KR20210132860A - Air lubrication system of a ship having high volume fraction of air in a center portion of the ship and air lubrication method using thereof - Google Patents

Abstract

An air lubrication system for a ship is provided. In one embodiment, a ship to which an air lubrication system that generates air bubbles is applied to the bottom of the ship comprises: a front air injection port installed in the bow of the ship; and a rear air injection port installed in the rear of the front air injection port in the bow portion of the ship, wherein the front air injection port and the rear air injection port are extended to have a predetermined length in the width direction of the ship, and the area where the front air injection port is installed and the area where the rear air injection port is installed may include an overlapping area in the longitudinal direction of the ship. By reducing the fluctuating pressure generated in a thruster (propeller), a high-efficiency thruster can be installed on a ship.

Description

AIR LUBRICATION SYSTEM OF A SHIP HAVING HIGH VOLUME FRACTION OF AIR IN A CENTER PORTION OF THE SHIP AND AIR LUBRICATION METHOD USING THEREOF

The present invention relates to an air lubrication system and an air lubrication method for a ship, and more particularly, to an air lubrication system and an air lubrication method for a ship having a high air volume fraction in the center of the ship.

A vessel in operation is affected by frictional resistance, which is a type of resistance caused by the viscosity of water. In order to reduce the frictional resistance that affects the operation of such ships, research on air lubrication has been conducted.

The air lubrication method is a method of covering a part of the hull surface submerged in water with an air film. On the surface of the hull covered with air, contact with water is changed to contact with air, thereby reducing the frictional resistance of the ship due to the viscosity of water.

The purpose of the air lubrication system to which this air lubrication method is applied is to form air bubbles by basically spraying air to the surface of the ship's bottom through a plurality of air jets. can be reduced

However, ships to which the conventional air lubrication system is applied did not consider the arrangement of the air lubrication device in order to achieve the concept of reducing frictional resistance by simply injecting air into the bottom of the ship, or simply applying an air layer over the entire area of the bottom of the ship. An air lubrication device was arranged to form.

In addition, ships to which the conventional air lubrication system is applied can achieve the effect of reducing frictional resistance, apart from that, an air cushion is formed on the upper part of the propeller (propeller), and cavitation occurs. As the fluctuating pressure generated from the thruster (propeller) increased, there was a problem that the efficiency of the thruster could not be increased, there was a problem that the noise generated from the thruster was large, and the frictional resistance by the air lubrication system was not reduced in a rough marine environment. There was a problem that didn't happen.

Therefore, by reducing the fluctuating pressure generated in the thruster (propeller), a high-efficiency thruster is installed on the ship, the noise generated from the thruster (propeller) is reduced, and a frictional resistance effect can be achieved even in a rough marine environment. development of air lubrication system is urgently needed.

The problem to be solved by the present invention is that, in a ship to which an air lubrication system is applied, by arranging a plurality of air lubrication devices in an optimal position, the fluctuating pressure generated in the thruster (propeller) is reduced, and a high-efficiency thruster is installed on the ship. It is intended to provide an air lubrication system for ships that can be installed, can reduce the noise generated by the propeller (propeller), and achieve friction resistance even in harsh marine environments.

In addition, the problem to be solved by the present invention is an air lubrication method of a ship to which an air lubrication system for generating air bubbles at the bottom of a ship is applied, by arranging a plurality of air lubrication devices in an optimal position, By reducing the fluctuating pressure generated in the (propeller), a high-efficiency thruster can be installed on the ship, the noise generated from the thruster (propeller) can be reduced, and the frictional resistance effect can be achieved even in harsh marine environments. To provide an air lubrication method.

In order to solve the above problems, in an embodiment of the present invention, in a ship to which an air lubrication system for generating air bubbles at the bottom of a ship is applied, the forward air installed in the bow of the ship nozzle; and a rear air nozzle installed at the rear of the front air jet in the bow of the ship, wherein the front air jet and the rear air jet are extended with a predetermined length in the width direction of the ship, the front air The area in which the jet port is installed and the area in which the rear air jet port is installed include an overlapping area in the longitudinal direction of the ship.

According to an embodiment of the present invention, by arranging a plurality of air lubrication devices in an optimal position, it is possible to form an air layer having a high air volume fraction from the center of the ship to the stern.

