JP2000289685A - Frictional resistance reducing ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate many fine bubbles on a hull and to effectively reduce the frictional resistance of the hull by erupting gas into the water from the vicinity of the bow during navigation. SOLUTION: In the navigation state of a high-speed ship, gas is fed into a chamber 11 by a gas feeding means 13 and is erupted from holes 10a, and micro-bubbles are generated from the erupted gas. The generated micro-bubbles are moved toward the stern 1d from the vicinity of the bow 1a on water streams on a hull shell plate 1. Diffusion suppressing plates 3. suppressing the water streams toward the water surface L from the hull shell plate 1 are provided, thus the water streams toward the water surface L from the hull shell plate 1 are suppressed, and micro-bubbles hardly flow toward the water surface L from the hull shell plate 1. Micro-bubbles are hardly separated from the hull shell plate 1, the hull shell plate 1 is covered with many micro-bubbles, and the frictional resistance of a hull T can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ship for reducing frictional resistance, and relates to a technique for reducing frictional resistance by interposing minute air bubbles on a hull outer plate of a ship in a sailing state.

[0002]

2. Description of the Related Art JP-A-50-83992 and JP-A-53-1983.
JP-A-136289, JP-A-60-139586, JP-A-61-71290, JP-A-61-39691, and JP-A-61-128185 disclose a technique relating to a ship with reduced frictional resistance. I have. This friction drag reduction ship,
In the navigation state, gas such as air is blown out into the water from the hull surface (hull skin), causing a large number of microbubbles to intervene on the hull skin. Is to reduce the frictional resistance acting on the surface.

The present applicant has proposed a technique relating to such a frictional resistance reducing ship, in which a gas (for example, air) is blown into water from near the bow to interpose microbubbles on the hull outer plate. . This technique intends to diffuse microbubbles generated by ejecting gas from the vicinity of a bow along a streamline of water on a hull outer plate, and cover the entire hull with microbubbles.

[0004]

However, in order to cover the entire hull with microbubbles, if the microbubbles are diffused without restriction along the streamlines of water on the hull outer plate, the hull outer plate will reach the water surface. It has been found that the number of microbubbles that move away from the hull skin along with the flowing water flow increases, which partially reduces the effect of the microbubbles on reducing frictional resistance. In particular, in a high-speed ship, the bottom of the ship is relatively small compared to the ship side, and water tends to flow from the vicinity of the ship bottom to the surface of the water. further,
In a high-speed ship, the velocity of water on the hull skin increases as the sailing speed increases, so the turbulence increases and the water diffuses, making it easier for the microbubbles to separate from the hull skin and causing friction due to the microbubbles. It is difficult to obtain the effect of reducing the resistance.

The present invention has been made in view of the above-described problems, and has the following objects. (1) The frictional resistance of the hull is effectively reduced by interposing more microbubbles in the hull. (2) The power of the hull during navigation is reduced.

[0006]

The invention according to claim 1 is
In a ship that reduces frictional resistance between the hull and water by injecting gas into the water from the vicinity of the bow while navigating, the frictional resistance between the hull and water is reduced. Means provided with a projection for suppressing the flow of water from the plate toward the water surface is employed. This frictional resistance reducing ship is provided with a projection that suppresses the flow of water from above the hull skin to the water surface, so that the flow of water from above the hull skin to the water surface is suppressed, and It becomes difficult for microbubbles to flow from the outer skin of the hull toward the water surface. This makes it difficult for the microbubbles to separate from the hull skin, and many microbubbles cover the hull skin.

