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発行日: 1991/03/29
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原稿種別: 表紙
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発行日: 1991/03/29
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原稿種別: 付録等
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App1-
発行日: 1991/03/29
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発行日: 1991/03/29
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i-vii
発行日: 1991/03/29
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川北 千春
原稿種別: 本文
p.
1-10
発行日: 1991/03/29
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The air bubbles, which entrained to the ship bottom from tho bow, disturb reliable sound operation of underwater acoustic instruments on the bottom. This paper deals with a method to calculate air bubble locus around ship hulls and a guidance for the design of ship hull forms with less bubble entrainment and the arrangement of acoustic instruments. The size of bubbles studied is between 250μm and 550μm in radius. Because sound wave used in operation of the acoustic instruments is considered to be in resonance with the pulsation of the bubbles described above, and then the reliability of the instruments deteriorate remarkably. Firstly, a method to calculate air bubble locus around ship hulls was investigated. Secondly, the model test was carried out to observe bubble locus around ship model. Finally, the calculation method was applied to the design of ship hull forms. The method is based on an equation of bubble locus formulated by adding the rising velocity due to buoyancy of air bubble to the equation of stream line around a ship hull. As a result, bubble locus calculated by the present method agrees well with the observation in model tests. It is also shown that the U-shaped bow form with bulbous bow is less bubble entrainment to the ship bottom than the V-shaped bow form with normal bow.
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瀬戸 秀幸
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p.
11-28
発行日: 1991/03/29
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An attempt has been made to clarify the theoretical and computational aspect of the mathematical models of Rankine source type to the steady ship wave problems with special reference to the treatment of the open boundary in this paper. Following the classical linear theory, exact velocity potential expressions of Rankine source type have been derived for the two-dimensional free-surface flow. The existing Rankine source expressions have been proved to be slightly inconsistent with the classical ones with radiating waves at downstream infinity. Asymptotic solutions have been examined to a series of the linear free surface conditions with small higher order terms. A criterion for generating radiating waves downstream has been found with respect to the coefficients of the added terms. Study of Rankine source algorithms of upstream difference type has illustrated that the upstream differencing of the free surface condition causes almost the same effect as adding to it the small higher order terms and the criterion is effective for understanding the asymptotic behavior of the corresponding numerical solutions. A rationalization of a staggered collocation Rankine source scheme has been studied and the physical meaning as well as the numerical effect have been clarified. Extensions of this approach to three dimensions is straightforward. The present findings also give a good insight into the complicated nonlinear analyses.
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中武 一明, 山口 賢二, 安東 潤, 片岡 克己
原稿種別: 本文
p.
29-37
発行日: 1991/03/29
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Resistance and self-propulsion tests and wake measurements for two types of twin screw ships (bossing and split-stern types) were carried out in the towing tank of NKK corporation. On the other hand, we calculate the propulsive performance of these ships in the case of inward and outward rotating propellers by using source distribution on the hull surface, vortex distribution on the propeller plane, source and vortex distributions on the rudder center plane and measured axial and tangential wake distributions. Calculated results explain fairly well the effects of rotating direction of propeller on the propulsive performance.
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Chen-Jun YANG, Masahiro TAMASHIMA, Ryusuke YAMAZAKI
原稿種別: 本文
p.
39-56
発行日: 1991/03/29
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A numerical method based on potential flow theory is developed to calculate the performance and flow field of a propeller with boss cap fins. The vortex lattice method is applied to the calculation of both propeller and boss cap fins. The boss is calculated by using a panel method. A trailing vortex wake model is proposed for a propeller with boss cap fins, in which the axial variation of trailing vortex pitch is calculated by a wake alignment procedure. The slipstream velocity distributions and hydrodynamic forces are calculated for a propeller with and without boss cap fins. The numerical results show fairly good agreement with experimental data in slipstream velocity distributions. But it is necessary to treat the flow around boss cap fins more strictly so that the calculation of hydrodynamic forces acting on propeller blades, boss cap fins, and propeller boss including the boss cap can be improved.
