JPH09156574A - Friction resistance reduction method for ship - Google Patents
Friction resistance reduction method for shipInfo
- Publication number
- JPH09156574A JPH09156574A JP7337723A JP33772395A JPH09156574A JP H09156574 A JPH09156574 A JP H09156574A JP 7337723 A JP7337723 A JP 7337723A JP 33772395 A JP33772395 A JP 33772395A JP H09156574 A JPH09156574 A JP H09156574A
- Authority
- JP
- Japan
- Prior art keywords
- hull
- ship
- bubbles
- frictional resistance
- diameter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T70/00—Maritime or waterways transport
- Y02T70/10—Measures concerning design or construction of watercraft hulls
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は航行時に船体表面に
作用する粘性摩擦抵抗を低減できるようにする船舶の摩
擦抵抗低減方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing the frictional resistance of a ship, which can reduce the viscous frictional resistance acting on the surface of the hull during navigation.
【０００２】[0002]
【従来の技術】船舶の航行時には、流体としての海水の
粘性のために船体の周りに海水による境界層が形成され
るが、この境界層の中では、海水の流速は船体表面が零
で船体表面から離れるに従い急激に大きく変化する傾向
にあり、船体の表面に海水の粘性摩擦抵抗が作用し船体
の推進性能を悪化させる原因となっており、船舶の推進
に大きな動力が必要となっている。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 the seawater as a fluid. It tends to change drastically as it moves away from the surface, and viscous frictional resistance of seawater acts on the surface of the hull and deteriorates the propulsion performance of the hull, requiring a large amount of power to propel the ship. .
【０００３】近年、船舶の推進動力を小さくするため
に、船体の表面に作用する粘性摩擦抵抗を低減させて、
船舶の推進性能を向上させるようにするための研究が進
められている。In recent years, in order to reduce the propulsion power of a ship, the viscous frictional resistance acting on the surface of the hull is reduced,
Research is being conducted to improve the propulsion performance of ships.
【０００４】これまで、平板と流体とを相対変位させ
て、該平板の表面から気泡を噴出して境界層内に気泡を
吹き込むことにより、平板の表面に作用する粘性摩擦抵
抗の低減を図るようにした考え方がある。Up to now, the relative displacement between the flat plate and the fluid causes the bubbles to be ejected from the surface of the flat plate to blow the bubbles into the boundary layer, thereby reducing the viscous frictional resistance acting on the surface of the flat plate. There is a way of thinking.
【０００５】[0005]
【発明が解決しようとする課題】しかし、平板の場合は
その表面に気泡を沿わせることはできるが、表面に曲面
を有する船体の場合、気泡がその表面に沿い流れること
は考えられておらず、船体の如き曲面に応用した例はな
い。However, in the case of a flat plate, bubbles can be made to follow its surface, but in the case of a hull having a curved surface, it is not considered that the bubbles will flow along that surface. There is no example applied to curved surfaces such as hulls.
【０００６】そこで、本発明者等は、表面が曲面をなす
船体の表面から水中に噴出させた気泡が船首の垂線から
船尾の垂線までの間でどのような軌跡を描いて流れるか
について、種々の計算及び実験を繰り返して研究を重
ね、曲面を有する船体表面に沿いながら船首部が船尾部
まで流れる気泡があることを求め、気泡により摩擦抵抗
低減を図る考え方が船体に適用できることを見い出して
本発明をなした。Therefore, the inventors of the present invention have variously determined how the bubbles ejected from the surface of the hull having a curved surface into the water flow along the trajectory from the vertical line of the bow to the vertical line of the stern. By repeating the calculations and experiments described above, the authors found that there is a bubble that flows along the curved hull surface to the stern of the bow, and that the idea of reducing frictional resistance by the bubble can be applied to the hull. Made an invention.
【０００７】したがって、本発明は、船体の表面に沿う
ように気泡を流すことにより船体の浸水面の表面の境界
層内にボイドを作り、摩擦抵抗を低減させるようにしよ
うとするものである。Therefore, the present invention is intended to reduce the frictional resistance by causing bubbles to flow along the surface of the hull to create voids in the boundary layer on the surface of the water surface of the hull.
