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Published: June 30, 1979
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Article type: Appendix
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Article type: Appendix
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Published: June 30, 1979
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Jiro OKAMOTO, Yoshikatsu NAGATA, Toshio WATANABE, Hiroshi HUZIMURA
Article type: Article
Pages
1-14
Published: June 30, 1979
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Sea-Land Service, Inc. intended replacement of their 4 "Elizabethport" class steam turbine driven container ships by new slow speed diesel engine driven vessels, in order to have bigger container carrying capacity and better fuel economy. These existing container ships had been converted from T-3 tankers in 1962 by inserting new midbodies of container hold structure and the owners planned to utilize the container hold structure as a part of new ship. "The fore and aft bodies with all necessary equipment, accommodation and machinery shall be newly built and be joined to existing midbody."……was the Owner's unique idea. This idea needed comprehensive and sophisticated capability of high potential, and Mitsubishi Heavy Industries, Ltd. Kobe Shipyard was selected to realize this unique project and developed various alternatives for construction procedure. Finally the Shipyard adopted "Short ship" idea from among them as the most realistic, reliable and economical procedure, and they attained successfully. This paper is a brief report of this unique shipbuilding work performed in the Shipyard under extensive cooperation of the Owners, United States Coast Guard and American Bureau of Shipping.
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Hiroyuki SADAKANE
Article type: Article
Pages
15-20
Published: June 30, 1979
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The ship behavior on a billow with a extreme wave height can not be known sufficiently because of the non-linearity of various factors. To study the outline of the first roll of a ship in this case, the experimental research is carried out in the water tank using box-shaped models. The rolling features and the relation between the model stability and the rolling amplitude [θ_<al>]_m are shown. From the investigation of these results and the heeling moments measured, it is seen that the heeling moment due to a breaking billow is caused not only by wave slope but by the break of wave crest.
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Osamu YAMAMOTO
Article type: Article
Pages
21-26
Published: June 30, 1979
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The model test systems on ship hydrodynamics were developed from the viewpoint of Laboratory Automation at Tsu Ship Model Basin. The auther joined in developing these systems and accomplished the ship motion test system in Waves (SMW). In order to confirm the accuracy of the test results obtained on this system, ship motion tests were carried out in head, beam and following waves with 5-meter model ship of the S-175 container ship design which was the subject of the computer studies on ship motions in 15th ITTC. The test results in head and following waves showed that these coincide with the results of experiments already published. But the test results in beam waves did not agree with the theoretical calculation by New Strip Method. Therefore, the ship motions in regular beam waves were calculated with Salvesen-Tuck-Faltinsen Method and compared with the our test results. Consequently it was verified that the results of ship motion test in regular beam waves carried out at Tsu Ship Model Basin coincide with the theoretical calculation by STF method concerning to the gains and the phases of the frequency response functions.
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Hiroshi ISSHIKI
Article type: Article
Pages
27-36
Published: June 30, 1979
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In the previous paper, the reciprocity and energy theorems were discussed from a general point of view, but the results were not reported in full detail. In the present paper, the individual theorems and their mutual relationships are investigated thoroughly. Most of the results for a fixed body have already been known as the Haskind theorem, the Bessho theorems etc. In the present paper, the theorems associated with a freely floating body are also discussed in full detail. As already discussed briefly in the previous paper, following complementary relations are obtained, when no external damping exists : If "displacement" and "force" in the results for a fixed body are replaced by "force" and "displacement" respectively, the results for a free body are obtained. General conditions for a perfect absorption of wave energy are also given in close relation to the reciprocity and energy theorems.
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Hiroshi ISSHIKI
Article type: Article
Pages
37-44
Published: June 30, 1979
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Theories of a floating body are usually dealt with in "frequency domain", and it may be said that relations between "time domain" and "frequency domain" have not been clarified sufficiently. For an example, variational problems which is equivalent to the boundary value problems in frequency domain may be derived, but their relations to the Hamilton principle in time domain are not clear enough. In the present paper, these problems are discussed using a one dimensional oscillator, and variational problems in frequency domain are derived as Fourier transforms of variational problems in time domain. A new variational problem in time domain, which is different from Hamilton's principle, are derived. Applications to the theory of a floating body are also discussed sufficiently.
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Masataka FUJINO, Atsushi KIRITA, Akira NISHIHATA
Article type: Article
Pages
45-55
Published: June 30, 1979
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First of all, in this paper, the authors examine whether or not the assumption introduced in the first report that the hydrodynamic force caused by the adverse rotation of propeller is able to be expressed by a simple linear equation of the equivalent side-slip velocity υ_s at the stern is valid even in the case where a ship has remarkable sway and yaw motions. From the analysis of experimental results, it is found that the expression of the unbalanced hydrodynamic forces as a linear equation of υ_s ceases to be valid when the υ_s value exceeds a certain limit which varies depending on the advance constant J_p. However, the υ_s expression is still useful for determining the course stability when a ship is braked by working the propeller in the adverse direction. In order to investigate the effectiveness of the mathematical model to describe the hydrodynamic forces acting on the ship's hull which is under the braking action of propeller, ship's trajectory and time histories of some state variables are computed for various cases and compared with the experimental results observed by a free-running model.
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Masahiko MORI
Article type: Article
Pages
57-66
Published: June 30, 1979
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A propeller induces the hydrodynamic forces to bend the propeller shaft when it works in the wake field of a ship, and, in consequence, care should be taken so as to prevent the bearing from the worse wear or seizure. Such forces are computed with the quasi-steady propeller theory, and also examined through some records on the deflection of a shaft and the simple analysis of a wake distribution, the way of which has been once proposed by the author. A warning is given against the wing propeller of a twin screw ship which is rotated inwards.
