JP2018154198A - Vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain improvement in friction resistance reduction effect in a vessel.SOLUTION: A bottom 13 is at least provided with an inclination 61 where draft becomes deeper toward a stern 12 side at a position closer to the stern 12 than an air blowing out unit 36 in a vessel mounted with a friction reduction device 31 blowing out air inside water from the air blowing out unit 36 of the bottom 13.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ship provided with a friction reducing device that reduces frictional resistance acting on a hull.

  As a technique for reducing the frictional resistance acting on the hull of a ship, a technique is known in which air (bubbles) is blown into water to cover the surface of the hull with bubbles. In this hull frictional resistance reduction device, a gas supply pipe is connected to a gas chamber (air chamber), and a plurality of air jets are provided on the outer plate of the ship bottom in the gas chamber. A baffle plate is disposed between the air outlet and each air outlet. Therefore, the air supplied from the gas supply pipe to the gas chamber collides with the baffle plate and is diffused, and is ejected from each air ejection port into the water in a substantially uniform state. As such a hull frictional resistance reduction device, for example, there is one described in Patent Document 1 below.

JP 2007-26041 A

  By the way, in general, a displacement-type merchant ship is designed and constructed on the premise of an even keel in a loaded state, and the bottom of the ship is parallel to the water surface in the loaded state. For example, in a container ship, a container guide rail that guides the container is installed on the deck along the vertical direction in a loaded state, and the container can be loaded smoothly. In addition, tankers such as LNG ships and LPG ships are provided with tanks so that the liquid stored in the tanks is parallel to the deck. Therefore, in any ship, the bottom of the ship is designed to be horizontal to the water surface in the loaded state. When the ship operates at a predetermined speed, the hull sinks due to the negative pressure due to the ship bottom flow velocity, and the sinking amount on the bow side increases, and the ship sails in a state where the bow is lowered.

  The hull frictional resistance reduction device reduces the frictional resistance over a wide range by blowing air into the water from the outlet provided on the bottom of the ship and allowing the blown bubbles to flow toward the stern without leaving the surface of the bottom of the ship. Is desirable. However, as described above, a general ship is in a bow-down state in which the bottom of the ship is horizontal with respect to the water surface in the loaded state and the bow side sinks with respect to the stern side in the sailing state. For this reason, the bubbles blown out into the water from the blowout port flow toward the stern side and are separated from the surface of the bottom of the ship, so that the friction reducing effect cannot be sufficiently exhibited. As a countermeasure, it is conceivable to increase the amount of air ejected into the water from the outlet, but this leads to an increase in the size and cost of air blowers and compressors and an increase in power consumption.

  This invention solves the subject mentioned above, and aims at providing the ship which aims at the improvement of a frictional resistance reduction effect.

  In order to achieve the above object, a ship according to the present invention is equipped with a friction reduction device that blows air out from an air blowing part at the bottom of the ship, wherein the ship bottom is at least stern on the stern side of the air blowing part. An inclined surface in which the draft is deepened toward the side is provided.

  Therefore, when air is blown into the water from the air blowing part, this air becomes a large number of bubbles and flows to the stern side along the surface of the ship bottom, but there is an inclined surface where the draft becomes deeper toward the stern side on the ship bottom. Since it is provided, it becomes difficult for many bubbles to flow to the stern side, the density of the bubbles is increased, and the effect of reducing frictional resistance can be improved.

  In the ship according to the present invention, the air blowing portion is provided on the bow side from an intermediate position of the captain, and the inclined surface is located at a rudder axis center from a position at which 10% of the length between water lines has shifted from the rudder axis to the bow side. It is characterized in that it is provided in a region between the position where 90% of the length between the water lines has shifted to the bow side.

  Therefore, by providing the inclined surface in the optimum region in the ship length direction, it is possible to suppress the bubble diffusion and improve the frictional resistance reduction effect.

  In the ship of the present invention, the inclined surface is provided in an area of 20% or more of the length between waterlines along the ship length direction.

  Therefore, by setting the length of the area of the inclined surface in the ship length direction, it is possible to suppress the bubble diffusion and improve the frictional resistance reduction effect.

