JPH07259046A - Wave eliminating device - Google Patents

Abstract

PURPOSE:To eliminate waves by allowing them to deform caissons installed underwater so that the caissons generate emissive waves having the opposite phase to the incident waves, and thereby reducing the wave height of the waves passing by. CONSTITUTION:A pair of caissons 3, 4 are immerged underwater parallel with the advancing direction of the waves in a water area having a depth (h), and to them 3, 4. water-tight films 1, 2 are attached which are deformable flexibly. The two films lie within the horizontal plane at a depth h' under the static water surface, and the caissons are positioned conversely up and down to each other and fixed while a spacing is reserved in between which corresponds to approx. half the wavelength L of the incident waves W. When the films 1, 2 are deformed by the pressure of the incident waves advancing in the OX direction, the air in the two caissons flows freely via a communication pipe 5 so that emissive waves are produced.

Description

The present invention relates to a device for generating a radiation wave having a phase opposite to that of an incident wave by the deformation of a submarine installed below the surface of water and reducing the wave height of a passing wave to cancel the wave. It is a device that can be easily constructed at low cost based on a principle different from the method of wave-breaking and wave-dissipating. The principle of the present invention is as described below. Figure 1 shows a side view of the wave peaks and bottoms lined up in the traveling direction of the incident wave. It is assumed that it is proceeding in the direction of. Here, the water depth is h, the bottom of the water is indicated by O'X ', and two submarines 3 and 4 having flexible film surfaces 1 and 2 indicated by the broken line from the water surface to the depth of h'are separated by about half wavelength L / 2. It is fixed above the two points A and B on the bottom of the water, and the air inside them is connected by the hollow tube 5, and the membrane surfaces 1, 2 and the plates 10, 13 are sufficiently strong. The smaller the specific gravity is, the more desirable it is, and it is better to make it equal to or less than that of seawater. A particularly indispensable condition for this device is that the two enclosures are on opposite sides with respect to the horizontal plane containing the membrane surfaces 1 and 2, the reason for which will be described later. When there is no wave by injecting air into a pair of these submarines, the internal air pressure is in equilibrium with the hydrostatic pressure of the external fluid at the depth h ', and both membrane surfaces are in the same horizontal plane as indicated by the broken line. It is possible to maintain an equilibrium state. At this time, the wavelength as shown by the broken line W _i from the right side When an incident wave with a wave propagates and there is a wave peak on the position A of the right sub-chamber 3, the external fluid pressure exceeds the internal air pressure of the sub-chamber 3 on the film surface 1. At this moment, since there is a wave bottom at the position of the left sub-chamber 4 and the external fluid pressure is lower than the internal air pressure of the sub-chamber 4 on the film surface 2, the flow of air from the right sub-chamber to the left sub-chamber occurs and the right membrane surface 1 is As shown by 6 in the figure, the surrounding fluid is sucked and the latent volume is contracted, and at the same time, the left membrane surface 2 eliminates the surrounding fluid and expands the latent volume as shown by 7. Thus, as shown in FIG. 6, in the vicinity of the right submarine, the wave peak of the incident wave W _i immediately above it is depressed as shown by W _r in correspondence with the volume decrease (hatched portion) of the submarine 3 below it, and conversely on the left. In the submarine, the wave bottom rises as indicated by W _r in response to the increase in the volume of the submarine (hatched portion). In this way, it can be considered that the incident wave W _i (broken line) induces a periodic fluctuation of the latent volume due to the fluctuation of the internal pressure of the fluid, thereby generating a new wave. This wave is called a radiation wave, and the shaded portion in the waveform of FIG. 6 corresponds to its amplitude, but as described above, the peak of the incident wave corresponds to the wave bottom of the radiation wave and the wave bottom of the incident wave is Since it corresponds to the peak of the radiated wave, the phase is reversed. As a result, the amplitude of the wave radiated by the film deformation of the submarine will pass through it. Therefore, it can be said that the characteristic feature of this wave breaking device is that the wave is prevented by a mechanism completely different from that of the breakwater breakwater that extinguishes the energy of the incident wave and the upright breakwater that cuts off the wave by reflection. Further, as shown in FIG. 7, when the latent box has a plate structure without a deformable film, this latent box system produces an incident wave W _i
As shown by the solid line W _s for the incident wave W _{i, the} wave peak decreases, the wave bottom rises, and the phase changes. This is called a scattering wave, and the wave-dissipating action of this device appears as a reduction in the height of the passing wave as a result of the superposition of the radiated wave and the scattered wave. Therefore, the function of the device is not to dissipate the energy of the incident wave, but to suppress the passage of the wave by the above two effects. In particular, the effect of radiation waves is the main feature of this device, and its operation is carried out by an underwater device, and the device itself does not receive a large wave force, and construction maintenance is easy. In this device, as described above, (i) the positions of the deformed membrane surfaces at rest are within one horizontal plane parallel to the still water surface. (Ii) The main body of the submarine must be on the upside down side with respect to this horizontal plane. The feature is that the two conditions are essential.
Because it is an indispensable requirement for maintaining the static stability of the latent membrane surface necessary to generate the radiated wave, and the above method is the only way to satisfy it. The above condition (i) is obvious, and when the membrane surfaces of both sub-chambers are at different water depths, the hydrostatic pressure acting on the deeper sub-membrane is greater than the hydrostatic pressure for the shallower sub-membrane, so that it is inevitably air. Is gathered in the shallower submerged box and the membrane surface cannot be deformed in response to the water pressure fluctuation caused by the waves. In condition (ii), as shown in FIG. 8, in the case of a pair of bilaterally symmetrical submersibles at the same water depth, even if the hydrostatic pressures on both membrane surfaces were initially equal, a small amount was found on the membrane surface 1 of the right submerged vessel. When the pressure drops ρgΔh '(ρ is the density of seawater; g is the acceleration of gravity) and the membrane surface decreases by Δh', the air must be incompressible and the total volume must be constant. Because of this, a part of the air in the right sub-chamber moves to the left sub-chamber and its membrane surface 2
Will be pushed up by Δh '. As a result, left membrane surface 2
The hydrostatic pressure acting from the outside is reduced by ρgΔh ', and the difference from the hydrostatic pressure acting on the right membrane surface 1 is 2ρgΔh'.
As a result, the right membrane surface further decreases, the left membrane surface rises, and the imbalance between the two continues to expand indefinitely, and finally air gathers in the left submarine and the right subcellular loses its volume, and both do not function as a submarine. Become. Therefore, as shown in Fig. 9, if the submerged boxes are installed upside down and opposite to each other with respect to the film surface of the same water depth, an imbalance Δh '
Even if a pressure occurs, the change in the external water pressure on both the left and right membrane surfaces acts to cancel the imbalance, so that the stability is always maintained and the operation corresponding to only the fluctuation pressure due to the wave is realized. . The structure shown in FIG.
The film surface is not always necessary, and even if the film surface is removed, the air is always above the water surface, so the wave-eliminating device of the present invention achieves its function. However, since it is inconvenient for horizontal vibration to occur on the water surface in this sub-chamber, in order to prevent this, a partition wall for partitioning the sub-chamber 4 in the vertical direction is provided. FIG. 10 shows that the depth of the membrane surface from the water surface is h '= for a rectangular submersible where the length l is twice the water depth h (= 2.0 h) and the thickness d is 0.2 times (= 0.2 h). 0.2h Submarine spacing B '=
When the film surface is deformed (FIG. 1 or 6) and not deformed (FIG. 7) at 4.0 h, the wave passage rate K _t (ratio between the wave height and the incident wave height) is theoretically calculated. The horizontal axis represents the water depth / wavelength ratio h / L. The solid line is the case where the film surface is deformed (radiated wave), and the broken line is the case where it is not deformed (scattered wave). Comparing the two, it is clear that the wave-eliminating device of the present invention has a remarkable effect of the radiated wave and the passing rate is sufficiently low to perform effective wave-elimination. Regarding the implementation of the present invention, since the submarine is always submerged and there is almost no difference between the internal air pressure and the external water pressure, there is a feature that it is not necessary to give great strength to the submarine and the membrane surface. Yes Great advantage in production and construction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 FIG. 2 FIG. 3 FIG. 4 FIG. 5 is an explanatory diagram relating to the configuration and structure of the device of the present invention, FIG.
FIG. 9 is an explanatory diagram relating to the principle of the present invention. FIG. 10 is a diagram showing the result of theoretical calculation showing the effect of the device of the present invention. 1, 2 ………… Membrane surface 3, 4 ………… Submersible 2 ′ ……………… 1 ′, 2 ″ in the suburb… Upper and lower plates Water surface 4 ′ ……………… Bilateral symmetry 5 …… ………… Left submersible of communication pipe 6,7 ………… Deformed 7 ′ ………… Raised / lowered water surface Membrane surface 8 ……………… Horizontal plate 7 ″ ………… Symmetrical left submersible Deformed membrane surface 9,12 ・ ・ ・ Jack belly 10,13,15 ・ ・ ・ Version 11,14,16 …… Hinge 17 …… Vertical partition OX ………… Still water surface O′X ′ …… Water bottom surface L ……………… Wavelength h, h ′ …… water depth and depth of the submerged membrane surface B ′ ……………… Interval between submarines d ……………… Thickness of the submarine l …………… Length of the submarine W …………… Passed wave W _i ……… Incident wave W _r ……… Radiated wave W _s ……… Scattered wave