【０００８】[0008]
【課題を解決するための手段】本発明は、上記課題を解
決するために、船体の浸水部表面から該船体の浸水部表
面に沿い流れる微小気泡の直径を求めて水中に噴出さ
せ、該微小気泡を船体の浸水部表面に沿わせ、該船体の
浸水部表面に微小気泡によるボイドを形成させて航行時
の摩擦抵抗を低減させることを特徴とする船舶の摩擦抵
抗低減方法とする。SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention obtains the diameter of minute bubbles flowing along the surface of the inundation part of the hull from the surface of the inundation part of the hull, and ejects the bubbles into the water. A method for reducing frictional resistance of a ship, characterized in that bubbles are caused to flow along a surface of a water-immersed portion of a ship and voids are formed on the surface of the water-immersed part of the ship by minute bubbles to reduce frictional resistance during navigation.
【０００９】巡航速度での航行時に、微小気泡を船体表
面から噴出させると、微小気泡は船体表面に沿って流れ
るので船体の浸水部表面の境界層内にボイド率の高い気
泡層が形成されることになり、摩擦抵抗が低減されるこ
とになる。When the minute bubbles are ejected from the surface of the hull during navigation at a cruising speed, the minute bubbles flow along the surface of the hull, so that a bubble layer having a high void ratio is formed in the boundary layer on the surface of the inundated portion of the hull. Therefore, the frictional resistance is reduced.
【００１０】直径が５００μm 程度の微小気泡を噴出さ
せると、船体の浸水部表面に沿って船尾側まで流れ、浸
水部表面の任意の点におけるボイド率を向上させる。When minute bubbles having a diameter of about 500 μm are ejected, they flow to the stern side along the surface of the flooded part of the hull, and improve the void ratio at any point on the surface of the flooded part.
【００１１】[0011]
【発明の実施の形態】以下、本発明の実施の形態を図面
を参照して説明する。Embodiments of the present invention will be described below with reference to the drawings.
【００１２】図１は本発明の実施の一形態を示すもの
で、たとえば、船体１の船首部２における吃水線Ｄ．Ｌ
よりもやや下側に位置する船側部に、船体表面に沿い後
方へ向け斜め下向きに微小気泡４をジェット状に噴出さ
せるようにするスリット状の噴出口３を設け、巡航速度
での航行時に、微小気泡４を上記噴出口３より水中に噴
出させて船体１の浸水部表面に沿わせ、船体表面の境界
層へ微小気泡４を吹き込むようにし、船体１の表面と海
水６との間にボイド５を形成させるようにして摩擦抵抗
低減を図るようにする。なお、噴出口３は船首部２の図
示した位置以外の位置に設けたものでもよい。FIG. 1 shows an embodiment of the present invention. For example, the water-draining line D. L
A slit-shaped jet port 3 is provided on the side of the ship that is located slightly below the jet side so as to jet the micro bubbles 4 obliquely downward toward the rear along the surface of the hull, and when sailing at cruising speed, The minute bubbles 4 are jetted out into the water through the jet outlets 3 along the surface of the inundated portion of the hull 1 so that the minute bubbles 4 are blown into the boundary layer on the surface of the hull, and the voids are formed between the surface of the hull 1 and the seawater 6. 5 is formed to reduce frictional resistance. The ejection port 3 may be provided at a position other than the illustrated position of the bow 2.
【００１３】船舶の巡航速度での航行時に、微小気泡４
を、所定の流速で噴出口３から噴出させると、水流と共
に微小気泡４は船体１の浸水部表面に沿って後方へ拡散
しながら流れる。この際、微小気泡４が、船体表面に沿
いながら船首側から船尾側に至るまで流れて、船体１の
浸水部表面を覆うようになれば、該船体の浸水部表面に
ボイドが形成されることになり、このボイドが船体まわ
りに形成されると、船体航行時の摩擦抵抗は低減される
ことになる。During the navigation at the cruising speed of the ship, the micro bubbles 4
Is ejected from the ejection port 3 at a predetermined flow rate, the minute bubbles 4 flow along the surface of the water body while diffusing backward along the surface of the inundated portion of the hull 1. At this time, if the minute bubbles 4 flow along the surface of the hull from the bow side to the stern side and cover the surface of the flooded part of the hull 1, voids may be formed on the surface of the flooded part of the hull. When this void is formed around the hull, the frictional resistance during navigation of the hull is reduced.