  In the ship of this invention, the said inclined surface is set to the inclination angle of 0.001 degree to 2 degree | times with respect to the waterline along a ship length direction, It is characterized by the above-mentioned.

  Therefore, by setting the region of the optimum inclination angle of the inclined surface, it is possible to improve the viscous frictional resistance reduction effect while suppressing the increase in wave resistance and viscous pressure resistance.

  In the ship of the present invention, the inclined surface is provided in a region having a width of 30% or more of the ship width.

  Therefore, by providing the inclined surface in the optimum region in the ship length direction, it is possible to suppress the bubble diffusion and improve the frictional resistance reduction effect.

  The ship according to the present invention is characterized in that a bow side horizontal plane having a constant draft is provided along the captain direction on the bow side from the inclined surface in the ship bottom.

  Therefore, by providing the bow side horizontal surface on the bow side from the inclined surface, it is possible to improve the effect of reducing the viscous frictional resistance while suppressing the increase of the wave resistance and the viscous pressure resistance.

  The ship according to the present invention is characterized in that a stern side horizontal plane having a constant draft is provided along the length of the stern from the inclined surface at the bottom of the ship.

  Therefore, by providing the stern side horizontal plane on the stern side from the inclined surface, it is possible to improve the viscous frictional resistance reduction effect while suppressing increases in wave resistance and viscous pressure resistance.

  The ship according to the present invention is characterized in that a plurality of the air blowing portions are provided at predetermined intervals in the ship length direction.

  Therefore, it is possible to suppress the diffusion of bubbles in the ship width direction and improve the frictional resistance reduction effect.

  The ship according to the present invention is characterized in that the ship bottom is provided with a recess on the stern side of the air blowing part.

  Therefore, the air blown out into the water from the air blowing portion becomes a large number of bubbles and is temporarily stored in the concave portion, thereby suppressing the diffusion of the bubbles in the ship width direction and improving the frictional resistance reduction effect. be able to.

  In the ship according to the present invention, the ship bottom is provided with a guide portion that suppresses air diffusion outside the air blowing portion in the ship width direction.

  Therefore, the air blown into the water from the air blowing portion becomes a large number of bubbles, and the diffusion of the bubbles in the ship width direction is suppressed by the guide portion, so that the effect of reducing the frictional resistance can be improved.

  According to the ship of the present invention, it is possible to improve the frictional resistance reduction effect.

FIG. 1 is a schematic side view of a ship equipped with the friction reduction device according to the first embodiment. FIG. 2 is a schematic bottom view of a ship equipped with a friction reducing device. FIG. 3 is a schematic diagram showing an air supply system. FIG. 4 is a graph showing the bubble position with respect to the ship bottom. FIG. 5 is a schematic side view of a ship equipped with the friction reduction device of the second embodiment. FIG. 6 is a schematic bottom view of a ship equipped with a friction reducing device. FIG. 7 is a schematic bottom view of a ship equipped with the friction reducing device of the third embodiment. FIG. 8 is a schematic bottom view of a ship equipped with the friction reducing device of the fourth embodiment. FIG. 9 is a schematic longitudinal sectional view of a ship equipped with a friction reducing device. FIG. 10 is a schematic longitudinal sectional view of a ship equipped with a friction reducing device representing a first modification of the fourth embodiment. FIG. 11 is a schematic longitudinal sectional view of a ship equipped with a friction reducing device representing a second modification of the fourth embodiment. FIG. 12 is a schematic bottom view of a ship equipped with the friction reduction device of the fifth embodiment. FIG. 13 is a schematic longitudinal sectional view of a ship equipped with a friction reducing device.

  Hereinafter, preferred embodiments of a ship according to the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment, and when there are two or more embodiments, what comprises combining each embodiment is also included.

[First Embodiment]
FIG. 1 is a schematic side view of a ship equipped with the friction reducing device of the first embodiment, FIG. 2 is a schematic bottom view of the ship equipped with the friction reducing device, and FIG. 3 is a schematic diagram showing an air supply system. .

  The ship of the first embodiment is a large ship having a captain of 100 m or more, for example, a large oil tanker (VLCC, ULCC), an LNG ship, an LPG ship, a passenger ship (car ferry), etc., and is equipped with a friction reducing device. doing.

