JP2001328584A - Friction drag reduction ship - Google Patents

Abstract

(57) [Problem] To provide a frictional resistance reduced ship capable of reducing frictional resistance with low energy consumption and effectively reducing energy consumption during navigation. SOLUTION: A concave portion 20 provided to be depressed from a submerged surface 12 of a hull, and rotatably supported inside the concave portion 20, and at least a part of the submerged surface 12 of the hull is projected and arranged. A negative pressure forming member 22 that forms a negative pressure point 41 in the water that has a low pressure with respect to the gas space
One end is open to the gas space and the other end is the concave portion 2 for guiding the gas from the gas space to the negative pressure point 41 in the water.
In order to arrange the fluid passage 21 opened to zero and at least a part of the negative pressure forming member 22 in a predetermined projecting state from the submerged surface 12 of the hull, the negative pressure forming member 22 is supported and the negative pressure forming member is supported. An angle adjusting mechanism 23 for adjusting the arrangement angle of the device 22 is provided.

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 ship for reducing the frictional resistance of a hull, and more particularly to improving the overall energy efficiency by efficiently discharging bubbles into water.

[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 air bubbles are interposed near a surface of a hull outer plate (submerged surface). There has been proposed a method of reducing frictional resistance between a hull and water.

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, in the method of injecting pressurized gas into water, energy for operating the pressurizing device is required, and the amount of energy saved by reducing frictional resistance is reduced. Resulting in. In particular, when gas is blown into water at a relatively large depth such as the bottom of a large ship, it is necessary to pressurize the gas to a high pressure corresponding to the water pressure (hydrostatic pressure), which consumes a large amount of energy. Resulting in. 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) To reduce frictional resistance with low energy consumption and effectively reduce 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 recess provided in a state recessed from the submerged surface, and rotatably supported inside the recess,
A negative pressure forming member that forms a negative pressure point in the water that has a low pressure with respect to the gas space by disposing at least a portion of the hull from the submerged surface of the hull; A fluid passage having one end opened to the gas space and the other end opened to the concave portion, and at least a part of the negative pressure forming member arranged in a predetermined projecting state from the submerged surface of the hull. In addition, a technology is provided that includes an angle adjusting mechanism that supports the negative pressure forming member and adjusts an arrangement angle of the negative pressure forming member.

According to the present invention, since at least a part of the negative pressure forming member is arranged so as to protrude from the submerged surface of the hull, a negative pressure portion is formed in the water. The gas is guided from the gas space to a negative pressure point in the water via the, and bubbles are released into the water. In addition, by adjusting the arrangement angle of the negative pressure forming member by the angle adjusting mechanism, the projecting state of the negative pressure forming member from the submerged surface of the hull is controlled according to the navigation state, and the effect of bubbles in water is reduced. It becomes possible to release it.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a frictional resistance reducing boat according to the present invention is applied to a small fishing boat will be described below with reference to the drawings. In FIG. 2, reference numeral M denotes a frictional resistance reducing ship, 10 denotes a hull, 11 denotes a bubble generator, 12 denotes a hull outer plate (submerged surface), 13 denotes a propulsion device, 14 denotes a rudder, and 15 denotes a water surface (draft line). ing.

As shown in FIG. 2 (b), the bubble generating device 11 penetrates the hull 10 and is opened above and below the waterline 15 with a concave portion 20 provided to be recessed from the submerged surface 12 at the bottom of the ship. It comprises a fluid passage 21 and a negative pressure forming member 22 disposed inside the concave portion 20.

The recess 20 is provided here as an internal space of a chamber 30 attached 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 is connected to the hull outer panel 12 inside. The chamber 30 is made of an integrally molded product made of hard polyurethane, and is detachably attached to the hull outer panel 12.

The fluid passage 21 here is provided with a chamber 30
AIP (Air Induction Pip) connected to
e) Internal space of 31. That is, the chamber 3
At 0, a discharge port 30a for discharging bubbles into water is provided so as to be located at the back of the concave portion 20 and at the rear (stern side) of the negative pressure forming member 22, and is formed of a tubular member. A gas inlet tube 31 is connected to the outlet 30a. Therefore, one end of the fluid passage 21 has the gas introduction pipe 3.
The air outlet 31a is opened to the gas space (atmosphere) through the air inlet 31a, and the other end is opened to the water through the outlet 30a of the chamber 30. In addition, a desired flow rate of the fluid with a small pressure loss
The cross-sectional area and shape of the inside of the gas introduction tube 31 are determined so that the gas flows.

The negative pressure forming member 22 is provided on the submerged surface 12 of the hull.
Is arranged so as to project from at least a portion thereof, by utilizing the flow of water relative to the hull 10 during navigation,
A negative pressure point which becomes low pressure with respect to the gas space (atmosphere) at a predetermined ship speed Vs is formed in the water behind (stern side) itself. Are rotatably supported by an angle adjusting mechanism 23.