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木原 和之, 濱田 知聰, 大仲 茂樹, 北村 徹
原稿種別: 本文
p.
57-69
発行日: 1991/03/29
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"Hi-Stable Cabin Craft (HSCC)" is a new concept of high speed passenger crafts, which has the motion stabilised cabin. The cabin is supported on the main hull by means of hydraulic actuators which act to absorb motion of the main hull in accordance with the control signal from an on-board computer and motion sensors. In July of 1990, a 200 passenger HSCC "VOYAGER" was completed, and is now in service in SHIMONOSEKI-KOKURA-YAHATA route. Trial results show that 75% of the roll and pitch motion of the main hull is absorbed and the cabin is kept almost horizontal. Also accelerations at the cabin is reduced to one-third of that on the main hull and the level is almost equal to that in the passenger cabin of "SHINKANSEN". Thus the passengers are enjoying a crusing without suffering from sea sick.
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新開 明二, 矢頭 康彦
原稿種別: 本文
p.
71-83
発行日: 1991/03/29
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This report presents a numerical method for analyzing aero-dynamic characteristics of double membrane sails which are used in sailing yachts. The method has three principal features, that is, it is able to applied (i) to estimations of the ability of sloop-rigged yachts, (ii) to computations of aero dynamic characteristics of a jib fitted with a sheet, (iii) to analysis of fluid flow around double membrane sails. Its algorithm is made up based upon the Vortex Panel Method. A series of numerical calculations are executed for any combinations consisted with a double membrane sail and a single mambrane sail (or a wing section or a double membrane sail) by using the proposed method. The numerical results are compared with calculation results obtained by the other method, and the usefulness of the method is discussed in any conditions.
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安川 宏紀
原稿種別: 本文
p.
85-100
発行日: 1991/03/29
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Theoretical investigation is made into bank effect on ship maneuverability in a channel with varying width. First, a method to calculate asymmetric forces such as lateral force and yawing moment acting on a ship in the proximity of arbitrary shaped bank is introduced. Calculation is made by use of the present method and comparison is made with the experiments. And it is confirmed that the present method is a useful mean for obtaining the characteristics of the asymmetric forces. Next, simulation study is made in order to investigate the bank effect on the ship maneuvering motion in the channel with varying width. As a result, it is shown that in the channel with varying width course-keeping is relatively difficult due to the effect of the asymmetric forces, and potential hazards of collision and grounding are considerably large.
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貴島 勝郎, 吉川 芳孝, 何 青
原稿種別: 本文
p.
101-112
発行日: 1991/03/29
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It is well known that the hydrodynamic interaction forces between ships or between ship and bank wall affect ship manoeuvring characteristics. In the previous paper, one of the authors has already proposed the calculation method based on the slender body theory for estimation of the hydrodynamic interaction forces between ships. In this paper, we apply the calculation method to the case of two ships in the proximity of the bank wall, circular pier and oval shape pier. The characteristics of hydrodynamic forces acting on ships are discussed. Furthermore, the manoeuvring motions of ships during passing through the proximity of the bank wall and pier by using these hydrodynamic interaction forces are discussed. From these discussions, the characteristics of the hydrodynamic forces acting on ships are as follows. When one ship passes the other ship through the proximity of bank wall or pier, the bow inward-moment acts on a ship before the ship passes the pier, and after that the bow outward-moment acts on a ship. The lateral force acting on a ship during passing through the proximity of pier changes remarkably. If lateral distance between two ships is as same as that between ship and bank wall or pier, the hydrodynamic interaction forces between ships are larger than that of between ship and bank wall or pier.
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和田 洋二郎
原稿種別: 本文
p.
