JP2017165386A - Hull frictional resistance reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hull frictional resistance reduction device using the air, capable of reducing a frictional resistance, to solve an issue of reduction of net CO2 emission amount that cannot be solved by: a method of surrounding the full with air bubbles to reduce frictional resistance that the hull receives, with a drawback of a significant increase in a power energy used for delivering the air to a hull bottom, thus, resulting in occurrence of the power energy consumption; and a method of storing the air in the hull bottom in the water, with a drawback of difference in water surface positions, i.e. contact surface positions between air and water, among respective air chambers, resulting in occurrence of new resistance in the air chambers.SOLUTION: A hull frictional resistance reduction device comprises: inclined fixed wings 13 in an underwater part, to turn flowing water coming into an air absorbing chamber 10 to make vortexes so as to create a negative pressure causing the air voluntarily introduced into the underwater part. In addition, vent holes are provided in upper parts of multiple partitions for air storage hubs in the underwater part so that the air storage hubs can be communicated to level water surface positions of the air storage hubs, whereby, frictional resistance on the hull can be reduced.SELECTED DRAWING: Figure 1

Description

    The present invention relates to a hull frictional resistance reduction device, and more particularly to a hull frictional resistance reduction device that reduces frictional resistance by interposing air at the boundary surface between the hull surface and water (seawater or fresh water). is there.

    While global warming has been raised, there is an international demand for CO2 reduction. CO2 reduction in international shipping is no exception. In recent years, it has been compiled as a revised provision of the MARPOL Convention, and for new ships from 2015, CO2 reduction with specific standard values is required, reducing fuel energy consumption for ship navigation Innovative technology is being developed. One of them is a technique for reducing the frictional resistance of a ship using air.

    As shown in Patent Document 1 as a currently known technique, friction is generated between the hull and water by sending air to the ship bottom using a powerful power blower and covering the hull under the water surface with bubbles. There are some which aim to reduce this.

    In addition, as shown in Patent Document 2, there is an apparatus in which an air tank is provided at the bottom of a ship to collect air and reduce the frictional resistance generated between the ship and water by reducing the surface area of the ship in contact with water.

  Patent No. 5826590   JP2015-199489 PR   JP 2010-58777 A

    In the technique of Patent Document 1 shown first, even if the hull below the surface of the water is covered with air bubbles and the frictional resistance received by the hull can be reduced, the power energy for sending air to the bottom of the ship at the same time is greatly consumed. It does not lead to a reduction in quantity. As the draft of the ship becomes deeper, the pressure for exhaling air has to be increased, and there is a problem that further power energy is consumed.

    Further, in the technology of Patent Document 2, during actual voyage, various hulls are shaken, so that an air outflow occurs in the air tank provided on the bottom of the ship. Variations in the amount of air inside. In order to solve this, there is a problem that the air tanks must be refilled with air. The amount of air in the air tank is maintained at 40 to 90%. If the amount of air in each air tank is 50%, for example, all the air tanks are always approximately 50% and uniform. However, if variation occurs, the position of the water surface in each air tank, that is, the position of the contact surface of air and water is different in each air tank, so that there is a problem that a new resistance is generated in the air tank. is there.

    Further, in the technique of Patent Document 3, air is sucked without using power, and is sucked by a negative pressure generated at the rear part of the hub. If the air is sucked through the plurality of fixed blades and the hub, pressure loss may occur.

    An object of the present invention is to provide a hull frictional resistance reduction device that solves the above-described problems and enables reduction of the frictional resistance of a ship using air.

    According to a first aspect of the present invention, a hub is provided inside the cylinder, and a plurality of fixed wings are attached around the hub. Next, the fixed wing is attached and fixed to the inner surface of the cylinder. When the air suction device is placed in running water, water enters from the inflow port and collides with the fixed wing, and if the fixed wing is angled so as to swirl the inflow water, a vortex is formed at the rear of the hub. A large negative pressure is generated at the rear of the hub in the water.

    Next, an air chamber having a wide space is provided so as to surround the cylinder, and a ventilation pipe that communicates with the atmosphere and one of the air chambers communicate with each other, pass through the fixed wing and the inside of the hub, and at the rear portion of the hub. An air exhaust port is provided and communicates from the air intake port of the ventilation pipe through the air chamber, then through the inside of the fixed wing to the exhaust port at the rear of the hub.

