spreading due to waves and to recover oil. becomes easier.

As shown in FIG. 7, when the wave calming body is used as an oil fence, the wave calming body 10 is made of a resin material or the like in the shape of a hose. After dropping and laying the hose-shaped wave calming body 10 in a predetermined sea area, the hose-shaped wave calming body 1 is
0, water 10-2 and air 10-1 are put in a predetermined ratio as shown in FIG. 7(b).

In this way, inside the wave calming body 10 and elsewhere,
Provide means to fix the cross-sectional shape, angle, and position. The cross-sectional shape of the wave suppressing body 10 is, for example, the cross-sectional shape shown in FIG. 1, and the cross-sectional shape shown in FIG.
As shown in , the tip of the semi-ellipse is directed in the traveling direction of the surface waves, that is, outward, and the center of the semi-ellipse and semicircle of the cross section of the wave suppressing body 10 is 0.2 to 0.25 R below the stationary liquid level 11. , and the long axis of the semi-ellipse is 10° to 15° relative to the liquid level 11.
Install it diagonally downward.

FIG. 8 is a diagram showing the case where the wave calming body of the present invention is used to prevent erosion of the coast. As shown in the figure, a wave calming body 10 having the cross-sectional shape shown in FIG. Install as shown. As a result, the waves crashing toward the cliff 40 are calmed by the wave calming body 10, and the sea surface 41' between the wave calming body 10 and the cliff 40 becomes a calm sea surface, and erosion of the cliff 40 can be prevented. .

FIG. 9 is a diagram showing an example in which the wave calming body of the present invention is used as a breakwater in a harbor. As shown in the figure, a wave calming body 10 having the cross-sectional shape shown in FIG. 1 is installed on a sea surface 51 a predetermined distance away from a pier 50. As a result, the waves crashing toward the pier 50 are calmed by the wave calmer 10, and the sea surface 51' between the wave calmer 10 and the pier 50 becomes a calm sea surface. In addition, in FIGS. 8 and 9, in this case, the wave suppressing body 10 is fixed to a foundation or the like with a wire or the like.

FIG. 10 is a diagram showing an example of using the wave calming body of the present invention as a surf riding practice area, where FIG. 10(a) is a plan view and FIG. It is an enlarged sectional view. A wave calming body 10 having a cross-sectional shape shown in FIG. 1 is installed to surround a predetermined range of a predetermined sea area or a lake area 60. A wave-making device 61 that generates waves is placed at that predetermined position. Wave calming body 1
0 points the tip of the semi-ellipse inward and the semicircular part outward, and as shown in Figure 2, the center is 0.2 to 0.25 from the static liquid level 1.
R below and the long axis of the semi-ellipse at 15° with respect to the liquid level 11.
Install it diagonally downward.

The waves generated by the wave making device 61 spread from the wave making device 61 as a base point, but they do not propagate outward from the wave suppressing body 10 or only propagate very weakly. Therefore, even if large waves are created by the wave making device, the waves do not affect the outside of the wave calming body 10, and the area surrounded by the wave calming body 10 can be used as a practice area for surf riding.

FIG. 11 is a diagram showing an example in which the wave calming body of the present invention is used as tourist equipment. As shown,
The inside of the wave calming body 10 is a promenade 10-5, and transparent walls 10-3 and 10-4 made of a transparent material such as glass are provided on both sides of the promenade 10-5. By installing the wave calming body 10 having such a structure in a predetermined sea area, it is possible to simultaneously observe from the inside of the wave calming body 10 underwater where large waves 71 exist on the sea surface and underwater where calm waves 72 exist. Therefore, by using this wave calming body 10, it is possible to develop an attractive tourist facility as a seaside promenade.

Note that in FIG. 12, dy/dx=ta
Let nθ, y=H−h, and now let usinθ be equal to the velocity at the point at depth H, then
This results in

dy/dx=tanθ=B/C=D/E=1/F Now, 2
When setting πy/L=η, 2πx/L=ξ, from this, considering the following, and from the condition that η=0 at ξ=0, the calculation results are shown in Figures 13(a) and (b). .

FIG. 14 is an external view showing an experimental apparatus for testing the effect of suppressing surface waves by the wave suppressing body according to the present invention. As shown in the figure, a wave generator 81 is arranged near one end of a long water tank 80, a wave generator 81 is arranged near one end of the water tank 80, and a wave having the cross-sectional shape shown in FIG. The sedative body 82 is arranged as shown in FIG. A wave detector a and a wave detector b are arranged at a position a predetermined distance away from the wave suppressing body 82 in front (on the side of the wave generator 81) and at a position a predetermined distance away from the rear. The wave generator 81 is activated to generate and propagate surface waves toward the wave suppressor 82.