113-128
発行日: 1991/03/29
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Prediction method of speed drop in oblique waves is discussed. Added resistance in those waves is assumed to be estimated as a summation of three components due to motion, lateral drifting and mean rudder angle. Speed drop is calculated by the same method as in head waves using this added resistance. The validity of this method is confirmed by comparison with self-propulsion test results of a container and a tanker model. Drifting angle and mean rudder angle required in the above are calculated by use of equilibrium equations derived from equation of manoeuvring motion, where wave drifting forces are considered to be steady external force. Calculated results favorably agree with self-propulsion test results.
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眞鍋 大覚
原稿種別: 本文
p.
129-141
発行日: 1991/03/29
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There are several special places where their bay or estuary oscillates before tidal wave arrives. This undulation is called "Abiki", at the moment when the earthquake generates. The phase difference between the original time of earthquake and initial departure of sea-level is only ±4.081sec, so that if we notice and analyse this fact, we can estimate the arrival time of tidal waves. After this simultaneous wave appears, various sort of succesive wave system follows, whose travelling speeds are, 1512.548m/sec of hydraulic sonar wave, 326.049m/sec of atomospheric sonar wave, and finally 205.654m/sec of Oceanic tidal wave.
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菅 信, 田口 晴邦
原稿種別: 本文
p.
143-151
発行日: 1991/03/29
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The simplest capsize equation is represented by a forced Duffing's equation with a softening spring of nonlinear cubic term. The equation has three control parameters, that is the damping coefficient κ, forcing amplitude B and forcing frequency Ω. The capsizing equation is solved by the numerical time integration for a vast amount of combinations of the control parameters and consequently the control space κ-B-Ω is divided into the capsizing and non-capsizing regions. The boundaries between the two regions has a very complicated and fractal-like characteristics. This paper describes the results of the numerical investigation into these fractal capsize boundaries. Many examples of the control plane and its magnifications are illustrated, which suggest the multi-fractal features of the capsize boundaries. These boundaries look like a tail wing of bird, a plunging wave, a fountain or fireworks and jaws of shark. The fractal dimension of these boundaries, which is associated with the uncertain fraction between the capsizing and non-capsizing regions due to the error of the parameter value in the control space, is also calculated. The numerical capsize boundaries are compared with the fold and flip bifurcation boundaries. The bifurcation boundaries can qualitatively approximate the numerical capsize boundaries, but are located in the numerical capsizing region. This means that the bifurcation boundaries can not be used as a safety criterion without multiplying some safety factor. An alternative formula for the capsize boundary is proposed. The effects of the initial conditions on the capsize boundaries are also examined, and it is shown that such effects can not be neglected. This implies that when we apply the bifurcation theory for a safety criterion, the initial conditions should be restricted to some reasonable bounds. Further investigations into the effects of the forcing phase, and the capsize equation of a biased ship as well as a Mathieu type capsize equation, should be continued.
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許 平, 高木 幹雄
原稿種別: 本文
p.
153-169
発行日: 1991/03/29
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A numerical method is presented for solving the two-dimensional flow in time domain induced by the motion of a body with a large-amplitude. In this method, a free-surface boundary condition is linearized, but a body boundary condition satisfies the changes of the underwater form of the body. The flow around the body is divided into two parts: a wave field and an impulsive flow. The wave field is induced by the motion of body during previous time step, and is represented by a finite sum of harmonics. The impulsive flow is induced by the impulsive motion of body during the current time step, and it is required that the instantaneous body boundary condition is satisfied at each time step. The body boundary condition based on the stream function is applied to the integral equation to get a good accuracy. By making use of this metod, the hydrodynamic forces acting upon a heaving circular cylinder, a swaying circular cylinder and a rolling rectangular cylinder with a large amplitude are evaluated. The free-surface wave profiles around the bodies are shown schematically. It is also shown that the hydrodynamic coefficients as well as the amplitudes and the phase lags of higher-order hydrodynamic forces agree well with the experimental results.
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垣野内 勉, 谷田 宏次, 高橋 則夫, 浅野 利夫, 小池 裕二
原稿種別: 本文
p.
