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Article type: Cover
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Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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Article type: Index
Pages
Toc1-
Published: September 30, 1983
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Ishio NISHIOKA, Shozo FUKUDA, Kunio SAKI, Masato HIROMATSU
Article type: Article
Pages
1-9
Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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A high performance sea water pump for a deep submergence research vehicle has been developed. This pump is small in size, light in weight, and capable of pumping 41/min. under the waser pressure equivalent to the depth of 6000m and operates at the high speed of 2250rpm. The pump is a three-throw reciprocating type with self-aligning plungers, and clearance seals. The pumping efficiency is 79% at the dischare pressure of 630kgf/cm^2, and the leakage from plunger seals is only about 60cc/min and was stable at the durability test for 500 hours. In order to develop the sea water pump, various studies as shown were performed. l) feasibility study on pump types 2) screening tests of plunger and cylinder liner for various material combinations of ceramics. 3) study to improve the manufacturing accuracy of plunger and cylinder liner. 4) photo-elastic stress analysis of valve block. The development of the pump of this kind shall be a great contribution to the 6000m deep submergence research vehicle project.
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Yasuharu TERADA, Akira KOMATSU, Shuji KANDA, Morihiko INOKUMA, Minoru ...
Article type: Article
Pages
11-15
Published: September 30, 1983
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A high pressure sea water pump has been developed for variable ballast system of 6,000m deep submersible and for high pressure sea water power source of under water working machine system. To develop the very high delivery pressure, small, lightweight, high operating speed and high efficiency pump, the axial plunger type is adopted in this sea water pump. To minize the wear and corrosion caused by the siltcontaminated sea water, and to enable the pumping by a close clearance sealing with high speed, ceramic materials are used for cylinders and plungers. Various tests, such as friction tests of cylinder and plunger, performance tests and endurance tests of sea water pump etc. are carried out, and good performances are obtained. From test results, outlet flow is 6.4 l/min, Volumetric efficiency is 81% and overall pump efficiency is 87.4% (for 2,000rpm operating speed, 630kgf/cm^2 delivery pressure).
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Yoshiyuki INOUE, Seishichi NAKAGAWA
Article type: Article
Pages
17-24
Published: September 30, 1983
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Previously authors made a reseach work about statical analysis of mooring lines and effects of sea bed condition on it. In this paper, we extended the computer program which was made at that time and made it possible to calculate three-dimensional configuration of mooring line in the presence of a current forces which varies both in magnitude and direction with depth. Using this computer program, some numerical results of mooring performances are resented. From that we made cosideration, especially in case of deep sea mooring, for some parameters such as magnitude, direction and profile of current attacking on the line, line's extention, line's scope (line's length/water depth) and kind of mooring line. Further we made a rough design of moorings about water depth of 1,000 meters class semi-submersible rig and discussed about the effects of sea current and line's extention on it.
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Jun OBOKATA, Norio SASAKI
Article type: Article
Pages
25-33
Published: September 30, 1983
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In the last report, the relation of the shapes of single point moored ships and their slow oscillation in current was investigated. In practice, not only current but wind and wave have to be considered, and it has been said that the slow oscillation is excited by current and stabilized by wind. However the interaction of different external forces, especially the effect of the relative direction of them on the slow oscillation, has not been examined sufficiently, and almost all of the studies on this problem have been carried out only numnerically, and moreover the results of them are not always same. Aiming at the interaction of current and wind, the effect of the relative direction of them were investigated in this paper by the two theoretical approaches, and model tests were conducted to verify the theoretical results. And it is ascertained that the slow oscillation becomes small when the directions of current and wind are different and becomes large when the directions are identical. Dynamic stability analysis cannot indicate the amplitude of the oscillation, it shows only whether the ship is stable or not, but can make the effects of various factors on the oscillation clear, and it can make it easy to find out the direction for the system modification. Examples of the application of the dynamic stability analysis to investigate the system to suppress the oscillation are also denoted in this paper.
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Norihiro MATSUMOTO, Keiji SUEMITSU
Article type: Article
Pages
35-44
Published: September 30, 1983
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Mathematical models which are constructed from hydrodynamic characteristics of a ship are generally used to simulate maneuvering motion. We calculated the lateral force and yaw moment acting on a hull, which were the main terms in the mathematical model, by a theoretical method, This method was originally proposed by Fuwa, but we simplified his method for practical use. Moreover, we considered the three dimensional effect at the ends and the effect of wave making at the bow. In the calculation method, free vortices were generated at a distance from the keel line. The distance "So" was expressed in terms of the mean draft "d" as follows; S_0=So/d=0.006(Cb・B/d)+0.003 for 40 segments The above empirical equation was determined from the results of eight ships. Further, captive model tests were carried out using the segmented models, and the longitudinal distribution of lateral forces were obtained. After comparison between the experimental results and the calculated ones, the present calculation method was verified.
