著者

徳永 純一郎 延永 尚志 中谷 龍男 岩崎 徹 福田 和廣 國武 吉邦

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1998, no.183, pp.45-52, 1998 (Released:2009-09-16)

参考文献数

7

被引用文献数

1 3

---

This paper proposes a new concept for the frictional drag reduction technique. The new technique makes use of a specific coating surface (Super-Water-Repellent Surface) which has a highly repellent effect and an ability to form a thin air film over it under water. When supplying a small amount of air to the specific coating surface from the outside continuously, the supplied air (secondary air) is absorbed in and joined with the primary air film and spread to form a filmy air flow along the surface. This technique reduces the frictional drag because of this phenomenon.A frictional drag test in the rectangular pipe flow and a resistance test of horizontal flat plate were carried out in order to verify the validity of this technique. As a result of these tests, it was confirmed that drag reductions of about 80% and about 55% were obtained for flow velocities of 4 m/s and 8 m/ s, respectively.

著者

藤野 正隆

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1968, no.124, pp.51-72, 1968-12-20 (Released:2010-01-22)

参考文献数

10

被引用文献数

3 3

---

前節で述べたように実験周波数には上限と下限があるが, さらに各状態での実験結果を比較するには特定のω'についての結果を用いることにした。そのためマリナー型船についてはω'=0.22~0.26, 東京丸についてはω'=0.17~0.20の結果を選んで以下の解析に使用した。

著者

新谷 厚

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1985, no.158, pp.33-39, 1985 (Released:2009-09-04)

参考文献数

8

被引用文献数

1

---

In this report, we deal with statistical analysis for resistance of high speed ship forms in still water.Ship forms are classified into two types, i. e. naked hull with bow dome and without bow dome.Multiple regression equations for residual resistance are obtained by regression analysis on results of resistance test. And also, multiple regression equations for wetted surface area are obtained.Using these formulae, it will be able to estimate easily effective horse power over a wide range of speed.Estimation formulae are very available when designed, and in the future there is a possibility of finding the direction to improve ship forms.

著者

永井 保 吉田 靖 樋口 道之助 近藤 潔

出版者

公益社団法人日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

no.141, pp.39-49, 1977-06

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Analysing correlations among resistance at Froude number F_∇(= ∇/√<∇^<1/3>g>) =3.5, trim angles at F_∇=2.5 through 3.5, by using model test data in still water of the high speed craft, the clear correlation was found to exist between resistance at F_∇=3.5 and trim angle at F_∇=2.5. Therefore, the sequential unconstrained minimization technique was first applied to get the smallest total resistance hull form for each 30 minutes interval of trim angle change, and then followed the discussion concerning deviations arisen and resistance performance due to obtained hull form parameters. Using diagrams related to the total resistance at F_∇=3.5 and the trim angle at F_∇=2.5, we clarified finally the influence of the unit trim angle on the total resistance coefficient within high speed range.

著者

児玉 良明 角川 明 高橋 孝仁 石川 暁 川北 千春 金川 健 戸田 保幸 加藤 洋治 地本 晶彦 山下 和春 永松 哲朗

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.2002, no.192, pp.1-13, 2002 (Released:2007-05-30)

参考文献数

17

被引用文献数

5 2

---

This paper is the first half of the report on the study on microbubbles carried out by the SR239 project of the Shipbuilding Research Association of Japan, and describes the preparatory study for the full-scale experiment using a 116m-long ship. In the present study, first the skin friction reduction effect by microbubbles was investigated including the use of an array-of-holes plate for bubble generation, the effects of streamwise pressure gradient, surface curvature, and vertical plate, the sea-water effect, and the effect of bubble size. Bubble generators for the full-scale experiment were designed and built, and a preliminary injection experiment was carried out. Two new measuring devices for the full-scale experiment were developed; they are skin friction sensors and local void ratio sensors. Microbubble experiments were carried out in a 400m-long towing tank using a 50m-long flat plate ship, in order to obtain the scale effect data and to confirm the validity of the new devices for the full-scale experiment. The use of adhesives to fix measurement devices and cables on the hull surface was tested and established. The hydrodynamic fairing of the cables was also tested and established. Finally, a preliminary microbubble experiment using a small ship was carried out and the bubble behavior was observed.