171-180
発行日: 1991/03/29
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This paper deals with the development of a two axis active mass damper using the hydraulic actuator to reduce the vibration occurred in ships. The authors have produced a prototype model of an active mass damper and verified high performance ensured by Model Test and corresponding simulate calculations. The conclusions obtained are as follows. (1) From the experiment, the vibration of the model structure was reduced to about 1/5 by this device at sinusoidal excitation test. (2) At the excitation test using the wave form acquired from the actual running ship, the vibration of the model structure was also reduced to about 1/5. From an efficiency viewpoint, this device should be superior to the conventional passive one, of which efficiency might be decreased in case of random vibration with fluctuating amplitude compared with sinusoidal vibration. (3) As same performance was obtained at the simultaneous two directions exciting test, this device is found to be effective for the vibration in an arbitrarily direction in a holizontal plane that offen ocurred on actual running ships.
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香川 洸二, 藤田 一誠, 野中 光之, 松尾 守, 渡辺 栄一
原稿種別: 本文
p.
181-188
発行日: 1991/03/29
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The previous report presented deveropment of tunned liquid damper which has air chamber and water in a tank of U-shape in order to use the water as the mass of dynamic damper. Natural frequency of the damper can be controlled by adjusting the air pressure in the tank. The damper was improve to be semi-active control type. The conclusion obtained are as follow. (1) The expected mechanism of the present damper with semi-active control system was confirmed by the simulation test. (2) From the expriment of the ship it was confirmed that the vibration of the superstructure was reduced by the present damper and that this system was valid for practical use.
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前田 正広, 山越 道郎
原稿種別: 本文
p.
189-207
発行日: 1991/03/29
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This paper presents an analysis for two dimensional elastic problem by combining a transfer matrix method with a finite element method, in order to reduce the computer storage and computation time. The field matrix is derived from the stiffness matrix of the finite element method. The technique of replacing unknown vectors is used to avoid the loss of numerical accuracy occurring in recurrent multiplication of the field and point matrices. Numerical calculation is carried out on static bending and free vibration of cantilever beam and bending of plane structure with openings. Significant reduction in computation time is achieved in the present method over the ANSYS-PC finite element method, which enables us to use smaller computer.
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錦戸 真吾, 星野 徹二, 川添 強, 松尾 信太郎, 斉藤 正洋
原稿種別: 本文
p.
209-220
発行日: 1991/03/29
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A new high strength stainless steel (MCRS; M__-itsubishi C__-orrosion R__-esistance S__-teel), which can replace the conventional copper alloys, has been developed to improve propulsive efficiency of marine propeller. This steel has superior characteristics of corrosion fatigue strength and erosion resitance to those of nickel aluminum bronze which is the popular material for marine propeller. This paper shows characteristics of MCRS, production engineering of marine propeller made of MCRS, and improvement of propeller efficiency which will be expected by use of MCRS.
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今給黎 孝一郎, 木村 昌敬, 松尾 栄人, 長田 文一
原稿種別: 本文
p.
221-224
発行日: 1991/03/29
公開日: 2018/03/01
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What energy conservation was in the 1970s and 1989s for large marine diesel engines to achieve, higher output rating is becoming in recent years. Consequently, turbochargers serving such uprated main diesel engines are now faced with demands for the compressor ratio π_c which is high enough to match the increased engine power output. The turbocharger compressor pressure ratio, which now stands at as high as π_c=3.0 to 3.5 already, is expected to approach the even higher level of π_c=4.0 in the future. Important to achieving a high level of pressure ratio in the single-stage turbocharging are design considerations that ensure not only the compressor structural integrity adequate for that purpose but also its functional capability to operate at a high level of efficiency and with an appropriate margin of safety against the surging in the high-pressure region while at the same time staying adequately clear of the surging even in the low-pressure region as well. A new series of MET turbochargers developed by Mitsubishi Heavy Industries this time employing new, splitter bladed impeller are capable of meeting all such requirements.