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Norihiro MATSUMOTO, Keiji SUEMITSU
Article type: Article
Pages
45-61
Published: September 30, 1983
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Many expressions of hydrodynamic forces on a ship are proposed to construct a mathematical model for describing maneuvering motion. One of them is the mathematical model which expresses hydrodynamic forces by considering the individual open-water characteristics of the hull, propeller and rudder and the interference effects among them. This mathematical model began to be commonly used because of its convenience in practical usage and rationality. However, when applying the model to a full shape ship and predicting maneuvering motion at large helm angles by the analized results of the ordinary captive model tests, the predicted motions were very different from the measured motions of the free running tests. And it was found that the difference was caused by the poor treatment of interference effects between the hull, propeller and rudder. In this paper, we proposed to settle the problem by carrying out circular motion tests which correspond to steady turning. Further, we analized the test results and derived new expressions for the interference effects. The present coefficients describing interference effects were arranged together with the ship particulars, so they can be easily treated in the program for numerical simulations. Lastly, the prediction of maneuvering motions corresponding to the free running tests were made. Judging from the good coincidence between the predicted results and the measured ones, the new mathematical model was proved appropriate for describing interference effects.
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Masahiro MATSUI, Takamune KITAZAWA, Mitsuyasu NAGAHAMA
Article type: Article
Pages
63-71
Published: September 30, 1983
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Four wall sided models whose water lines are shown in Fig. 1 are used to observe non-linear waves in the water circurating channel, and scale effect is discussed. The half model of model B, which is in fitted to the side window, is also used to scrutinize the stream lines in front of the bow. Successive vortices in the surface layer in front of bows are observed and a schima of the flow around bow is illustrated.
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Shoichi NAKAMURA, Shigeru NAITO, Koichiro MATSUMOTO, Kenji SUSUKIDA, A ...
Article type: Article
Pages
73-81
Published: September 30, 1983
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It is well known that the measured resistance increase in waves of a ship with blunt bow is larger than the computed one for the range of shorter wave length. To study the reason, the following experiments are carried out by using a simplified ship model with blunt bow. (1) Measurement of resistance increase in regular head waves when the model is free to heave, pitch and surge. (2) Measurement of diffraction force in regular head waves when the model is restrained. (3) Measurement and analysis of unsteady wave pattern when the model is performing forced heave, pitch and surge oscillation in still water. (4) Measurement and analysis of unsteady wave pattern when the model is restrained and when the model is free to heave and pitch. (5) Measurement of distribution of head loss behind the model when the model is performing forced pitch oscillation in still water.
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Yoshikazu KASAHARA
Article type: Article
Pages
83-90
Published: September 30, 1983
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This paper presents the results of an experimental investigation of the wake resistance component measured on two models of a ship with wide beam and shallow draft (Cb=0.55). These models had the same forebody shape but they had different afterbody shapes. In the Tsu Ship Model Basin, resistance tests, wake survey at 0.5L_<pp> behind A.P. of models and wave pattern measurements were carried out together with a supplemental wake survey near the stern of the models. It was found that on both models the sum of the wake resistance obtained by the wake survey and the wave pattern resistance obtained by wave pattern analysis agreed well with the resistance derived from force measurement. In the head loss distribution at 0.5L_<pp> behind A.P., the center peak, the inner side peaks and the outer side peaks were observed within the breadth of the models. The resistance component due to the stern wave breaking was separated from the wake resistance by separating the outer side peaks from the other peaks of the head loss distribution.
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Masamitsu ITO, Shosaburo YAMASAKI, Masamitsu OKU, Masahiro TAMASHIMA, ...
Article type: Article
Pages
91-105
Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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Propeller wake trajectories of controllable pitch propeller (CPP) model were visualized by the air injection method and the solid particle tracer method over the wide range of operating conditions. The analysis of the wake data resulted that; (l) Even at the off-design pitch settings, the propeller wake forms thin vortex sheet as well as at the design pitch setting. (2) At any pitch settings the propeller wake can be devided into two parts. One is the inboard vortex sheet which has approximately same wake pitch as the geometrical pitch of the wing section where the wake flows out and another is the tip vortex near the blade tip whose pitch varies with the attack angle near the tip. (3) The variation of the wake radius depends on the propeller load. Based on the experimental wake data a CPP wake model is proposed. The geometry of the propeller wake can be drawn as functions of the propeller geometry and the propeller operating condition. Expressions of the wake model are presented in equations (6) to (18) in this paper. Both at the design and the off-design pitch settings the correspondence of the calculated wake geometry with the measured wake geometry is fairly good in spite of a relatively simple wake model.
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Seikoo OGIWARA
Article type: Article
Pages
107-119
Published: September 30, 1983
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This paper describes a numerical method for solving free surface flow around ship. The velocity potential is expressed as a sum of the basic velocity potential of double model flow and the perturbed wavy potential. The perturbation potential is solved using Rankine sources which are distributed on the hull surface and the undisturbed free surface. The method of solution is based on the iteration procedure to satisfy the hull surface condition and the double model linearized free surface condition. The method of numerical calculation is examined on the flow around a two dimensional submerged circular cylinder and three dimensional mathematical hull form. The effectiveness of successive approximations is examined, and it is found that the solution of 2nd approximation is required to satisfy the boundary condition on general hull form. Further, the wave profile, pressure distribution on the hull surface and wave resistance that is obtained by integration of pressure on the hull surface are calculated, and good agreement with experimental results are obtained. Finally, from the view point of practical use, this method is applied to predict wave resistance of full ship in ballast condition, and the effect of bow bulb on free surface flow and wave resistance is discussed in comparing with experiment.
