AIR LUBRICATION DEVICE OF SHIP

Abstract

An air lubrication apparatus of a ship includes an air ejecting unit and a restraining section. The air ejecting unit ejects air from the ship bottom. The restraining section restrains relative reduction of a thickness of an air layer which covers a center line region of the ship bottom.

Description

INCORPORATION BY REFERENCE

The present application claims a priority based on Japanese Patent Application No. 2010-198205 filed on Sep. 3, 2010. The disclosure thereof is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an air lubrication device for a ship and an air lubrication method for a ship, in which friction resistance of a ship body is reduced by using air ejection.

BACKGROUND ART

A technique is known which reduces friction resistance of a ship body by covering a surface of a ship bottom with a flow of air bubbles at the time of navigation.

Referring to FIGS. 1A and 1B, a ship friction resistance reducing apparatus disclosed in Japanese Patent Publication JP 2008-114710A will be described. Gas rooms 2 are provided in a ship bottom 1 section of a ship on the side of the bow. The gas rooms 2 are provided in a ship width direction. Gas holding plates 5 of a pair are provided along the both sides of the ship bottom from the bow to the stern. Gas is ejected from the gas rooms 2 into water, and a flow of bubbles is generated to flow backward along the ship bottom 1. The gas holding plates 5 prevent dissipation of the flow of bubbles into the sides of the ship. In this way, friction resistance of the ship body can be reduced.

SUMMARY OF INVENTION

An air lubrication device for a ship according to a first aspect of the present invention includes an air ejecting unit configured to eject air from a ship bottom of the ship, and a restraining section configured to restrain the thickness of an air layer which covers a center line region of a ship bottom from being relatively reduced.

The ship bottom includes a port-side region on a port side with respect to the center line region, and a starboard-side region on a starboard side with respect to the center line region. The air ejecting unit includes N central air outlets provided in the center line region, N port-side air outlets provided in the port-side region, and N starboard-side air outlets provided in the starboard-side region. The N is a natural number. The restraining section includes another central air outlet provided in the center line region.

The ship bottom includes a port-side region on a port side with respect to the center line region, and a starboard-side region on the starboard side with respect to the center line region. The air ejecting unit ejects the air from the center line region, the port-side region, and the starboard-side region. The restraining section includes a port-side wall surface provided between the center line region and the port-side region to restrain movement of the air from the center line region to the port-side region, and a starboard-side wall surface provided between the center line region and the starboard-side region to restrain movement of the air from the center line region to the starboard-side region.

The ship bottom includes a port-side region on a port side with respect to the center line region, and a starboard-side region on a starboard side with respect to the center line region. The air ejecting unit ejects the air from the center line region, the port-side region, and the starboard-side region. The restraining section includes a roller provided in the center line region. The roller rotates around a rotational axis parallel to a ship width direction such that a surface flow of the air in the center line region is accelerated toward a stern of the ship.

An air lubrication method for a ship according to a second aspect of the present invention includes ejecting air from a ship bottom of the ship, and restraining a thickness of an air layer covering a center line region of the ship bottom from being relatively reduced.

The ship bottom includes a port-side region on a port side with respect to the center line region, and a starboard-side region on a starboard side with respect to the center line region. N central air outlets are provided in the center line region. N port-side air outlets are provided in the port-side region. N starboard-side air outlets are provided in the starboard-side region. Another central air outlet is provided in the center line region. The N is an integer equal to or more than 1. The ejecting includes ejecting the air from the central air outlets, the port-side air outlets, and the starboard-side air outlets. The restraining includes ejecting air from the other central outlet.

The ship bottom includes a port-side region on a port side with respect to the center line region, and a starboard-side region on a starboard side with respect to the center line region. The ejecting includes ejecting the air from the center line region, the port-side region, and the starboard-side region. The restraining includes restraining movement of the air from the center line region to the port-side region by a wall surface, and retraining movement of the air from the center line region to the starboard-side region by a wall surface.