The negative pressure forming member 22 is made of a member having a substantially isosceles triangular cross section in a direction perpendicular to the support shaft 32, and a plurality of members (here, 3
) Surfaces 22a, 22b, and 22c. Further, the negative pressure forming member 22 is disposed at a predetermined arrangement angle around the support shaft 32 by the angle adjusting mechanism 23, so that a part of the predetermined surfaces 22a and 22b protrudes from the submerged surface 12 of the hull. At a different arrangement angle, the predetermined surface 22a is arranged substantially flush with the submerged surface 12 of the hull. The negative pressure forming member 22 is made of a molded product made of hard polyurethane.

As shown in FIG. 3, for example, the angle adjusting mechanism 23 supports bearings 33 and 34 fixed to the chamber 30 so as to rotatably support the support shaft 32, and assists the rotation of the support shaft 32. For this purpose, it is provided with levers 35 and 36 fixed to the support shaft 32 outside the chamber 30 and a fixing portion 37 for locking the rotation of the support shaft 32. In this example, when the operator rotates the support shaft 32 via the levers 35 and 36, the negative pressure forming member 2 is rotated around the support shaft 32.
The arrangement angle of the negative pressure forming member 22 is determined by changing the arrangement angle of 2 and locking the support shaft 32 by the fixing portion 37. The angle adjusting mechanism 23 is not limited to the configuration in which the arrangement angle of the negative pressure forming member 22 is manually adjusted, but includes, for example, a driving motor or the like, so that the arrangement angle of the negative pressure forming member 22 is adjusted. It may be configured to drive automatically. The bearing 3
The reference numerals 3 and 34 have a sufficient sealing mechanism so that water does not enter the hull from underwater.

The shape and position of each component of the bubble generator 11 are set so that the flow of water behind (at the stern of) the negative pressure forming member 22 during navigation is in a desired state. CFD: Computational Fluid Dynamics)
It is designed based on the results of flow field analysis and cruising tests by, for example, when navigating at a predetermined ship speed Vs,
The height of the negative pressure forming member 22 and the shape of the chamber 30 are determined so that a negative pressure portion having a low pressure with respect to the gas space (atmosphere) is formed in the water behind the negative pressure forming member 22.

The negative pressure forming member 22, the chamber 30,
The material of the gas inlet tube 31 is, in addition to the hard polyurethane described above, a metal or resin that has been subjected to a corrosion-resistant treatment, such that the surface mainly has corrosion resistance to seawater and that marine organisms do not easily adhere to the surface. Is preferably used. In addition, one or more bubble generating devices 11 are arranged according to the size of the bottom of the ship.

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, water (seawater) has entered into the fluid passage 21 to almost the same water level as around the hull 10. When the hull 10 enters the navigating state by the thrust of the propulsion device 13 (see FIG. 2), a water flow 40 relative to the hull 10 is formed.

In the navigation state, when a predetermined boat speed Vs is reached, as shown in FIG. 1A, the angle of the negative pressure forming member 22 is adjusted by the angle adjusting mechanism 23 so that the negative pressure is formed. Part of the member 22, ie, the negative pressure forming member 2
2 is a part of the submerged surface 1 of the hull.
2 so as to protrude.

At this time, since the flow path of the water is narrowed by the surface 22a of the negative pressure forming member 22, the flow velocity of the water flowing along the bottom of the ship increases, and the sharp angle of the protruding end causes the separation area in the water. Are formed, by which
The hydrostatic pressure in the water behind the surface 22a of the negative pressure forming member 22 is locally reduced, and a negative pressure portion 41 is formed, which becomes low with respect to the atmosphere.

At this time, since the pressure at the discharge port 30a facing the negative pressure point 41 is lower than the pressure at the air intake port 31a, a pressure gradient force is exerted on the fluid (seawater and air) in the fluid passage 21. Acting, the seawater is discharged from the fluid passage 21, and the air flowing in from the air intake 31a flows through the fluid passage 21 and is sent into the water.

Then, the gas sent into the water separates from the gas-liquid interface 43 and mixes into the water as bubbles 42, and the hull 1
The frictional resistance of the hull 10 is reduced by interposing a large number of bubbles 42 near the submerged surface 12 of zero.

At this time, the energy required for sending air into the water is mainly energy for changing the position of the gas. This energy is supplied to the negative pressure forming member 22.
Thus, it is obtained by changing the flow state of water, which is less than the energy consumed when a gas is pressurized and jetted into water. Therefore, energy consumption during navigation is effectively reduced by reducing the frictional resistance of the hull 10.