    According to a second aspect of the present invention, an opening is provided near the bow bottom of a ship, and the air suction device according to the first aspect is installed. The inlet of the air suction device is opened near the bow bottom of the ship, and the outlet of the air suction device leads to an air release port provided on the ship bottom or the shore side of the ship, so that the ship always navigates. Water enters from the inflow port, creates a large negative pressure at the rear part of the hub, sucks the air without power, and the air sucked from the air opening provided on the bottom of the ship or on the shore side is discharged.

    As an air reservoir corresponding to the present invention according to claim 3, a plurality of air reservoirs comprising a plurality of vertical and horizontal partition plates are provided in a flat portion of the bottom of the ship (stern side) downstream of the air opening provided on the bottom of the boat. . Air released from the air opening is caught in an air reservoir provided in the flat portion of the bottom of the ship, and the air accumulates in the air reservoir, thereby reducing the surface area in contact with the hull below the water surface and water.

    Next, vents are provided on the upper part of the partition plate, that is, on the side in contact with the ship bottom so that the amount of air trapped in each air reservoir is substantially uniform. For example, if one reservoir holds 80% of the volume of air, and the adjacent reservoir holds only 40% of its volume, then there is a gap between both reservoirs. If a vent is provided in the upper part of the partition plate, the air flows naturally from a place with a large amount of air to a place with a small amount of air. Therefore, the positions of the water surfaces in the two adjacent air reservoirs are the same.

    According to a fourth aspect of the present invention, the hull frictional resistance reducing device according to the second aspect is provided, and a plurality of air pockets according to the third aspect are arranged on the downstream side (stern side) of the air opening provided on the bottom of the ship. . During the navigation of the ship, air is always released from the air opening, and air starts to accumulate from an air reservoir near the air opening. Furthermore, air is supplied to all the air reservoirs through an air vent provided in the partition plate even in an air reservoir where the air discharged from the air release port does not reach directly.

    The present invention according to claim 5 is any one of the hull frictional resistance reduction devices using the air suction device, and when supplying a large amount of air to the bottom of a ship such as a deep draft, Air can be sent to the bottom of the ship using external power such as a blower.

    A method of interposing air to reduce the frictional resistance applied to a ship hull has been known for a long time. However, the energy consumed to supply air to the vicinity of the bottom of the ship underwater has to be reduced at the same time. However, by using the present invention, the water flowing into the air suction device near the bow collides with the fixed wing, creating a flow that turns by itself, and the negative pressure created by the swirling flow causes air to be sucked by itself to the bottom of the ship. The hull frictional resistance is reduced. As a result, it is possible to supply air to the vicinity of the ship bottom without consuming power energy, reducing the frictional resistance of the hull, and contributing to the reduction of CO2 emission from the ship.

In the air suction device 10 of the present invention, water enters from the left inflow port 18a, hits a plurality of fixed wings 13 attached to the central hub 12, becomes a swirling flow, and a negative pressure is generated at the rear portion of the hub 12. Conceptual diagram. BRIEF DESCRIPTION OF THE DRAWINGS In one Example of the ship equipped with the hull frictional resistance reduction apparatus of this invention, the conceptual diagram which opens the bow bottom vicinity and attaches the air suction device 10. FIG. 1 is an example of a ship equipped with a hull frictional resistance reduction device in which an air reservoir 30 of the present invention is provided in the vicinity of a ship bottom 21, and (a) is an embodiment in which the air reservoir 30 is attached to the ship bottom 21 of an existing ship. (B) is one Example which shows a part of several air reservoir 30 which consists of several vertical and horizontal partition plates 31 and 32, and the vent 33 on the flat part of the ship bottom 21. FIG. (C) is one Example which shows the position of the whole air reservoir 30 and the vent 33 on the flat part of the ship bottom 21. FIG. Furthermore, (d) is the conceptual diagram of one Example which has arrange | positioned the air pocket 30 in the position of the double ship bottom 21. FIG. The conceptual diagram of one Example of the ship body frictional resistance reduction apparatus which sends together air into the ship bottom using together the external power 40, such as the air suction device 10 of this invention, and a blower. The conceptual diagram of one Example of the ship body frictional resistance reduction apparatus by the bubble 23 using the air suction apparatus 10 of this invention. FIG. 4A is a conceptual diagram of an embodiment in which bubbles are reduced by changing the shape of the air suction device 10 and bubbles having a small buoyancy are used in FIG.