著者

松村 竹実 浦 環

出版者

公益社団法人日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

no.183, pp.91-100, 1998-06

被引用文献数

4 1

---

This paper proposes an artificial neural network system for regressive estimation of wave making resistance, which is significantly important in preliminary design of high-speed ship. The neural network can explicitly realize nonlinear mapping between hull form and wave making resistance. The system is composed of two kinds of neural networks ; Estimating Net and Descriptive Net. The Estimating Net learns the relation between hull form parameters and wave making resistance coefficients from a number of model-resistance test data. Consequently, when Froude Number, principal particular rations, and area curve parameters of a hull form are given, the Estimating Net of the learned data points in the hull form parameters space. It provides the information about the density of the learned data at the input point in the above parameters' space. In this paper, the test data of 62 models : Series 60, are used for the construction of the system. The leaning is successful and the results of playback calculation show good agreement with the original test data. Some applicable cases for non-learned hull forms are also explained. It is shown that the accuracy of the estimation is in accordance with the output of the Descriptive Net. When other model test data are available, it is easy to modify the constructed system, taking advantage of leaning ability of neural networks.

著者

胡 長洪 福地 信義 中島 徹

出版者

公益社団法人日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

no.189, pp.127-135, 2001-06

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In many compartment natural-convection problems associate with functional design of beat transfer for ships and ocean structures, large temperature difference occurs between the surrounding walls. Examples of such heat transfer problems include a cabin of a passenger ship when the neighboring cabin is on fire, and reefer holds of a refrigerating cargo ship. In these situations, heat radiation exchange among the wall surfaces cannot be neglected if the wall emissivities are not very small. In this paper, a numerical study is reported on combined turbulent convection, heat radiation and conduction in a rectangular enclosure with all six surrounding walls having finite emissivity and conductance. The turbulent convection is computed by a large eddy simulation (LES) method. The emphasis of the study is on the effects of wall radiation exchange on turbulent natural convection in a rectangular enclosure. For comparison with the computation, a laboratory experiment is also carried out on a rectangular enclosure with one sidewall heated by electric heaters. The effect of wall radiation on the natural convection is investigated by changing the wall emissivities. Excellent agreement of temperature between numerical predictions and the experimental measurements is obtained.

著者

正木 宣恒

出版者

公益社団法人日本船舶海洋工学会

雑誌

造船協會會報 (ISSN:05148499)

巻号頁・発行日

no.42, pp.129-162, 1928-03-15

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呉海軍工廠造船部に於ては、可なり古くより請負工事を實施し居り、請負基準につきては、長年月の經驗と統計とによる相當確實なる工數表、單價表を制定せられあり、然るに尚此の基準決定を確立する為めに、更に作業の時間研究によりて、工事の基準決定用諸元の研究調査を行ひ、請負基準を科學的に處理決定せんとせり。而して各種方面に亘る造船作業に適應せしむる爲めに、時間研究法を短時間、長時間、既定的、未定的の4に分類し、根本的研究として先づ未定的及長時間研究をなし、一日中の許容時間及添加時間等の割合を定め、工場設備、管理法、作業方法等の適否を見出し、採集したる記録を充分比較吟味して、第2段の既定的及短時間研究に進み基準時間の決定に到達するを最良法と認めたり。實行の結果豫期以上の成績を得、二十幾年來制定せられたる工數表、單價表を確實化し得るに至れり。〓鋲時間研究の一例に見るも、短時間研究と長時間研究とによる標準時間の差約1割に達せる如きは、見逃す能はざる事實なりと認む。

著者

淺羽 隆太郎

出版者

公益社団法人日本船舶海洋工学会

雑誌

造船協會會報 (ISSN:05148499)

巻号頁・発行日

no.42, pp.203-224, 1928-03-15

---

The auther investigated theoretically the relation between the size of the stabilizer and the amplitude of rolling in several cases ; 1. When the ship is forced to roll by the stabilizer, [numerical formula] denoting the couple produced by the stabilizer by W_m&xotime; and the maximum attainable amplitude is given by [numerical formula] 2. When the rolling is quenched by the stabilizer in the still water, [numerical formula] 3. Rolling amongst regular waves. In the case of synchronism, the maximum amplitude is reduced by the stabilizer to θ given by the equation [numerical formula] provided &xotime;≦φπ/4. If the size of the stabilizer is so chosen as &xotime;=φπ/4,the maximum amplitude is only φπ/4. The larger the size, the less the amplitude, but a vibratory rolling occurs in some cases owing to the too large power of the stabilizer. The theory is compared with the model experiment made by Dr. Motora, showing a fair coincidence.

