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Article type: Cover
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Published: December 30, 1976
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Article type: Cover
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Published: December 30, 1976
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Article type: Appendix
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App1-
Published: December 30, 1976
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Yozo AZUMA, Shigeru HIRANO, Tadahiko KATO, Yasuo HORIBA, Teruyuki NONA ...
Article type: Article
Pages
1-15
Published: December 30, 1976
Released on J-STAGE: March 30, 2018
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Conventional design engineering systems aided by computer have their system flow and operation flow programmed to their intended functions and are necessary to revise the system itself to meet environment change. The comprehensive system for design engineering aided by computer (SEABIRD SYSTEM) is able to meet changes in application flexibly by recombining the subsystems, and accordingly has been in use for designing of various kinds including ships design. The system is applied for all operations from key plan (functional design) to yard plan (production design) combining various subsystems prepared in accordance with necessary work flow.
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Akinori MORIMOTO, Hiroshi MINAMI, Toshiyuki IWAI
Article type: Article
Pages
17-24
Published: December 30, 1976
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This paper is to roport on the unattended control of lay down welding at prefablication stage. The unattended control unit and the handy tool which are able to make automatically arcing, reliable relay and cut off have been developed.
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Tetsuo TAKAHEI, Tetsuo TAGORI
Article type: Article
Pages
25-35
Published: December 30, 1976
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In the recent polluted condition on the inland waterways, high-speed small crafts have been suffering from propeller damages presumably caused by floating obstacles. A study has been made with the models in the circulating water channels at Tokyo University and Kawasaki Heavy Industries, Ltd. for the effective propller-guards as a countermeasure to collision of driftwoods with propeller blades. The model crafts used for the tests are a single-screw pilot boat and a twin-screw patrol boat shown in Figs. 1 and 2 and Figs. 3 and 4 respectively. Various types of guards were designed and tested with driftwood models thrown into the water. The configuration of the most effective one among a series of guard designs for the single-screw boat is shown in Fig. 10 and that for the twin-screw boat is the 11th scheme shown in Fig. 11. Employing these guards, the collision rate of the driftwood models and the index of damage of the propellers have been reduced almost down to 40 percent. The sea trials with the 15 meter twin-screw patrol boat fitted with the above-mentioned 11th guard proved that the guard did not cause any harm to the speed performance as well as the maneuvearabilty.
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Masatoshi BESSHO, Toshiaki MIZUNO
Article type: Article
Pages
37-45
Published: December 30, 1976
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Many researches have becn done on ducted propellers experimentally and theoretically, but few of them touches the thrust of duct and thrust deduction with regard to its form and attack angle. This paper presents an approximate formula of the duct thrust and thrust deduction as a linear function of its attack angle, camber and slip ratio of the propeller assuming the duct is very short and thin. Secondly, the mutual interference between duct and ship main hull are discussed in relation to the thrust deduction of ducted propeller behind ship. Finally, the propeller in the duct can be treated as an axial flow pump and then its efficiency as a pump can be estimated. Then, it is shown that the propulsive efficiency of ship is a product of this pump efficiency and the duct or hull-duct efficiency as like as a product of propeller one and hull efficiency. This duct or duct-hull efficiency is a ratio of the effective work done of whole system divided by the work done by the propeller as a pump. This method of analysis enables us to design a ducted propeller by the theory of axial flow pump.
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Mitsuhisa IKEHATA
Article type: Article
Pages
47-58
Published: December 30, 1976
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In this paper the author describes a new prediction method of ship performances. This method is based on a mathematical model of the hydrodynamical action of a propeller in the given velocity field of the flow in the propeller disk. The thrust and torque of model propeller behind the model ship can becalculated by providing the measured wake patterns behind the model ship and assigning the rovolutions per second of the propeller. Simulating this process, when the wake patterns of the full scale ship are estimated by Sasajima-Tanaka method, thrust, torque and power generated by the actual propeller behind the full scale ship are predicted. For one numerical example, the predicted results of a large oil tanker have shown the good agreement with its trial resuls. By this method, the full scale wake fraction need not to bo estimated by practical means. Subsequently, the effects of non-uniformity of flow on propulsion factors, particularly effective wake fraction and relative rotative efficiency, have been made clear, and the scale effect on propulsion factors have been taken into account of itself.
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Yoji HIMENO, Yasuo KOMATSU, Taketoshi OKUNO, Norio TANAKA
Article type: Article
Pages
59-66
Published: December 30, 1976
Released on J-STAGE: March 30, 2018
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This paper presents two methods for predicting the characteristics of the viscous wake field behind a ship. One is an extension of the usual calculation method for ship boundary layers to the ship wake problem, in which the formula for the velocity profiles and the entrainment equation are modified considering the wake flow field. The other method which may be regarded as the first approximation to the three-dimensional wake layer equations, consists of a new formula for the cross flow angle in the wake and Squire and Young's empirical formula in tthe main stream direction. The results of the calculations according to these methods show reasonable agreements with the experimental result. Furthermore, the discussions concerning the pressure distribution on the ship hull and along the center plane of the wake are made in view of the displacement effects of ship boundary layer and wake.
