JPH10100989A - Frictional resistance reducing device for submarine ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To run a submarine ship at high speed only when required. SOLUTION: An opening 4 is provided at a position on a hull outside plank 3 located at the stem 2 of a hull 1, where small static pressure occurs. A porous plate 6 with a number of air blow ports 5 is fitted into the opening 4 with water tightness. A sea-chest 7 is mounted inside the porous plate 6 and an air bomb 8 is connected to the sea-chest 7 via an air feed pipe 10. Pressure air 11 is blown from the air blow ports 5 into water, resulting small bubbles 12 are carried along a stream line and the surface of the hull 1 is covered with the small bubbles 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reducing the frictional resistance of a submersible, which is capable of reducing the frictional resistance acting on the hull during cruising.

[0002]

2. Description of the Related Art During the navigation of a ship, a boundary layer of seawater is formed around the hull due to the viscosity of seawater as a fluid. In this boundary layer, the flow velocity of the seawater is zero and the hull surface is zero. It tends to change drastically as it moves away from the surface, and the frictional resistance of seawater acts on the surface of the hull, which is one of the major factors of the hull resistance.

[0003] Therefore, in recent years, studies have been made to improve the propulsion performance by reducing the frictional resistance acting on the surface of the hull, and as one of the measures, micro-bubbles (micro-bubbles) are generated from the hull surface. A microbubble propulsion method is being pursued to reduce the frictional resistance acting on the surface of the hull by injecting small bubbles into the boundary layer on the surface of the hull. ing.

[0004] Some submersibles that run while the entire hull is submerged are submerged, and such submersibles have a hull shape with small shape resistance. There is a demand that the friction resistance be reduced by adoption so that the boat can sail at a higher speed for a certain period of time.

[0005]

However, the adoption of the microbubble propulsion method for submersibles is still a research subject and has not been put to practical use.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a device for reducing the frictional resistance of a submersible, which embodies the micro-bubble propulsion method and enables the submersible to run at a higher speed only when necessary. .

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide an opening in a hull outer plate at a position where a static pressure of a bow is small, at least over a lower half circumference, and to provide an opening in the opening. , A perforated plate provided with a number of air outlets is fitted in a watertight manner, and a sea chest is attached to the inside of the perforated plate so as to surround the air outlets. It is configured to connect the other end of the air supply pipe to which one end is connected.

[0008] When the submarine needs to run at high speed, if pressurized air is supplied from the pressurized air supply source through the air supply pipe into the sea chest and blown out from the air blowout port, it is generated. Since the microbubbles are sent toward the bottom and stern along the streamline, the surface of the hull can be covered with the microbubbles, and the frictional resistance acting on the hull can be reduced. Since the air outlet is provided at a position where the static pressure at the bow is small, the pressure of the compressed air at the time of generation of microbubbles can be small.

Further, if the air outlet is directly formed in the hull outer plate of the bow instead of fitting the perforated plate into the opening of the bow, the structural strength of the hull is advantageous. Becomes

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 (a), 1 (b) and 1 (c) show an embodiment of the present invention. In a submersible in which a hull 1 is completely submerged and travels, a bow 2 An opening 4 is provided in the hull outer panel 3 at a position where the static pressure is small (a position where the flow velocity is the fastest and the negative pressure acts) over at least a lower half circumference,
For example, a perforated plate 6 in which air outlets (pores) 5 having a diameter of 2 mm are vertically and horizontally perforated at an arrangement pitch of 5 mm is fitted into the opening 4 in a watertight manner.
A sea chest 7 is attached to the inside of the container so as to surround the air outlet 5, and an air supply with a flow control valve 9 having an air cylinder 8 connected to one end of the sea chest 7 as a pressurized air supply source. The other end of the supply pipe 10 is connected, and pressurized air 11 from the air cylinder 8 is introduced into the sea chest 7 through the air supply pipe 10 and blown out into the water from the air outlets 5 to form microbubbles 12. Is generated, and the generated microbubbles 12 are placed on a streamline to flow.

When the hull shape is given, the present inventors
A calculation formula for the motion considering the turbulent diffusion of microbubbles flowing along the streamline around the hull and the void fraction distribution at an arbitrary position was established. The influence of turbulent diffusion is obtained by changing the flow velocity in the X-axis, Y-axis, and Z-axis (upward) directions using random numbers based on the assumption of isotropic turbulence, and disturbing the trajectory of microbubbles. Considering. That is, the random motion of the microbubbles was directly simulated by the Monte Carlo method.
When the motion of the microbubbles is calculated, the void ratio can be obtained by dividing the volume of the microbubbles existing in the inspection area (in the cell) at a certain time by the volume of the inspection area (cell).

