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Article type: Cover
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Published: September 30, 1985
Released on J-STAGE: April 01, 2018
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Article type: Index
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Published: September 30, 1985
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Article type: Appendix
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Published: September 30, 1985
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Takashi FUJITANI
Article type: Article
Pages
1-9
Published: September 30, 1985
Released on J-STAGE: April 01, 2018
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SPB is the initials of S (for Self-supporting), P (for Prismatic shape) and B (for IMO type B). This paper is to present the historical background and the main featune of SPB LNG containment system which is based on the orthodox shipbuilding technology. The author has been involved in the gas carrier technology for more than 20 years. In 1961, he began the development of a large gas carrier technology, which has resulted in the building of large gas carriers among which the typically important ships from the view point of historical development are an LPG carrier A (46,500 M^3 built 1965,the world largest at that time and the original design of following ships and SPB), an LPG/NH_3 carrier B (19,500 M^3 built 1967, the first gas carrier of USCG apply and for NH_3 use in Japan), Ethylene carriers (built 1968,AI-alloy 5083-0 tanks for 104℃ use), and an LPG carrier (built 1980,80,000 M^3 IMO Type B). Those are all of the self-supporting prismatic tank technology, and give the basis of developing SPB LNG containment system together with the abundant experience of constucting land LNG storage tanks. The self-supporting prismatic LNG tank of Al-alloy 5083-0 is well known that it has been used with a great success for LNG transport since Methane Pioneer in 1959, followed by Methane Progress and Methane Princess, and Esso LNG carriers. The ethylene carriers mentioned above are the similar self-supporting tank design with Al-alloy 5083-0 material. Taking into full account of the reputed success record of those gas carriers of self-supporting prismatic tanks, our team succeeded to apply the IMO type Bconcept to the self-supporting prismatic LNG tank utilizing progressed analytical and experimental methods and enabled the rationalized SPB LNG containment system. The design has been given full approvals as IMO type B by USCG as well as the world major classification societies (ABS,BV,DNV,LRS,NK and GL).
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Takashi FUJITANI, Yoshitoh OKUMURA
Article type: Article
Pages
11-16
Published: September 30, 1985
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A number of studies have been presented in regard with the economy of LNG carrier. This paper, firstly, discusses the relation between the economy of a conventional LNG carrier driven by steam turbine engine and the different boil off gas rates. And, further, an economical feasibility of the future diesel engine driven LNG carrier, which installs the reliquefaction plant on board ship to liquefy the boil off gas, is discussed herewith, taking into account of the practical operation pattern of the plant, and proposes some break even point of the investment to the reliquefaction plant.
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Tsugukiyo HIRAYAMA, Yoshizo HAGINO, Tatsuo MATSUNO, Kenji WATANABE
Article type: Article
Pages
17-29
Published: September 30, 1985
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There is no need to say that the real time and quantitative estimation of sea state around a running ship is very important on the view point of prevenlting marine casualties or keeping safety sailing. Up to this time, as ship borne wave recorder, there is well known Tucker type recorder and ultrasonic relative wave recorder which is overhung from a ship bow also exist. However, those recorders have a weak point that they are influenced by the rocal disturbance from the hull of a moving ship. Moreover, the buoy or throwed away type is also developed, but it is difficult for usual use and was used for experimental use only in the past. Therefore, it is actual circumstaces that the estimation of sea state from running ship is mainly depending on visual observations, but this method is difficult to apply at night and individual differences are large especially about the estimation of swell. On the other hand, present report concerns about the development of a system on board which can estimate wave spectra or its statistics in real time by introducing a cheap microcomputer. This system is based on the method of estimating wave spectra by using the known frequency transfer functions of ship motions and measured ship motions by sensors on board like accelerometer and vertical gyro. Here, the wave direction is also obtained from ship borne rader. By this relatively cheap system, even at night, we can make usual estimation of sea spectra and then sea state sitting in a running ship, and also we can contribute to the accumulation of reliable data of ocean waves.
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Hisaaki MAEDA, JIN Yan
Article type: Article
Pages
31-40
Published: September 30, 1985
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Motions of a pilot boat in the vicinity of a large ship are investigated in order to design a stable pilot platform for minimizing the risk to pilots in the process of embarkation or disembarkation from 1arge ships in rough seas. A theoretical method is discussed, and theoretical values show a good agreement with results of experiments from model tests. With this method, the motions are estimated and it is found that 1) heaving amplitude is very large over a wide range of frequency. 2) in swaying motion there is not only collision to large ships but also drifting from them. 3) rolling amplitude shows a large value at the resonant frequency.