In addition, according to an embodiment of the present invention, it is possible to reduce the fluctuating pressure generated in the thruster (propeller) to install a high-efficiency thruster on a ship.

In addition, according to an embodiment of the present invention, it is possible to reduce the noise generated by the propeller (propeller).

In addition, according to an embodiment of the present invention, it is possible to achieve a frictional resistance effect even in a rough marine environment.

1 to 3 are views showing the air lubrication system of a ship according to an embodiment of the present invention, FIG. 2 is a view showing the bow in FIG. 1, and FIG. 3 is an area in which an air layer sprayed from the air nozzle is formed. will be.
4 and 5 are numerical analysis results based on computational fluid dynamics for the volume fraction of air of the air lubrication system of a ship, and FIG. 4 is a comparative example, and FIG. 5 is the present invention. The numerical analysis results of the air lubrication system of a ship according to an embodiment of
6 is a flow analysis calculation result of the air lubrication system of a ship according to an embodiment of the present invention in a BF (Beaufort) scale 5 sea state, and FIG. 7 is a work of the present invention in a BF (Beaufort) scale 5 sea state It shows the friction drag of the air lubrication system of the ship according to the embodiment.
8 is a view showing the degree of reduction in fluctuating pressure when the air lubrication system of a ship is operated according to an embodiment of the present invention, and FIG. shows the degree of net power saving of the air lubrication system of

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only this embodiment allows the disclosure of the present invention to be complete and provides those of ordinary skill in the art the content of the present invention. It is provided for more complete information.

When an element is referred to as being positioned 'above' or 'below' another element in this specification, it means that the element is positioned directly 'above' or 'below' another element, or an additional element is placed between those elements. It includes all meanings that can be interposed. In this specification, the terms 'upper' or 'lower' are relative concepts set from the viewpoint of the observer. may mean

The same reference numerals in the plurality of drawings refer to elements that are substantially the same as each other. In addition, terms such as 'comprise' or 'have' are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, and includes one or more other features, number, or step. , it should be understood that it does not preclude the possibility of the existence or addition of , operation, components, parts, or combinations thereof.

In order to solve the above problems, an embodiment of the present invention, in a ship to which an air lubrication system for generating air bubbles at the bottom of a ship is applied, a front air injection port installed in the bow of the ship; and a rear air nozzle installed at the rear of the front air jet in the bow of the ship, wherein the front air jet and the rear air jet are extended with a predetermined length in the width direction of the ship, the front air The area in which the jet port is installed and the area in which the rear air jet port is installed include an overlapping area in the longitudinal direction of the ship.

In this case, in the longitudinal direction of the ship, the area where the front air jets are installed may be included in the area where the rear air jets are installed.

In this case, when the width of the ship is B, the area in which the rear air injection port is installed may be within 0.5B.

In addition, the center of the front air jet port of the ship and the center of the rear air jet port may be located on the same line in the longitudinal direction of the ship.

In this case, the same line may be a center line of the ship extending the center of the thickness of the ship along the longitudinal direction of the ship.

On the other hand, when the stern is 0 LOA and the bow is 1.0 LOA based on the overall length of the ship, the rear air jet port and the front air jet port may be spaced apart by a distance of 0.1 LOA or less.

In this case, the front air nozzle may be installed within 0.7 LOA to 0.85 LOA.

Another embodiment of the present invention is an air lubrication method of a ship to which an air lubrication system for generating air bubbles is applied to the bottom of the ship, the front air injection port installed in the bow of the ship and the bow of the ship In the , the air is injected from the rear air nozzle installed at the rear of the front air nozzle, but the front air jet air layer formed by the air injected from the front air jet port is a rear air jet formed by the air injected from the rear air jet port To provide an air lubrication method of a ship to which an air lubrication system is applied, which increases the air volume fraction of the air layer in the central part of the ship extending along the longitudinal direction of the ship by being included in the air layer.

At this time, the center of the front air injection port and the rear air injection port is located on the center line of the vessel extending along the longitudinal direction of the vessel, based on the thickness direction center of the vessel, along the longitudinal direction of the vessel. It is possible to increase the air volume fraction of the air layer in the central part of the extending vessel.

