JP2002274478A - Frictional resistance reducing device of ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frictional resistance reducing device of a ship for achieving frictional resistance of the ship with the inexpensive constitution. SOLUTION: An air injection pipe 1 having an ejector X using water L1 as a driving fluid, and air A as a driven fluid, is arranged in a state of pointing a water intake port 7 forward in the sailing direction of a hull 20 in the water, and opening a blowout port 6 in the vicinity of a ship's bottom surface. With such constitution, when dynamic pressure of the water L1 acting on the water intake port 7 exceeds water pressure acting on an blowout port 6 part on the ship's bottom surface 22 side, when the water L1 flows in from the water intake port 7 by the differential pressure and flows to the blowout port 6 side by passing through the ejector X, the air A is sucked in by the sucking action of the water L1 , and becomes bubble mixed water L2 including innumerable bubbles 10, and is blown out to the ship's bottom 22 side from the blowout port 6, a surface of the ship's bottom surface 22 and a ship's space surface 21 is covered with the innumerable bubbles 10 rising by buoyancy, and the frictional resistance to the water L1 is reduced to enhance propelling performance of the hull 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reducing frictional resistance of a ship using air bubbles.

[0002]

2. Description of the Related Art Heretofore, there has been an idea of improving the propulsion performance of a ship by reducing frictional resistance caused by the viscosity of water when the ship sails, and as one means for realizing this, a submerged portion of the ship is used. A technique has been proposed in which air is blown into the surface of a surface to generate air bubbles, and the surface of the submerged portion is covered with the air bubbles to reduce frictional resistance (for example, Japanese Patent Application Laid-Open No. H08-163,086).
000-142555 and JP-A-9-118288).

[0003]

However, the friction resistance reducing apparatus proposed in the prior art has a structure in which compressed air is forcibly blown into a submerged portion of a ship to generate air bubbles. It is necessary to provide a pressurized air supply source such as a dedicated one, so that the production cost of the apparatus is high, and the driving power of the compressor is also required for the operation, so that the operation cost is high. , Etc.

Accordingly, an object of the present invention is to provide a frictional resistance reducing device for a ship which can realize the frictional resistance of the ship with a less expensive configuration.

[0005]

As specific means for solving the above problems SUMMARY OF THE INVENTION The frictional resistance reduction device for a vessel according to the present invention, the driving fluid water L _1, which is taken from water intake 7 air intake An air injection pipe 1 provided with an ejector X that uses air A taken in from 9 as a driven fluid and having an ejection port 6 provided downstream of the ejector X,
It is characterized in that the water intake port 7 is directed forward in the traveling direction of the hull 20 in the water, and the jet port 6 is arranged so as to be opened near the bottom face 22 of the boat.

[0006]

According to the apparatus for reducing frictional resistance of a ship according to the present invention, the following effects can be obtained.

That is, when the hull 20 travels, the water L ₁ colliding with the water intake port 7 is supplied to the water intake port 7 as the hull 20 travels.
The dynamic pressure due to acts. Since the dynamic pressure increases as the cruising speed of the hull 20 increases, when the cruising speed reaches a predetermined speed or higher, the power acting on the water intake 7 is supplied to the injection port located on the bottom surface 22 side of the hull 20. beyond the water pressure acting on the outlet 6 parts, by the differential pressure of both of them, water L ₁ from the water intake 7 flows, will be incorporated into the air injection tube 1.

The water L ₁ introduced into the air injection pipe 1 from the water intake port 7 flows through the ejector X to the jet port 6 side, and is jetted out of the water toward the ship bottom 22 side. that is, in this case, in the ejector X, water L ₁ is a driving fluid flowing here, air a as the driving fluid is sucked from the air inlet 9, the air a is mixed into water L ₁ and it produced bubbly water L ₂ which contains an infinite number of bubbles 10 by being agitated, the bubbly water L ₂ flows toward the ejection port 6 side, the vessel bottom and eventually from該噴outlet 6 It is ejected near the surface 22. Then, the myriad of bubbles 10 mixed in the bubble-mixed water L ₂
Separates sequentially from the water L _1, the water rises buoyancy. This by countless bubbles 10 of buoyancy increase the surface of the ship bottom surfaces 22 and tonnage surface 21 of the hull 20 is covered, the frictional resistance in the ship bottom 22 and tonnage surface 21 due to the viscosity of water L ₁ is reduced, this The hull 2 is reduced by the reduced frictional resistance.
0 propulsion performance will be improved.