The ship bottom includes a port-side region on a port side with respect to the center line region, and a starboard-side region on a starboard side with respect to the center line region. The ejecting includes ejecting the air from the center line region, the port-side region, and the starboard-side region. The restraining includes accelerating a surface flow of the air toward a stern in the center line region.

The present invention provides an air lubrication device for a ship and an air lubrication method for a ship, capable of covering the entire ship bottom with a layer of air of uniform thickness.

BRIEF DESCRIPTION OF DRAWINGS

The above objects, other objects, effect, and characteristics of the present invention will be more clarified from the description of embodiments together with the attached drawings.

FIG. 1A is a side view showing a ship having a conventional ship friction resistance reducing apparatus;

FIG. 1B is a bottom view of the ship having the conventional ship friction resistance reducing apparatus;

FIG. 2 is a bottom view showing a ship according to a first embodiment of the present invention;

FIG. 3 is a conceptual diagram showing streamline distribution in the vicinity of a ship bottom of the ship according to the first embodiment;

FIG. 4A is a bottom view of a ship according to a second embodiment of the present invention;

FIG. 4B is a sectional view of the ship according to the second embodiment;

FIG. 5A is a bottom view of a ship according to a third embodiment of the present invention;

FIG. 5B is a sectional view of the ship according to the third embodiment;

FIG. 6A is a bottom view of a ship according to a fourth embodiment of the present invention; and

FIG. 6B is a conceptual diagram for showing a rotational direction of a roller provided to the ship according to the fourth embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

An air lubrication device for a ship and an air lubrication method for a ship according to the present invention will be described below with reference to the attached drawings.

First Embodiment

A ship according to a first embodiment of the present invention will be described with reference to FIG. 2. The ship has a ship body 10 and an air lubrication device 20. The ship body 10 has a bow 11, a stern 12, a ship bottom 13, port 14, and starboard 15. A ship length direction and a ship width direction of the ship body 10 are indicated by X and Y, respectively. The ship bottom 13 includes a center line region 13a, a port-side region 13b on the side of the port 14 with respect to the center line region 13a, and a starboard-side region 13c on the side of the starboard 15 with respect to the center line region 13a. The center line region 13a extends in the ship length direction X along a center line CL of the ship body 10. The port-side region 13b and the starboard-side region 13c extend in the ship length direction X to put the center line region 13a therebetween.

The air lubrication device 20 has an air ejecting unit 30 for ejecting air from the ship bottom 13 into water, and a restraining section 40 which restrains the thickness of a layer of air that covers the center line region 13a from being relatively reduced. The air ejecting unit 30 has a central air outlet 31 (hereinafter, to be referred to as an air outlet 31) provided in the center line region 13a, a port-side air outlet 32 (hereinafter, to be referred to as an air outlet 32) provided in the port-side region 13b, and a starboard-side outlet 33 (hereinafter, to be referred to as an air outlet 33) provided in the starboard-side region 13c. The air outlet 31 is positioned on the center line CL. The air outlets 31, 32, and 33 are arranged on the side of the bow 11 of the ship bottom 13. The position of the air outlet 31 in the ship length direction X is different from those of the air outlets 32 and 33 in the ship length direction X. In order to eject air into water, each of the air outlets 31, 32, and 33 has a slit hole extending into the ship width direction Y, or a group of small holes arranged in the ship width direction Y. During navigation of the ship according to the present embodiment, the air ejecting unit 30 ejects air from the air outlets 31, 32, and 33 into water. Since a layer of air ejected from the air outlets 31, 32, and 33 covers the ship bottom 13, friction resistance of the ship body 10 can be reduced.

The restraining section 40 includes central air outlets 41 (hereinafter, to be referred to as air outlets 41) provided in the center line region 31a. The air outlets 41 are arranged on the center line CL on the side of the stern 12 with respect to the air outlet 31. In order to eject air into water, the air outlets 41 each have a slit hole extending into the ship width direction Y, or a group of small holes arranged in the ship width direction Y. The air outlets 41, and the air outlets 31 and 41 are arranged away from each other in the ship length direction X. The restraining section 40 controls air to be ejected from the air outlet 41 into water.