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Shoichi HARA, Michiaki IGAI, Sadahiro NAMIE
Article type: Article
Pages
41-48
Published: September 30, 1985
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In case of accidents of tankers and seaside oil refineries, oil control barriers are usually set on the sea surface to prevent spilled oil from spreading, and many types of the barriers ware developed so far. However, the existing oil control devices are not always effective for containing oil slicks on the actual sea surface. Hence, the improvement in the performance of barriers has been required especially for the high values of current velocity, wave height and wind velocity. The evaluation standard of the performance about C and D type of oil boom has been made and its development is now being proceeded. The combination system of air bubble type of oil boom and the conventional one have been investigated so far and the fundamental performance of the former in existance of waves and current has been mainly clarified by the authors. In the paper, the characteristics of motion of the buoyant type of oil boom are discussed. In calculating the motion of an oil boom, the research was performed so far by modelling its form as the cylinder or the plate. The modelling is somewhat different from the actual form. The calculation on the actual case using the source method is compared with the measured value in order to examine the propriety of the modelling. Moreover, the calculation followed by Milgram's method is also compared with that by source method. Supposing the case of the oil boom which is towed at the bottom of its skirt part, the hydrodynamic coefficient is calculated by the source method in cases of inclinations of the oil boom and falt plate.
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Yoshiharu SHIRAKI, Masao SAITO, Etuji KAJITA
Article type: Article
Pages
49-57
Published: September 30, 1985
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In the recent years, dredging operation in rough open sea is more often needed compared with the past years. As to dredging by cutter suction dredger, the situation is the same. To ensure good dredging performance in more severe wind and wave conditions, several technical problems need to be solved. In order to solve these problems at the basic design stage, it is essential to estimate hull motions and the loads on the spud or the spud carriage and on the cutter head. In this paper, the details of the behaviour of a cutter suction dredger and loads on the spud in waves are discussed. Numerical calculations and model experiments have been made to clarify relations between hull motions and the loads on the spud, and on basis of there results, reliability of estimation was evaluated. The calculated were in agreement with the experimental ones. It was therefore confirmed that numerical calculation method has a practically reliable accuracy. And this paper explains the following items in reference to the practical design applications of the 8000ps cutter suction dredgher working with spud in waves. (1) The effect of water depth on hull motions and loads on the spud (2) Results of elastic suppocted device equipped on spud keeper to decrease the loads on the spud (3) Relationship between hull motion and ground bearing forces of spud at seabed
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Yoshiho IKEDA, Masahiro TAKAGI, Norio TANAKA
Article type: Article
Pages
59-69
Published: September 30, 1985
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The paper deals with the viscous effect on the hydrodynamic forces acting on a semisubmersible. To predict the forces by the Hooft's method, the values of drag, added mass and lift coefficients for each element of it are needed. They are obtained at low K_c number by the forced oscillation test for two-dimensional cylinders with the same cross sections as the lowerhull and the column. The drag and lift coefficients are found to be significantly dependent on the angle of attack. The predicted results for hydrodynamic forces acting on a rolling and swaying submersible using the measured hydrodynamic coefficients are in fairly good agreement with the experimental ones.
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Masahiro YAMAGUCHI, Isamu SAITO, Jun ISHIZAKA
Article type: Article
Pages
71-79
Published: September 30, 1985
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It is important to measure and check the cavitation pattern and vibration around the propeller when they develop ship hull form on the propulsion performance. In this paper, the authors set the flow liner in the cavitation tunnel in order to simulate the flow in fu11 scale, which they estimate from the wake measured in the towing tank. The flow liner is obtained by the idea to make the flow stable, and it is here considered as the body to accelerate the flow near the propeller. They change size and position of the flow liner in the cavitation tunnel and measure the wake at the propeller position. They calculate the flow with the flow liner in the cavitation tunnel by means of Hess and Smith method with the wall effect and the first order approximation of 3-dimensional turbulent boundary layer theory. They get the results that the wake distribution measured with the flow liner in the cavitation tunnel shows better coincidence with the estimated wake distribution in full scale and that the effect of the flow liner on the wake is larger by the potential flow than by the 3-dimensional boundary layer. If the difference of nominal wake fraction between measurement and computation would be due to the vortex distribution with the longitudinal axis, the flow liner will give some effects on the vortex distribution.
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Nobuo NAGAMATSU, Hodaka SHIMIZU
Article type: Article
Pages
81-89
Published: September 30, 1985
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Knowledge of the flow field around a propeller is essential for the design of energy saving devices around a propeller. In this paper, Laser Doppler Velocimeter (LDV) was used in circulating water channel to measure flow field around a model propeller in uniform flow. Experimental results were compared to data measured by 5-hole pitot tube. And flow field was calculated by the theory of infinite number of blades considering approximate contraction effect and calculated results were compared to experimental data. The good agreement was obtained between calculated values and measured values.