  As shown in FIGS. 1 and 2, the hull 10 has a bow 11, a stern 12, a ship bottom 13, a port 14, and a starboard 15. In this embodiment, the ship length direction (front-rear direction) of the hull 10 is represented as the X direction, the ship width direction (width direction) as the Y direction, and the ship height direction (up and down direction) as the Z direction. CL represents a center line in the width direction of the hull 10, and WL represents a full load water line of the hull 10.

  In the hull 10, an engine room 17 is partitioned by a partition wall 16 on the stern 12 side, and a main engine (for example, a diesel engine) 18 is disposed in the engine room 17. The main engine 18 is drivingly connected to a propeller 19 that transmits propulsive force. Further, the hull 10 is provided with a rudder 20 for controlling the direction of the hull 10 at the stern 12.

  Further, the hull 10 includes an air supply equipment room 21, a hold 22, a deck 23, a deck exposure part 25, a partition wall 26, a ship bottom skin 27, and ship side skins 28 and 29. The air supply device room 21 is arranged on the bow 11 side from the hold 22. The air supply equipment room 21 and the hold 22 are partitioned by a partition wall 26. The deck 23 forms the floor surfaces of the air supply equipment room 21 and the hold 22. The deck exposure unit 25 is, for example, the upper deck of the bow 11 and is disposed above the air supply device room 21.

  The friction reducing device 31 includes an air supply device 32, an air cooler 33, a ventilation tube 34, an air suction port 35, an air blowing portion 36, a seawater intake portion 37, and a pump 38. The air blowing portion 36 is disposed on the ship bottom 13 on the bow 11 side. The air supply device 32 and the air cooler 33 are installed in the air supply device chamber 21. The ventilation tube 34 and the air suction port 35 are disposed in the deck exposure unit 25. The ventilation tube 34 communicates with the air supply device chamber 21 and is used to ventilate the air supply device chamber 21. The air suction port 35 is connected to the air supply device 32. The air supply device 32 is connected to the air blowing portion 36 via the air cooler 33. The seawater intake unit 37 is connected to the air cooler 33 via a pump 38.

  The ship bottom 13 is disposed on a flat portion (flat surface) of the ship bottom skin 27 in the hull 10, extends to the bow 11 side along the center line CL (captain direction X) of the hull 10, and includes the stern 12. It extends to the side and extends to both sides along the ship width direction Y. The air blowing part 36 and the seawater intake part 37 are arranged on the center line CL of the hull 10 in the ship bottom 13, and the seawater intake part 37 is arranged on the bow 11 side from the air blowing part 36. The air blowing portion 36 is disposed along the ship width direction Y.

  The air supply device 32 pressurizes the air sucked from the air suction port 35 and supplies the pressurized compressed air from the air cooler 33 to the air blowing unit 36. The pump 38 supplies seawater taken from the seawater intake unit 37 to the air cooler 33. The air cooler 33 cools the compressed air using seawater. The air cooler 33 is a heat exchanger that exchanges heat between compressed air and seawater, for example. The air cooler 33 may be configured to cool the compressed air by spraying seawater into the compressed air, or may be configured to cool the compressed air by blowing the compressed air into the seawater. The air blowing unit 36 blows out the compressed air supplied from the air supply device 32 into the water. That is, air is blown into the water from the air blowing portion 36 of the ship bottom 13, and bubbles formed by the blown air are sent to the surface of the ship bottom 13 that becomes a flat surface, and the ship bottom 13 is covered by the bubbles. The frictional resistance of the hull 10 is reduced.

  Further, as shown in FIG. 3, the air blowing portion 36 disposed on the ship bottom 13 on the bow 11 side includes a plurality of gas chambers 41 provided inside the hull 10, and the inside of each gas chamber 41 and the outside of the hull 10. And a plurality of air outlets 42 provided on the ship bottom outer plate 27. The gas chamber 41 is a sealed space, and an air supply device 32 is connected via an air cooler 33. The plurality of air outlets 42 are passages that penetrate from the gas chamber 41 through the ship bottom outer plate 27 to the outside of the hull 10, that is, in water. The plurality of air outlets 42 are arranged along the ship length direction (X direction) of the ship bottom 13 and at predetermined intervals in the ship width direction (Y direction). Therefore, the compressed air blown out into the water from the plurality of air outlets 42 becomes bubbles, and flows rearward through the flat portion of the ship bottom 13 and diffuses in the width direction.