According to a second aspect of the present invention, in the frictional resistance reducing ship according to the first aspect, the projection is formed in the vicinity of the bottom of the boundary layer formed on the hull outer plate in the flow of water from the hull outer plate to the water surface. The means provided at the height which suppresses only the flow of water is adopted. In this frictional resistance reducing ship, the projections are erected at a height that suppresses the flow of water near the bottom of the boundary layer (turbulent boundary layer) formed on the hull skin, so that wave-making resistance is reduced. Does not increase too much. In addition, it has been found that among the microbubbles that flow on the hull skin of a ship with reduced frictional resistance, the microbubbles near the bottom of the boundary layer generally work most effectively to reduce frictional resistance. Since the protrusion suppresses the flow of water near the bottom, the flow of the microbubbles toward the water surface, which is effective in reducing the frictional resistance, is suppressed.

The invention according to claim 3 is the invention according to claim 1 or 2
In the frictional resistance reducing ship of (1), means is used in which the projection is provided extending from the vicinity of the bow in the stern direction. In this frictional resistance reducing ship, since the protrusion is provided extending from the vicinity of the bow in the stern direction, the flow of water from the hull outer plate to the water surface is continuously suppressed.

According to a fourth aspect of the present invention, in the frictional resistance reducing ship according to the third aspect, a means is employed in which the projections are provided on both sides of the bottom of the ship. In this frictional resistance reducing ship, the projections are provided on both sides of the ship with the bottom sandwiched therebetween, and a large amount of microbubbles intervene in a region mainly located on the bottom sandwiched between the projections.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a ship for reducing frictional resistance according to the present invention will be described below with reference to FIGS. In this embodiment, the present invention is applied to a high-speed ship. FIG. 1 is a diagram showing the main configuration of this high-speed ship.
(A) is a side view, (b) is a bottom view. 2 is a sectional view taken along the line AA shown in FIG. 1, and FIG. 3 is a sectional view taken along the line BB shown in FIG. In these figures, reference symbol T indicates a hull, 1 indicates a hull skin, and L indicates a water surface. Reference numeral 2 denotes a gas blowing portion for blowing out gas, and reference numeral 3 denotes a diffusion suppressing plate which is a projection for suppressing the flow of water from the hull outer plate 1 to the water surface L.

The hull T is formed in a substantially spherical shape with the bow 1a protruding downward from the bottom 1c and protruding forward of the bow 1a, and ejects gas (for example, air) into the water near the top protruding downward. A gas blowing section 2 is provided.

As shown in the enlarged sectional view of FIG. 4, the gas blowing section 2 is formed in a concave shape recessed from the hull outer panel 1. Further, a blowing plate 10 curved toward the inside of the hull is fixed to the hull outer plate 1, and the blowing plate 10 has a large number of holes 10a. A partition 12 is provided on the inner side of the hull of the gas blowing section 2 so as to form a chamber 11, and is connected to gas supply means 13 for supplying gas into the chamber 11. FIG. 5 is a front view of the gas blowing unit 2, and the gas blowing unit 2 includes a hull T
Is formed in an elliptical shape having a major axis in the width direction.

The diffusion suppressing plate 3 is disposed on the water surface L from above the hull outer plate 1.
In the flow of water heading toward the hull outer plate 1, the water is set up at a height (for example, 10 mm) that suppresses only the flow of water near the bottom of the boundary layer (turbulent boundary layer) formed on the hull shell 1. As shown in the sectional views of FIGS. 2 and 3, the diffusion suppressing plate 3 is formed of a plate-like member having a substantially rectangular cross section,
It is joined to the hull outer panel 1 by welding.

As shown in FIG. 1, the diffusion suppressing plates 3 are provided to extend in the longitudinal direction from the vicinity of the bow 1a in the direction of the stern 1d, and are provided one by one on each of the right and left sides of the ship bottom 1c. . The diffusion suppressing plate 3 is provided near the bow 1a and the stern 1d.
The distance between the two is gradually widened toward the bottom, and the water surface L is gradually approached from the vicinity of the bottom 1c. Also, FIG. 3 (AA sectional view) and FIG.
As shown in (BB sectional view), the hull T is closer to the center of the hull T in the longitudinal direction (BB sectional view) than the vicinity of the bow 1a (AA sectional view). A relatively flat portion is formed widely, and the interval between the diffusion suppressing plates 3 is determined according to the spread of the flat portion of the ship bottom 1c.