At this time, the rear air nozzle and the front air nozzle are spaced apart by a distance of 0.1 LOA or less, and when the width of the ship is B, the time point of the air layer formed by the rear air nozzle is within 0.5B. When air is sprayed from the air nozzle, and the stern is 0 LOA and the bow is 1.0 LOA based on the overall length of the ship, the point of time of the air layer formed by the front air nozzle is 0.7 LOA to 0.85 LOA. Air can be sprayed from the front air nozzle.

Hereinafter, it will be described in detail with reference to the drawings.

1 to 3 are views showing an air lubrication system of a ship according to an embodiment of the present invention, FIG. 2 is a view of the bow in FIG. 1, and FIG. 3 is an area in which an air layer sprayed from an air nozzle is formed. will be.

Referring to FIG. 1 , the air lubrication system of the ship for generating air bubbles in the bottom of the ship 1 includes a front air jet port 10 , and a rear air jet port 20 .

Here, in the present invention, the thruster (propeller) is disposed near the stern, that is, 0 OLA, and its illustration is omitted in FIG. 1 .

The front air jet port 10 and the rear air jet port 20 are for generating air bubbles at the bottom of the ship 1, for example, at the base of the ship, and may be installed in the bow of the ship 2, and the front air nozzle (10) may be installed so as to be closer to the bow than the rear air injection port 20. At this time, the ship bow (2) is 0.5 LOA when the stern is 0 LOA and the bow is 1.0 LOA based on the total length of the ship. to 1.0 LOA range.

The front air injection port 10 and the rear air injection port 20 are places where air is discharged from the air injection device (not shown) to the outside of the ship, and the air injection operation can be driven by the bow control unit (not shown), For example, after compressed air formed in a compressor (not shown) is supplied to an air injection device (not shown), the air is discharged to the bottom of the vessel 1 through the front air injection port 10 and the rear air injection port 20 . can be For example, the front air jet port 10 and the rear air jet port 20 may have a structure connected to a single air jet device. For example, the front air injection hole 10 may be provided in the front air injection device (not shown), and the rear air injection hole 20 may have a structure provided in the rear air injection device (not shown). For example, a front control unit (not shown) and a rear control unit (not shown) for controlling each of the front air injection device (not shown) and the rear air injection device (not shown) may be included, and accordingly, the front compressor ( Not shown) and a rear compressor (not shown) may be included. For example, a control unit (not shown) for controlling both the front air injector (not shown) and the rear air injector (not shown) may be included, and accordingly, the compressed air formed by the compressor (not shown) is converted into the Compressed air may be supplied to the front air injector (not shown) and the rear air injector (not shown), or the compressed air formed by the front compressor (not shown) is supplied to the front air injector (not shown), and the rear Compressed air formed by a compressor (not shown) may be supplied to the rear air injection device (not shown).

The front air jet port 10 and the rear air jet port 20 extend to have a predetermined length in the width direction of the ship, and the area where the front air jet port 10 is installed and the area where the rear air jet port 20 is installed is the longitudinal direction of the ship. may contain overlapping regions. That is, the width of the front air jet port and the width of the rear air jet port may have an overlapping region when viewed in the longitudinal direction of the ship.

Accordingly, it is possible to increase the air volume fraction in the overlapping area.

In the longitudinal direction of the ship, the area in which the front air jets 10 are installed may be included in the area in which the rear air jets 20 are installed.

Accordingly, the front air nozzle 10 can be installed with a predetermined length along the width direction of the ship in the area where it is necessary to increase the air volume fraction at the bottom of the ship 1, and the number of air jets can be minimized while minimizing the number of air jets. It is possible to secure the maximum area of the vessel bottom (1) in which the volume fraction is increased.

The center of the front air jet port 10 and the center of the rear air jet port 20 of the ship are located on the same line in the longitudinal direction of the ship, for example, the same line is the center of the thickness of the ship in the longitudinal direction of the ship. It may be a ship centerline (3) extending along the .

That is, the front air jet port 10 and the rear air jet port 20 are installed so that their centers are located on the ship center line 3 , so that the air layer formed at the bottom of the ship 1 is symmetrical with respect to the ship center line 3 . By doing this, it is possible to prevent unnecessary resistance from occurring in the operation of the ship, and to form the air layer up to the stern of the ship with a high air volume fraction.