  The air supply device 32 includes a gas chamber 41, an air outlet 42, a compressor 43, a main air supply pipe 44, a main chamber 45, and a plurality of sub air supply pipes (air supply passages) 46. ing. The compressor 43 is connected to an air suction port 35 via an air intake pipe 47. The compressor 43 is connected to a main chamber 45 via a main air supply pipe 44. For example, the compressor 43 can pressurize the taken-in air to 500 kPa or more (desirably, 700 kPa to 1300 kPa). The main air supply pipe 44 is provided with an on-off valve 48, a flow meter 49, and a pressure gauge 50.

  The main chamber 45 can store a predetermined amount of compressed air supplied under pressure by the compressor 43 at a predetermined pressure. The main chamber 45 is connected to the downstream end of the main air supply pipe 44 and to the other upstream end of each of the plurality of sub air supply pipes 46. Each sub air supply pipe 46 has a downstream end connected to the gas chamber 41. The auxiliary air supply pipe 46 is provided with a flow rate adjustment valve 51 and a shutoff valve 52.

  Therefore, when the on-off valve 48 is opened and the compressor 43 is driven, the compressor 43 pressurizes the taken-in air to a predetermined pressure and sends it to the main chamber 45 through the main air supply pipe 44. The main chamber 45 is compressed air. Is stored at a predetermined pressure. Here, when the flow regulating valve 51 and the shutoff valve 52 are opened, the compressed air in the main chamber 45 is supplied to each gas chamber 41 via each sub air supply pipe 46, and the compressed air supplied to each gas chamber 41. Are blown out into the water from a plurality of air outlets 42 and flow to the stern 12 side along the surface of the ship bottom 13 which becomes bubbles and becomes a flat surface.

  As shown in FIGS. 1 and 2, the ship according to the present embodiment is provided with an inclined surface 61 on the bottom 13 at which the draft is deeper at the stern 12 side than the air blowing portion 36 toward the stern 12 side. . In this embodiment, the ship bottom 13 itself is an inclined surface 61 inclined by a predetermined inclination angle θ so that the draft becomes deeper toward the stern 12 side. That is, the ship bottom 13 that is the inclined surface 61 is inclined at a predetermined inclination angle θ downward in the ship height direction Z toward the stern 12 with respect to the horizontal line WL1 parallel to the full load water line WL.

  However, it is not necessary to incline the entire region of the ship bottom 13 to form the inclined surface 61, and the air blowing portion 36 is provided on the bow 11 side from the intermediate position in the ship length direction X. What is necessary is just to be provided in the stern 12 side from the blowing part 36. FIG.

  For example, the length in the ship length direction X from the position P1 of the rudder axis to the intersection P2 between the front end of the hull 10 on the bow 11 side and the full load water line WL is defined as a length L between water lines. At this time, the inclined surface 61 is shifted from the position P3 of the rudder axis center P1 to the bow 11 side by 10% of the length L between the water lines, from the position P3 to the bow 11 side from the position P1 of the rudder axis. Preferably, it is provided in the region A between the position P4 shifted by 90%. In addition, the formation area of the inclined surface 61 is not limited to the area A from the position P1 to the position P4, and the rudder axis from the position shifted from the rudder axis position P1 to the bow 11 side by 20% of the length L between waterlines More preferably, it is provided in a region between the center position P1 and a position shifted by 80% of the length L between water lines from the center position P1 to the bow 11 side.

  Further, the inclined surface 61 is preferably provided in a region of 20% or more of the length L between water lines along the ship length direction X. The inclined surface 61 is preferably set to an inclination angle θ of 0.001 degrees to 2 degrees with respect to the full-length draft line WL (horizontal line WL1) along the ship length direction X. This inclination angle θ is set based on experiments based on the length from the air blowing portion 36 with respect to the bubble diffusion width. The inclination angle θ is preferably 0.1 to 0.2 degrees.