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勝呂 幸男, 岡村 充彦
原稿種別: 本文
p.
225-237
発行日: 1991/03/29
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According to the increase of LNG requirement, LNG carriers have been recently, built in Japan. The main propulsion turbines, which being provided for these carriers, are requested to establish high reliabilities. In this circumstances, these main propulsion turbine and associated auxilieries are applied manufacturer's latest design or new developing technologies. This report deals with the high reliability technologies especially as rotor vibration, blade vibration, journal and thrust bearings, reduction gear and torsional vibration, drain attack and others.
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真谷 捷郎, 多田 益男, 矢島 浩, 阪井 大輔, 勝田 順一, 中島 正樹
原稿種別: 本文
p.
239-248
発行日: 1991/03/29
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From among the welded joints produced in TMCP-manufactured 50kgf/mm^2-class high tensile steel plates, combinations of the fillet joint boxing the stiffener, etc. to plate surface and the plate-to-plate high-heat-input butt joint located at different proximities to each other were taken up for experimental study of their fatigue strength at the toe of fillet weld and the softened part of butt weld HAZ, respectively, which were overlapped in some instances. Through the experimental study, in which the stiffener boxing was performed first to be followed by plate-to-plate butt welding and vice versa, the following conclusions were obtained. (1) The fatigue strength at the toe of fillet weld boxing the stiffener to plate surface is not affected by the proximity between the toe of fillet weld and that of plate-to-plate butt weld. (2) The fatigue strength at the toe of the stiffener boxing fillet weld is likewise unaffected by the change in sequence of the two welding operations (the stiffener boxing followed by the plate-to-plate butt welding and vice versa). (3) Whether boxing the stiffener to plate surface with the toe of fillet weld overlapping the softened part of plate-to-plate high-heat-input butt weld HAZ or doing same to plain plate surface devoid of such a butt joint, the fatigue strength at the toe of fillet weld remains equal in both instances. Neither is the fatigue strength at the toe of stiffener boxing fillet weld appreciably affected by the softening of HAZ of adjoining plate-to-plate high-heat-input butt joint.
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矢島 浩, 多田 益男, 土師 利昭, 石川 忠, 勝田 順一
原稿種別: 本文
p.
249-258
発行日: 1991/03/29
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Taking up the ship hull steel plates produced by controlled rolling in α-γ (ferriteaustenite) two-phase region, a study was performed to explore the mechanism of generation of separation as well as to devise a method for quantitatively evaluating the generation of separation. Also, the steel plates developing the separation were examined for their mechanical strength, fracture toughness, and fatigue strength to establish an allowable limit of separation for their use in ship hull application. The conclusions obtained from the study performed this time may be capsulized as follows. (1) The steel plates produced by controlled rolling in two-phase region and developing the separation in the process indicate no appreciable adverse effects of the separation on their material properties (mechanical strength, fracture toughness, and fatigue strength) both in the rolling direction and perpendicular to the rolling direction, and equal or even exceed separation-free steel plates in overall characteristics. (2) With the steel plates produced by controlled rolling in two-phase region and developing the separation the decline in fracture toughness in the direction of plate thickness is of nearly same order as that of the separation-free steel plates when the maximum separation index SImax. is about 0.5 or less. (3) From (1) and (2) above, it can be said that the steel plates produced by controlled rolling in two-phase region and developing the separation may be used as the ship hull steel plate under the same conditions that are employed for the separation-free steel plates provided the maximum separation index is about 0.5 or less.
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豊貞 雅宏, 後藤 浩二
原稿種別: 本文
p.