Referring to FIG. 2 , when the width of the ship is B, the area in which the rear air injection port 20 is installed may be within 0.5B, for example, within 0.3B. For example, the area in which the front air jets 10 are installed may be 0.2 to 0.6 times the area in which the rear air jets 20 are installed.

Within the above numerical range, it is possible to achieve a frictional resistance effect even in a rough marine environment by minimizing the length of the air nozzle and minimizing the amount of air injected, and increasing the air volume fraction of the air layer formed from the center of the ship to the stern, and the thruster ( It is possible to reduce the fluctuating pressure generated in the propeller) and reduce the noise generated by the propeller (propeller). It can refer to a nearby area.

Assuming that the stern is 0 LOA and the bow is 1.0 LOA based on the overall length of the ship, the rear air jets 20 and the front air jets 10 may be spaced apart by a distance d of 0.1 LOA or less.

Within the above numerical range, it is possible to effectively increase the air volume fraction of the air layer formed in the area where the rear air jets 20 overlapping the area where the front air jets 10 are installed.

At this time, the front air nozzle 10 may be installed within 0.7 LOA to 0.85 LOA.

Within the above numerical range, it is possible to effectively increase the air volume fraction of the air layer formed from the center of the ship to the stern, thereby minimizing the length of the air nozzle and the amount of air injected, while achieving a frictional resistance effect even in a rough marine environment, and the thruster It can reduce the fluctuating pressure generated in the (propeller) and reduce the noise generated by the propeller (propeller).

Referring to FIG. 3, through the optimal arrangement of the aforementioned front air jets 10 and rear air jets 20, the front air jet air layer 12 formed by the air injected from the front air jet port 10 is the rear air By being included in the air layer 22 of the rear air jet port formed by the air injected from the jet port 20, it is possible to increase the air volume fraction of the air layer at the center of the vessel extending along the longitudinal direction of the vessel.

The present invention also provides an air lubrication method for a ship to which an air lubrication system for generating air bubbles in the bottom of the ship is applied, the air volume fraction of the air layer extending along the longitudinal direction of the ship The height provides an air lubrication method of a ship to which an air lubrication system is applied. Each configuration and effect of the air lubrication system of the ship described with reference to FIGS. 1 to 3 may be applied as it is, and the description overlapping with the above description will be omitted.

In the front air nozzle 10 and the ship bow 2 installed in the ship bow 2, air is sprayed from the rear air jet 20 installed in the rear of the front air jet 10, but the front air jet 10 ) can be included in the air layer formed by the air injected from the air layer formed by the air injected from the rear air injection port (20).

For example, the front air injection port 10 and the rear air injection port 20 may be driven at all times during the operation of the ship, that is, the air may be injected at all times. In the present invention, the driving may refer to operating so that air is discharged through the air nozzle.

For example, the front air jets 10 and the rear air jets 20 may be selectively driven according to the marine environment in which the vessel operates. For example, in a gentle marine environment where the wave height is within a preset numerical range, only the rear air nozzle 20 is driven, and in a rough marine environment where the wave height exceeds the preset numerical range, the front air nozzle 10 is also added to improve energy efficiency and minimize the amount of injected air, while achieving a frictional resistance effect even in a rough marine environment, reducing the fluctuating pressure generated in the thruster (propeller), noise can be reduced.

The center of the front air jet port 10 and the rear air jet port 20 is located on the center line 3 of the vessel extending along the longitudinal direction of the vessel based on the thickness direction center of the vessel. By driving (10) and the rear air injection port (20), it is possible to increase the air volume fraction of the air layer in the center of the ship extending along the longitudinal direction of the ship.

The rear air jets 20 and the front air jets 10 are spaced apart by a distance of 0.1 LOA or less, and when the width of the ship is B, the time point of the air layer formed by the rear air jets 20 is within 0.5B. When the air is injected from the rear air nozzle 20 as much as possible, and the stern is 0 LOA and the bow is 1.0 LOA based on the total length of the ship, the time of the air layer formed by the front air jet 10 is 0.7 LOA to By driving the front air jets 10 and the rear air jets 20 to inject air from the front air jets 10 within 0.85 LOA, Increase and reduce the fluctuating pressure generated in the thruster (propeller) by allowing the air layer to extend with a high air volume to the thruster (propeller) disposed on the stern, and reduce the noise generated by the thruster (propeller).

