JP2001106173A - Friction drag reduction ship - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a frictional resistance reduced ship capable of reducing the power required for sending gas into water and effectively reducing the navigating power of the ship. SOLUTION: A gas delivery portion 20 provided to project from the hull into the water so as to increase the flow velocity of water flowing along the hull outer plate 10 at a delivery port 21, one end is opened to the atmosphere and the other end is opened to the atmosphere. A gas passage 22 that is opened to the water through the outlet 21 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces the frictional resistance between a hull and water by sending gas into the water from an outlet near the bow during navigation, thereby interposing fine bubbles on the hull outer plate. It relates to a ship that reduces frictional resistance.

[0002]

2. Description of the Related Art JP-A-50-83992 and JP-A-53-1983.
JP-A-136289, JP-A-60-139586, JP-A-61-71290, JP-A-61-39691, and JP-A-61-128185 disclose a technique relating to a ship with reduced frictional resistance. I have. This friction drag reduction ship,
In the navigation state, a gas such as air is sent out into the water from the hull surface (hull skin) to cause a number of microbubbles (microbubbles) to intervene on the hull skin. Is to reduce the frictional resistance acting on the surface.

The present applicant has proposed a technique relating to such a frictional resistance reducing ship, in which a gas (eg, air) is sent out into the water from near the bow and microbubbles are interposed on the hull outer plate. . This technology intends to diffuse the microbubbles along the streamline of water on the hull skin by sending out gas from the vicinity of the bow, and to cover the hull skin with the microbubbles. Conventionally, when sending gas into water, a gas supply device such as a blower is used as a power source for sending the gas.

[0004]

However, if gas is sent out using a gas supply device such as a blower, a new power is required to operate the gas supply device.
This would reduce the savings in sailing power reduced by microbubbles. Therefore, it is difficult to effectively save the power energy during the navigation of the ship.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has an object to reduce the power required for sending gas into water and to effectively reduce the cruising power of the ship. The purpose is to provide.

[0006]

Means for Solving the Problems To solve the above-mentioned problems, the invention according to claim 1 sends out gas into water from a delivery port near a bow during navigation, thereby forming fine bubbles on a hull outer plate. A frictional resistance reducing ship for reducing frictional resistance between a hull and water by interposing the gas, wherein a gas protruding from the hull into the water so as to increase the flow velocity of water flowing along the hull outer plate at the outlet. A technique including a delivery unit and a gas passage that is open at one end to the atmosphere and the other end to the water through the outlet is adopted. According to a second aspect of the present invention, in the boat of the first aspect, a technology is employed in which the gas delivery portion is formed in a shape that suppresses occurrence of separation in water. According to a third aspect of the present invention, in the ship of the first or second aspect, the gas delivery section is formed in a streamlined shape. According to a fourth aspect of the present invention, there is provided a ship for reducing frictional resistance according to any one of the first to third aspects,
A technique is employed in which the outlet is provided near the top of the gas delivery unit. In the present invention, the above problem can be solved by employing these techniques.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the frictional resistance reducing ship according to the present invention will be described below with reference to the drawings. FIG.
Shows a main part configuration near the bow of the frictional resistance reducing ship S according to the present embodiment, reference numeral 10 denotes a hull outer plate, and L denotes a water surface (waterline).

The frictional resistance reducing ship S has a gas delivery section 20 provided on the starboard and port side near the bow 10a and protruding into the water from the hull, a delivery port 21 provided near the top of the gas delivery section 20, and one end. Is opened to the atmosphere and the other end is opened to the water through the outlet 21.

In the present embodiment, two gas delivery units 20 are arranged on the starboard side and port side, respectively, in the vicinity of a predetermined draft, and one gas passage 22 is individually provided for one gas delivery unit 20. It is provided in.

[0010] As shown in FIG.
Is formed in a chamber shape having a space therein, and the bonding agent PA is formed in a state where the edge thereof is in contact with the hull outer panel 10.
The contact portion is filled and fixed from the outside of the hull. In addition, a gas introduction pipe (A
An IP (Air Induction Pipe) 23 is welded, whereby the space in the gas introduction pipe 23 and the space in the gas delivery unit 20 communicate with each other to form the gas passage 22 described above. Further, the gas delivery section 20 and the gas introduction pipe 23 forming the gas passage 22 are each subjected to a corrosion-resistant treatment so that the inner wall is not corroded by seawater, and further apply an extra pressure loss so as to become a fluid flowing in the passage. The cross-sectional area and shape are determined so as not to occur. The bonding agent PA flows through the boundary between the hull outer plate 10 and the outer surface of the gas discharge unit 20 so that the outer surface of the hull outer plate 10 and the gas discharge unit 20 are connected as smoothly as possible, in addition to fixing the gas delivery unit 20 to the hull outer plate 10. The purpose is to suppress turbulence in water.

