JP2000272578A - Frictional resistance reducing ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost of construction of a hull while power required for injecting gas is reduced, by providing a blow port injecting gas to a separation region in a protrusion part set up to a hull shell plate so as to form the separation region in the water. SOLUTION: A gas blow part 2 provided in a hull in the vicinity of a bow of a hull shell plate 1 is provided with a blow port 12 in the downstream end part 11b of a nozzle shell plate 11 covering a hull shell plate opening hole 10 formed with a slot in a hull width direction of the hull shell plate 1 from outside a hull, also a rectangular chamber 13 is formed by providing a partition 14 inside the hull. A downstream end part 11b of the nozzle shell plate 11 set up in a condition protruded from the hull shell plate 1 is formed in almost L at a right angle in a rapidly closing shape, and a separation region Wa decreasing pressure by a separation vortex or the like is formed in the water in the vicinity of the downstream end part 11b. In this way, a supply pressure of gas can be low suppressed in the case that the gas supplied from a gas supplier 3 is jetted into the separation region Wa from the blow port 12, so that power required for injecting the gas 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. Conventionally, when injecting gas into water, a plate made of a porous material such as a porous plate or a plate having a large number of holes is arranged near the bow, and gas is ejected through the holes in these plates. Is going.

[0004]

However, when a gas is ejected using a porous plate, the power required for ejecting the gas increases because the pressure loss when passing the gas through the porous plate is extremely large. However, the savings in navigation power reduced by microbubbles are reduced.
In addition, when gas is blown out using a plate with a large number of holes, it is necessary to perform complicated processing on the plate or the outer shell of the hull, resulting in large costs and a lot of time. Would.

The present invention has been made in view of the above-described problems, and has the following objects. (1) The power required for gas ejection is reduced, thereby reducing the power required when the ship is navigating. (2) The construction cost of the hull is reduced.

[0006]

In order to achieve the above object, according to the present invention, as a first means relating to a frictional resistance reducing ship, a gas is blown out from the vicinity of a bow into the water during navigation so that the ship is provided with an outer hull. In a frictional resistance reduction ship that reduces the frictional resistance between the hull and water by interposing fine bubbles on the board, a protrusion installed on the hull outer plate so as to form a separation area in the water, and a gas in the separation area A means having a blowout outlet is employed. Further, as the second means, in the first means, a means is employed in which the blow-out port has a shape in which a gas is jetted downstream in the separation area. Further, as a third means, in the first or second means, a means in which the gas blowing portion is formed in a shape having a small resistance is employed. As a fourth means, in any one of the first to third means, the projection is disposed on the bottom of the ship near the bow while extending in the width direction of the hull, and the outlet is provided in the width direction of the hull. A means formed in a long slit shape is employed.

[0007]

FIGS. 1 and 2 are graphs showing characteristics of a model ship, in which gas (air) is jetted into water by the above-described means according to the present invention (nozzle type), and into a water through a conventional porous plate. It is compared with the case of blowing out air (porous plate). FIG. 1 shows the change in the total resistance of the model ship with respect to the air flow rate, and FIG. 2 shows the change in the differential pressure with respect to the air flow rate when the sailing speed of each model ship is 7 m / s. The differential pressure here indicates the pressure difference between the inside of the air supply pipe (gas supply pipe) and the bottom of the ship.

FIG. 1 shows that in a conventional model ship using a porous plate, the differential pressure increases significantly with an increase in the air flow rate. This is because the pressure loss in the porous plate when passing air through the porous plate is extremely large, and it is difficult to jet a predetermined amount of air unless the pressure on the gas supply side is increased. In addition, when the pressure on the gas supply side increases, the power required for gas supply increases. Even if the frictional resistance of the hull is reduced by microbubbles to reduce the navigating power, the savings are reduced by the power for gas supply. Will be reduced by the increase in

Therefore, in order to effectively reduce the navigating force by reducing the frictional resistance due to the microbubbles, it is necessary to reduce the power for supplying the gas. One of the methods is to reduce the pressure on the gas supply side. It is important to control. In order to keep the pressure on the gas supply side low, it is necessary to omit elements having a large pressure loss, such as a porous plate, and to reduce the water pressure on the outlet side for jetting air. In particular, the water pressure at the bottom of the ship is further increased according to the depth, and when the outlet is disposed at such a position, it is necessary to take sufficient measures to reduce the water pressure. Generally, in a fluid, for example, behind a dull object whose rear end is sharply closed, a separation area is formed, in which pressure decreases. Therefore, the present invention employs the above-described means in order to reduce the pressure at the air outlet.

