JPH10100983A - Frictional resistance reducer for ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably blow pressure air with efficient operation in case that plural air blowers are assembled at stages different in static pressure on a hull outside plank. SOLUTION: Openings 5a, 5b are provided at upper and lower stages different in static pressure on a hull outside plank 3 and air blowers 9a, 9b are assembled in the openings 5a, 5b. On a deck at a stem 2, an extraction blower device 17 with a blower 17a having small discharge pressure and a blower 17b having large discharge pressure is arrarjged. The air blower 9a at the upper stage and the blower 17a are connected together via an air feed pipe 14a and the air blower 9b at the lower stage and the blower 17b are connected together via an air feed pipe 14b.

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 frictional resistance of a ship which blows out fine bubbles along the surface of the hull in order to reduce the frictional resistance acting on the hull surface during navigation.

[0002]

2. Description of the Related Art When a ship is navigating, a boundary layer of seawater is formed around the hull due to the viscosity of seawater as a fluid. In this boundary layer, the 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 seawater frictional resistance acts on the hull surface, which is one of the major factors in 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. And injects microbubbles into the boundary layer on the surface of the hull's submerged part (submerged part) to cover the surface of the hull's submerged part with microbubbles, thereby reducing frictional resistance acting on the hull surface. Research on the microbubble propulsion method is ongoing.

[0004] In order to realize the microbubble propulsion method and reduce the frictional resistance of the hull, the applicant of the present invention has proposed FIG.
An application for a frictional resistance reducing device as shown in (b) has been filed. That is, in a streamline region where the streamline 4 is directed to each direction of the bottom and stern at the inundation portion of the bow portion 2 of the hull 1 and at a position where the static pressure is small (slightly below the draft line DL). Position), an opening 5 is provided in the hull outer plate 3, and a perforated plate 7 in which a number of air outlets (pores) 6 are perforated at a required arrangement pitch is attached to the opening 5, and A sea chest 8 is provided inside the plate 7 so as to surround the air outlet 6 to form an air blower 9, while the bow 2 of the hull 1 is formed.
And a blower 12 driven by a motor 11 is installed as a pressurized air supply device, and has a flow control valve 13 having one end connected to the blower 12. The other end of the air supply pipe 14 is connected to the sea chest 8 of the air blower 9, and compressed air 15 is blown out from the air blowout port 6 to generate microbubbles 16 having a required diameter. is there.

[0005] In the case of the frictional resistance reducing apparatus of the above-mentioned application, the generated microbubbles 16 can flow on the streamline 4 toward the bottom and stern of the boat, so that the surface of the hull is reduced to the microbubbles 1.
6, the frictional resistance of the hull 1 can be reduced.

In the above description, the position of the air blower 9 is determined based on the required power for blowing the pressurized air 15 by the water line D. It is desirable that the position of the static pressure be as small as possible to L, but depending on the shape of the hull, the region of the streamline toward the ship bottom or stern may be distributed in the vertical direction.

In this case, as shown by a two-dot chain line in FIG. 2A, it is assumed that another air blower 9 is assembled to the lower part of the air blower 9.

[0008]

However, when the air blowers 9 are mounted vertically in two stages, the static pressure is larger at the position where the lower air blowers 9 are mounted than at the position where the upper air blowers 9 are mounted. Therefore, if the air supply pipe 14 is branched and the pressurized air 15 is blown out by one blower 12, the discharge pressure of the blower 12 cannot be increased. If only two units are used, the operation is performed with the discharge pressure of the blower 12 for the upper air blower 9 being reduced, which causes a problem of poor efficiency. Further, it is conceivable to use a combination of a separate blower and an electric motor corresponding to a static pressure in advance, but there is still a problem in terms of operating efficiency.

In view of the above, the present invention is intended to stably blow out pressurized air with efficient operation when a plurality of air blowers are assembled at different static pressures on the hull outer panel. Is what you do.

[0010]

In order to solve the above-mentioned problems, the present invention provides a hull shell at the bow by blowing compressed air into the water from the front of the hull to generate microbubbles. An air blower is assembled in two stages in the vertical direction, and two blowers, each designed to have a discharge pressure corresponding to the magnitude of the static pressure acting on each of the upper and lower air blowers, are connected to one motor. Equipped with a bleed-type blower device consisting of an upper air blower and a blower with a smaller discharge pressure, and a lower air blower and a blower with a larger discharge pressure with an air supply pipe. Connected configuration.

The pressurized air from the blower having a small discharge pressure is sent to the upper air blower, and the pressurized air from the blower having a large discharge pressure is sent to the lower air blower.
Efficient operation is performed, and pressurized air is stably blown from the upper and lower two-stage air blowers.