As described above, according to the apparatus for reducing the frictional resistance of a ship according to the present invention, the dynamic pressure of water inevitably generated as the hull 20 travels is used to make the hull 20 closer to the bottom surface 22 of the hull 20. Since air can be injected into the air as bubbles 10 and does not require a pressurized air generation source such as a compressor as in the prior art, a frictional resistance reduction device can be provided at lower cost and the operating cost can be reduced. Useful effects such as suppression can be obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described based on preferred embodiments.

FIG. 1 shows a state in which the frictional resistance reducing device according to the present invention is attached to the bow of a hull 20. This frictional resistance reducing device uses the dynamic pressure of water accompanying the navigation of the hull 20 to inject air as bubbles into the ship bottom surface 22 side, and countless air bubbles rising in buoyancy increase the ship bottom surface 22.
And for reducing the frictional resistance with water by covering the surface of the ship's abdominal surface 21, and is provided with the air injection pipe 1 described below.

As shown in FIG. 2, the air injection pipe 1 is formed of a pipe having a predetermined diameter.
At one end 1a side, a water intake port 7 opening to the side surface is provided.
The nozzle 2 is connected to the water inlet 7 so as to extend coaxially within the air injection pipe 1. Further, an air chamber 8 having an air inlet 9 is provided outside the nozzle 2 so as to include the nozzle 2. Also, on the tip side of the nozzle 2,
A throat 3 that gradually changes in diameter while surrounding the tip of the nozzle 2 and extends with a constant diameter, and a diffuser 4 that gradually changes in diameter continuously at the tip of the throat 3 are provided. Throat 3 and diffuser 4
This constitutes an ejector X.

On the other hand, the other end 1b of the air injection pipe 1 is
The hull 20 is appropriately curved so as to correspond to the curvature of the corner portions of the flank 21 and the bottom 22 of the hull 20.

The air injection pipe 1 constructed as described above.
Are arranged along the abdominal surface 21 on the bow side of the hull 20 with the one end 1a facing upward and the other end 1b facing downward, and constitute a frictional resistance reducing device. In this case, when the air injection pipe 1 is arranged on the hull 20 side, the jet port 6 is opened near the bottom 22 of the hull 20, and the water intake port 7 is immersed in water of a predetermined depth. The length of the air injection pipe 1 and the length of the hull 20 are set so that the hull 20 is directed forward in the running direction, and the air intake 9 is opened at a predetermined height above the water surface.
The mounting height, mounting direction, etc. are set.

In the frictional resistance reducing apparatus according to the present invention, the number of the air injection pipes 1 is not limited, and a plurality of the air injection pipes 1 may be juxtaposed if necessary. 1 can also constitute a frictional resistance reducing device. In this case, for example, as shown in FIG.
1 or the ship's side 21 extending linearly in the bow and stern direction
, A plurality of air injection pipes 1, 1,... Are arranged with their water intake ports 7 being directed forward in the traveling direction of the hull 20.

Next, the operation and effect of the frictional resistance reducing device provided with the air injection pipe 1 will be described.

First, when the hull 20 is stopped, or when the hull 20 is traveling at a low speed below a predetermined speed, the water L ₁ caused by the hull 20 traveling is supplied to the water intake port 7.
Or dynamic pressure of not acting, from less than the water pressure acting on the spout 6 as was acting, internal air injection tube 1 is in a state filled with water L _1.

When the cruising speed of the hull 20 increases and the dynamic pressure of the water L ₁ applied to the water inlet 7 increases in accordance with the cruising speed, and this exceeds the water pressure acting on the jet port 6. ,
Due to the pressure difference between these two, the water L _{1 in the} forward direction of travel is
But while extruding water L ₁ already present in the air injection pipe 1 downward, taken sequentially the water taking flows from the inlet 7 above the air injecting pipe 1, it flows toward the ejector X side .

In the ejector X portion, the water L ₁ taken in from the water intake port 7 is sequentially jetted from the nozzle 2 to the throat 3 side, so that the pressure of the jetted water flow is reduced and the suction force is reduced. Occurs. Thus, while the water L ₁ is filled in the air chamber 8, the suction force of the jet water flow acts on the water L _1, water L ₁ is the nozzle 2
And flows toward the jet port 6 side integrally.