Referring again to FIG. 1, when the above means is used (nozzle type), even if the air flow rate increases, the state where the differential pressure is small is maintained, and the pressure on the gas supply side is low. It turns out that it is suppressed. That is, according to the above-described means, since a projection provided on the hull outer plate so as to form a separation area in water and an air outlet for jetting air in the separation area are provided, from the air outlet in the separation area with low water pressure. Air can be jetted, the pressure on the gas supply side can be kept low, and the power required for jetting can be reduced.

FIG. 2 shows that regardless of the air flow rate, the model ship according to the above-described means exhibits almost the same total resistance as the model ship using the conventional porous plate. In the case of a porous plate, previous studies have confirmed that microbubbles can reduce the frictional resistance, and the total resistance shown in Fig. 2 is the hull where the frictional resistance was reduced by the microbubbles. Is the resistance value. Therefore, FIG. 1 shows that even in the model ship by the above-described means, the same frictional resistance reduction effect as that of the porous plate can be obtained. That is, according to the above-described means, it is possible to reduce the above-described power required for jetting the gas, and at the same time, it is possible to obtain the same effect of reducing the frictional resistance as in the related art.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the present invention is applied to a flat bottom ship such as a tanker. FIGS. 3A and 3B are diagrams showing a main configuration of the frictional resistance reducing boat A according to the present embodiment. FIG. 3A is a side view (starboard side) near the bow, and FIG. 3B is a bottom view. In this figure, reference numeral 1 denotes a hull skin, 2 denotes a gas blowing unit, 3 denotes a gas supply device, L
Is a waterline.

A gas outlet 2 is provided on the bottom 1b of the hull 1 near the bow 1a. The gas blowing part 2
As shown in the cross-sectional views of FIGS. 4 and 5, a hull outer plate opening hole 10 formed in the hull outer plate 1 and being a long hole in the hull width direction, and covers the hull outer plate opening hole 10 from the outside of the hull. Skin 11 formed as described above and this nozzle skin 11
And a partition 14 provided to form a rectangular chamber 13 inside the hull of the hull outer plate opening 10, and these are mainly configured. ing.

The nozzle outer plate 11 projects from the hull outer plate 1 at a predetermined height from the hull outer plate 1 so that the cross-sectional shape shown in FIG. 4 has a substantially trapezoidal shape having a slope on the end face 11a on the upstream side (bow side). It is formed by a plate-shaped member in the state as described above. And the nozzle outer plate 11 is a downstream end (stern side) end 11b.
Is formed in a substantially L-shape having right-angled corners, and is a non-smooth, sharply closed shape, so that a peeling area Wa is generated in the downstream water immediately after that. Further, as shown in FIG. 3, the nozzle outer plate 11 is disposed on the bottom 1 b near the bow 1 a while extending in the width direction of the hull.
Along with this, a peeling area Wa is formed over the hull width direction.

The air outlet 12 is a rectangular opening formed at the downstream end (stern side) 11b of the nozzle outer plate 11 facing the downstream side, and has a length substantially equal to that of the hull outer plate opening hole 10. And is formed in a slit shape elongated in the hull width direction. Thus, the blow-out port 12 blows out the gas supplied from the gas supply device 3 toward the downstream side within the separation area Wa formed by the nozzle outer plate 11. The slit width (height) p of the outlet 12 is, for example, 2 mm. Due to this slit width p, the nozzle outer plate 1
The height of the projection 1 from the hull outer plate 1 is determined, and the height of the nozzle outer plate 11 is extremely small compared with the size of the entire hull, and therefore, the wave-making resistance is small.

The gas supply device 3 is provided inside the hull,
The gas supply pipe 15 is connected to supply gas to the chamber 13. The gas supply device 3 includes, for example, a blower (not shown) and a control unit, and the control unit controls the blower to control a gas supply amount to be supplied to the gas blowing unit 2.

When the gas (air) is supplied from the gas supply device 3 in the frictional resistance reducing ship A thus configured, the pressure of the gas is made uniform in the chamber 13. Then, this gas is sent to the inside of the nozzle outer plate 11 through the hull outer plate opening hole 10, the flow direction is changed by the nozzle outer plate 11 to the downstream direction, and then the gas is ejected from the outlet 12 to the downstream method. Is done. Then, microbubbles (microbubbles) are generated from the jetted gas by the shear flow in the turbulent boundary layer formed on the surface of the hull shell 1, and the microbubbles are generated by the flow of water flowing through the bottom 1b. It is diffused along the line and covers the bottom 1b. Then, the frictional resistance of the hull shell 1 against water is reduced due to the interposition of the microbubbles, whereby the navigating power of the ship A with reduced frictional resistance is reduced.