著者

元良 信太郎

出版者

公益社団法人日本船舶海洋工学会

雑誌

造船協會會報 (ISSN:05148499)

巻号頁・発行日

no.32, pp.75-84, 1924-09-18

被引用文献数

1

著者

尾崎 雅彦 南浦 純一 北島 良則 溝上 宗二 竹内 和久 畠中 勝則

出版者

公益社団法人日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

no.187, pp.185-192, 2000-06

被引用文献数

3

---

Ocean sequestration of the captured CO_2 from fossil fuel burning is a possible option to mitigate the increase of CO_2 concentration in the atmosphere. It can isolate huge amount of CO_2 from the atmosphere for long time in relatively low cost, if it is acceptable from the viewpoint of the oceanic environmental impact. The dissolution type treated in this paper is based on the idea that CO_2 dissolved and sufficiently diluted in seawater does no more harms than slightly increasing the concentration of CO_2 already contained in the seawater. The concept of CO_2 dispersion in the ocean depths by ship is a promising implementation for the efficient dilution. That is, liquefied CO_2 is delivered by ship to the site and injected into ocean depths of 1,000 to 2,500m with a suspended and towed pipe by a slowly moving ship. The constant movement of releasing point of CO_2 causes no stagnation and accumulation of CO_2 in seawater. The released CO_2 will form plenty of droplets, and then they rise gently due to the buoyancy, while reducing in the size to disappear by dissolution in the ambient seawater. Since the turbulent diffusion in the intermediate ocean is dominant horizontally, use of the vertical journey of CO_2 droplets will be very effective for the initial dilution. Thus, authors have good prospects for the dilution ratio of one to a hundred thousands in a couple of hours after injection on an engineering realistic scale, by means that the initial size of droplets is controlled. Drop formations from a fixed nozzle are investigated referring the common knowledge on textbooks. And the possibility of generating relatively large size of droplets from a moving nozzle is experimentally studied. As a result, it is found that the horizontal nozzle towed by the slowly moving ship is promising for the control of the drop formations in a realistic scale .

著者

茂里 一紘 土井 康明 伊藤 昌広 岸本 由豆流

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1991, no.169, pp.143-149, 1991 (Released:2009-09-04)

参考文献数

4

---

A semi-submersible displacement-type high-speed ship with wings is studied on its stability control by flaps.The vehicle, called HSV (High-speed Semi-submersible Vehicle with wings) here, is consisting of a main hull, main and tail wings with flaps, and a strut to support the super-structure. The HSV floats at a certain draft like a conventional ship while it is still, and it submerges when it moves forward due to a downward lift force induced by the main wings. HSV cannot have enough upright moment as conventional ships because of its small waterplane area. HSV is expected to be stable by an active control of flaps.Experiments are carried out to study about the possibility of the stability control by the flaps of the main and tail wings. An automatic control system is developed under which HSV is towed with the heaving, rolling, pitching and yawing motions free. The angles of attack of flaps are controlled after the measured ship motion in order to stabilize the motion.It is concluded that, although the control is not perfect due to the mechanical limitation of the used system, HSV can run stably by the active control of the flaps. The experiments among regular waves made clear that waves could not be a serious factor for the stability of HSV.

著者

永井 保 浜本 剛実 守 国夫

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1972, no.131, pp.281-295, 1972 (Released:2009-09-04)

参考文献数

10

被引用文献数

2 2

---

Taking pictures of the motion of a water surface at the impact of flat and concaved rectangular plates on the water, we obtained the phenomena which the air was entrapped and compressed between the water surface and plate surface, while blowing out through the contact part of both surfaces. In order to develop the equation of air motion reasonably, we took the energy dissipation due to volume change of entrapped air into consideration, hence, an unknown coefficient was herein introduced. It was suitably determined from measured data by the dropping test already done by one of authors. The aspect ratio of rectangular plate was chosen beyond about three, and plates have one-third or full scale when compared with the plate panels of both destroyers and torpedo boats. We finally obtained the experimental formula of impulsive water pressure covering M/ρl2 from about 2 through 7, which might be considered most useful for practical purpose.To get the elasto-plastic response of concaved rectangular plates, the damping effect due to compressed air was also introduced into the theoretical treatment, and this damping coefficient was approximately determined so as to satisfy the critical damping condition of the plate, such as the case of flat plates. We therefore obtained the experimental formula of the response.Within plate scantlings used in our experiment, if the plate is repeatedly dropped on the water from the same height the induced concavity will finally converge to the certain magnitude. And hence, applying those two formulae obtained above to solve such phenomena, reasonable coincidences concerning concavities after each drop were obtained between the computed results by numerical analysis and measured data.