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Masatoshi BESSHO, Masahiko KOMATSU
Article type: Article
Pages
67-74
Published: December 30, 1976
Released on J-STAGE: March 30, 2018
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The authors computed pressure distributions on a flat plate when it oscillates on water surface in the former report. It is generally believed that their results stand for of a very shallow draft ship, but there lies some question if it does really. For this question, the authors develope the discussion and especially with regard to the end shape. Then, if the draft of a ship is very deeper than the wave height, the flat plate modeling is adequate, and the solutions obtained correspond to a ship having flared side wall but there is a difficulty for such ship that the wetted surface area changes periodically when she dipps and heaves. The second part of the present report is devoted to the discussion about the resolvent of the integral equation of the boundary value problem. Applying this result, the authors discuss problems, the effect of small slits, the slight change of the breadth and the wave-excited swaying force of a flat plate.
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Toshiaki MIZUNO
Article type: Article
Pages
75-83
Published: December 30, 1976
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The effect of viscosity on the drifting force for two-dimensional floating body oscillating on the regular beam waves is discussed mainly in this paper. Firstly, the drifting force acting on the eight cylinders of Lewis Form section heaving, swaying and rolling among the beam waves is calculated according to Maruo's theory and by using linearized wave theory. Secondly, by taking the linearized viscous damping force into consideration, an expression for the drifting force is presented and the results of the numerical calculation for the cylinders mentioned above are shown and examined.
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Shoichi NAKAMURA, Kyosuke MATSUI, Matao TAKAGI, Shinichi ARAI
Article type: Article
Pages
85-91
Published: December 30, 1976
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An experiment on the slow drift oscillations of a moored box-type floating body in irregular waves is carried out in the Experiment Tank of Osaka University. The natural periods of the swaying motion of its system are changed systematically by changing the spring constant of the mooring lines, and the mean wave periods of irregular waves are also changed. The phenomena of the slow drift are confirmed from the results of spectral analysis of the measured swaying motions. The results of experiments are compared with those of theoretical calculations by Pinkster's method and Zarnick's method, and fairly good agreement is obtained.
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Yoshiyuki YAMAMOTO, Norihiro MATSUBARA, Takahide MURAKAMI, Kazuo NISHI ...
Article type: Article
Pages
93-101
Published: December 30, 1976
Released on J-STAGE: March 30, 2018
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In this paper, dynamic behaviors of containers in a hold during voyages are investigated experimentally and tbeoretically. Rolling tests were conducted with a column of container models on an apparatus with a rolling bed. The container loads acting to a guide rail on the cell construction and to the inner bottom plate depend the lateral distance of a container column from the center line as well as upon the amplitude and frequency of ship's rolli1ng. Dynamic behaviors of containers are affected primarily by the clearance between the container and a guide rail. Results of the experiments are in good accordance with the present theory based on the matrix method.
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Kazuo UMEZAKI, Hiroyuki MIZUNO, Yumiko SHIMODA
Article type: Article
Pages
103-111
Published: December 30, 1976
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Ship vibration characteristics is one of the important problem in the initial design stage. But it is very difficult to predict its characteristics value in high accuracy, because in the initial design stage, there are many unknown factors. Therefore the vibration characteristics values are predicted usually by using the simply theoretical formula which are modified with consideration of the correlation between actually measured data and theoretical value, on every type of ship. In general, the actually measured data has always some experimental error and the theoretical value includes some error caused by ideal or approximate treatment of phenomena and structural simplification. As these error terms can be treated as statistical value, statistical approach can be used for the derivation of empirical formula. From the above mentioned reason, the authors developed the statistical method to predict the ship vibration characteristics. Using this method, prediction can be easily carried out on the basis of the measured data of the similar ships with a few factors which are known in the initial design stage.
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[in Japanese], [in Japanese]
Article type: Article
Pages
113-124
Published: December 30, 1976
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[in Japanese]
Article type: Article
Pages
125-131
Published: December 30, 1976
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Article type: Appendix
Pages
133-135
Published: December 30, 1976
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Article type: Appendix
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Published: December 30, 1976
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Article type: Appendix
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Published: December 30, 1976
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Article type: Appendix
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Published: December 30, 1976
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Article type: Cover
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Published: December 30, 1976
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Article type: Cover
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Published: December 30, 1976
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