In addition, even if three or more air blowers are vertically assembled and the blower of the bleed-type blower device is provided corresponding to each air blower, efficient operation is similarly performed.

[0013]

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

FIG. 1 shows an embodiment of the present invention. In a ship having a hull shape in which a streamline region heading toward the bottom and stern is distributed in a vertical direction at a bow 2, FIG. 2) Upper and lower two-stage openings provided with air blowers 9a and 9b having the same configuration as the air blower 9 shown in (b) at different positions of the static pressure of the hull outer panel 3 in accordance with the streamline distribution. Assemble to 5a and 5b, and bow part 2 of hull 1
The two blowers 17a and 17b, which are designed to correspond to the magnitude of the static pressure acting on the upper and lower two-stage air blowers 9a and 9b and the discharge pressure corresponding thereto, are arranged coaxially on the deck.
The air blower device 17 connected to the motor 11 is equipped with an air blower 17a, and the upper air blower 9a and the blower 17a having a smaller discharge pressure are connected by an air supply pipe 14a. The air blower 9b and the blower 17b having a larger discharge pressure are connected by an air supply pipe 14b.

When the electric motor 11 is driven during navigation, the pressurized air discharged from the blower 17a having the smaller discharge pressure is supplied to the upper air blower 9a through the air supply pipe 14a, so that the air is blown into the water. The pressurized air blown out and discharged from the blower 17b having the larger discharge pressure is supplied to the lower air blower 9b through the air supply pipe 14b to be blown out into the water.

In the above, the discharge pressures of the blowers 17a and 17b are controlled by the upper blower 9a and the lower blower 9a.
Since it is designed to correspond to the static pressure acting on b, the pressurized air can be stably blown from each of the air blowers 9a and 9b. Therefore, more efficient operation can be performed than in the case where two same blowers are used and a throttle is given to one, or when a combination of separate blowers and electric motors is prepared.

The present invention is not limited to the above embodiment. For example, when three or more air blowers are vertically assembled, the number of blowers of the bleed-type blower device 17 is adjusted accordingly. It goes without saying that various changes can be made without departing from the spirit of the present invention.

[0018]

As described above, the apparatus for reducing frictional resistance of a ship according to the present invention exhibits the following excellent effects. (1) An air blower, which is configured to generate fine air bubbles by blowing out pressurized air from the front part into the water on the hull outer plate of the bow part, is assembled vertically in two stages, and Equipped with a bleed-type blower device that connects two blowers, each designed to the magnitude of the static pressure acting on each air blower and the discharge pressure corresponding to one motor, to the upper air blower and discharge pressure And the lower air blower and the blower with a larger discharge pressure are connected by an air supply pipe, so that the blower with the smaller discharge pressure is discharged from the blower with the smaller discharge pressure. The pressurized air can be sent to the upper air blower and the pressurized air discharged from the blower with the higher discharge pressure can be sent to the lower air blower, so that the upper and lower air blowers with different static pressures Pressurized air can be stably blown out from the dispenser, and efficient operation can be performed. (2) Even when the air blowers are assembled in three or more stages in the vertical direction, and the blower of the bleed air blower is provided corresponding to each air blower, the same as described in the paragraph (1), Pressurized air can be stably blown out from the air blowers at different positions of the static pressure, and efficient operation can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a bow showing one embodiment of a frictional resistance reducing device for a ship according to the present invention.

FIG. 2 shows an example of a recently proposed device for reducing frictional resistance of a ship, in which (a) is a schematic side view of a bow portion,
(B) is an AA direction enlarged arrow view of (A).

[Explanation of symbols]

 2 bow 3 hull skin 5a, 5b opening 9a, 9b air blower 11 electric motor 14a, 14b air supply pipe 15 pressurized air 16 microbubble 17 bleeding blower device 17a, 17b blower

Claims (2)

[Claims] 1. An air blower, which generates fine bubbles by blowing pressurized air into the water from a front part of a hull outer plate of a bow part, is vertically assembled in two stages, and Equipped with a bleed-type blower device that connects two blowers, each designed to the magnitude of the static pressure acting on each air blower in the stage and the discharge pressure corresponding to one motor, to the upper air blower A device for reducing frictional resistance of a ship, comprising a configuration in which a blower having a smaller discharge pressure and a blower having a lower stage and a blower having a larger discharge pressure are connected by an air supply pipe. . 2. The ship friction reduction device according to claim 1, wherein the air blowers are vertically assembled in three or more stages, and a blower of a bleed-type blower device is provided corresponding to each air blower.