【００１４】摩擦抵抗低減に効果のある微小気泡４は、
船体の浸水部表面の任意の点においてボイド率の向上に
寄与するものであり、したがって、その微小気泡４の直
径を求めて、その直径の微小気泡４を噴出口３より水中
に噴出させるようにすることにより、微小気泡４が船体
１の浸水部表面に沿い張り付くように流れて、船体の浸
水部表面の任意の点においても高いボイド率が得られる
状況にすることができ、摩擦抵抗低減を図ることが可能
となる。The micro bubbles 4 effective in reducing frictional resistance are
It contributes to the improvement of the void ratio at any point on the surface of the flooded part of the hull. Therefore, the diameter of the minute bubble 4 is obtained, and the minute bubble 4 of that diameter is jetted out into the water from the jet port 3. By doing so, the minute bubbles 4 flow along the surface of the flooded part of the hull 1 so as to stick, and it is possible to obtain a high void ratio at any point on the surface of the flooded part of the hull, and reduce the frictional resistance. It is possible to plan.
【００１５】本発明者等は、船体の形状が与えられる
と、その船体表面に沿い流れる微小気泡の拡散状況を計
算により求め、気泡の直径の違いにより、船側部では直
ちに浮上するものと、船側部では大きく拡散するもの
と、船底部及び船側部で表面に沿い流れるものとがある
ことを見い出し、微小気泡４の直径が、以下の実施例に
示す如く、１００μm 、１０００μm 、５００μm であ
る場合の拡散状況を調べたところ、図２に示す如き結果
が得られた。Given the shape of the hull, the inventors of the present invention calculated the diffusion state of the minute bubbles flowing along the surface of the hull, and the difference between the diameters of the bubbles caused the surface to float immediately on the side of the ship. It was found that there is a large amount of diffusion in the part and a part that flows along the surface in the bottom and side of the ship, and the diameter of the microbubbles 4 is 100 μm, 1000 μm, 500 μm as shown in the following examples. When the diffusion state was examined, the results shown in FIG. 2 were obtained.
【００１６】これに基づき、本発明は、船体１の形状に
応じて図２（ハ）に示すような拡散状況を示す直径の微
小気泡４を見付けて噴出口３より噴出させ、微小気泡４
で船体の浸水部表面を覆うようにしてボイド率を向上さ
せ、摩擦抵抗を低減させるようにする。Based on this, the present invention finds minute bubbles 4 having a diameter showing a diffusion state as shown in FIG.
The void ratio is improved by covering the surface of the inundated part of the ship with, and the frictional resistance is reduced.
【００１７】[0017]
【実施例】船体１の表面に作用する粘性摩擦抵抗の低減
に効果のある微小気泡４の直径は、乱れの速度による流
体力と浮力との相互関連により決まるものである。本発
明者等は、船舶の設計において、船体１の形状が与えら
れると、巡航速度でのその船体１の表面に沿いながら船
首垂線Ｆ．Ｐから船尾垂線Ａ．Ｐまで微小気泡４がどの
ような状態で流れるかを、計算により求めてシミュレー
ションしたところ、全長７ｍの模型船の場合には微小気
泡４の直径が５００μm 程度のときが最適であるという
ことが判明した。EXAMPLE The diameter of the micro-bubbles 4 effective in reducing the viscous frictional resistance acting on the surface of the hull 1 is determined by the mutual relation between the fluid force and the buoyancy due to the speed of turbulence. Given the shape of the hull 1 in the design of a ship, the present inventors have found that the bow perpendicular F.I. P to poop line A. A simulation was performed to find out in what state the microbubbles 4 flow up to P, and it was found that in the case of a model ship with a total length of 7 m, it is optimal when the diameter of the microbubbles 4 is about 500 μm. did.
