JP2002079986A - Ship reduced in friction resistance - Google Patents

Abstract

[PROBLEMS] To provide a method of reducing frictional resistance of a hull and a ship capable of effectively reducing power consumption during navigation by reducing frictional resistance with low energy consumption. SOLUTION: A concave portion 2 provided on a submerged surface 12 of a hull.
0, a fluid passage 21 having one end open to the atmosphere and the other end open to the inside of the recess 20, a wing body 22 having a wing 38 and arranged in the recess 20, and a wing body 22. A positioning mechanism 23 that movably supports in a predetermined direction and positions the wings 38 at a predetermined position; and the positioning mechanism 23 opens the inside of the concave portion 20 to the flow of water when frictional resistance is reduced. The wing 38 is positioned so as to have a negative pressure with respect to the atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frictional resistance reducing method for reducing the frictional resistance of a hull, and to a frictional resistance reducing ship.

[0002]

2. Description of the Related Art Conventionally, in order to reduce energy consumption during navigation of a ship or the like, a gas is fed into water and a number of bubbles are interposed near a surface of a hull outer plate (submerged surface). A technique for reducing frictional resistance between a hull and water has been proposed.

As a technique for generating bubbles in water, Japanese Patent Application Laid-Open Nos. 50-83992 and 53-136289 have been disclosed.
JP-A-60-139586, JP-A-61-712
No. 90, No. 61-39691, No. 61-12
No. 8185 has been proposed.

In these techniques, as a method of generating bubbles in water, gas pressurized by a device such as a pump or a blower is blown into water through a plurality of holes or a perforated plate provided in a hull.

[0005]

However, the method of injecting a pressurized gas into water requires energy for operating the pressurizing device, and reduces the amount of energy saved by reducing the frictional resistance. Resulting in.
In particular, when ejecting gas to a relatively deep place,
It is necessary to pressurize the gas to a high pressure according to the water pressure (hydrostatic pressure), which consumes a large amount of energy. In addition, when installing the pressurizing device on the hull, large costs such as facility costs and construction costs are incurred.

The present invention has been made in view of such circumstances, and has the following objects. (1) Reduce frictional resistance with low energy consumption,
Effective saving of energy consumption during navigation. (2) To efficiently mix bubbles in water to effectively reduce frictional resistance. (3) To reduce hull construction costs.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a frictional resistance reducing ship that releases bubbles on a submerged surface of the hull to reduce the frictional resistance of the hull. A concave portion provided on the submerged surface, a fluid passage having one end open to the atmosphere and the other end open to the inside of the concave portion, a wing body having wings and arranged in the concave portion,
A positioning mechanism that movably supports the wing body in a predetermined direction and positions the wing at a predetermined position, wherein the positioning mechanism is configured such that, when frictional resistance is reduced, the inside of the concave portion is opposed to a flow of water. The wing is positioned so as to be open and have a negative pressure with respect to the atmosphere. Also,
The invention according to claim 2 is the frictional resistance reducing ship according to claim 1, wherein the positioning mechanism is configured to reduce non-frictional resistance,
The wing is positioned so that the lower surface of the wing is substantially the same height as the submerged surface of the hull. According to a third aspect of the present invention, in the frictional resistance reducing ship according to the first or second aspect, the switching mechanism has an operating means capable of operating the position of the wing from the deck side. I have.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a frictional resistance reducing ship according to the present invention is applied to a small boat will be described below with reference to the drawings. In FIG. 2, reference symbol M denotes a small boat as a frictional resistance reducing boat, 10 denotes a hull, 11 denotes a bubble generator,
Reference numeral 12 denotes a hull skin (submerged surface), 13 denotes a propulsion device, 14 denotes a rudder, and 15 denotes a water surface (waterline). In this embodiment, as shown in FIG. 2 (b), a plurality of bubble generating devices 11 are arranged on the bottom of the ship near the bow in the width direction of the ship.

[0009] As shown in FIG.
Recess 2 provided in a state depressed from submerged surface 12 at the bottom of ship
0, a fluid passage 21 having one end opened to the atmosphere and the other end opened to the inside of the recess 20, a wing body 22 arranged inside the recess 20 and having wings,
And a positioning mechanism 23 that movably supports the wing along a side surface thereof and positions the wing at a predetermined position.