For example, the injection holes provided in the front air injection port 10 and the rear air injection port 20 can be opened and closed, and the rear air injection port ( 20) can control the opening and closing of the injection hole.

For example, the front air injection port 10 and the rear air injection port 20 are provided with a predetermined length and width at the bottom of the ship 1, and the injection hole provided in the front air injection port 10 and the rear air injection port 20 can be opened and closed, the opening and closing of the injection hole of the front air injection port 10 can be controlled so that the time point of the air layer formed by the front air injection port 10 is within 0.7 LOA to 0.85 LOA.

4 and 5 are numerical analysis results based on computational fluid dynamics for the volume fraction of air of an air lubrication system of a ship, and FIG. 4 is an air lubrication of a ship according to a comparative example. Figure 5 shows the numerical analysis results of the system, respectively, the numerical analysis results of the air lubrication system of the ship according to an embodiment of the present invention.

Here, the volume fraction of air refers to the volume ratio occupied by air, that is, the degree to which air is contained, and in the case of 1, it refers to being filled with air, and when 0, it refers to being filled with water.

Referring to FIG. 4 , in the air lubrication system of the ship according to the comparative example, it is difficult to secure the air volume fraction above a certain level by arranging the air jets in only one place in the longitudinal direction or staggering the air layers without overlapping. have. Accordingly, it can be confirmed that the air lubrication system of the ship according to the comparative example rapidly deteriorates the frictional resistance reduction performance as the air volume fraction falls below an appropriate level.

5, in the air lubrication system of a ship according to an embodiment of the present invention, by arranging the air nozzles to overlap forward and rearward from the ship bow to the center of the ship, compared to the numerical analysis result according to the comparative example, the It can be seen that a high air volume fraction can be secured.

As such, in the air lubrication system of a ship according to an embodiment of the present invention, when an air layer having a high air volume fraction is formed in the central part of the hull bottom, that is, near the ship center line, disturbances such as currents, currents, waves, etc. that are actually present in the sea In spite of this, it is possible to effectively secure the frictional resistance reduction performance by securing a high level of air volume fraction.

In addition, the air lubrication system of the ship according to an embodiment of the present invention, by intensively injecting air into the center of the ship, so that the air layer moves to the stern while maintaining a high air volume, at the upper end of the propeller located in the stern The air layer acts as an air cushion. Accordingly, it is possible to effectively suppress cavitation generated on the propeller blade surface, and to remarkably reduce the fluctuating pressure and underwater radiation noise generated during the cavitation generation and collapse process. In this way, it is possible to reduce the fluctuating pressure acting on the propeller blade surface, so that it is possible to install a high-efficiency thruster, and it is possible to improve the energy efficiency of vessel operation.

6 is a flow analysis calculation result of the air lubrication system of a ship according to an embodiment of the present invention in a BF (Beaufort) scale 5 sea state, and FIG. 7 is a work of the present invention in a BF (Beaufort) scale 5 sea state It shows the friction drag of the air lubrication system of the ship according to the embodiment.

6 and 7, the air lubrication system of a ship according to an embodiment of the present invention is formed while stably maintaining the air layer up to the stern even in a harsh marine environment where the hull roll motion acts. can be checked

8 is a view showing the degree of reduction in fluctuating pressure during the operation of the air lubrication system of a ship according to an embodiment of the present invention, and FIG. shows the degree of net power saving of the air lubrication system of Refers to metrology points near the transom.

Referring to FIG. 8, the air lubrication system of a ship according to an embodiment of the present invention, as shown in FIGS. By double arranging to overlap the center of the ship, an air layer is formed up to the stern while maintaining a high air volume fraction in the center of the ship compared to the prior art, forming an air cushion at the top of the propeller, and flowing into the propeller surface It can be confirmed that the cavitation is suppressed by the air layer that is used, so that the fluctuating pressure generated from the propeller can be effectively reduced.

Accordingly, in the air lubrication system of a ship according to an embodiment of the present invention, cavitation is suppressed by the air flowing into the propeller surface, thereby reducing the underwater radiation noise generated from the propeller.