Further, in the present embodiment, the arrangement angle of the negative pressure forming member 22 is adjusted by the angle adjusting mechanism 23 according to the navigation condition, so that the negative pressure forming member 22 from the submerged surface 12 of the hull is adjusted. Control the protruding state. That is, for example, when the ship speed does not reach the predetermined ship speed Vs or when the effect of reducing the frictional resistance due to bubbles due to stormy weather cannot be expected, a negative pressure is formed by the angle adjusting mechanism 23 as shown in FIG. The arrangement angle of the member 22 is adjusted, and the predetermined surface 22a of the negative pressure forming member 22 is disposed substantially on the same plane as the submerged surface 12 of the hull, so that the negative pressure forming member 22 is in a non-projecting state. Thus, an increase in drag against the water flow 40 is suppressed, and energy consumption is reduced. Further, by controlling the projecting height of the negative pressure forming member 22 according to the traveling speed, control is performed such that bubbles are effectively released into the water.

As described above, in this embodiment, by controlling the projecting state of the negative pressure forming member 22 from the submerged surface 12 of the hull in accordance with the navigation state, air bubbles are effectively produced in the water in accordance with the navigation speed. Thus, the frictional resistance of the hull can be effectively reduced by effectively discharging the hull or suppressing an excessive increase in the drag of the hull.

In addition, by adjusting the arrangement angle of the negative pressure forming member 22, the state of the negative pressure forming member 22 projecting from the submerged surface 12 of the hull is controlled.
Can be configured simply and compactly, and the bubble generator 11 can be easily added to and attached to an existing hull.

In the present embodiment, the negative pressure forming member 22
By arranging the predetermined surface 22a on the substantially same surface as the submerged surface 12 of the hull, the opening of the concave portion 20 is widely closed by the surface 22a in order to make the negative pressure forming member 22 non-projecting state. At the same time, the unevenness on the submerged surface 12 of the hull is reduced, so that an increase in drag with respect to the water flow 40 is effectively suppressed.

Further, since the chamber 30 and the negative pressure forming member 22 shown in FIG. 2 are formed of a molded product made of hard polyurethane, it is easy to reduce the cost by the effect of mass production. Further, since the chamber 30 is removably attached to the hull outer panel 12, labor for maintenance can be reduced.

Since the bubbles 42 mixed in the water are formed at an internal pressure lower than the hydrostatic pressure corresponding to the water depth, when the bubbles 42 move at a constant water depth (for example, the bubbles move along the ship bottom). (Time), a larger water pressure acts on the bubble 42 as the distance from the negative pressure portion 41 increases, and the size of the bubble 42 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.

Further, since the bubble generating device 11 has a simple structure 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 shapes, combinations, and the like of the components shown in the above-described embodiment are merely examples, and can be variously changed based on design requirements without departing from the gist of the present invention. The present invention includes the following modifications, for example.

In the above embodiment, the angle adjusting mechanism 23 is manually operated based on the traveling speed and the weather.
The present invention is not limited to this, and the configuration may be such that the angle adjusting mechanism 23 is automatically driven based on data such as the traveling speed to adjust the arrangement angle of the negative pressure forming member 22.

In the above-described embodiment, an example in which the present invention is applied to a small fishing boat has been described. However, the present invention is not limited to this, and the present invention is applicable to other vessels such as tankers and container vessels, such as large vessels and high-speed vessels. Applicable. The size and number of the air bubble generators 11 and their locations are appropriately set according to the shape of the hull.

[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. Further, by controlling the projecting state of the negative pressure forming member by the angle adjusting mechanism, it is possible to effectively reduce frictional resistance according to the traveling state, and to save energy consumption during traveling.
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.

FIG. 3 is a sectional view taken along the line AA shown in FIG. 2;

[Explanation of symbols]

 M boat for reducing frictional resistance 10 hull 11 bubble generator 12 hull outer plate (submerged surface) 15 water surface (waterline) 20 concave portion 21 fluid passage 22 negative pressure forming member 31 gas inlet tube 30a outlet 31a air inlet 22a, 22b, 22c surface 23 Angle adjustment mechanism

Claims (1)

[Claims] 1. A frictional resistance reducing ship that releases bubbles to a submerged surface of a hull to reduce frictional resistance of the hull, comprising: a concave portion provided in a state depressed from a submerged surface of the hull; A negative pressure forming member that is freely supported and forms a negative pressure portion in the water that is at a low pressure with respect to the gas space by being disposed at least partially protruding from the submerged surface of the hull; A fluid passage open at one end to the gas space and open at the other end to the concave portion, for guiding the gas to the negative pressure portion, and at least a part of the negative pressure forming member is set at a predetermined distance from a submerged surface of the hull. An angle adjustment mechanism for supporting the negative pressure forming member and adjusting an arrangement angle of the negative pressure forming member in order to dispose in a protruding state.