As shown in FIG. 2, a cooling water inlet 14 provided inside the hull for taking in water for cooling the inboard equipment is arranged at a position closer to the water surface L than the diffusion suppressing plate 3. . A valve 14a and a pump (not shown) are connected to the cooling water inlet 14 on the inner side of the hull, and these pumps operate the pump to take in water and cool down onboard equipment such as a generator inside the hull T. It is configured to send water for use.

Next, the operation of the thus constructed high speed ship will be described. When the high-speed ship is in the navigating state, gas is supplied into the chamber 11 by the gas supply means 13. Then, in the gas blowing section 2, the supplied gas is jetted from the holes 10a, and microbubbles are generated from the jetted gas. The generated microbubbles move from the vicinity of the bow 1a toward the stern 1d, riding on the flow of water on the hull outer panel 1.

At this time, the gas blowing portion 2 is provided on the protruding top of the bow 1a, and the flow velocity of water flowing along the hull outer plate 1 increases at the top, so that the gas blowing portion 2 The pressure drops. Thereby, the gas supply means 13
Gas can be ejected with small power.

Further, in this embodiment, since the diffusion suppressing plate 3 for suppressing the flow of water from the hull outer plate 1 to the water surface L is provided, the flow of water from the hull outer plate 1 to the water surface L is provided. Is suppressed, and microbubbles flowing along with the flow of water are less likely to flow from above the hull outer panel 1 in the direction of the water surface L.
As a result, the microbubbles are less likely to separate from the hull outer panel 1, and many microbubbles cover the hull outer panel 1, so that the frictional resistance of the hull T can be effectively reduced.

Further, since the diffusion suppressing plate 3 is erected at a height that suppresses only the flow of water near the bottom of the boundary layer (turbulent boundary layer) formed on the hull outer panel 1, It does not make the wave resistance too large. Further, in the frictional resistance reducing ship, of the microbubbles flowing on the hull skin 1, microbubbles near the bottom of the boundary layer most effectively act to reduce the frictional resistance, so that water near the bottom of the boundary layer is reduced. By suppressing the flow by the diffusion suppressing plate 3, many microbubbles effective for reducing the frictional resistance are present near the surface of the hull outer plate 1. As a result, the frictional resistance can be effectively reduced without greatly increasing the wave-making resistance, and the power required for navigation of the hull T can be effectively reduced.

Further, the diffusion suppressing plates 3 erected on both the left and right sides.
Is provided extending from the vicinity of the bow 1a in the direction of the stern 1d, so that the flow of water from above the hull outer plate 1 to the water surface L is continuously suppressed. In addition, the diffusion suppressing plate 3 is a ship bottom 1c.
Is provided on both sides of the ship, and a large amount of microbubbles is interposed in a region mainly around the bottom 1c of the diffusion suppressing plate 3 from the vicinity of the bow 1a to the stern 1d. In a ship with reduced frictional resistance, microbubbles interposed in the ship bottom 1c are particularly effective in reducing frictional resistance. Further, in general, in a high-speed ship, water is easily diffused, and microbubbles are easily separated from the hull outer panel 1. However, as in the present embodiment, the diffusion suppressing plate 3 is appropriately disposed on the hull outer panel 1, and the bottom 1c By interposing a large number of microbubbles in a predetermined region mainly composed of the above, the effect of reducing the frictional resistance by the microbubbles can be easily obtained in a high-speed ship.

In the present embodiment, the cooling water intake 14
However, since the microbubbles whose movement toward the water surface L is suppressed by the diffusion suppression plate 3 are arranged at a position closer to the water surface L than the diffusion suppression plate 3, the amount of inflow to the cooling water inlet 14 decreases. . Therefore, there is a low possibility that the gas contained in the water flowing into the cooling water inlet 14 causes a trouble in the onboard equipment.