Referring to FIG. 3, effect of the present embodiment will be described. FIG. 3 is a conceptual diagram showing a streamline distribution in the vicinity of the ship bottom 13. In some ship types, streamlines SL extend outwardly. Therefore, when the restraining section 40 does not eject air from the air outlets 41 into water, the thickness of the layer of air covering the center line region 13a becomes relatively thin, compared with the thickness of the layer of air covering the port-side region 13b or the starboard-side region 13c. In the present embodiment, since the restraining section 40 ejects air from the center line region 13a into water, an amount of air ejected from the center line region 13a is relatively increased, so that the thickness of the layer of air covering the center line region 13a is controlled to be restrained from being relatively reduced.

It should be noted that a single air outlet 31, 32, and 33 may be provided as shown in FIG. 2, or, a plurality of air outlets 31, 32, and 33 may be provided for every plural pieces. The two air outlets 41 may be provided as shown in FIG. 2, or, alternatively, only a single air outlet 41, or three and more air outlets 41 may be provided.

Second Embodiment

The ship according to a second embodiment of the present invention will be described with reference to FIG. 4A. The ship according to the second embodiment is the same as the ship according to the first embodiment, excluding the following point. The restraining section 40 according to the present embodiment has gas holding plates 42 and 43. The gas holding plate 42 is provided between the center line region 13a and the port-side region 13b, to extend into the ship length direction X. The gas holding plate 43 is provided between the center line region 13a and the starboard-side region 13c to extend into the ship length direction X. In the present embodiment, the gas holding plates are not provided on both outsides of the ship bottom 13 (the outside of the port-side region 13b and the outside of the starboard-side region).

Referring to FIG. 4B, the gas holding plates 42 and 43 project downward from the ship bottom 13. The gas holding plate 42 has a port-side wall surface 42a directed inward (hereinafter, to be referred to as a wall surface 42a). The gas holding plate 43 has a starboard-side wall surface 42b directed inward (hereinafter, to be referred to as a wall surface 42b). The wall surfaces 42a and 43a extend into the ship length direction X. The wall surface 42a limits movement of air from the center line region 13a to the port-side region 13b. The wall surface 43a limits movement of the air from the center line region 13a to the starboard-side region 13c. Therefore, the thickness of the layer of air covering the center line region 13a is controlled to be restrained from being relatively reduced.

Third Embodiment

The ship according to the third embodiment of the present invention will be described with reference to FIG. 5A. The ship according to the third embodiment is the same as the ship according to the first embodiment, excluding the following point. The restraining section 40 according to the present embodiment has a groove section 44 formed in a center line region 13a. The groove section 44 extends in a ship length direction X. The air outlet 31 is provided in a bottom surface 44a of the groove 44.

Referring to FIG. 5B, the groove section 44 has a port-side wall surface 44b (hereinafter, to be referred to as a wall surface 44b), which is provided between the center line region 13a and the port-side region 13b and which is directed inward, and a starboard-side wall surface 44c (hereinafter, to be referred to as a wall surface 44c), which is provided between the center line region 13a and the starboard-side region 13c and which is directed inward. The wall surfaces 44b and 44c extend in the ship length direction X. The wall surface 44b limits movement of air from the center line region 13a to the port-side region 13b. The wall surface 44c limits movement of air from the center line region 13a to the starboard-side region 13c. Therefore, the thickness of the layer of air covering the center line region 13a is restrained from being relatively reduced.

Fourth Embodiment

The ship according to a fourth embodiment of the present invention will be described with reference to FIG. 6A. The ship according to the fourth embodiment is the same as the ship according to the first embodiment excluding the following point. The restraining section 40 according to the present embodiment includes rollers 45 provided in the center line region 13a. The rollers 45 are arranged on the center line CL on the side of the stern 12 compared with the air outlet 31. The rollers 45 and the air outlet 31 and the roller 45 are arranged away from each other in a ship length direction X. The roller 45 partly exposed from an opening 13d formed in the center line region 13a. A driving unit (not shown) rotates the roller 45 around a rotational axis S parallel to the ship width direction Y.