【００１８】図２は上記計算を実証するために行った実
験結果を示すもので、いずれも図１に示す船体１におい
て、船尾垂線Ａ．Ｐから船首垂線Ｆ．Ｐまでの垂線間長
さを１０等分したときの船尾垂線Ａ．Ｐからの各スクエ
アステーションＳ．Ｓ．１〜１０のうちの、スクエアス
テーションＳ．Ｓ．５部の断面図である。（イ）は直径
が１００μm の微小気泡４を噴出させた場合を示すもの
で、微小気泡４が船体１の浸水部表面に張り付かずに広
範に拡散し、全長にわたって船体浸水部表面に沿う流れ
が得られず、ボイド率の高いボイド５を形成できない状
態となっている。（ロ）は直径が１０００μm の微小気
泡４を噴出させた場合を示すもので、微小気泡４は径が
大きく浮上力が大き過ぎるため、船側部では張り付かず
に浮上してしまい、船側部でのボイド５が消失した状態
となっている。（ハ）は直径が５００μm の微小気泡４
を噴出させた場合を示すもので、微小気泡４は拡散し過
ぎることはなく、船側部でも浮上消失することもなく、
船体１の浸水部の表面に全面的に張り付くように沿わさ
れており、ボイド５が良好に形成されている。これらの
結果から明らかなように、直径が５００μm 前後の微小
気泡４を噴出させたときに微小気泡４を船体１の表面に
沿わせ易くすることができ、ボイド率を最も高めること
ができた。FIG. 2 shows the results of an experiment conducted to verify the above calculation. In each case, the stern perpendicular line A. P perpendicular to bow F. Stern perpendicular line when the length between perpendicular lines to P is divided into 10 equal parts. Each square station from P.S. S. Square Station S.I. S. It is sectional drawing of 5 parts. (A) shows the case where the micro bubbles 4 with a diameter of 100 μm are ejected. The micro bubbles 4 spread widely without sticking to the surface of the inundation part of the hull 1, and flow along the surface of the inundation part of the hull over the entire length. Is not obtained, and the void 5 having a high void ratio cannot be formed. (B) shows the case where the micro bubbles 4 with a diameter of 1000 μm are ejected. Since the micro bubbles 4 have a large diameter and the levitation force is too large, the micro bubbles 4 do not stick to the side of the ship and ascend to the side of the ship. Void 5 has disappeared. (C) is a micro bubble 4 with a diameter of 500 μm
The figure shows a case where the microbubbles 4 do not diffuse too much, and neither floats nor disappears on the side of the ship.
The voids 5 are formed so as to be entirely attached to the surface of the inundated portion of the hull 1, and the voids 5 are well formed. As is clear from these results, when the micro bubbles 4 having a diameter of about 500 μm were ejected, the micro bubbles 4 could be easily made to follow the surface of the hull 1, and the void ratio could be maximized.
【００１９】因に、図３はスクエアステーションＳ．
Ｓ．１での収束時のボイド率分布を示すもので、船首部
２で噴出させた微小気泡４が船尾部でも船底のボイド率
が高いことが判る。Incidentally, FIG.
S. It shows that the void ratio distribution at the time of convergence at 1 is high, and the void ratio of the micro bubbles 4 ejected at the bow portion 2 is high even at the stern portion.
【００２０】[0020]
【発明の効果】以上述べた如く、本発明の船舶の摩擦抵
抗低減方法によれば、航行時に、船体表面から、その船
体表面に沿い船尾側まで流れるような直径の微小気泡を
噴出させて、該微小気泡を船体の浸水部表面に沿わせて
海水との間にボイドを形成させるようにするので、船体
の浸水部表面の境界層内を微小気泡で覆うことができて
該船体の浸水部表面の任意の点でのボイド率を向上させ
ることができ、これにより、船体表面に作用する粘性摩
擦抵抗を低減することができて、船舶の推進性能を飛躍
的に向上させることができる、という優れた効果を発揮
する。As described above, according to the method for reducing the frictional resistance of a ship of the present invention, during navigation, by ejecting minute bubbles having a diameter that allows them to flow from the surface of the hull to the stern side along the surface of the hull, Since the voids are formed along the surface of the flooded portion of the hull to form seawater with the seawater, the boundary layer on the surface of the flooded portion of the hull can be covered with the fine bubbles and the flooded portion of the hull can be covered. It is possible to improve the void rate at any point on the surface, which can reduce the viscous frictional resistance that acts on the surface of the hull and dramatically improve the propulsion performance of the ship. Shows excellent effects.
【図１】本発明の船舶の摩擦抵抗低減方法の実施の一形
態を示す概要図である。FIG. 1 is a schematic view showing an embodiment of a method for reducing frictional resistance of a ship according to the present invention.
【図２】微小気泡の船体表面に沿う拡散状況をスクエア
ステーションＳ．Ｓ．５で求めた結果を示すもので、
（イ）は直径が１００μm の微小気泡の場合の断面内ボ
イド率分布を示す図、（ロ）は直径が１０００μm の微
小気泡の場合の断面内ボイド率分布を示す図、（ハ）は
直径が５００μm の微小気泡の場合の断面内ボイド率分
布を示す図である。FIG. 2 shows the diffusion status of micro bubbles along the surface of the hull at Square Station S. S. It shows the result obtained in 5.