259-268
発行日: 1991/03/29
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It is generally known that stress and strain relation is affected by not only temperature but also strain rate. Constitutive relations between stress, strain, strain rate, and temperature are very important as basic reserch for the study of dynamic problems and then have been proposed by many reserchers. The greater part of these proposals was introduced by paying attension to excessive stress from the stress in quasi-static condition due to strain rate. However the definition of the quasi-static condition is vague and then we are confronted with the difficulty what strain rate corresponds to the quasi-static condition. Considering that strain rate temperature parameter (R) defined by Bennet has a very similar physical quantity with temperature in dynamic condition, we introduce the constitution equation as a function of R in this study for the purpose of avoiding above problem. If we calculate using the experimental results of temperature and strain rate, the estimated stress approximately agree with the experimental value except the condition of very high loading rate where the estimated stress is little higher than experimental stress. It is because the temperature rise becomes very high due to plastic work in high loading rate and the measured temperature at the specimen surface may be lower than that at the center of the specimen.
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在田 正義, 内藤 正一, 柴田 俊明, 田村 兼吉
原稿種別: 本文
p.
269-281
発行日: 1991/03/29
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Corrosion preventing characteristics of paint coating on steel plates depend on many factors relating to the method to coat. One of the most important factors is the coating thickness distribution. This distribution is mainly determined by detailed configuration of structures to be coated. Corrosion fatigue strength of paint coated fillet weld joint was experimentally investigated from the view point to evaluate the effects of coating thickness distribution on the corrosion preventing characteristics of coating film. Three kinds of T-figured fillet weld joint test specimens were tested in air or in artificial ocean water (SOW), under pulsating bending load. Coating thickness distribution around fillet weld parts were measured and evaluated by σ/t_m (σ-standard deviation of coating thickness distribution, t_m-mean value of coating thickness). Three configurations of fillet weld were adopted. They were "as weld", "weld metal cut by straight line" and "weld metal dressed by Φ 12". Conclusions obtained are as following. (1) Coating thickness distributions at weld part are largely affected by fillet weld detailed configurations. (2) Fatigue strength of filled weld joint test specimens without coating film depends largely on their configuration at higher stress level, but not depends on the configuration at lower stress level. (3) Corrosion fatigue strength of fillet weld joint test specimens with coating film is almost same as that of joint specimens in air, if the coating thickness distribution level is good enough. (4) Bad coating thickness distribution results in the reduction of corrosion fatigue strength of weld joint specimens even at higcer stress level. It is because that the coating breaks at bad coating distriution part at early stage of fatigue loading. (5) Thus the evaluation of coating thickness distribution at weld parts can be determined by the comparison of corrosion fatigue strength of coated specimens with that of uncoated specimens in air.
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篠田 岳思, 福地 信義
原稿種別: 本文
p.
283-290
発行日: 1991/03/29
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The fact that a number of indeterminable elements are to be solved as design factors at the design stage of ship equipments, introduces a certain amount of fuzziness in the state equation parameters. Such fuzziness and the indeterminancy within the governing factors are to be carefully analyzed for their inter-relationships at the design stage, especially in the case of strongly parameter dependent phenomena. Mathematical models based upon the theory of fuzzy sets, that can provide a right solution to these problems are presented here. As a practical example, the phenomena of the incidence and outburst of cell fires like that in the case of marine fires are considered and the corresponding threshold curves that decide the possibility of an outburst are determined.
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古林 義弘
原稿種別: 本文
p.
291-306
発行日: 1991/03/29
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In the cryogenic liquefied gas tanks of LNG or LH_2 tanker buoyancy driven flow occurs induced by the inevitable heat flow through tank walls from the surroundings of higher temperatures. Flow pattern is not limited to the boundary layer flow along the wall but the bulk flow is dominant due to the enclosed configuration of tank. In this paper a numerical study is performed for the turbulent two-dimentional liquid flow in a symmetrical rectangular enclosure where the positive heat flux exists through the verticel wall and horizontal bottom and negative heat flux at the free surface of liquid caused by the natural evaporation of vapor. The ω-φ, vorticity-stream function equations converted from the original continuity and mean momentum equations and mean thermal energy equation are solved using a two-dimentional turbulent model of 0-equation. Results have been obtained in the range of Rayleigh number of 5.41×10^<17> to 5.41×10^<11> (8.19×10^<18> to 8.19×10^<12>), eddy kinematic viscosity of 9.94×10^<-4> to 9.94×10^<-1>m^2/h (7.06×10^<-4> to 7.06×10^<-1>) and eddy diffusivity for heat 1.10×10^<-3> to 1.10m^3/h (7.84×10^<-4> to 7.84×10^<-1>) for LNG (LH_2) and for the study of the correlation between an actual tank and theory pressure built up calculations have been performed in the same procedures as above-mentioned.