The recess 20 is provided here as an internal space of a rectangular chamber 30 joined to the hull outer panel 12 from the inside of the hull. That is, the chamber 30 is formed in a box shape whose one surface is open, and the open end thereof is joined to the hull outer panel 12 inside.

[0011] The fluid passage 21 here is provided with a chamber 30.
AIP (Air Induction Pip) connected to
e) Internal space of 31. The chamber 30 is provided with an opening 30a for introducing gas into water, and a gas introduction pipe 31 made of a tubular member is connected to the opening 30a. In addition, as shown in FIG.
By using a flexible tubular member as 1, the installation space can be made more efficient.

The wing body 22, as shown in FIG.
5, mainly composed of struts 36, 37 and wings 38. The base 35 has a chamber structure and has an inclined surface 35a below. Here, the inclined surface 35a is formed in a curved shape that is upwardly convex, and is formed so that its height gradually increases toward the front (bow side) in the traveling direction Dv. At both ends in the width direction of the inclined surface 35a,
One end of each of the struts 36 and 37 is joined, and the other end of each of the struts 36 and 37 is joined to both ends of the wing 38 in the width direction. Struts 36, 3
The wings 7 and the wings 38 are each formed in a predetermined airfoil, and are arranged with the leading edge and the trailing edge directed in the traveling direction Dv of the hull. The wings 38 are arranged with the convex wing surface facing upward.
The shapes of the wing 38 and the struts 36 and 37 are N
Various airfoil types such as an ACA airfoil and an oval airfoil are applicable, and are determined according to the shape of the hull and the ship speed (standard sailing speed).

In the wing body 22, the base 35, the struts 36, 37, and the wings 38 are combined with each other to form a cylindrical shape, and form a curved water channel 39 that is convex upward in the vertical direction. . Further, openings 35b and 35c are formed on the upper surface and the lower surface (inclined surface 35a) of the base 35, and through the openings 35b and 35c, the water passage 3 is formed.
9 communicates with the space above the base 35.

Referring back to FIG. 3, the positioning mechanism 23
A link mechanism is provided to slide the wing 38 up and down along the side surface of the recess 20, and the height position of the wing 38 from the submerged surface 12 can be changed by operating the lever 40. The lever 40 is disposed on the deck side,
The operating position is held by a locking means such as a hook. The positioning mechanism 23 includes a lever 4
A flexible member 41 such as a bellows for isolating the recess 20 from the deck side while absorbing the movement of zero is provided.

The ship M having the reduced frictional resistance constructed as described above.
The method for reducing the frictional resistance of the hull according to the present invention will be described below with reference to FIG. In the stopped state, in the recess 20,
Water (seawater) has entered almost the same water level as the periphery of the hull 10. The hull 1 is propelled by the thrust of the propulsor 13 (see FIG. 2).
When the 0 goes into navigation, a water flow 50 relative to the hull 10 is formed.

In the navigation state, when a predetermined boat speed (for example, a standard navigation speed) is reached, the lever 40 is operated as shown in FIG.
The wing body 22 is moved downward by 3 so that the wing 38 protrudes from the submerged surface 12 of the hull by a predetermined height. At this time, the inside of the recess 20 is opened to the flow 50 of water, and the recess 2
A separation zone is formed in the water by the step at the entrance of zero. Then, the water pressure (hydrostatic pressure) in the water channel 39 decreases due to the separation area. Further, in the water channel 39, since the flow path of the water gradually narrows along the inclined surface 35a, the flow velocity of the water flowing through the water channel 39 increases rearward, and the water pressure further decreases. As a result, the water pressure in the water channel 39 becomes locally negative with respect to the atmosphere.

Due to the pressure difference with respect to the atmosphere, a pressure gradient force Pf acts on the fluid (seawater and air) inside the fluid passage 21 and the recess 20, and air flows into the fluid passage 21 and the recess 20 from the atmosphere. I do. Then, the air is sent into the water in the water channel 39 through the openings 35b and 35c of the wing body 22.

At this time, the gas sent into the water is mixed into the water as bubbles 52, and a large number of bubbles 52 are present near the submerged surface 12 of the hull 10, so that the frictional resistance of the hull 10 is reduced. .