    FIG. 1 shows an air suction device according to an embodiment of the present invention. A hub 12 is disposed at the center of the cylinder 11, and a plurality of fixed wings 13 are provided around the hub 12, and one end of the fixed wing 13 is fixed to the inner surface of the cylinder 11. On the other hand, an air chamber 14 is provided outside the cylinder 11 so as to surround the cylinder 11. The upper part is connected to a ventilation pipe 15, and one end of the ventilation pipe 15 has an intake port 16 communicating with the atmosphere. . The intake port 16 passes through the ventilation pipe 15 and the air chamber 14, passes through the fixed blade 13 and the inside of the hub 12, and communicates with the exhaust port 17 at the rear of the hub 12.

    As shown in FIG. 1, for example, when flowing water enters the inlet 18 a of the air suction device 10 from the left side, it passes through a plurality of fixed blades 13 fixed between the hub 12 and the cylinder 11. The fixed wing 13 has an angle, and the water that has flowed in begins to swirl, forms a large swirling flow at the rear of the hub 12, and a large negative pressure is generated at the center thereof. Atmospheric air is sucked in from the intake port 16 and self-priming of air from the exhaust port 17 into the water begins. In order to make self-sufficiency without applying pressure, if a slightly thicker ventilation pipe is prepared and an air chamber is provided rather than using a plurality of thin ventilation pipes, the pressure loss during suction can be reduced.

    FIG. 2 shows an embodiment in which the air suction device 10 of the present invention is attached to the hull 20, and an opening is provided in the vicinity of the bow bottom of the hull 20, and the flow of the air suction device 10 is performed when the ship is sailing. Water enters the air suction device 10 from the inlet 18a and is discharged as a two-phase flow of water and air from an air opening 22 provided in the ship bottom 21 slightly behind. Of course, the shape, installation location, number, and the like of the air suction device 10 can be adjusted to the optimum one according to the type, size and application of the ship. For example, in the case of a thin hull with a small area at the bottom of the ship bottom, the air suction device 10 can be installed on both sides near the bow, and the air release ports 22 can be provided on both sides.

    Next, FIG. 3 shows an embodiment of the hull frictional resistance reducing device shown in claims 3 and 4. (A) shows an embodiment in which a plurality of air reservoirs 30 composed of a plurality of vertical and horizontal partition plates 31 and 32 are attached to the lower part of the bottom 21 of the existing hull 20. (B) shows the air reservoir 30 which consists of the vertical partition plate 31 parallel to the flow direction FD and the horizontal partition plate 32 perpendicular | vertical to the flow direction, attached to the ship bottom 21 lower part, and also in a part upper part of the vertical partition plate 31. This is an embodiment in which a vent 33 b is provided also in the upper part of the vent 33 a and the horizontal partition plate 32. (C) is a conceptual diagram in which the bottom 21 of the hull 20 is looked up from directly below, and has an air release port 22 in the vicinity of the bow and a concept of an embodiment in which a plurality of air reservoirs 30 are arranged on the flat portion of the bottom 21. FIG. The shape, dimensions, installation location, number, etc. of the vents 33 may be optimally designed by each ship. (D) shows an embodiment in which the air reservoir 30 is incorporated in, for example, a double ship bottom from the beginning, such as a new shipbuilding. It should be noted that the air reservoir 30 shown in FIG. 3 can be adapted to the optimum shape, the installation location, the number, etc. of the air reservoir 30 according to the type, size and application of the ship.

    As shown in FIG. 3, by providing the vents 33 above the vertical and horizontal partition plates 31 and 32 of the air reservoir 30, the amount of air in all the air reservoirs 30 can be kept almost uniform by itself. The position of the water surface in the reservoir 30 can be almost unified. Furthermore, if air can always be supplied from the air release port 22, the air can be almost fully stored in all the air reservoirs 30 regardless of which air reservoir 30 catches the air. Therefore, the surface area where the hull 20 below the water contacts the water can be reduced, and the frictional resistance of the hull 20 can be reduced.