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Sumitoshi MIZOGUCHI, Ryo TASAKI
Article type: Article
Pages
121-129
Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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Resistance tests and propulsion tests varing propeller load were carried out in regular and irregular head waves with a model of S-175 container ship. The test results were analysed with two formulae proposed by Adachi, et al. for the potential hull-propeller interaction in still water, one of which gave the resitance increase due to propeller load, G factor, and other gave the wake factor, 1-w. The results are as follows; (l) The formulae fit well not only for the results in still water but also for those in waves. G and 1-w are then presensed with the propeller load, the wake factor at zero propeller load, 1-w_0, and two coefficients common both in still water and in waves. (2) The difference between the resistance at zero propeller load and one without propeller, R_c-R_0, and the wake factor at zero propeller load, 1-w_0, in waves are shown. They are influenced by wave and ship motions. (3) The thrust deduction coefficient of conventional definition, t, does not give a consistent prediction of propulsive performance in waves when the propeller load is heavy. A rational power prediction method of a ship in a seaway is proposed further using the formulae. Examples are presented for the container ship and a bulk carrier.
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Yukio UEDA, RASHED Sherif M. H., Keiji NAKACHO, Haruo SASAKI
Article type: Article
Pages
131-142
Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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In recent years, many offshore oil drilling rigs are produced. In order to guarantee their structural strength, it is very important to estimate their ultimate strength by clarifying their plastic collapse behaviors. The authors propose the Idealized Structural Unit Method as a very effective method to analyze nonlinear behaviors (including buckling, plastification, etc.) of large structures. Applicability of the method bas been confirmed by applying formerly developed some idealized structural units to actual problems such as the ultimate transverse strength analysis of ship structures. In this research, the Idealized Structural Unit Method is applied to the analysis of the ultimate strength of offshore structures (jacket type). Firstly, the idealized structural unit is developed for steel pipe members used in offshore structures. Then, its accuracy of idealization is confirmed in the unit member and a simple pipe structure. Finally, the ultimate strength of a full-sized big model of jacket is analyzed in a very short CPU time so as to show the applicability of the method.
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Toshimasa KAWANISHI, Hideo MASUDA, Wataru KATO, Satoshi HABARA
Article type: Article
Pages
143-149
Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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A new compliant offshore structure, the guyed tower, has been proposed as a deep water production and drilling platform. The guyed tower is an offshore platform that rests on a spud can bearing foundation and is hold upright by multiple guylines. This paper presents a model test of the response of a guyed tower system subjected to earthquake excitation. Based on the results of the test, it can be confirmed that for the purpose of the design of guyed tower the horizontal component of earthquake must be sufficiently taken into consideration.
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Hiroshi KAWABE
Article type: Article
Pages
151-158
Published: September 30, 1983
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The property of the kernel function on the boundary element method is developed for the solution of problem in the two dimensional elastostatics and the plate bendings. The integration method of the kernel function is introduced.
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Katsuyuki TOMIYOSHI, Mikihiko NAKAYAMA, Kazuo KADA, Hideo ONO, Kouyu I ...
Article type: Article
Pages
159-166
Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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To investigate crack propagation behavior in plate under bending load, the following experiments were carried out using carbon-manganese steel (NK's KL24B) for LPG tank material and alminium alloy (A5083-O) for LNG tank material. (l) Surface crack propagation test under dynamic pure bending load. (2) Through crack brittle fracture test under pure bending load. Main findings from the above tests are as follows: From experiment (l): a) A surface crack penetrates the plate when the crack length becomes about 15 times the plate thickness under pure bending load. b) The propagation rate of surface crack can be well expressed by the following formula. da/dN=C(αΔσ_b√<πa>)^m α=0.2∼0.4 From experiment (2): a) The equivalent tensile stress σ_<eff> for brittle fracture initiation under pure bending load can be expressed as follows: σ_<eff>=βσ_b β:<0.52 for carbon-manganese steel=0.47 for alminium alloy The above effective coefficient obtained by the experiments well correspond with theoretical ones. b) Brittle crack propagation length in alminium alloy is small under pure bending load.
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[in Japanese]
Article type: Article
Pages
167-169
Published: September 30, 1983
Released on J-STAGE: March 30, 2018
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[in Japanese]
Article type: Article
Pages
171-192
Published: September 30, 1983
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Article type: Appendix
Pages
193-194
Published: September 30, 1983
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Article type: Appendix
Pages
App1-
Published: September 30, 1983
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Article type: Appendix
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Published: September 30, 1983
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Article type: Appendix
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Published: September 30, 1983
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Article type: Appendix
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Published: September 30, 1983
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Article type: Appendix
Pages
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Published: September 30, 1983
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Article type: Appendix
Pages
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Published: September 30, 1983
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Article type: Cover
Pages
Cover2-
Published: September 30, 1983
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Article type: Cover
Pages
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Published: September 30, 1983
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