The energy required for sending air into the water is mainly for changing the position of the gas. This energy is supplied to the recess 20 and the wing body 22.
This is obtained by changing the flow state of water, and is less than the energy consumed when jetting a pressurized gas into water. Therefore, energy consumption during navigation is effectively reduced by reducing the frictional resistance of the hull 10.

Since the bubbles 52 mixed in the water are formed at an internal pressure lower than the hydrostatic pressure according to the water depth, when the bubbles 52 move at a constant water depth (for example, when the bubbles move along the ship bottom) Then, as the distance from the location where the bubbles 52 are generated to the stern direction, a large water pressure acts on the bubbles 52, and the size of the bubbles 52 gradually decreases. Applicants' previous studies indicate that relatively small bubbles are preferred to reduce the frictional resistance of the hull. Therefore, the air bubbles generated by the negative pressure also have an advantageous effect on the reduction of the frictional resistance from this point.

In the present embodiment, cavitation occurs together with the peeled area due to the step at the entrance of the recess 20. Therefore, the gas and the water are positively mixed at the boundary surface between the gas and the water due to the stirring action by the separation area and the cavitation, and the separation of the bubbles 52 from the gas-liquid interface is promoted.

In addition, the circulating flow generated around the wing 38
(The flow velocity on the wing surface side facing upward is larger than that on the wing surface facing downward.)
An upward lift acts on the hull via 8. Therefore, this lift causes the hull, especially the bow side, to float,
The inundation area of the hull 10 is reduced, and the frictional resistance of the hull 10 is further reduced.

The circulating flow 生 じ る generated around the wing 38 acts in a direction to increase the flow velocity in the water channel 39,
The reduction of the water pressure in the water channel 39 is promoted, and the suction force of the bubbles 52 into the water increases.

Furthermore, this circulating flow 生 じ also occurs around the struts 36, 37 supporting the wings 38, and these circulating flows Γ generate vortices in the water behind. Circulation flowΓ
The vortex generated by the turbulence changes the vortex structure in the turbulent boundary layer near the wall, which contributes to the frictional resistance, and diffuses the momentum of water in the boundary layer, thereby contributing to the reduction of the frictional resistance of the hull.

The circulating flow 生 じ る sufficiently occurs even at low speeds (for example, about 10 knots), so that the above-described frictional resistance reducing effect is exhibited for a wide range of speeds.

In the present embodiment, the height of the wings 38 is adjusted by the positioning mechanism 23 in accordance with the navigation conditions such as the navigation speed, so that the bubbles are effectively released into the water. . This adjustment can be easily performed by the occupant by using the lever 40 arranged on the deck side.

In the present embodiment, for example, when the ship speed does not reach a predetermined speed or when the effect of reducing the frictional resistance due to bubbles due to stormy weather cannot be expected, as shown in FIG. 23 positions the wings 38 so that the lower surface of the wings 38 is substantially flush with the submerged surface 12 of the hull. This suppresses an increase in drag on the flow 50 of water. That is, by disposing the lower surface of the wing 38 on substantially the same plane as the submerged surface 12 of the hull, the opening of the concave portion 20 is widely closed, and the unevenness on the submerged surface 12 of the hull is reduced. The increase in drag with respect to the flow 50 is effectively suppressed.

As described above, in this embodiment, by controlling the height of the wings 38 protruding from the submerged surface 12 of the hull in accordance with the navigation conditions, air bubbles can be effectively released into the water, In this case, it is possible to suppress an excessive increase in the drag of the vehicle and reduce energy consumption during navigation.

Further, since the bubble generating device 11 has a simple configuration and does not require a device for pressurizing gas, it goes without saying that the construction cost of the hull 10 can be reduced.

The various shapes and combinations of the constituent members shown in the above-described embodiments are merely examples, and various changes can be made based on design requirements without departing from the gist of the present invention. For example, in the above-described embodiment, the positioning mechanism 23 is manually operated via the lever 40 based on the navigation conditions. However, the present invention is not limited to this, and the positioning mechanism 23 is automatically operated based on data such as the navigation speed.
To adjust the protrusion height of the wing 38.

In the above-described embodiment, an example in which the present invention is applied to a small ship is shown. However, the present invention is not limited to this, and other ships such as a large ship such as a tanker and a container ship, a large ship and a high-speed ship may be used. Is also applicable. The size, number, and location of the bubble generators 11 are appropriately set according to the shape of the hull.