  Therefore, when the compressed air is blown into the water from the air blowing portion 36, the compressed air becomes a large number of bubbles and flows toward the stern 12 along the surface of the bottom 13. At this time, a large number of bubbles flowing toward the stern 12 side along the surface of the stern 13 are diffused downward in the height direction Z, but the bottom 13 is an inclined surface 61 where the draft becomes deeper toward the stern 12 side. Therefore, a large number of bubbles are difficult to flow to the stern 12 side, and the density (void ratio) of the bubbles is increased. Therefore, the frictional resistance reduction effect of the hull 10 is improved.

  FIG. 4 is a graph showing the bubble position with respect to the ship bottom. As shown in FIG. 4, the conventional ship bottom is a horizontal plane in which the draft is constant toward the stern 12, and the bubble position represented by the alternate long and short dash line diffuses away from the ship bottom. The distance d1 from the position increases as it goes toward the stern 12 side, and the effect of reducing the frictional resistance of the hull 10 is diminished due to the decrease in bubble density. On the other hand, the bottom 13 of the present embodiment is an inclined surface 61 in which the draft becomes deeper toward the stern 12 side, and the bubble position represented by the alternate long and short dash line diffuses in a direction away from the bottom of the ship. The distance d2 from the bubble position is maintained substantially constant even when going to the stern 12 side, and the effect of reducing the frictional resistance of the hull 10 is improved as compared with the conventional case by maintaining the bubble density.

  As described above, in the ship according to the first embodiment, in the ship on which the friction reducing device 31 that blows air into the water from the air blowing part 36 of the ship bottom 13 is mounted, the ship bottom 13 is at least stern 12 from the air blowing part 36. An inclined surface 61 is provided on the side where the draft becomes deeper toward the stern 12 side.

  Therefore, the air blown into the water from the air blowing portion 36 becomes a large number of bubbles and flows toward the stern 12 along the surface of the ship bottom 13. At this time, since the inclined surface 61 in which the draft is deepened toward the stern 12 side is provided on the bottom 13, a large number of bubbles are difficult to flow to the stern 12 side, the density of the bubbles is increased, and the frictional resistance is reduced. The effect can be improved.

  In the ship of the first embodiment, the air blowing part 36 is provided on the bow 11 side from the intermediate position in the ship length direction X, and the inclined surface 61 is shifted from the rudder axis position P1 to the bow 11 side by 10% of the length L between the water lines. It is provided in a region A between the position P3 and the position P4 where the inter-waterline length L is shifted 90% from the rudder axis position P1 to the bow 11 side. Therefore, by providing the inclined surface 61 in the optimum region in the ship length direction X, it is possible to suppress the bubble diffusion and improve the frictional resistance reduction effect.

  In the ship of the first embodiment, the inclined surface 61 is provided in the region of 20% or more of the inter-waterline length L along the ship length direction X. Therefore, by setting the length of the region of the inclined surface 61 in the ship length direction X, it is possible to suppress the bubble diffusion and improve the frictional resistance reduction effect.

  In the ship of the first embodiment, the inclined surface 61 is set to an inclination angle θ of 0.001 degrees to 2 degrees with respect to the full load water line WL along the ship length direction X. Therefore, by setting the region of the optimum inclination angle of the inclined surface 61, it is possible to improve the viscous frictional resistance reduction effect while suppressing the increase in the wave resistance and the viscous pressure resistance.

[Second Embodiment]
FIG. 5 is a schematic side view of a ship equipped with the friction reducing device of the second embodiment, and FIG. 6 is a schematic bottom view of the ship equipped with the friction reducing device. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  As shown in FIGS. 5 and 6, the ship according to the second embodiment is provided with an inclined surface 62 on the bottom 13 at least on the stern 12 side from the air blowing portion 36 so that the draft becomes deep toward the stern 12 side. Yes. In the present embodiment, the inclined surface 62 is provided in a region where the width is 30% or more of the ship width W. That is, the ship bottom 13 extends along the center line CL (captain direction X) of the hull 10 to the bow 11 side and the stern 12 side, and its width decreases toward the bow 11 side and the stern 12 side. The inclined surface 62 is provided on the stern 12 side with respect to the ship width Wf = 0.3W and on the bow 11 side with respect to the ship width Wr = 0.3W.