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浅井 孝悦, 川野 始
原稿種別: 本文
p.
307-314
発行日: 1991/03/29
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Cargo tank system is a fundamental part of liquefied gas carrier and rules main design features of the carrier. With respect to the large LPG carriers, a prismatic tank system was installed in the first carrier in the world. This tank system has been improved step by step and now the most of the carriers have this system. However, the prismatic tank system has inevitable shortcomings suchas heavy tank weight, many number of components, long weld length and much construction man-hours. It is not step by step improvement but development of a new tank system that is able to overcome these shortcomings. Development of liquefied gas carrier with new tank system takes large cost and long period. Therefore, the preliminary study is required to appraise the concept of a new tank system and to plan suitable steps of development. In this paper, a new basic concept of the upright cylindrical tank system is preliminarily studied for LPG carrier. This preliminary study includes evaluation of tank shapes, initial design of 82,000 m^3 LPG carrier and strength analysis of tank with tank support. Result of the preliminary study shows feasibility of improved LPG carrier with upright cylindrical tank system.
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岩本 才次
原稿種別: 本文
p.
315-330
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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The present paper proposes a new modified algorithm of Random Choice Method, which is applied to shallow water problem for a tank with bottom slope. The modified computer program of Random Choice Method is made up, and the behavior of shallow water wave in an arbitrary bottom-sloped tank forced to swaying motion is calculated by using the method, and shallow water model tank tests are carried out on any conditions. Close agreement between numerical calculation results and experimental results is obtained. With those considerations, it is shown that the modified method of Random Choice Method is useful for the shallow water problem of fluid in an arbitrary bottom-sloped tank forced to swaying motion.
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緒方 源信, 磯崎 芳男, 尾崎 雅彦, 田崎 広毅, 山田 賢司, 椛田 剛, 原田 幸夫
原稿種別: 本文
p.
331-342
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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Today's enviroimental problem has become to be a matter of the globe, and the fact, increasing green and decreasing desert, is now one of the most serious problems on the earth. In the coastal waters, seaweed beds provide cradles, nurseries and dwellings for fish and shellfishes, but they are decreasing their territories because of various reasons which makes fishery product declined. One of our treatment for decay of seaweed beds is a system on the tension leg platform at sea, providing sunbeam underseas where light is not enough for growing seaweeds. Shimizu Corporation and Mitsubishi Heavy Industries, Ltd. worked jointly to develop the system and carried out field tests on it for more than three years. The purpose of the field test is to confirm that the system works properly at sea and that seaweeds grow well under the system. The first test was carried out at sea near the shipyard. The second test is now under test at sea of 10m water depth and will be cotinued until March 1991. These tests gave satisfactory results, so we can expect that the system will make one of the main units of marine ranching system. The system can be also used as unts of fishing for joy and under water sight seeing apparatus.
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緒方 源信, 江崎 恒夫, 河本 達郎, 畑田 信行, 酒井 能具, 田上 征志
原稿種別: 本文
p.
343-352
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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In Japan, sea food, especially raw fish, has been for a long time one of the most favorite food, and these days, live fish cooking is becoming more popular in daily food life. Transportation of live fish is still mainly supported by skills of truck drivers and captains of live fish boats. So it is necessary to upgrade the technical level of live fish tanks in order to help those experts who must cope with increased transportation time, and attain efficient loading and higher quality standard of live fish. As a shipbuilder, we are very much familiar with sea water treatment which is one of the key technologies of live fish tanks, then we started a new business of live fish transportation and reservation system. We have developed several types of live fish tanks, and done many times transportation trial of various kinds of live fish using our systems. Here we explain two of them, one is 3m^3 marine type live fish container and the other is 10m^3 trailer type.