Referring to FIG. 6B, the rollers 45 rotate around the rotation axes S so that a surface flow of the center line region 13a is accelerated toward the stern 12. Since the rollers 45 accelerate the surface flow of the center line region 13a toward the stern 12, a flow velocity in the center line region 13a is increased. Therefore, the thickness of the layer of air covering the center line region 13a is controlled to be restrained from being relatively reduced.

The two rollers 45 may be provided as shown in FIG. 6A, or, alternatively, a single roller 45, or three and more rollers 45 may be provided.

The air lubrication device 20 according to the above embodiments is effective not only for full ships but also for slender ships.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes may be added to the above embodiments, and the embodiments may be combined. For example, the air outlets 31, 32, and 33 may be replaced by a single air outlet formed to lie across the port-side region 13b, the center line region 13a, and the starboard-side region 13c.

Claims

1. An air lubrication device of a ship, comprising: an air ejecting unit configured to eject air from a ship bottom of said ship; anda restraining section configured to restrain a thickness of a layer of the air which covers a center line region of said ship bottom from being relatively reduced.

2. The air lubrication device according to claim 1, wherein said ship bottom comprises: a port-side region on a port side of said center line region; anda starboard-side region on a starboard side of said center line region,wherein said air ejecting unit comprises:N central air outlets provided in said center line region;N port-side air outlets provided in said port-side region; andN starboard-side air outlets provided in said starboard-side region,wherein said N is an integer equal to or more than 1, andwherein said control section comprises another central air outlet provided in said center line region.

3. The air lubrication device according to claim 1, wherein said ship bottom comprises: a port-side region on a port side of said center line region; anda starboard-side region on a starboard side of said center line region,wherein said air ejecting unit ejects the air from said center line region, said port-side region, and said starboard-side region, andwherein said restraining section comprises:a port-side wall surface provided between said center line region and said port-side region to retrain movement of the air from said center line region to said port-side region; anda starboard-side wall surface provided between said center line region and said starboard-side region to retrain movement of the air from said center line region to said starboard-side region.

4. The air lubrication device according to claim 1, wherein said ship bottom comprises: a port-side region on a port side of said center line region; anda starboard-side region on a starboard side said center line region,wherein said air ejecting unit ejects the air from said center line region, said port-side region, and said starboard-side region,wherein said restraining section comprises a roller provided for said center line region, andwherein said roller rotates around a rotation axis parallel to a ship width direction such that a surface flow of the air in said center line region is accelerated toward a stern of said ship.

5. An air lubrication method of a ship, comprising: ejecting air from a ship bottom of said ship; andrestraining a thickness of an air layer which covers a center line region of said ship bottom of ship, from being relatively reduced.

6. The air lubrication method according to claim 5, wherein said ship bottom comprises: a port-side region on a port side of said center line region; anda starboard-side region on a starboard side of said center line region,wherein N central air outlets are provided in said center line region, N port-side air outlets are provided in said port-side region, N starboard-side air outlets are provided in said starboard-side region, and another central air outlet is provided for said center line region,wherein said N is an integer equal to or more than 1,wherein said ejecting comprises ejecting the air from said central air outlets, said port-side air outlets, and said starboard-side air outlets, andwherein said restraining comprises ejecting air from said another central air outlet.

7. The air lubrication method according to claim 5, wherein said ship bottom comprises: a port-side region on a port side of said center line region; anda starboard-side region on a starboard side of said center line region,wherein said ejecting comprises ejecting the air from said center line region, said port-side region, and said starboard-side region, andwherein said restraining comprises:constraining movement of the air from said center line region to said port-side region by a port-side wall surface provided between said center line region and said port-side region; andretraining movement of the air from said center line region to said starboard-side region by a starboard-side wall surface provided between said center line region and said starboard-side region.

8. The air lubrication method according to claim 5, wherein said ship bottom comprises: a port-side region on a port side of said center line region; anda starboard-side region on a starboard side of said center line region,wherein said ejecting comprises ejecting the air from said center line region, said port-side region, and said starboard-side region, andwherein said restraining comprises accelerating a surface flow of the air toward a stern of said ship in said center line region.