Claims (1)

(1) As shown in FIG. 1, a pair of two water-tight and rigid hollow boxes 3 and 4 of substantially the same shape parallel to the traveling direction of the wave in the water area of water depth h (hereinafter referred to as The water-tight membrane surfaces 1 and 2 which can be flexibly deformed are attached to the sub-chamber. Both membrane surfaces are in the horizontal plane h'below the still water surface, and the sub-clauses are located upside down with respect to each other. _i is fixed at an interval of about 1/2 of the wavelength L, and the communication tube 5 is used to allow the air in both sub-chambers to freely flow. A wave-eliminating device (2) having a function of reducing the wave height of a passing wave W traveling to the film. (2) In the wave-eliminating device according to claim 1, the film surfaces 1 and 2 to be attached to the submerged box. 2. A wave breaking device using a system of vertically moving a horizontal plate 8 vertically by a belly 9 as shown in FIG. 2 instead of flexibly deforming the plate (3) In the wave breaking device according to claim 1. A wave breaking device using a plate 10 and a belly 12 and a hinge 11 shown in FIG. 3 in place of the film surfaces 1 and 2 of the latent box (4). The wave breaking device according to claim 1, wherein As shown in FIG. 4, instead of 1 and 2, the plate 13 and the hinge 14 are provided on the horizontal plane, and the plate 15 and the hinge 16 are provided on the vertical side surface of the submarine. Wave extinction device that increases the wave extinction effect by increasing the change in air volume 5) In the wave canceling device according to claim 1, instead of the film surface 2 of the left submarine box 4 shown in FIG. 1, several vertical partition walls 17 are provided as shown in FIG. Wave-eliminating device that allows the water surface to maintain a substantially horizontal position and to move up and down