FIG. 15 shows the experimental results using the experimental apparatus with the above configuration.
and shown in FIG. In FIG. 15, the frequency of the surface wave generated by the wave generator 81 is 1.58 Hz, and the wave speed is 1.0.
6 m/s, wavelength = 0.672 m, and in the figure, a is the detected wave by wave detector a, and b is the detected wave by wave detector b. As shown in the figure, the surface waves are greatly suppressed by the wave suppressor 82.

In addition, in FIG. 16, the surface wave frequency = 0.95 Hz, wave speed = 1.41 m/s, wavelength = 1.4
8 m, and in the figure, a is the detected wave by wave detector a, and b is the detected wave by wave detector b. As shown in the figure, the surface waves are greatly suppressed by the wave suppressor 82.

[0039]

[Effects of the Invention] As explained above, the wave calming body of the present invention can hydrodynamically effectively block the propagation of surface waves. It can be widely used in devices that suppress surface waves. In particular, since the wave calming body does not require attachments, it is lightweight and has an extremely simple structure, and can be easily installed, for example, by fixing it to the foundation with wire, resulting in low construction costs and a short construction period.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a wave suppressing body of the present invention.

FIG. 2 is a sectional view showing an example in which the wave calming body of the present invention is installed on a liquid surface.

FIG. 3 is a diagram showing a wave propagation state for explaining the principle of the present invention.

FIGS. 4(a), 4(b), and 4(c) are diagrams for explaining the wave calming effect of the wave calming body of the present invention, respectively.

FIG. 5 is a diagram showing a schematic configuration of a wave calming device using the wave calming body of the present invention.

FIG. 6 is a diagram showing a schematic configuration of a wave calming device using the wave calming body of the present invention, FIG. 6(a) is a plan view, and FIG. 6(b) is an enlarged A-A of the same figure (a). It is a cross section.

FIG. 7 is a diagram showing a case where the wave calming body of the present invention is used as an oil fence, FIG. 7(a) is a plan view, and FIG. 7(b) is a plan view.
is an enlarged sectional view taken along the line AA in FIG.

FIG. 8 is a diagram showing a case where the wave calming body of the present invention is used to prevent erosion of a coast, etc.

FIG. 9 is a diagram showing an example of using the wave calming body of the present invention as a breakwater in a port.

FIG. 10 is a diagram showing an example of using the wave calming body of the present invention as a surf riding practice area, FIG. 10(a) is a plan view, and FIG. 10(b) is a plan view.
is an enlarged cross section taken along the line A-A in the same figure (a).

FIG. 11 is a diagram showing an example of the case where the wave calming body of the present invention is used as tourist equipment.

FIG. 12 is an explanatory diagram for calculating the curved shape of the wave-suppressing body of the present invention.

FIGS. 13(a) and 13(b) are diagrams showing calculation results of the curved surface shape of the wave-suppressing body of the present invention, respectively.

FIG. 14 is an external view showing an experimental apparatus for testing the effect of surface wave suppression by the wave suppressor according to the present invention.

FIG. 15 is a diagram showing experimental results of the experimental apparatus of FIG. 14.

FIG. 16 is a diagram showing experimental results of the experimental apparatus of FIG. 14.

Claims (5)

[Claims] Claim 1: A wave suppressing body that floats on the liquid surface and blocks the propagation of surface waves, the surface of the wave suppressing body facing the surface wave having a shape that makes it difficult for surface waves to be reflected, and the opposite surface having a shape that makes it difficult for surface waves to be reflected. A wave calming body characterized by having a shape that prevents surface waves passing through the wave calming body from generating disturbances that become downstream surface wave generation sources. 2. The wave calming body according to claim 1,
A wave calming body characterized by having a shape that allows surface waves that have overcome the wave calming body to easily return in a direction opposite to the traveling direction of the surface waves. 3. The wave suppressing body according to claim 1 or 2, wherein the cross section of the wave suppressing body is a semi-ellipse obtained by cutting an ellipse with its short axis, and a semicircle having the same diameter as the short axis diameter of the semi-ellipse. What is claimed is: 1. A wave calming body having a shape that is a combination of the above, and wherein the tip of the semi-elliptical portion is substantially opposed to the traveling direction of surface waves. 4. Cross over the wave calming body on the opposite side of the wave calming body to the side facing the surface waves, and actively direct the surface waves under the calming body and in a direction substantially opposite to the traveling direction of the surface waves. A wave calming device characterized by having a guide board for returning waves. 5. The wave calming body according to claim 1, 2 or 3 is disposed in a predetermined region of the liquid surface facing the direction of travel of the surface waves, and the wave calming body is placed on the side opposite to the direction of travel of the surface waves. A wave calming device characterized by calming the liquid level.