    FIG. 4 shows an embodiment of a hull frictional resistance reduction device that uses the air suction device 10 of the present invention and an external power 40 such as a blower to send air to the bottom of the ship. 10 and an external power 40 such as a blower is connected to one end of the ventilation pipe 15. A check valve (not shown) is attached above the connection position between the ventilation pipe and the external power 40, so that air supplied from the external power 40 does not flow to the intake port 16 and is always air. It is discharged from the exhaust port 17 of the inhaler 10. Since the negative pressure is always generated in the air suction device 10 while the ship is sailing, the consumption of the motive energy of the external power 40 is reduced.

    In FIG. 5 (a), the outlet 18b of the cylinder 11 of the air suction device 10 of the present invention is narrowed, and the air sucked into the negative pressure generated at the rear part of the hub 12 swirls violently. The velocity in the direction of the rotation axis is accelerated from the flow toward the narrowed outlet 18b, and is sheared in the accelerating flow to become fine bubbles 23. (B) is a conceptual view of the bottom 21 of the double bottom as viewed from directly below. The number of fine bubbles 23 discharged from the air suction device 10 (not shown) is increased along the center of the bottom 21. The air opening 22 is provided. In general, in order to obtain fine bubbles 23, when air is discharged from the ship bottom 21 into the flow of water, the air is discharged in a direction perpendicular to the flow direction of the water so that the air is sheared by the water flowing in the vertical direction. To. However, in the present invention, the fine bubbles 23 sheared by the swirling flow or the flow accelerating in the direction of the rotation axis are already in a two-phase flow with water and are discharged from the air opening 22 into the water flow at the bottom 21. Similarly, since water can be discharged along the flow direction of water, the fine bubbles 23 can cover the ship bottom 21 while forming an air film so as to crawl the ship bottom 21. Therefore, efficient hull frictional resistance reduction can be achieved. Furthermore, since the flow from the air suction device 10 to the air release port 22 is a two-phase flow of water and fine bubbles 23, for example, in the device from the air suction device 10 in the ship bottom 21 to the air release port 22, Since the adhesion of marine organisms such as barnacles is reduced, maintenance becomes easier.

    Although several embodiments of the hull frictional resistance reducing device have been described above, it is needless to say that an optimum design suitable for the use, scale, etc. of the vessel is made. In particular, in the case of a device applied to the bottom of a ship, it is natural to give it strength in consideration of a docked case.

DESCRIPTION OF SYMBOLS 10 Air suction apparatus 11 Cylinder 12 Hub 13 Fixed wing 14 Air chamber 15 Ventilation pipe 16 Intake port 17 Exhaust port 20 Hull 21 Ship bottom 22 Air release port 23 Bubble 30 Air reservoir 31 Vertical partition plate 32 Horizontal partition plate 33 Vent port 40 External power FD (relative to the hull) water flow direction

Claims (5)

A hub is provided inside a cylinder provided in the underwater portion, a plurality of fixed wings are attached around the hub, and the fixed wings are fixed to the inner surface of the cylinder.
An air chamber is provided so as to surround the cylinder, and the air chamber communicates with a ventilation pipe that leads to the atmosphere on one side,
Next, through the inside of the fixed wing and the hub, an air exhaust port is provided at the rear of the hub,
A hull frictional resistance reduction device having an air suction device, characterized in that the air inlet, the air passage, the fixed wing, and the rear outlet of the hub communicate with each other.   2. The air suction device according to claim 1, wherein an inlet of the air suction device is opened near a bow bottom of the ship, and an outlet of the air suction device is an air release port provided on a ship bottom or a side of the ship. A hull frictional resistance reduction device having an air suction device.   Hull friction with an air reservoir, characterized in that a plurality of air reservoirs composed of a plurality of vertical and horizontal partition plates are provided on a flat portion of the ship bottom, and vents are provided on the upper portion of the partition plates, that is, on the side in contact with the ship bottom. Resistance reduction device.   The hull friction reduction device according to claim 2, wherein the hull friction resistance reduction device has the air pocket.   5. The hull frictional resistance reduction device according to claim 2 or 4, wherein an external power such as a blower is used in combination to send air to the bottom of the ship.