[0020] Then, as water L ₁ from the air chamber 8 is discharged, water L ₁ of the gas chamber 8 is gradually replaced by the air A introduced from the air inlet 9, the gas chamber 8
The inside will be filled with air A. Air chamber 8 above
When the inside is filled with the air A, the suction force of the jet water flow from the nozzle 2 acts on the air A in the air chamber 8, and the air A is sequentially sucked to the ejector X side and the jet water flow from the nozzle 2 by mixed is stirred and, the bubbly water L ₂ containing a myriad of gas bubbles 10 are generated. After the pressure of the bubble-containing water L ₂ is increased in the diffuser 4, the water L ₂ sequentially flows toward the jet port 6 and is blown out from the jet port 6 toward the vicinity of the ship bottom surface 22.

The myriad of bubbles 10 blown out into the water as the bubbly water L ₂ from the ejection port 6, wherein the separated water L _1, sequentially buoyancy rises towards the water surface W side. The surface of the hull bottom surface 22 or the flank surface 21 of the hull 20 is covered with the innumerable bubbles 10 whose buoyancy rises, so that the frictional resistance of the hull bottom surface 22 or the hull surface 21 is reduced, and the propulsion performance of the hull 20 is accordingly reduced. Is to be improved.

As described above, according to the frictional resistance reducing device of this embodiment, the dynamic pressure of water inevitably generated as the hull 20 travels is used to move the hull 20 toward the bottom surface 22 of the hull 20. Since air can be injected as air bubbles 10 and does not require a pressurized air generation source such as a conventional compressor, the frictional resistance reducing device itself can be provided at a lower cost, and its operating costs can be reduced. It can be suppressed.

The throat 3 parts of the ejector X
Water L from the nozzle 2 in minutes ₁Spouting water stream into air
A is mixed with water L_TwoAs this is the above diff
When flowing from the fuser 4 to the jet port 6 side, the bubble 1
0 naturally has its own buoyancy, but the buoyancy of this bubble 10
The bubbled water L is higher than the rising speed._TwoHigh flow velocity
Below, the bubble 10 does not increase buoyancy,
Water L_TwoFlows to the above-mentioned ejection port 6 side
No obstacles will occur.

In this case, since the air chamber 8 is communicated with the outside air through the air intake 9, the air A introduced into the air chamber 8 from the air intake 9 is supplied to the air intake 8. Since the pressure in the air chamber 8 is reduced to a negative pressure at the inlet 9, the suction effect on the air A by the jet water flow from the ejector X is properly maintained, and the air bubbles 10 are injected into the vicinity of the bottom surface 22 of the ship. The action will be performed continuously in good condition.

Further, in this embodiment, the water intake port 7 and the ejector X are provided near one end 1a of the air injection pipe 1 (ie, at a position relatively close to the water surface W). Of course, the set position can be appropriately changed according to various conditions such as the traveling speed of the hull 20 and the depth position of the bottom surface 22. The same applies to the setting of the diameter of the water inlet 7 and the ejector X.

Further, as in this embodiment, when the jet port 6 of the air injection pipe 1 is opened rearward in the traveling direction of the hull 20, when the hull 20 cruises, since the jetting direction front portion close to the outlet 6 is pressure decreases due to negative pressure becomes dead water, ejection of the bubbly water L ₂ becomes more easily, vessel bottom face 2 a greater amount of air bubbles 10
2 can be reliably injected.

Further, for example, the bottom 2 of the hull 20
2 is provided with a guide groove extending in the bow and stern direction, it is also possible to allow the bubbles 10 blown out from the jet port 6 of the air injection pipe 1 to the vicinity of the ship bottom surface 22 to reach the stern side through the guide groove. In such a case, the effect of reducing the frictional resistance can be obtained in a wider area of the ship bottom surface 22.

[Brief description of the drawings]

FIG. 1 is an overall view of a frictional resistance reducing device according to the present invention.

FIG. 2 is an enlarged sectional view of the frictional resistance reducing device.

FIG. 3 is a view taken in the direction of arrows III-III in FIG. 1;

[Explanation of symbols]

1 is an air injection pipe, 2 is a nozzle, 3 is a throat, 4 is a diffuser, 6 is a spout, 7 is a water intake, 8 is an air chamber, 9 is an air intake, 10 is a bubble, 20 is a hull, and 21 is a hull. Ship's side,
Reference numeral 22 denotes a ship bottom.

Claims (1)

[Claims] An ejector (X) using water (L ₁ ) taken from a water intake (7) as a driving fluid and air (A) taken from an air intake (9) as a driven fluid.
And an air injection pipe (1) provided with a jet port (6) on the downstream side of the ejector (X). The water inlet (7) is placed underwater in the traveling direction of the hull (20). A friction resistance reducing device for a ship, wherein the jet outlet (6) is arranged in a state of being opened in the vicinity of the bottom surface (22) of the ship.