In addition, by spraying air intensively in the center of the ship, it prevents the sprayed air from leaking out to the outer surface of the ship even in harsh marine environments, that is, in situations such as strong currents and high wave heights. can be improved

Referring to FIG. 9 , when the air lubrication system of a ship according to an embodiment of the present invention is operated, it can be confirmed that net power saving is possible up to the BF (Beaufort) scale 6 sea state.

As described above, the detailed description of the present invention has been made by the embodiments with reference to the accompanying drawings, but since the above-described embodiments have only been described with preferred examples of the present invention, the present invention is limited only to the above embodiments. It should not be understood, and the scope of the present invention should be understood as the following claims and their equivalents.

For example, the drawings are schematically shown with each component as a main body to help understanding, and the thickness, length, number, etc. of each illustrated component may differ from the actual one in the course of drawing creation. In addition, the material, shape, dimension, etc. of each component shown in the above-mentioned embodiment are only one example, and are not specifically limited, Various changes are possible in the range which does not deviate substantially from the effect of this invention.

1: the bottom of the ship
2: ship bow
3: Vessel centerline
10: front air nozzle
20: rear air nozzle
11: Front air nozzle width
21: rear air nozzle width
12: front air nozzle air layer
22: rear air nozzle air layer

Claims (10)

In a ship to which an air lubrication system that generates air bubbles is applied to the bottom of the ship,
a front air nozzle installed in the bow of the ship; and
In the bow portion of the ship, a rear air injection port installed in the rear of the front air injection port;
including,
The front air injection port and the rear air injection port are extended to have a predetermined length in the width direction of the ship,
The air lubrication system of a ship, wherein the area where the front air jets are installed and the area where the rear air jets are installed include an overlapping area in the longitudinal direction of the ship. The method according to claim 1,
In the longitudinal direction of the ship, the area where the front air jets are installed is included in the area where the rear air jets are installed. 3. The method according to claim 2,
When the width of the ship is B, the area where the rear air injection port is installed is within 0.5B, the air lubrication system of the ship. 3. The method according to claim 2,
The air lubrication system of a ship, wherein the center of the front air nozzle of the ship and the center of the rear air nozzle are located on the same line in the longitudinal direction of the ship. 5. The method according to claim 4,
The same line is a center line of the ship extending along the longitudinal direction of the ship with the center of the thickness of the ship, the air lubrication system of the ship. 4. The method according to claim 3,
When the stern is 0 LOA and the bow is 1.0 LOA based on the overall length of the ship,
The air lubrication system of a ship, wherein the rear air nozzle and the front air nozzle are spaced apart by a distance of 0.1 LOA or less. 7. The method of claim 6,
The front air nozzle is installed within 0.7 LOA to 0.85 LOA, the air lubrication system of the ship. In the air lubrication method of a ship to which an air lubrication system that generates air bubbles at the bottom of the ship is applied,
In the front air nozzle installed in the bow of the ship and the bow of the ship, air is sprayed from the rear air jet installed in the rear of the front air jet,
The front air jets air layer formed by the air injected from the front air jets is included in the rear air jets air layer formed by the air injected from the rear air jets,
An air lubrication method of a ship to which an air lubrication system is applied, which increases the air volume fraction of the air layer in the central part of the ship extending along the longitudinal direction of the ship. 9. The method of claim 8,
The center of the front air jet port and the rear air jet port is located on the center line of the vessel extending along the longitudinal direction of the vessel with respect to the center of the thickness direction of the vessel,
An air lubrication method of a ship to which an air lubrication system is applied, which increases the air volume fraction of the air layer in the central part of the ship extending along the longitudinal direction of the ship. 10. The method of claim 9,
The rear air nozzle and the front air nozzle are spaced apart by a distance of 0.1 LOA or less,
When the width of the vessel is B, the air is injected from the rear air nozzle so that the time point of the air layer formed by the rear air nozzle is within 0.5B,
When the stern is 0 LOA and the bow is 1.0 LOA based on the overall length of the ship, the air is injected from the front air nozzle so that the point of time of the air layer formed by the front air nozzle is within 0.7 LOA to 0.85 LOA , Air lubrication method of ships to which air lubrication system is applied.

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