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新開 明二, 山口 悟, 石田 聡成, 上田 真希
原稿種別: 本文
p.
353-362
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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This report deals with a construction of the support system for determinations of the sea state by using image information data transmitted from the Geostationary Meteorological Satellite (GMS). The support system consists of three basic software tools. The tool 1 presents digital techniques for the image analysis of meteorogical information data from GMS. The tool 2 is composed of a simple approach to forecasting wind velocity system based upon a weather chart referring to meteorological data and of a utility of forecasting wind waves by using Wilson's approach based upon the SMB method. The tool 3 presents a digital simulation technique of random waves by using Walsh Tranform algorithm. The technique can be applied to a rendering method in numerical random simulations for a variety of marine environments (wind, wind waves etc.). A series of numerical computations are executed for a sea state in the North Pacific Ocean withn a winter day by using the present support system. It is confirmed that the support software tools is effective in simulations of wind and wind waves in an area of sea within an optional day, and that those tools reduce hugely the computer execution time requirement.
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緒方 源信, 馬場 栄一, 平井 隆弘, 長井 利彰
原稿種別: 本文
p.
363-374
発行日: 1991/03/29
公開日: 2018/03/01
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At natural upwelling zone, phyto-planktons are multiplied by photosynthesis reaction, and rich fish grounds are formed consequently. "Shiomaki Shoo" bank, located off Tsunoshima island, Yamaguchi prefecture, Japan, is known as one of natural upwelling zones. We carried out flow visualization test using topographycal scale model, and found existence of two kinds of Karman vortices in the wake behind the bank top even in submerged condition. The one is collective small size surface vortices observes just behind the bank top. The other is vortices appears by about two or three kirometers pitch after the bank. A brief theoretical analysis indicates that if water depth of a bank top is shallow enough, the flow around the bank is very close to two dimensional flow, which is same one as what is made around island. Thus we found a key to study artificial topolographycally generated upwelling structures on the submerged bank at sea.
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加用 芳男, 緒方 源信
原稿種別: 本文
p.
375-383
発行日: 1991/03/29
公開日: 2018/03/01
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One of the present authors has found, by model tests, a wake strikingly similar to a Karman vortex street behind a submerged topography. This paper then discribes the results of flow visualization which was made for a better understanding of the wake resembling a Karman vortex street behind three-dimensional surface obstacles such as cones and circular cylinders under various submergence. It is found that a Karman vortex street is formed when the submergence of obstacles is small enough to diffuse the wake up to the free-surface. After the wake distributes fully in depthwise, the wake seems to behave like a two-dimensional one. The atmospheric island wakes observed in satellite pictures are other examples of the two-dimensional flow around three-dimensional topography. This phenomenon is basically understood that tow-dimensional flows can be apply to three-dimensional obstacles when the stable stratification in the air exists. In the case of free-surface flows, the present authors confirm numerically and experimentally that two-dimesional flows appear to approximate the flow structure when the submergnece of the obstacle is small even if no stratification of the fluid exsts. The images of a surface obstacle due to the free-surface can be considered as the cause to force streamlines from upstream to go round the obstacle and to produce a two-dimensional wake, i.e. a Karman vortex street, behind it.
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田村 欣也
原稿種別: 本文
p.
385-409
発行日: 1991/03/29
公開日: 2018/03/01
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原稿種別: 付録等
p.
411-
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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原稿種別: 付録等
p.
App3-
発行日: 1991/03/29
公開日: 2018/03/01
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原稿種別: 目次
p.
Toc1-
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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-
原稿種別: 表紙
p.
Cover3-
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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-
原稿種別: 表紙
p.
Cover4-
発行日: 1991/03/29
公開日: 2018/03/01
会議録・要旨集
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