著者

恵美 洋彦 湯浅 通史 熊野 厚 山本 規雄 有馬 俊朗 海野 昌俊

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1993, no.174, pp.735-744, 1993 (Released:2009-09-04)

参考文献数

7

被引用文献数

9 9

---

Protections of corrosion in main hull structures and offshore structures have a great influence on their life. The authors have studied on protective means of the corrosions with investigation of actual conditions of aging effects to coatings in water ballast tanks for 22 ships aged 4 to 20 years.In the report, is described, i) a tendency of secular deterioration of the coatings, ii) primary factor of infulence to the deterioration, iii) forecast method of the coating conditions with aging effects, and iv) a proposal of the best specification and a maintenance for a long life service of ships.

著者

林 昌奎 小林 豪毅 山西 一臣 鈴木 文博

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.2003, no.194, pp.241-246, 2003 (Released:2007-05-30)

参考文献数

8

被引用文献数

2

---

Microwave remote sensing is effective technique for sea surface measurement. For example, it enables us to know the wind vector on global scale. In order to develop more advanced measurement, it is necessary to understand the mechanism of microwave scattering at sea surface. This phenomenon consists of two physical processes. One is the formation of sea surface by the composite action of wind, waves and currents, and the other is microwave scattering at that surface. Because these processes are so complicated, appropriate models are not established. In this paper, the relation between sea surface condition and microwave scattering is investigated. Microwave scattering from wind wave surfaces is measured in the experimental tank and the results are analyzed by scattering coefficients and Doppler spectra. In order to connect these values with water surface parameters, surface condition is investigated minutely. The energy of high frequency waves is expressed by the friction velocity, and so it is presumed that there is the universal law between friction velocity and scattering coefficient. Since wind-generated current exist, the usual dispersion relation is not available. Furthermore, very high frequency components move at the phase velocity of components near the spectral peak. The results of Doppler spectra agree with that phenomenon.

著者

川島 敏彦 芳村 康男 鈴木 四郎 大本 耕司

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.2003, no.193, pp.1-9, 2003 (Released:2007-05-30)

参考文献数

7

被引用文献数

3

---

Fishing boats have several restrictions on their machinery arrangements and space utility on deck. For the improvement of the stability and the deck utility, the fitting of a bulge on sidewall of the vessel is one of the solutions. However, the bulge generally makes a significant increase of hull resistance and loss of speed.At the principal design stage of the elongation of the fisheries research ship“Ushio-maru”, the University of Hokkaido, the authors examined the suitable form of the bulge to improve the stability without increase of the hull resistance. For this purpose, systematic calculations of wave making resistance by Rankine's source method and model experiments using a circulating water channel have been conducted. In this process, it has been found that the optimized bulge form can decrease the hull resistance.In this paper, the authors discuss about the mechanism of the hull resistance decrease by a bulge based on the view point of flow field around hull and propose the suitable method to design the bulge form. Thistechnique has been applied to the actual elongation design of“Ushio-maru”, and then it has been confirmed by the experimental model tests as well as the full scale trials.

著者

藤田 譲 堀 徹 井上 清 村田 修二 摩嶋 禎規

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1989, no.165, pp.215-224, 1989 (Released:2009-09-16)

参考文献数

9

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Wooden ships up to around 55 m in length have been so far designed and built with hulls of double skin planking which consists of each single layer of longitudinal planking and diagonal planking crossing with an angle of 45°. Based on successful operation of these ships, large-scaled wooden ships of around 70 m are recently under consideration adopting hulls of triple skin planking. The triple skin planking consists of the outer skin of a single layer of longitudinal planking and the inner skin of double layers of diagonal planking wihch cross the longitudinal planks with angles (θ) of ±45°.Experiments and theoretical investigation as listed in the followings have been made in order to establish design formulae for the longitudinal bending and shear strength of hulls of the triple skin planking : (1) Simplified formulae are induced for calculating the rigidities and the stresses of the triple skin planking, and the practical methods are shown on the longitudinal and shear strength of hulls.(2) The results of the structural loading tests of the box-shaped ship model sizing 6.54 × 0.9 × 1.04 m are compared with the structural analyses by the three-dimensional (3D) truss model. The structural members of the test model are in 1/2 scale of those of a prototype ship except the overall dimensions.(3) The results of the same kind of 3D truss analyses made for the whole hull of the prototype ship are compared with the calculations by simplified formulae.It is concluded as follows : ·The 3D truss model reasonably represents the behaviour of the triple skin planking.The simplified calculation methods can be applied to actual ship design.·The effectiveness of the diagonal planking on the longitudinal bending strenth is 25 % theoretically when θ= ±45°, and a practical value of 20 % is proposed.·The inner skin of two layers of diagonal planking predominantly carries shear forces. The axial stresses of diagonal planks are simply obtained by doubling the shear stresses when θ= ±45°.·Longitudinal members such as gunwale, chine and keel contribute to the shear strength of a hull by their sectional areas multiplied by a factor of 4G/E theoretically when the rotations of the sections are restrained by neighbouring members. The actual degree of contribution is subject to further investigation.