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Seiji TAKEZAWA, Mitsuhiro ISHIDA
Article type: Article
Pages
91-108
Published: September 30, 1985
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Generally the wave slope is important characteristic especially in connection with angular motions of floating body. But, in spite of this fact, there are very few reports discussed the wave slope in irregular water wave. The previous report (KSRNo.195) has mainly investigated on statistical characteristic of the wave elevation in artificial irregular water wave. Therefore this report newly treats characteristic of the wave slope in irregular deep water wave. By recently developed instrumentation, wave elevation and wave slope timehistory were simultaneously measured at the fixed point. We calculated directly statistics of these amplitudes and periods, and estimated the power spectra of wave elevation and wave slope too. The relation between the direct statistics of measured wave slope timehistory and the estimated values from wave slope spectra was exactly investigated as well as the case of wave elevation. It was shown from these analysis that linear relations between wave elevation and wave slope exist in most case of artificial irregular deep water waves, but drastic nonlinear phenomena appear in wave slope of high and steep irregular water waves, and there is a upper limit value of the maximum wave slope because of breaking of individual waves, and that value is approximately equal to 0.6. Moreover, the statistical characteristics of wave length and wave steepness were clarified. Thus, we showed the various statistical informations on the wave slope of irregular waves were found from the measured irregular wave slope timehistories. Then we think that these results can be applied in the actual deep ocan wave.
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Kimio YOKOTA, Hideyuki MORIHANA, Kouichi UIRAGAMI, Yutaka YAMAUCHI
Article type: Article
Pages
109-119
Published: September 30, 1985
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Titanium alloy is one of the best candidate for the pressure sphere of a Deep Submergence Research Vehicle. The authors applied the material (Ti-6AI-4V ELI) for the medium scale pressure vessels of "SHINKAI 2000". In the case of a large scale pressure sphere of about 2m in diameter, and of about 70mm in thickness, a technical limit prevented the material from application, such as the manufacturing process of heavy thickness plate and hot forming. With the response to the requirement of a large scale material today, the pressure sphere made of titanium alloy has come to a real structure in Japan. The authors have already established the manufacturing process of the titanium sphere by building a full scale model in the field of hemisphere fabrication, precise machining, electron beam welding, and of nondestructive testing. In this report, the authors have investigated the collapse behaviour of titanium alloy spheres using 3 machined models, and also confirmed the current design procedure to be reasonable. In addition the authors have investigated the influence or room temperature creep on the collapse behaviour by the model test of 160 hours continuous loading under 105% of design pressure, and by the simulation analysis using the elastic plastic large deformation analysis with the finite element method. As a result, the current design procedure is also reasonable for titanium alloy and as long as the procedure is applied, the room temperature creep is not necessary to be considered in design. This result, combined with the former established of fabrication procedure, confirmed the titanium alloy (6AI-4V ELI) to be effective for the pressure sphere of the Deep Submergence Research Vehicle in Japan.
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Hajimu MANO, Hiroshi KAWABE
Article type: Article
Pages
121-132
Published: September 30, 1985
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Authors investigated the optimum configuration problem around a hole in an infinite elastic plate under the uniform loading in the previous report. Although two optimum configurations expressed by the mathematical descriptions for the given aspect ratio were proposed, there was a remaining problem that the value of the stress concentration factor could be decreased further a lower limit value. In this report, the fundamental property of the stress distribution around a hole is studied, it has been shown that the optimum stress distribution which have the minimum value of the stress concentration factor must be uniform in tension and compression stresses respectively. Authors propose the method of conformal mapping and the iteration method using the variational principle of the stress function to find the optimum configuration having that of stress distribution. As the result of investigation, the optimum configuration have a part which sticks out like an angle. The minimum value of the stress concentration factor for the given aspect ratio is shown and the standard of judgment for practical usage is determined
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[in Japanese]
Article type: Article
Pages
133-145
Published: September 30, 1985
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[in Japanese]
Article type: Article
Pages
147-151
Published: September 30, 1985
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Article type: Appendix
Pages
153-
Published: September 30, 1985
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Article type: Appendix
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Published: September 30, 1985
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Article type: Appendix
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Published: September 30, 1985
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Article type: Appendix
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Published: September 30, 1985
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Article type: Appendix
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Published: September 30, 1985
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Article type: Appendix
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App6-
Published: September 30, 1985
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Article type: Appendix
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App7-
Published: September 30, 1985
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Article type: Cover
Pages
Cover2-
Published: September 30, 1985
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Article type: Cover
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Published: September 30, 1985
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