The gas delivery section 20 increases the flow velocity of water flowing along the outer surface during navigation,
The shape is determined so as to suppress separation of the boundary layer in water (generation of wake). In the present embodiment, the spherical outer surface is formed so as to protrude toward the underwater side by a predetermined height H so that a negative pressure is generated near the top at a predetermined traveling speed Vs. The shape of the gas delivery section 20 including such a height H is determined by a computational fluid dynamics (CFD).
l Fluid Dynamics) is designed by flow field analysis.

In the present embodiment, the outlet 21 is a cross-shaped opening provided at the top of the gas delivery unit 20. Although the shape of the outlet 21 is not limited to this shape as described later, there is an advantage that by forming the opening in a cross shape, it is possible to easily form an opening for widely sending a certain amount of gas. .

As the material of the gas sending portion 20, a material whose surface has corrosion resistance to seawater is mainly used. In addition to a metal subjected to corrosion resistance, a resin is also used. In selecting such a material for the gas delivery unit 20, in addition to cost and strength, consideration is also given to whether marine organisms easily adhere to the surface.

Next, the operation of the ship S for reducing frictional resistance will be described. In this frictional resistance reducing ship S, in the stopped state, the seawater has entered the gas passage 22 to the same height as the water level around the hull. When in navigation,
Seawater flows along the hull skin 10, and near the bow 10a, the seawater flows along the outer surface of the gas delivery unit 20. Since the gas delivery unit 20 is provided so as to protrude spherically into the water from the hull, the flow path of seawater flowing on the outer surface of the gas delivery unit 20 is locally narrowed, and the flow rate of the seawater toward the top is reduced. growing. Set sailing speed V
s, as the flow velocity increases, the pressure near the top of the gas delivery unit 20 decreases to a negative pressure, and after the seawater in the gas passage 22 is discharged, the gas passage 22 is continuously removed from the atmosphere.
Air flows into the (gas introduction pipe 23), and the air is sent out from the outlet 21 into the water.

The air sent from the outlet 21 generates microbubbles (microbubbles), which flow toward the bottom and stern of the ship and cause
, The frictional resistance between the hull shell 10 and the water is reduced.

That is, the frictional resistance reducing ship S of the present embodiment
According to the present invention, in the navigation state, the flow velocity of the water flowing along the outer surface of the gas delivery unit 20 increases, and the pressure near the top of the gas delivery unit 20 provided with the delivery port 21 becomes negative pressure. In addition, a gas (air) can be guided from the atmosphere into the water through the gas passage 22 without any additional power, and the gas can be sent out from the outlet 21 into the water. Therefore, it is possible to effectively reduce the sailing power of the ship by reducing the frictional resistance due to the microbubbles. Moreover, in the present embodiment, the shape of the gas delivery unit 20 is determined so as to suppress the separation of the boundary layer in the water (the generation of the wake). Is suppressed.

The various shapes and combinations of the constituent members 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.

For example, in the above-described embodiment, the gas delivery portion 20 is formed in a shape having a spherical outer surface, is relatively easy to manufacture, and hardly disturbs the flow of water flowing along the surface. There is an advantage. However, as shown in FIG. 3, the gas delivery section 30 may be formed so as to be elliptical when viewed toward the hull shell. The elliptical gas delivery unit 30 is provided with the spherical gas delivery unit 2 described above.
As compared with zero, the resistance to the flow of water in the long axis direction can be further reduced.

Further, as shown in FIG. 4, the gas delivery section 31 may be formed in a shape having an angle formed by combining a plurality of curved surfaces. In the gas delivery section 31 of FIG. 4, for example, during high-speed navigation, it is possible to further reduce the resistance to the flow of water in the long axis direction.

Further, the gas delivery unit described so far is
The upstream and downstream sides are formed symmetrically with respect to the flow direction of water, which has the advantage that flow field analysis is easy to perform and easy to manufacture, but the gas delivery section is symmetrical upstream and downstream. It is not limited to. For example, as shown in FIG.
By forming 2, the water flowing along the gas delivery unit 32 may be made to flow in a regular state downstream of the gas delivery unit 32 without being disturbed. Also, the gas delivery unit 3
The shape of the outlet 33 provided in the nozzle 2 may be various shapes such as a porous shape in addition to the elliptical shape shown in FIG.