  The ship bottom 13 is provided with a bow-side horizontal plane 63 with a constant draft along the ship length direction X on the bow 11 side of the inclined surface 62. The bottom 13 is provided with a stern-side horizontal surface 64 with a constant draft along the length X in the stern 12 side of the inclined surface 62. That is, the ship width Wf between the inclined surface 62 and the bow side horizontal surface 63 is 0.3 W, and the ship width Wr between the inclined surface 62 and the stern side horizontal surface 64 is 0.3 W. However, the inclined surface 62 may be provided on the stern 12 side from a position away from the air blowing portion 36 by a predetermined distance in the stern direction.

  Therefore, the compressed air blown out into the water from the air blowing portion 36 becomes a large number of bubbles and flows toward the stern 12 along the surface of the ship bottom 13. At this time, a large number of bubbles flowing toward the stern 12 along the surface of the ship bottom 13 are less likely to flow toward the stern 12 when flowing through the inclined surface 62, and the density (void ratio) of the bubbles increases. Therefore, the frictional resistance reduction effect of the hull 10 is improved.

  Thus, in the ship of the second embodiment, the width of the inclined surface 62 is provided in an area of 30% or more of the ship width W. Therefore, by providing the inclined surface 62 in the optimum region in the ship length direction X, it is possible to suppress the bubble diffusion and improve the frictional resistance reduction effect.

  In the ship according to the second embodiment, a bow side horizontal plane 63 having a constant draft along the ship length direction X is provided on the bow 11 side of the inclined surface 62 of the ship bottom 13. Accordingly, it is possible to improve the viscous frictional resistance reduction effect while reducing the hull resistance on the bow 11 side and suppressing the increase in wave resistance and viscous pressure resistance.

  In the ship of the second embodiment, a stern side horizontal plane 64 having a constant draft along the ship length direction X is provided on the stern 12 side from the inclined surface 62 in the ship bottom 13. Accordingly, it is possible to improve the viscous frictional resistance reduction effect while reducing the hull resistance on the stern 12 side and suppressing the increase of wave resistance and viscous pressure resistance.

[Third Embodiment]
FIG. 7 is a schematic bottom view of a ship equipped with the friction reducing device of the third embodiment. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  As shown in FIG. 7, the ship of the third embodiment is provided with a plurality (three in this embodiment) of air blowing portions 36 a, 36 b, 36 c at a predetermined interval in the ship length direction X on the bottom 13. Yes. In the ship bottom 13, an inclined surface 61 is provided on the stern 12 side at least from the air blowing portion 36 a on the bow 11 side so that the draft becomes deeper toward the stern 12 side.

  Therefore, the compressed air blown into the water from each of the air blowing portions 36a, 36b, and 36c becomes a large number of bubbles and flows toward the stern 12 along the surface of the bottom 13. At this time, a large number of bubbles that flow toward the stern 12 along the surface of the ship bottom 13 are less likely to flow toward the stern 12 when flowing through the inclined surface 61, and the density (void ratio) of the bubbles increases. Therefore, the frictional resistance reduction effect of the hull 10 is improved.

  Thus, in the ship of 3rd Embodiment, the several air blowing part 36a, 36b, 36c is provided in the ship length direction X of the ship bottom 13 at predetermined intervals. Therefore, by blowing air from the air blowing portions 36a, 36b, 36c along the center line CL of the ship bottom 13, it is possible to suppress the diffusion of bubbles in the ship width direction and improve the frictional resistance reduction effect.

[Fourth Embodiment]
FIG. 8 is a schematic bottom view of a ship equipped with the friction reducing device of the fourth embodiment, and FIG. 9 is a schematic longitudinal sectional view of the ship equipped with the friction reducing device. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  As shown in FIGS. 8 and 9, the ship of the fourth embodiment is provided with a plurality of (two in this embodiment) air blowing portions 36 a and 36 b at a predetermined interval in the ship length direction X on the ship bottom 13. ing. In the ship bottom 13, an inclined surface 61 is provided on the stern 12 side at least from the air blowing portion 36 a on the bow 11 side so that the draft becomes deeper toward the stern 12 side.