FIG. 5 is a sectional view showing a main part of another embodiment of the present invention.
Hull U is a catamaran. Also in the hull U of this catamaran, the same diffusion suppression plate 20 as that shown in the above-described embodiment is erected on each of the hull outer plates 21 and 22 of the hull U. As a result, more microbubbles intervene in the effective area on the ship bottom and on the ship side, and the frictional resistance can be effectively reduced.
As described above, the present invention can effectively reduce the frictional resistance simply by appropriately setting the diffusion suppressing plate in accordance with the hull shape, so that it can flexibly cope with various shapes of the hull. It is possible.

[0023]

As described above, according to the present invention, the following effects can be obtained. In the frictional resistance reducing ship according to the first aspect, the flow of the water from the hull outer plate toward the water surface is suppressed by the projection, and the microbubbles flowing along the flow of the water are less likely to flow from the hull outer plate toward the water surface. Therefore, the microbubbles are less likely to separate from the hull outer plate, and many microbubbles cover the hull outer plate, so that the frictional resistance of the hull can be effectively reduced.

According to the second aspect of the present invention, the projection is provided so as to have a height that suppresses the flow of water near the bottom of the boundary layer (turbulent boundary layer) formed on the hull outer panel. As a result, many microbubbles near the bottom of the boundary layer, which are effective in reducing frictional resistance, will intervene near the surface of the hull outer panel,
The frictional resistance can be effectively reduced without significantly increasing the wave-making resistance, and the power required for navigation of the hull can be effectively reduced.

In the frictional resistance reducing ship according to the third aspect, the projection is provided extending from the vicinity of the bow in the stern direction.
The flow of water from the hull skin to the water surface can be continuously suppressed, and more microbubbles can be interposed on the hull skin.

In the frictional resistance reducing ship according to the fourth aspect, the protrusion is provided on both sides with the ship bottom sandwiched therebetween, so that a large amount of microbubbles is interposed in a region mainly of the ship bottom sandwiched between the protrusions. Therefore, the frictional resistance can be reduced more effectively.
Also, in a high-speed ship where water is easily diffused and microbubbles are easily separated from the hull skin, the protrusions are appropriately arranged on the hull skin so that many microbubbles are interposed in a predetermined area mainly at the bottom of the ship. By doing so, the effect of reducing frictional resistance due to the microbubbles can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a side view and a bottom view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA shown in FIG.

FIG. 3 is a sectional view taken along line BB shown in FIG.

FIG. 4 is a cross-sectional view of a gas blowing section according to one embodiment of the present invention.

FIG. 5 is a front view of a gas blowing section according to one embodiment of the present invention.

FIG. 6 is a cross-sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 T, U Hull L Water surface 1, 21, 22 Hull outer plate 1a Bow 1b Ship side 1c Bottom 2 Gas outlet 3,20 Diffusion suppressing plate (projection) 14 Cooling water intake

Claims (4)

[Claims] 1. A gas is blown out into the water from the vicinity of a bow (1a) during navigation to reduce frictional resistance between a hull (T) and water by interposing fine bubbles on a hull outer plate (1). In the frictional resistance reducing ship, the hull skin (1) is provided with a projection (3) for suppressing a flow of water from above the hull skin (1) toward the water surface (L). To reduce frictional resistance. 2. The projection (3) is provided on the hull skin (1).
It is characterized by being provided at a height that suppresses the flow of water near the bottom of the boundary layer formed on the hull skin (1), of the flow of water from above toward the water surface (L). The frictional resistance reducing ship according to claim 1. 3. A boat with reduced frictional resistance according to claim 1, wherein said projection (3) is provided to extend from near the bow (1a) toward the stern (1d). 4. The frictional resistance reducing ship according to claim 3, wherein the projections (3) are provided on both sides of the ship with the ship bottom (1c) interposed therebetween.