At this time, the nozzle outer panel 11 is installed so as to protrude from the hull outer panel 1 and has a downstream end 11b.
Is abruptly closed, so that the downstream end 1
A separation area Wa is formed in the water near 1b, and in the separation area Wa, the pressure decreases due to an internal separation vortex or the like. In the present embodiment, since the gas is ejected from the outlet 12 in the separation area Wa, the supply pressure of the gas is kept low, and the power required for ejecting the gas is reduced. Further, since the nozzle outer plate 11 has a shape in which the protruding height is extremely small compared with the size of the entire hull and the wave making resistance is small, a local increase in resistance to water by the gas blowing unit 2 can be ignored. It does not have a significant effect on navigational ability. The outlet 12
Is provided to eject gas in the downstream direction (stern direction), so that gas can be flowed into water without difficulty, and the power required for gas ejection is lower than when ejecting in other directions. Less is needed.

Further, the air outlet 12 is formed in a long slit shape in the width direction of the hull, and gas is blown from the entire area of the long air outlet 12 into the separation area Wa, so that microbubbles are generated in the width direction of the hull. It becomes easy to be interposed, and it is possible to effectively reduce the frictional resistance of the hull outer panel 1.

Furthermore, since the gas outlet 2 has the outlet 12 formed in a slit shape by a plate-like member, and requires almost no complicated processing, the time and cost required for the processing can be reduced. In addition, the outlet 12
Hole 1 formed on the hull skin 1 side to send gas to
0 may be a simple structure such as a long hole, and the processing cost can be significantly reduced, thereby reducing the construction cost of the hull.

In this embodiment, the present invention is applied to a flat-bottom ship. However, the hull is not limited to a flat-bottom ship, and may be a hull having a curved bottom.

In the present embodiment, the outlet 12 is a single rectangular opening having a slit shape.
It is also possible to arrange a plurality of partition plates inside one and divide it into a plurality of openings. Further, a plurality of gas supply pipes 15 connected to the chamber 13 may be provided in the hull width direction, whereby the gas can be more uniformly ejected in the hull width direction.

[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 separation portion having a low water pressure is generated by the projection, and the gas is jetted from the outlet in the separation region, so that the power required for jetting the gas can be significantly reduced. .
For this reason, the power required for jetting the gas does not significantly reduce the saving of the navigating power due to the microbubbles, and the power during the navigation of the ship can be reduced.

In the frictional resistance reducing ship according to the second aspect, since the blowout port blows the gas in the downstream direction in the separation area, the gas can be flowed into the water without difficulty, and the gas is blown out. The required power can be reduced as compared with the case of jetting in the other direction.

According to the third aspect of the present invention, since the wave-making resistance of the projection is suppressed to a small value, a local increase in resistance in water due to the projection can be suppressed, and the projection exerts an influence on the sailing power of the ship. The influence can be reduced.

In the frictional resistance reducing ship according to the fourth aspect, since the air outlet for jetting gas into the water is formed in a slit shape, complicated processing such as forming a large number of holes is not required, and the time required for processing is not required. And cost can be greatly reduced. In addition, the opening holes formed on the hull outer plate side to send gas to the air outlet along with this need only have a simple structure such as long holes, so that the processing cost can be greatly reduced, and by these, the construction cost of the hull Can be reduced.

[Brief description of the drawings]

FIG. 1 is a graph illustrating characteristics when the means according to the present invention is applied to a model ship.

FIG. 2 is a graph illustrating characteristics when the means according to the present invention is applied to a model ship.

FIG. 3 is a side view and a bottom view of a main part of the ship for reducing frictional resistance according to an embodiment of the present invention.

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

FIG. 5 is a rear cross-sectional view showing an outline of a gas blowing section according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS A Friction resistance reduction ship L Waterline Wa Separation area 1 Hull outer plate 2 Gas blowing part 1a Bow 1b Ship bottom 11 Nozzle outer plate (projection) 12 Outlet 15 Gas supply piping

Claims (4)

[Claims] 1. A frictional resistance is reduced by jetting gas into the water from the vicinity of a bow (1a) during navigation, thereby reducing frictional resistance between the hull and water by interposing fine bubbles on the hull outer plate (1). In the ship, a protrusion (11) installed on the hull outer panel (1) so as to form a separation area (Wa) in water, and an outlet (12) for jetting gas in the separation area (Wa).
A frictional resistance reduction ship comprising: 2. The discharge port (12) is provided in the separation area (W).
2. The frictional resistance reducing ship according to claim 1, wherein the shape is such that a gas is jetted downstream in a). 3. The frictional resistance reducing ship according to claim 1, wherein the projecting portion is formed in a shape having a small resistance. 4. The protruding portion (11) is disposed on a ship bottom (1b) near a bow (1a) in a state of extending in a hull width direction, and the outlet (12) has a slit elongated in a hull width direction. The frictional resistance reducing ship according to any one of claims 1 to 3, wherein the ship is formed in a shape.