著者

村重 淳 木下 健

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1990, no.168, pp.183-192, 1990 (Released:2009-09-16)

参考文献数

12

被引用文献数

1 2

---

Wave focusing has been attracting ocean engineers as one of the most promising techniques to control ocean waves. It creates a calm sea area and helps efficient utilization of wave energy. In the present work, a hydrodynamic singularity distribution which expresses a wave focusing lens is derived by the method of matched asymptotic expansion, assuming slenderness of the lens and high frequency of incident waves. The singularity distribution gives the following necessary conditions for scattered waves in each section of the lens : there is no reflection from the lens and the transmitted waves suffer a phase shift in passing the lens. The phase shift is given by the wavenumber and the distance between the section and the focus. From these conditions, we examine a sectional shape of the lens and determine the whole geometry.It is shown by experiments and numerical computations using the two dimensional doublet distribution method that a submerged chevron shape plate, which is suitably folded, scatters a wave system which satisfies the above conditions at a certain wave frequency, but not in wide band of wave frequencies because of dispersion of water waves.Then it is shown by experiments that a certain number of submerged circular cylinders, which are horizontally arranged at intervals just like a raft, transmits waves which have enough phase shift to focus waves but reflects almost no waves in wide band of wave frequencies.Finally, we examine performances of three types of lens, namely, submerged flat plate, submerged chevron shape plate, and submerged circular cylinders, in both regular and irregular waves. It is shown by numerical computations that the wave focusing efficiency of the lens consisting of circular cylinders is about twice that of the flat plate type lens and that the drift force acting on the former is less than half of that on the latter in irregular waves.

著者

川中 幸一 馬場 信弘

出版者

社団法人 日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.178, pp.33-40, 1995-12

参考文献数

10

被引用文献数

10 2

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Computational results of a two-dimensional gravity current in a lock-exchange flow is presented in which a finite volume of homogeneous fluid was released instantaneously into another fluid of slightly lower density when a lock gate was opened. The computations were performed in a two-dimensional channel by solving the incompressible Navier-Stokes equation for an inhomogeneous fluid, the continuity equation and the transport equation for solute by the finite volume method. For accurate representation of small density difference, the density variation relative to the characteristic density difference was used as one of primitive variables. The finite volume formulation holds the conservative property with respect to mass at the boundaries as well as at the density interface so that the total mass of the two fluids with different density remains constant. Some of standard numerical schemes were used to examine their performance to the density jump of the interface. The computed gravity current moves steadily in an initial phase, and the front speed decreases with distance in a self-similar phase when an internal bore on the interface reflected from the back of the lock reaches the front of the current. The effects of the bottom boundary layer on the internal structure of the current is investigated from numerical experiments with no slip and free-slip boundary conditions. The volume of the diluted fluid in a gravity current by the entrainment of ambient fluid is evaluated as a function of time to quantify the mixing. The result indicates that at low Reynolds numbers the subsequent mixing occurs in the early stage of the evolution of the gravity current in a lock-exchange flow.

著者

片岡 秀太郎 宮田 秀明 金井 亮浩

出版者

社団法人 日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.182, pp.113-120, 1997-12

参考文献数

9

被引用文献数

3

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A new technique for PPS (performance prediction simulation) to design sailing boats is developed. The performance of a sailing boat with 6 degrees of freedom is predicted. The boat sails in the simulation with automatic steering to get steady state and with automatic sail trimming to get better VMG (Velocity Made Good). With this technique the steady performance of sailing boats is predicted with sufficient accuracy on various conditions. This system is applied to the design procedure for a IACC (International America's Cup Class) sailing boat for which the steady sailing attitude plays an important role for the sailing performance.