  Further, in the bottom 13, recesses 71 a and 71 b are provided on the stern 12 side from the air blowing portions 36 a and 36 b. In other words, each of the recesses 71a and 71b is provided in a rectangular shape on the ship bottom 13, is formed to be recessed on the inner side of the ship, and has a substantially constant depth. Each air blowing part 36a, 36b is provided at the end part on the bow 11 side in each concave part 71a, 71b. However, the concave portions 71a and 71b may be provided immediately after the stern 12 side of the air blowing portions 36a and 36b, or may be provided separated by a predetermined distance.

  Therefore, the compressed air blown out into the water from each of the air blowing portions 36 a and 36 b becomes a large number of bubbles and flows toward the stern 12 along the surface of the bottom 13. At this time, a large number of bubbles flowing toward the stern 12 along the surface of the ship bottom 13 are temporarily stored in the recesses 71 a and 71 b, and are difficult to diffuse in the ship width direction Y, and flow through the inclined surface 61. Sometimes it becomes difficult to flow to the stern 12 side, and the density (void ratio) of bubbles becomes high. Therefore, the frictional resistance reduction effect of the hull 10 is improved.

  In addition, the structure of each recessed part 71a, 71b with respect to the ship bottom 13 is not limited to what was mentioned above. FIG. 10 is a schematic longitudinal sectional view of a ship equipped with a friction reduction device representing a first modification of the fourth embodiment, and FIG. 11 is a ship equipped with a friction reduction device representing a second modification of the fourth embodiment. It is a schematic longitudinal cross-sectional view.

  As shown in FIG. 10, a plurality (two in this embodiment) of air blowing portions 36 d and 36 e are provided on the ship bottom 13 at a predetermined interval in the ship width direction Y. Further, in the ship bottom 13, one recess 71 a is provided on the stern 12 side from the air blowing portions 36 d and 36 e. That is, the concave portion 71a is provided in a rectangular shape on the ship bottom 13 and is formed in a concave shape on the inner side of the ship, and has a substantially constant depth. Each air blowing portion 36d, 36e is provided at the end portion on the bow 11 side in the recess 71a.

  In addition, as shown in FIG. 11, a plurality (two in this embodiment) of air blowing portions 36 d and 36 e are provided on the ship bottom 13 at a predetermined interval in the ship width direction Y. In addition, a plurality of (two in the present embodiment) recesses 71c and 71d are provided in the ship width direction Y at a predetermined interval on the stern 12 side of the ship bottom 13 from the air blowing portions 36d and 36e. That is, each of the recesses 71c and 71d is provided in a rectangular shape on the ship bottom 13, is formed to be recessed on the inner side of the ship, and has a substantially constant depth. The air blowing portions 36d and 36e are provided at the ends on the bow 11 side in the recesses 71c and 71d.

  Thus, in the ship of the fourth embodiment, the bottom 13 is provided with the recesses 71a, 71b, 71c, 71d on the stern 12 side from the air blowing parts 36a, 36b, 36d, 36e. Therefore, the air blown into the water from the air blowing portions 36a, 36b, 36d, and 36e becomes a large number of bubbles and is temporarily stored in the recesses 71a, 71b, 71c, and 71d, thereby moving in the ship width direction Y. Bubble diffusion is suppressed, and the effect of reducing frictional resistance can be improved.

[Fifth Embodiment]
FIG. 12 is a schematic bottom view of a ship equipped with the friction reducing device of the fifth embodiment, and FIG. 13 is a schematic longitudinal sectional view of the ship equipped with the friction reducing device. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  As shown in FIGS. 12 and 13, the ship of the fifth embodiment is provided with an inclined surface 61 on the bottom 13 at which the draft becomes deeper toward the stern 12 side at least on the stern 12 side than the air blowing portion 36a. Yes. In addition, a pair of guide portions 81 that suppress the diffusion of air are provided on the ship bottom 13 outside the air blowing portion 36 in the ship width direction Y. Each guide part 81 is provided along the ship length direction X at a position close to the center line CL by a predetermined length from the end in the ship width direction Y on the ship bottom 13 (inclined surface 61). The guide portion 81 protrudes outward from the bottom of the ship, but the protrusion amount may be constant toward the stern 12 side, or may be decreased or increased. Moreover, although this guide part 81 is parallel to the ship length direction X, it may become wide toward the stern side or may become narrow.