The gas delivery section 34 shown in FIG.
It is formed in a streamlined manner. By forming the gas delivery unit 34 in a streamlined manner, separation of the boundary layer in water by the gas delivery unit 34 can be easily suppressed.

According to the shape of the gas delivery section, the outlet can be set to a negative pressure at a predetermined traveling speed according to the characteristics of the ship such as the shape of the hull and the traveling speed. The amount is appropriately determined so that the increase in resistance due to the gas delivery unit can be minimized while delivering an amount of air into water.

In the above-described embodiment, the gas delivery unit 20 is provided on the starboard side and the port side near the bow 10a, respectively.
They are arranged side by side near a predetermined draft. This is advantageous in that by providing the gas delivery unit 20 in a place where the water depth is as shallow as possible, it is easy to make the delivery port 21 a negative pressure, and it is possible to guide the air from the atmosphere to the sea with less power. For example, the present invention is preferably applied to a ship having a shape in which seawater easily flows from the shallow place to the bottom along the hull outer plate. However, the location of the gas delivery unit is not limited to this, and the gas delivery unit 40 may be provided at the bottom of the ship as shown in FIG. This friction reduction ship S
In 2, for example, in a ship having a wide bottom,
Providing a plurality of gas delivery units 40 on the bottom of the ship makes it possible to reliably cover the entire bottom of the ship with more microbubbles.

Further, as another embodiment, as shown in FIG. 8, a gas delivery section 42 may be provided in a flow path penetrating the hull. In the frictional resistance reducing ship S3, by sending gas into the flow passage penetrating the hull, gas (microbubbles) can be reliably flowed from a relatively shallow depth to the bottom of the ship.

[0025]

As described above, according to the present invention, the following effects can be obtained. In the frictional resistance reducing ship according to the first aspect, in the navigating state, the flow velocity of the water flowing along the outer surface of the gas delivery unit increases, and the delivery port can be set to a negative pressure. It is possible to guide the gas from the atmosphere into the water through the gas passage and send the gas into the water from the outlet without requiring new power. Therefore, it is possible to effectively reduce the sailing power of the ship by reducing the frictional resistance due to the microbubbles.

In the frictional resistance reducing ship according to the second aspect, the shape of the gas delivery portion is determined so as to suppress separation of the boundary layer in water. The increase in resistance due to the sending unit is suppressed,
Microbubbles can more effectively reduce the ship's navigational power.

In the frictional resistance reducing ship according to the third aspect, since the gas delivery portion is formed in a streamlined shape, separation of the boundary layer in water by the gas delivery portion can be easily suppressed.

According to the fourth aspect of the present invention, since the discharge port is provided near the top of the gas discharge section, the pressure of the discharge port can be easily reduced during navigation.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a main part configuration of a frictional resistance reducing ship of the present invention, wherein (a) is a side view (starboard side) near a bow, and (b) is a front view.

FIGS. 2A and 2B schematically show a gas delivery unit, where FIG. 2A is a longitudinal sectional view and FIG. 2B is a plan view.

FIG. 3 is a diagram showing another embodiment of the gas delivery unit.

FIG. 4 is a diagram showing another embodiment of the gas delivery unit.

FIG. 5 is a view showing another embodiment of the gas delivery unit.

FIG. 6 is a diagram showing another embodiment of the gas delivery unit.

FIG. 7 is a view showing another embodiment of a frictional resistance reducing ship in which a gas delivery unit is provided at the bottom of the ship.

FIG. 8 is a view showing another embodiment of a frictional resistance reducing ship in which a gas delivery unit is provided in a flow path of water penetrating a hull.

[Explanation of symbols]

 S Friction resistance reducing ship PA Bonding agent 10 Hull outer plate 10a Bow 20 Gas delivery unit 21 Outlet 22 Gas passage 23 Gas introduction pipe

Claims (4)

[Claims] 1. A frictional resistance reducing ship that reduces the frictional resistance between a hull and water by sending gas into the water from an outlet near a bow during navigation, thereby interposing fine bubbles on a hull outer plate. A gas delivery section provided to project from the hull into the water so as to increase the flow velocity of water flowing along the hull outer plate at the delivery port, one end being open to the atmosphere and the other end being the delivery port And a gas passage that is opened into the water through the water. 2. The frictional resistance reducing ship according to claim 1, wherein the gas delivery portion is formed in a shape that suppresses occurrence of separation in water. 3. The ship according to claim 1, wherein the gas delivery portion is formed in a streamlined shape. 4. The ship according to claim 1, wherein the outlet is provided near a top of the gas delivery unit.