(A) is a diagram showing the void fraction distribution in the cross section for micro bubbles with a diameter of 100 μm, (b) is a diagram showing the void fraction distribution in the cross section for micro bubbles with a diameter of 1000 μm, and (c) is the diagram It is a figure which shows the void fraction distribution in a cross section in the case of a 500 micrometer micro bubble.
【図３】収束時のボイド率分布を示す図である。FIG. 3 is a diagram showing a void rate distribution upon convergence.
１ 船体 ４ 微小気泡 ５ ボイド ６ 海水 1 Hull 4 Micro bubbles 5 Void 6 Seawater
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉田 有希 東京都江東区豊洲二丁目１番１号 石川島 播磨重工業株式会社東京第一工場内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuki Yoshida 1-1-1, Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Ltd. Tokyo No. 1 Factory
Claims (2)
面に沿い流れる微小気泡の直径を求めて水中に噴出さ
せ、該微小気泡を船体の浸水部表面の境界層内に沿わ
せ、該船体の浸水部表面に微小気泡によるボイドを形成
させて航行時の摩擦抵抗を低減させることを特徴とする
船舶の摩擦抵抗低減方法。1. The diameter of the microbubbles flowing along the surface of the flooded part of the hull is calculated from the surface of the flooded part of the hull and ejected into water, and the microbubbles are made to flow along the boundary layer of the surface of the flooded part of the hull, A method for reducing frictional resistance of a ship, characterized in that voids due to minute bubbles are formed on the surface of a water-immersed part of a hull to reduce frictional resistance during navigation.
００μm 程度とした請求項１記載の船舶の摩擦抵抗低減
方法。2. The diameter of the fine bubbles ejected on the surface of the hull is 5
The method for reducing frictional resistance of a ship according to claim 1, wherein the frictional resistance is about 00 μm.
Priority Applications (11)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7337723A JPH09156574A (en) | 1995-12-04 | 1995-12-04 | Friction resistance reduction method for ship |
| PCT/JP1996/002101 WO1997020727A1 (en) | 1995-12-04 | 1996-07-26 | Method for reducing the frictional resistance of a hull and a frictional resistance reduced vessel employing the same method |
| BR9611688A BR9611688A (en) | 1995-12-04 | 1996-12-03 | Method to reduce the resistance to ship hull friction which reduces the resistance to friction using such a method and method to analyze air bubbles ejected from the ship |
| PCT/JP1996/003526 WO1997020728A1 (en) | 1995-12-04 | 1996-12-03 | Method of reducing friction resistance of hull, ship whose friction resistance is reduced by the method, and method of analyzing jetted bubbles on ship |
| US09/068,844 US6186085B1 (en) | 1995-12-04 | 1996-12-03 | Method for reducing frictional resistance of hull, frictional resistance reducing ship using such method, and method for analyzing ejected air-bubbles from ship |
| CA002238036A CA2238036A1 (en) | 1995-12-04 | 1996-12-03 | Method for reducing frictional resistance of hull, frictional resistance reducing ship using such method, and method for analyzing ejected air-bubbles from ship |
| EP96939344A EP0865985A4 (en) | 1995-12-04 | 1996-12-03 | Method of reducing friction resistance of hull, ship whose friction resistance is reduced by the method, and method of analyzing jetted bubbles on ship |
| CN96199875A CN1091719C (en) | 1995-12-04 | 1996-12-03 | Method of reducing friction resistance of hull, ship whose friction resistance is reduced by the method, and method of analyzing jetted bubbles on ship |
| KR1019980704071A KR19990071792A (en) | 1995-12-04 | 1996-12-03 | Method of reducing frictional resistance of hull, Method of reducing frictional resistance using this method, and Method of analysis of blowing bubble in ship |
| NO982515A NO982515L (en) | 1995-12-04 | 1998-06-02 | Procedure for reducing the frictional resistance of a hull |
| FI981259A FI981259A (en) | 1995-12-04 | 1998-06-03 | Method for reducing the frictional resistance of a hull, a ship whose frictional resistance is reduced by a method and a method for analyzing bubbles blown from a ship |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7337723A JPH09156574A (en) | 1995-12-04 | 1995-12-04 | Friction resistance reduction method for ship |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09156574A true JPH09156574A (en) | 1997-06-17 |
Family
ID=18311367
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7337723A Pending JPH09156574A (en) | 1995-12-04 | 1995-12-04 | Friction resistance reduction method for ship |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09156574A (en) |
-
1995
- 1995-12-04 JP JP7337723A patent/JPH09156574A/en active Pending
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