Therefore, based on the void ratio distribution obtained in this way, a locus of a streamline in the bow portion 2 at which a void ratio effective in reducing frictional resistance is generated is obtained, and the above-mentioned perforated plate 6 is obtained. The mounting position was determined.

When it becomes necessary for the submarine to sail at high speed, pressurized air 11 from the air cylinder 8 is supplied to the air supply pipe 10.
Is introduced into the sea chest 7 and blown out into the water through the air outlet 5, the generated microbubbles 12 flow along the stream lines. At the bow 2, a streamline going into the bottom of the stern, a streamline going toward the stern, and a streamline going between the bottom and stern are generated.
The microbubbles 12 flow along the streamlines flowing in each direction, and as a result, the surface of the hull 1 can be completely covered with the microbubbles, and voids can be formed by the microbubbles 12. Due to the presence of the void, the frictional resistance of the hull 1 can be reduced. Therefore, the submersible can be run at high speed.

In the above description, the microbubbles 12 are generated by the orifice action when the pressurized air 11 passes through the air outlet 5 of the perforated plate 6, and contact the air outlet 5 and the air outlet 5. Bubbles are easily and reliably formed by relative movement with water. At this time, since the perforated plate 6 having the air outlet 5 is set at the position where the static pressure is the smallest, there is an advantage that the blowing pressure of the pressurized air 11 when generating the microbubbles 12 can be small.

Next, FIG. 2 shows another embodiment of the present invention. In a configuration similar to that shown in FIG. 1, an opening 4 provided in a hull outer plate 3 of a bow 2 is provided. Instead of attaching a perforated plate 6 having a large number of air outlets 5, the air outlets 5 are directly formed in the hull outer panel 3 at the same position.

As shown in FIG. 2, since the opening 2 is not provided in the bow 2, compared with the one shown in FIG.
This is advantageous in terms of the structural strength of the hull 1.

In the above-described embodiment, an example is shown in which the present invention is applied to a submersible that travels with the hull 1 completely submerged, but as shown in FIG. The present invention can be similarly applied to a running submerged submersible. In this case, a blower can be used as a source of pressurized air, and various other methods can be used without departing from the gist of the present invention. Of course, changes can be made.

[0019]

As described above, according to the apparatus for reducing frictional resistance of a submersible according to the present invention, an opening is provided at least in the lower half of the hull outer plate at a position where the static pressure at the bow is small. Into the opening, a perforated plate having a number of air outlets is fitted in a watertight manner, and a sea chest is attached to the inside of the perforated plate so as to surround the air outlets. Because the other end of the air supply pipe with one end connected to the supply source is connected, the microbubbles generated by blowing the pressurized air from the air blowing port are placed on the streamline flowing in each direction and flow This makes it possible to form a good void by covering the surface of the hull with microbubbles, reduce the frictional resistance acting on the hull, and improve the propulsion performance of the submarine, Also, on the bow By adopting a structure in which an air outlet is directly formed in the hull outer plate of the bow instead of fitting a perforated plate in the mouth, it is advantageous in terms of structural strength of the hull, etc. It has the effect.

[Brief description of the drawings]

1 shows an embodiment of a device for reducing frictional resistance of a submersible according to the present invention, in which (a) is a schematic side view, (b) is a view taken in the direction of arrows A in (a), () Is an enlarged view in the direction of arrows B-B in (b).

FIG. 2 is a schematic diagram showing another embodiment of the present invention.

FIG. 3 is a schematic side view showing an example of application to a semi-submerged submarine.

[Explanation of symbols]

 Reference Signs List 1 hull 2 bow 3 hull outer plate 4 opening 5 air outlet 6 perforated plate 7 sea chest 8 air cylinder (pressurized air supply source) 10 air supply pipe

Claims (2)

[Claims] An opening is provided at least in a lower half circumference of a hull outer plate at a position where a static pressure of a bow portion is small, and a perforated plate having a large number of air outlets is fitted in the opening in a watertight manner. A sea chest is attached to the inside of the perforated plate so as to surround the air outlet, and the sea chest is further connected to the other end of an air supply pipe having one end connected to a pressurized air supply source. An apparatus for reducing frictional resistance of a submersible, comprising: 2. The submersible according to claim 1, wherein an air outlet is directly formed in the outer shell of the hull instead of fitting the perforated plate into the opening of the bow. apparatus.