FIG. 5 shows a submerged surface 12 of a hull in addition to a recess 20 in which the above-mentioned wing is disposed as an air bubble generator.
(Here, the bottom of the ship). Here, between the plurality of recesses 20 arranged side by side in the ship width direction,
And a plurality of recesses 6 having a predetermined depth outside the plurality of recesses 20.
0, 61 and 62 are formed. This depression 60.6
As shown in FIG. 5B, the hulls 1 and 62 are formed so that the depth from the submerged surface 12 of the hull gradually decreases toward the stern (rearward in the traveling direction). Also, depression 6
An inclined surface 63 having a predetermined height from the submerged surface 12 of the hull is formed in a region in front of (0, 61, 62) (bow side) and adjacent to the depression. The inclined surface 63 generates peeling or cavitation at its corners to generate new air bubbles in water, or to reduce air bubbles released from the above-described recesses 20 by setting the insides of the depressions 60, 61, and 62 to a low pressure state. It is intended to lead to the depression. With this configuration, some of the air bubbles released from the concave portion 20 are
It fills the inside of 61 and 62 and diffuses in the ship width direction. Thereby, a wide range of the submerged surface 12 of the hull can be covered with dense air bubbles, and the effect of reducing frictional resistance can be promoted.

The various shapes and combinations of the components shown in the above-described embodiment are merely examples, and various changes can be made based on design requirements without departing from the gist of the present invention. The shape of the bubble generator and the depression
Computational Fluid Dynamics (CFD) so that the resistance (drag) to the water flow accompanying the hull navigation is as small as possible and the water flow changes to a desired state.
Designed by various analyzes such as flow field analysis by Dynamics.

[0034]

As described above, according to the present invention,
By utilizing the pressure gradient force, gas is sent into water with less energy consumption than when gas is pressurized,
The frictional resistance of the hull can be reduced. In addition, by positioning the wing height of the wing from the submerged surface of the hull by the positioning mechanism, effective reduction of frictional resistance can be implemented according to navigation conditions, and energy consumption during navigation can be reduced. it can. Further, a device for pressurizing the gas is not required, and the construction cost of the hull can be easily reduced.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a method for reducing the frictional resistance of a hull by a frictional resistance reducing ship according to the present invention.

FIG. 2 is a configuration diagram schematically showing an embodiment in which the method for reducing frictional resistance of a hull according to the present invention is applied to a ship.

3A and 3B are diagrams showing a configuration of a wing body, wherein FIG. 3A is a schematic longitudinal sectional view, and FIG.

FIG. 4 is a perspective view showing a configuration of a wing body.

5A and 5B show another embodiment of the frictional resistance reducing ship according to the present invention, wherein FIG. 5A is a plan view of the bottom of the ship viewed from underwater, and FIG. 5B is a view taken along the line AA shown in FIG. It is a typical sectional view.

[Explanation of symbols]

 M Friction drag reduction ship Γ Circulation flow 10 Hull 11 Bubble generator 12 Hull outer plate (submerged surface) 15 Water surface 20 Depression 21 Fluid passage 22 Wing body 23 Positioning mechanism 31 Gas introduction pipe 36, 37 Strut 38 Wing 40 Lever (operation means)

Claims (3)

[Claims] 1. A frictional resistance reducing ship that releases bubbles to a submerged surface of a hull to reduce frictional resistance of the hull, a concave portion provided on the submerged surface of the hull, one end of which is open to the atmosphere and the other end. A fluid passage opened to the inside of the recess, a wing body having wings and arranged in the recess, supporting the wing body movably in a predetermined direction, and positioning the wing at a predetermined position. And a positioning mechanism for positioning the wings such that when frictional resistance is reduced, the inside of the concave portion is opened to the flow of water and has a negative pressure with respect to the atmosphere. Characteristic low friction drag ship. 2. The locating mechanism according to claim 1, wherein when the non-frictional resistance is reduced, the wing is positioned such that the lower surface of the wing is substantially the same height as the submerged surface of the hull. The described frictional resistance reduction ship. 3. The frictional resistance reducing ship according to claim 1, wherein the switching mechanism has an operating means capable of operating the position of the wing from the deck side.