JP2010195174A - Method of generating bubbles in friction resistance reducing device in ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of generating fine bubbles of low pressure in a friction resistance reducing device in a ship which can obtain the more effective reduction of frictional resistance by generating bubbles by the pressure of a natural water flow. <P>SOLUTION: The method provide the reduction effect of friction resistance by generating fine bubbles of low pressure using a pressure reducing phenomenon in a portion between an intake 1 provided at a position of a waterline Y or a lower near bow X and an exhaust nozzle 2 provided at the bottom Z of the ship near the bow X in the friction resistance reducing device for the ship by sending the bubbles to the bottom of the ship at arbitrary water depth as necessary without pressurizing them, and furthermore by jetting out the bubbles from the exhaust nozzle 2 without being affected by a surrounding water pressure environment. The device is simpler, has cost effectiveness higher than a conventional one, reduces manufacturing and installing cost, the cost of energy consumption required for air pressurization, the cost of energy consumption required in the process of distributing the generated bubbles to required portions of a ship body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for generating bubbles in a frictional resistance reduction device for a large ship such as a tanker, and in particular, for reducing the frictional resistance generated between the water contact surface of the hull and water when operating a large ship. The present invention relates to a bubble generation method for generating low-pressure fine bubbles mainly under the pressure of natural water flow.

  Conventionally, bubble generating devices that reduce the frictional resistance generated between the water-contact surface of the hull and water during ship operation emphasize that bubbles are very small and can be easily generated even in high water pressure environments. Was placed.

  For example, in order to reduce water resistance during ship operation, various methods for interposing bubbles and air layers on the hull wall surface are disclosed. For example, pressurized air blown out from the ship side is blown toward the rear of the hull as a blowing speed slower than the ship speed, and microbubbles generated at the ship side are made more than microbubbles generated at the ship bottom. A method of feeding into the boundary layer with a small diameter is disclosed. For example, Patent Document 1 and Patent Document 2.

  However, in such a system, it is difficult to obtain fine sin bubbles, and in practice, energy consumption due to the blowing of bubbles is large, which is impractical. Therefore, the bubble resistance fluid is slanted in the boundary layer so that the frictional resistance can be reduced with less energy consumption, can be easily implemented, the bubble mixing ratio can be easily adjusted, and the friction can be effectively reduced. A technique of ejecting backward is disclosed. For example, as in Patent Document 3.

  In addition, a technique is disclosed in which microbubbles are generated using a reduced pressure with respect to atmospheric pressure to aim at a ship frictional resistance reduction effect. For example, Patent Document 4, Patent Document 5, and Patent Document 6.

JP 2008-18781 A JP-A-11-227474 Japanese Patent Laid-Open No. 07-156859 JP 2002-79986 A JP 2002-68073 A JP 2002-79985 A

  According to these methods, low-pressure microbubbles can be generated without pressurizing air, so two advantages can be obtained as compared with the conventional pressurization method. One is that the generated low-pressure micro-bubbles have a slight expansion property, which produces a more efficient friction reduction effect. The other is that since no air pressurizing device such as a compressor is used, bubbles can be generated with less energy consumption, and the cost required for the generation of bubbles can be reduced. However, the following problems can be pointed out even in the method of generating low-pressure microbubbles using the above-described reduced pressure.

  In these low-pressure microbubble generators, the generation process itself of low-pressure microbubbles is hindered by the influence of the surrounding water pressure, which prevents bubbles from being generated in a hydraulic environment higher than a certain hydraulic environment. is there.

  In particular, when trying to obtain the effect of reducing frictional resistance in large ships such as tankers where the water level at the bottom of the ship extends from 10 to 20 m, microbubbles should be generated using a device such as a compressor as in the pressurization method. These two advantages will disappear, because it will be necessary.

Therefore, the present invention is intended to solve these problems.
The first problem is not to provide a device for generating a high-pressure bubble having a negative property with respect to the frictional resistance reducing effect as described above, but it does not have a property to expand greatly even after being ejected out of the ship. An object of the present invention is to develop and provide a method for generating low-pressure microbubbles in a frictional resistance reducing device in a ship that can generate inflatable bubbles by the pressure of natural water flow and obtain a more effective frictional resistance reduction.