  Therefore, the compressed air blown out into the water from the air blowing portion 36 becomes a large number of bubbles and flows toward the stern 12 along the surface of the ship bottom 13. At this time, a large number of bubbles flowing toward the stern 12 along the surface of the bottom 13 are suppressed from spreading outward in the width direction Y by the guide portions 81, and when flowing through the inclined surface 61, And the bubble density (void ratio) increases. Therefore, the frictional resistance reduction effect of the hull 10 is improved.

  As described above, in the ship according to the fifth embodiment, the guide part 81 that suppresses the diffusion of air is provided on the ship bottom 13 outside the air blowing part 36 in the ship width direction Y. Therefore, the air blown into the water from the air blowing portion 36 becomes a large number of bubbles, and the diffusion of the bubbles in the ship width direction Y is suppressed by the guide portion 81, so that the effect of reducing the frictional resistance can be improved.

  In addition, in each embodiment mentioned above, although the inclined surfaces 61 and 62 provided in the ship bottom 13 were made into the flat surface, it is good also as a curved surface curved along the ship length direction X. FIG. Moreover, although the inclined surfaces 61 and 62 are provided in the whole area of the ship width direction Y, you may provide only in the area | region which approached the centerline CL.

10 Hull 11 Bow 12 Stern 13 Bottom 14 Port side (ship side)
15 Starboard (ship side)
21 Air supply equipment room 27 Ship bottom skin 28, 29 Ship side skin 31 Friction reduction device 32 Air supply device 33 Air cooler 34 Ventilation cylinder 35 Air suction port 36, 36a, 36b, 36c, 36d, 36e Air blowout portion 37 Seawater intake portion 38 Pump 61, 62 Inclined surface 63 Bow side horizontal plane 64 Stern side horizontal plane 71a, 71b, 71c, 71d Recess 81 Guide portion X Ship length direction Y Ship width direction Z Ship height direction

Claims (10)

In a ship equipped with a friction reducing device that blows air to the outside from the air blowing part at the bottom of the ship,
The ship bottom is provided with an inclined surface where the draft becomes deeper toward the stern side at least on the stern side than the air blowing portion.
A ship characterized by that.   The air blowing portion is provided on the bow side from an intermediate position of the captain, and the inclined surface is a water line from the rudder axis to the bow side from a position where 10% of the length of the water line is shifted from the rudder axis to the bow side. The ship according to claim 1, wherein the ship is provided in an area between a position where 90% of the distance is shifted.   The ship according to claim 1 or 2, wherein the inclined surface is provided in an area of 20% or more of the length between water lines along the ship length direction.   The said inclined surface is set to the inclination angle of 0.001 degree to 2 degree | times with respect to the water line along a ship length direction, The ship as described in any one of Claims 1-3 characterized by the above-mentioned.   The ship according to any one of claims 1 to 4, wherein the inclined surface is provided in a region having a width of 30% or more of a ship width.   The ship according to any one of claims 1 to 5, wherein a bow-side horizontal plane having a constant draft is provided along the captain direction on the bow side from the inclined surface in the ship bottom.   The ship according to any one of claims 1 to 6, wherein a stern-side horizontal plane having a constant draft is provided along the length of the stern from the inclined surface at the bottom of the ship.   The ship according to any one of claims 1 to 7, wherein a plurality of the air blowing parts are provided at predetermined intervals in the ship length direction.   The ship according to any one of claims 1 to 8, wherein the ship bottom is provided with a recess on a stern side from the air blowing part.   The ship according to any one of claims 1 to 9, wherein the ship bottom is provided with a guide part for suppressing air diffusion outside the air blowing part in a ship width direction.

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