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Shoichi NAKAMURA, Shigeru NAITO
Article type: Article
Pages
67-76
Published: June 30, 1979
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With a model of single screw high speed container ship, resistance and self-propulsion tests in regular head waves at light load condition are carried out. The experimental results of mean increase of resistance are compared with the results obtained from the theoretical calculations. Furthermore, with the same model, speed drop tests in regular and irregular head waves are carried out by using the engine simulated self-propulsion apparatus, and the measured results are compared with the values by the prediction method of nominal speed loss in waves taking account of the main engine characteristics. Propeller load fluctuations at racing condition in waves are also measured and the effects of propeller immersion and moment of inertia of main engine on the propeller load fluctuations are discussed.
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Kimio SAITO
Article type: Article
Pages
77-93
Published: June 30, 1979
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Newman (1965) expressed the wave exciting forces and moments on a body in terms of the incident wave and the far-field radiation potentials and showed the numerical results for the submerged ellipsoids. In the present paper, we assume that the ship is represented by the singularity distributions on the central axis and we derive the general expressions for the exciting forces on a ship in waves. Some accounts of the forward-speed effect on the wave exciting forces are considered in evaluating the strength of the singularity distributions. Comparisons among the calculated results by the present method, the usual strip theory, and the experimental results have been made.
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Takao INUI, Hisashi KAJITANI, Hideaki MIYATA
Article type: Article
Pages
95-107
Published: June 30, 1979
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The aim of this paper is to visualize the cause of the defect of wave making theories of ships through wide-ranged experiments. No effective wave making theory will be generated without precise understanding of physical phenomena. Flow field analysis and wave pattern analysis are extensively carried out with wide-beam fine ship models and a two-dimensional simple ship model. Singularities of the waves in the near-field of ships are carefully analysed and discussed, and following principal conclusions are attained. 1) Singular characteristics of wave making in the near-field of ships contribute to wave resistance in a different manner from Kelvin-Havelock's wave making theory. 2) Newman-Sharma's method cannot offer true value of wave resistance. 3) The discrepancies between C_w and C_<wp> is to be approximately measured as momentum loss behind ships, which is due to the properties of singular waves, not due to wave breaking. Wave breaking phenomena is only one of the properties of singular waves. 4) Terms including υ of the exact free surface condition take a significant part for the fulfillment of this condition.
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Hiroo OKADA, Koichi OSHIMA, Yoshio FUKUMOTO
Article type: Article
Pages
109-115
Published: June 30, 1979
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As a basic study on the buckling strength of a ship's bottom plating, deformation behaviour and buckling strength of rectangular plates (aspect ratio α=3 and α=4) with four simply supported edges, subjected to increasing compression and constant lateral pressure, are theoretically clarified in this paper following the previous paper. And the effect of aspect ratio of plates on the buckling strength of plates under such combined loads, is also discussed.
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Kouhei MATSUMOTO, Kenji ARIMA
Article type: Article
Pages
117-123
Published: June 30, 1979
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Many researchers have studied the added virtual mass of rectangular plate vibrating in water down to date. Kito studied vibration of a rectangular tank with water for many years, and Kumai researched local vibration of ships, namely, vibration of a panel in bulkheads. Recently Nagamoto and Fujii and others wrote very useful reports on the added virtual mass of some reinforced rectangular plates. In this paper, the present authors calculated natural frequencies and shape modes of a rectangular plate with all edges supported in water by Ritz's method, and showed good agreement between theoretical frequencies and experimental ones. Some difference between two kinds of added virtual mass calculated from velocity potential φ in each two boundary conditions, such as φ=0 or ∂φ/∂n=0, is shown. Furthermore, the present authors present a modified Kito's formula, which gives natural frequencies of the plate partly in water.
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Masanobu YAMAGUCHI
Article type: Article
Pages
125-131
Published: June 30, 1979
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In order to reduce vibration of ship hull which resonates with the second unbalanced moment of a main engine, four bladed propeller with unequal blade angle, which induces the even order component of bearing force, was designed. When this propeller is installed with appropriate phase lag for exciting effect of main engine, the second components of propeller and main engine are counterbalanced and vibration of ship hull is reduced. First in this paper, a simple estimation method of bearing force in effective wake is proposed. This method, which uses the data of self-propulsion test and nominal wake pattern, is applied to a tanker and a cargo ship, and thrust variation is compared with results of model experiment and Kumai's method. Next, bearing force of four bladed propellers with unequal blade angle is obtained from this method and experiment. And besides it is discussed based on the result of sea trial and the bearing force obtained from this method that the second order component of hull vibration of a 10,000 DWT cargo ship at resonance frequency reduces to a half, if four bladed propeller with unequal blade angle is applied to this vessel.
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Hideyuki SHURI, Toshimichi KURIHARA
Article type: Article
Pages
133-142
Published: June 30, 1979
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In recent years, statistical energy analysis (SEA) is developed and used in studies on the transmission of sound and vibration through the structure of aircrafts, ships etc. In this paper, SEA is applied to the problem on a small steel structure system. Examinations are carried out using a small speaker set in the system and white noise power is supplied as a noise source. It is found that the reasonable evaluation of internal loss factor of panels composing the system is the key to the analysis and the usefulness of the application of SEA on the problem is confirmed by good agreement between theoretical results and experiments.
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[in Japanese]
Article type: Article
Pages
143-149
Published: June 30, 1979
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[in Japanese], [in Japanese]
Article type: Article
Pages
151-156
Published: June 30, 1979
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[in Japanese]
Article type: Article
Pages
157-164
Published: June 30, 1979
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Article type: Appendix
Pages
165-166
Published: June 30, 1979
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Article type: Appendix
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Article type: Cover
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