  The second problem is that the generation of low-pressure microbubbles is affected by water pressure in the process of generating low-pressure microbubbles using the conventional decompression phenomenon, and the generation of bubbles is hindered. This is not to provide a method that needs to generate microbubbles in combination with an air pressurization device such as air pressure, but to reduce the influence of water pressure that inhibits bubble generation from the process itself of generating low pressure microbubbles using the decompression phenomenon. Friction resistance is reduced by removing the low-pressure microbubbles generated and sending them to the bottom of the ship at any depth without being pressurized, and by jetting them out of the jet without being affected by the surrounding water pressure environment. It is to develop and provide a method that makes it possible to obtain an effect.

  The third issue is to develop and provide a simpler and more cost-effective structure for the micro-bubble generator and the complicated structure of the water supply path in the conventional frictional resistance reduction device in a ship. Furthermore, the energy consumption cost required for air pressurization and the energy consumption cost required in the process of distributing the generated bubbles to the required part of the hull are reduced.

As means for solving the problems according to the present invention, the means for solving the first problem is based on the low-pressure microbubble generator in the low-pressure microbubble generation method. As shown in the figure, this apparatus is composed of two bubble generation portions that form a reduced pressure region with respect to atmospheric pressure. The reduced pressure region generated at this portion is used to naturally suck air into the water flow, It is characterized by generating low-pressure microbubbles with expansion properties.
The means for solving the second problem is due to the position configuration itself of the water supply path from the water intake to the jet outlet.
The means for solving the third problem is also due to the position configuration itself of the water supply path from the intake port to the jet port.

The present invention has the following effects.
1) It is possible to generate a large amount of low-pressure microbubbles that are more effective for reducing the frictional resistance of ships, regardless of air pressurization. The air sucked into the water from the decompression region formed at the site where the low-pressure microbubbles are generated is not pressurized at all and is instantly converted into microbubbles while maintaining the low-pressure state, and is jetted to the necessary site as it is with the water flow. The non-pressurized low-pressure microbubbles maintain non-expandability even when released into water, compared to the high-pressure bubbles generated by a conventional air pressurizer, and have a diameter of about 0.1 to 0.2 mm. Therefore, a more effective frictional resistance reduction effect is produced.
2) A large amount of low-pressure microbubbles can be generated without being affected by the hydraulic environment. At the same time, it can be discharged from a spout at an arbitrary depth in the ship. Unlike the conventional device that generates low-pressure microbubbles using the decompression phenomenon, the area where low-pressure microbubbles are generated is not located at the bottom of the ship. It is not necessary to create high-pressure bubbles with water pressure resistance in combination.
3) Cost-effective in the process of bubble generation and distribution to the outside of the ship. Since the natural water flow that flows in at the time of navigation can be used as it is as a power source for the water flow, the power for pressurizing the water flow is hardly used. Moreover, since the same water flow is used for the power necessary for the bubble generation process, an air pressurizing device is not required. It is possible to produce effects with less energy consumption.
4) The method for generating low-pressure microbubbles is extremely simple. That is, the technology required for production does not need to be special, and the cost is lower than that of a conventional known bubble generator, and the cost for maintenance is also low.

It is a partial missing side view which shows an example of the apparatus used for implementation of this invention. It is a partial expanded explanatory view which shows an example of the apparatus used for implementation of this invention. It is a front view which shows an example of the apparatus used for implementation of this invention. 1 shows an example of a primary bubble generation site and a primary bubble generation site of an experimental apparatus for verifying the implementation of the present invention, in which (a) is a partially broken perspective view, and (b) is a partial view. FIG. The primary bubble generation site | part of the experimental apparatus for verifying implementation of this invention, and the other example of a primary bubble generation site | part are shown, (a) is a partially missing perspective view, (b) It is a partial missing front view. It is a partial deficiency explanatory drawing which shows an example of the experimental apparatus for verifying implementation of this invention. It is a partial deficiency explanatory drawing which shows an example of the experimental apparatus for verifying implementation of this invention. It is a craft diagram which shows the data of the experimental apparatus for verifying implementation of this invention. It is explanatory drawing of the measuring device which measures the data of the experimental apparatus for verifying implementation of this invention.

  In the present invention, a water supply path for generating low-pressure microbubbles is provided in the hull of a ship, a water intake is provided under the draft line near the bow, a jet outlet is provided at the bottom of the ship, and an intermediate part of the water supply path is provided. The generation | occurrence | production site | part of a low voltage | pressure microbubble is provided in the position above the waterline of a part. There are two places where these low-pressure microbubbles are generated. The primary bubble generation part is the first air inflow pipe inside the water supply pipe forming the water supply path, and the two cross-sections are the water supply pipe and the air inflow pipe. Are connected to form a narrow gap, and the secondary bubble generation site is also formed in the second air inflow pipe that forms the water supply path, and the cross section of the water supply pipe is connected to the air inflow pipe. The two water tubes are connected to form a narrow gap.

  The present invention uses a reduced pressure region generated by a narrow gap at each of these bubble generation sites to suck air from an air inflow pipe and suck and mix it into a water stream flowing through a water supply path. This is a microbubble generator, and the water pump mainly supplies water from the intake port under the waterline to the position of the bubble generation site on the waterline at the start of navigation, or assists during low-speed navigation, etc. It is provided for the purpose of being used as power for water flow.

  An embodiment of the present invention will be described in detail with reference to the drawings. In a ship frictional resistance reducing device, a water intake (1) provided near a bow (X) and below a flood line (Y), and a bow ( The spout (2) provided on the ship bottom (Z) close to X) is connected by a single unbroken pipe consisting of water pipes (3a, 3a ') and air-water mixed water pipe (3b), A water pump (4) is installed in the water pipe (3a) at the same water level as the water inlet (1) behind the water inlet (1), and the water pipe (3a ') behind the water pipe (3a') is a draft line (Y ) When both pipes are stacked inward and outward from the stern of the water supply pipe (3a ') piped in the stern direction so as to be positioned above the vicinity, the gap is narrow. Bend the tip of the first air inflow pipe (5a) thin enough to allow the water flow direction to penetrate the water supply pipe (3a) And at the position where both pipes are parallel, the tip of the first air inflow pipe (5a) is cut, and the peripheral region or the vicinity of the position is set as the primary bubble generation site (A), and then the rear When the adjustment valve (6) is attached to the water supply pipe and the water supply pipe is overlapped with the water supply pipe inside and outside, the water supply pipe (3a ') is connected from the outside with the second air inflow pipe (5b) thick enough to form a narrow gap. It is attached so as to wrap, and the water supply pipe (3a ') is cut at a position where both pipes are parallel to each other, and the peripheral region or the vicinity of the position is set as the secondary bubble generation site (B), and the second air inflow pipe (5b) Is connected to the jet outlet (2) as an air / water mixed water pipe (3b) for sending the air / water mixed water stream, and the inflow water from the intake (1) Utilizing the depressurization phenomenon against atmospheric pressure generated at the bubble generation site (A) and the secondary bubble generation site (B) The air is sucked from the first air inflow pipe (5a) and the second air inflow pipe (5b) to generate low-pressure microbubbles, and together with the air / water mixed water supply flow ejected from the air / water mixed water supply pipe (3b). It is comprised from the generation | occurrence | production method of the bubble in the frictional resistance reduction apparatus in the ship characterized by making it eject from a jet nozzle (2), without using the motive power of.

  The adjustment valve mounted on the second air inflow pipe (5b) is functionally an air inflow increase adjustment valve.

Next, the configuration and functions of the apparatus used in the method for reducing the frictional resistance of a ship according to the present invention will be described in detail. 1) Water intake The size of the water intake (1) is large as long as the hull function is not hindered. Since it is desirable to take in water, the larger the better. Moreover, it is necessary to provide a filter so that dust and the like are not clogged at the primary bubble generation site (A) and the second bubble generation site (B).
2) Water pump Most of the water intake uses natural water flow as the ship progresses, but it is necessary to take water with the water pump (4) when the ship first starts or sails at low speed.
3) Low-pressure microbubble generator This is an apparatus for generating as many microbubbles as one of the main objects of the present invention. As shown in FIGS. 1 and 2, the primary bubble generation site (A), A second bubble generation site (B) is provided, and the first bubble generation site (A) is inserted through the first air inflow pipe (7a) into the water supply pipe (3a ′), and has an appropriate length. A strong pressure reduction region generated near the cut surface of the first air inflow pipe (7a) is used by cutting and flowing out of a narrow gap between the water supply pipe (3a ') and the first air inflow pipe (7a). Then, air is sucked from the first air inflow pipe (7a), and at the same time, low-pressure microbubbles are generated and mixed with the water flow, and sent to the secondary bubble generation site (B). The secondary bubble generation site (B) cuts the water supply pipe (3a ′) with a slight gap from the primary bubble generation site (A), and the cut site is covered by the second air inflow pipe (5b). On the other hand, the second air inflow pipe (5b) is sucked from the second air inflow pipe (5b) by the reduced pressure region generated near the position of the cut surface of the water supply pipe by the gap between the second air inflow pipe (5b) and the water supply pipe (3a '). Additional bubbles are generated in the mixed water and sent to the spout (2). At that time, an air regulating valve (6) is attached to the inlet of the upper end of the second air inlet pipe (5b) to adjust the amount of inflow of air.
4) Spout The air-water mixed water stream sent from the bubble generation site (A, B) and the spout from the end spout (2) are spouted to the ship bottom (Z). It is necessary to reduce the cross-sectional area at the tip of the jet outlet (2). The degree of reduction depends on the situation, but about half will be appropriate.

Next, for the purpose of more specifically verifying each configuration and function of the apparatus used in the method for reducing the frictional resistance of a ship according to the present invention, a low-pressure microbubble generation test and a water depth pressure test using a model prototype are also performed. Tried.
A major object of the present invention is to reduce the frictional resistance generated on the water contact surface of the hull by generating low pressure micro-bubbles on the water contact surface of the hull during ship operation, thereby reducing the energy required for propulsion of the hull. However, especially when used on large ships such as tankers, low-pressure microbubbles generated by using the depressurization phenomenon are sent to the bottom of the ship at an arbitrary depth and injected so as not to receive the surrounding hydraulic environment. Since ejecting from the exit is an important issue, the basis for providing a solution to the problem only by the consistency of theoretical assumptions is sparse. Therefore, the outline of the experiment, the results, and the inference obtained thereby are shown below.

  FIG. 4 shows a prototype used in the low-pressure microbubble generation test. The bubble generation site of the prototype is a small instrument having a diameter of about 30 mm, but the actual size of the large ship is matched to the actual size. Even in the case of replacement, the principle of generation of low-pressure microbubbles using the decompression phenomenon is the same. Moreover, although the positional relationship of two air inflow pipes differs from the bubble generator shown in FIG. 5, the function is the same.

FIG. 6 is a schematic diagram of the low-pressure microbubble generation test 1. The water pipe of the prototype is connected to a water tap, and one water tap is the power source for the water flow. In Test 1, the bubble generation site integrated with the tip was fixed at each position of 2 cm and 60 cm depth, and the occurrence of low pressure microbubbles was observed. As a result, a large amount of microbubbles were generated at a position of 2 cm depth. Although it was possible, it became impossible to generate at a water depth of 60 cm.
This phenomenon is caused by external air being sucked into the decompression area around the tip of the water pipe and air inflow pipe, and then being drawn into the water stream to be bubbled. Indicates that it is no longer available. From this result, when the bubble generating device in FIGS. 3 and 4 is actualized according to the actual size of a large ship and installed in the position of the water pressure environment of the bottom water level (about 10-15M), the flow velocity of the water flow in the water pipe is increased. Even so, it was inferred that bubble generation would be impossible. In addition, it is necessary to use an air pressurizing device such as a compressor to generate microbubbles at a water depth of 10 to 15M. In that case, it is easily assumed that low-pressure microbubbles having non-expandable properties are lost. It can be done. These inferences are related to the second issue.

  Next, a test 2 for generating low-pressure microbubbles was tried using the prototype shown in FIG. In this prototype, only the tip of the second air inlet pipe of the prototype shown in FIG. 6 is extended by 4M, and the sectional area of the tip of the second air inlet pipe (5b) in FIGS. Is characterized by being made small. The water pipe of the prototype is connected to two taps, and the two taps are used as a power source for water flow. The water depth of the aquarium is 4.5M.

The test 2 was performed as follows. As shown in FIG. 8, while the bubble generation part of the prototype is fixed at a position on the water surface, the tip is fixed vertically at each of the water depths of 0.1M, 1M, 2M, 3M, and 4M. The air suction speed was measured using a measuring instrument. As a result, as shown in FIG. 7, almost no difference in the amount of bubbles generated was observed except for the surface 0.1M of the water surface. From this result, it was inferred that the same result could be obtained even if the tip was fixed at a deeper depth than 4M. This reasoning is related to the solution of the second problem.
The reason why the air suction speed in air suction at a water depth of 0.1 M is faster than that at other water depths is that most of the bubbles are directly discharged to the water surface because the ejected bubbles are close to the water surface.

  The measurement method of the bubble generation amount used in the test 2 is based on the measuring device shown in FIG. (A) is an air inflow measurement balloon. Since the amount of bubbles generated and the amount of air sucked into the measurement balloon should be equal, this measuring device is connected to the first air inlet pipe and the second air inlet pipe of the prototype to measure the balloon from the beginning of bubble generation. The amount of bubbles generated per second was calculated by measuring the number of seconds until the air inside became empty. (Refer to the graph shown in FIG. 8)

  An object of the present invention is to reduce the frictional resistance by generating low-pressure fine bubbles on the water contact surface of the hull during navigation of the ship. As a function of the bubble generator for such a purpose, it is necessary to generate a large amount of bubbles. This is because the frictional resistance decreases as the density of microbubbles covering the ship bottom increases. For this reason, the amount of bubbles generated in the prototype was measured with a measuring instrument. The amount of bubbles generated at a water depth of 4 M at the tip was 160 cc / sec, and the amount of tap water used was 800 cc / sec. When converted to a volume ratio, the amount of water: the amount of bubbles generated = about 5.5: 1. Although it is difficult to evaluate because there is no comparison standard, it was confirmed that a large amount of microbubbles having a diameter of about 0.01 mm were generated from photography from a close distance. It was judged that the bubble generation function of the prototype was very efficient. From these experimental results, it was inferred that the same result would be obtained even if the prototype was built to the actual size of a large ship as long as the physical principle of low pressure microbubble generation was the same. This reasoning is related to the means for solving the problems of the present invention.

  The present invention can be utilized industrially by establishing and implementing the technology of the bubble generation method in the frictional resistance reducing device for a ship according to the present invention.

DESCRIPTION OF SYMBOLS 1 Intake port 2 Spout 3a Water pipe 3a 'Water pipe 3b Air-water mixed water pipe 4 Water pump 5a 1st air inflow pipe 5b 2nd air inflow pipe 6 Adjustment valve 7 Air inflow port 7a 1st air inflow port 7b 2nd Air inflow port A Primary bubble generation site B Secondary bubble generation site X Bow Y Flood line Z Ship bottom

Claims (1)

In the ship frictional resistance reduction device,
A water intake near the bow and below the inundation line;
A spout on the bottom of the ship near the bow
Connected with a single continuous pipe consisting of a water pipe and an air-water mixed water pipe,
At the same water level as the water intake behind the water intake, a water supply pump is installed in the water supply pipe,
At the position from the stern of the water pipe that is piped in the stern direction so that the water pipe on the rear is located above the vicinity of the inundation line,
When both pipes are stacked inside and outside than the water pipe, the tip of the first air inlet pipe that is thin enough to create a narrow gap is bent in the direction of water flow, inserted through the water pipe,
At the position where both pipes are parallel, cut the tip of the first air inflow pipe,
The surrounding area or the vicinity of the position is the primary bubble generation site,
Next, a regulating valve is attached to the rear, and when the water pipe is overlapped with the inside and outside of the water pipe, it is attached so as to wrap the water pipe from the outside with a second air inlet pipe that is thick enough to create a narrow gap,
Cut the water supply pipe at the position where both pipes are parallel, and use the surrounding area or the vicinity of the position as the secondary bubble generation site,
The second air inflow pipe is connected to the jet outlet as an air / water mixed water pipe for sending the air / water mixed water flow in the form extended as it is after that position,
The inflow water from the intake port draws air from the first air inflow pipe and the second air inflow pipe by utilizing a depressurization phenomenon with respect to atmospheric pressure generated at the primary bubble generation site and the secondary bubble generation site,
Along with the air-water mixed water stream that generates low-pressure microbubbles and is ejected from the air-water mixed water pipe,
A method of generating bubbles in a frictional resistance reduction device in a ship, characterized in that the jetting is performed from a spout without using any power.

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