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Article type: Cover
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Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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Article type: Cover
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Cover2-
Published: June 30, 1977
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Article type: Appendix
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App1-
Published: June 30, 1977
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Toshio WATANABE, Kazuo UMEZAKI, Mikihiro KOBAYASHI, Yumiko SHIMODA
Article type: Article
Pages
1-6
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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Estimation of fundamental quantity such as hull steel weight, pipe weight, painted area, etc. is very important for the ship's design, especially, at initial design stage. Estimation, however, by detail calculation is so difficult at initial design stage when design has not been developped in detail yet that actual results, technical experiences, etc. are necessary to it supplementary. As statistical treatment seems to be applicable effectively to such estimation, the possibility of the method has been investigated. As the results, it was found that the method using analysis is so useful for selecting variables and making the estimation simple, that it can be put to practical use.
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Ryusuke HOSODA, Hisaaki MAEDA, Takashi TOYAMA, Katashi TAGUCHI
Article type: Article
Pages
7-16
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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From a viewpoint of ship design, wave properties which are closely related to practical prediction of statistical ship responses and wave loads, were studied by making use of results from wave measurements and observations on the North Pacific and the West Pacific Ocean. The measured results were analyzed by means of spectral analysis. The analyzed results were compared with the results of visual observation on board and with those measured and observed on the North Atlantic Ocean. The estimated wave spectra were normalized and the spectral form thus obtained was compared with that of Pierson-Moskowitz type wave spectrum. Furthermore, influences of wave properties and spectral form on the practical accuracy of statistical prediction of ship rcsponses in rough seas were discussed by quoting an example of typical design problem. The above wave measurements and observations were carried out using throw-in type wave meters which had been developed through the sponsorship of SR-132 Committee of J.S.R.A..
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Shigeru AKAZAKI
Article type: Article
Pages
17-19
Published: June 30, 1977
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By a model experiment of a ship, the author noticed a fact that there is a special adherent layer of water between the hull and the layer commonly expressed as a displacement thickness. While the latter thickness is expressed by √<ν t_l>, where ν is the coefficient of the kinematic viscosity of water and t_l the time lapsed from the start of acceleration, the adherent layer is dependent on the velocity of the ship. The thrust of ship, or pulling weight F, during an acceleration is expressed as follows: - F=m_0M_α. Where, M=mass of the ship, m_0=1+m_5+m_6, m_5=coefficient of the added water mass due to the total resistance, and m_6=coefficient of the adherent mass. Then, α=F/(1+m_5+m_6) M. During the experiment, F, m_5 and M were kept constant, and the author found that m_6 changes in a special manner depending on V. In an experiment of l.5m model and F=1,000g, m_6 showed its effect when V has increased to 0.5 m/s and m_6=0.061, then it increased with V, and after V=1.389 m/s, m_6=0.087, m_6 remained constant. See Fig.2. After V has reached l.667 m/s, both V and m_6 were seen remaining constant.
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Isao TAKANASHI
Article type: Article
Pages
21-30
Published: June 30, 1977
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It is very important to understand shipping water quantitatively from the standpoint of preventing capsize and submersion, the most miserable sea disasters. This paper proposes an empirical equation to calculate a volume of shipping water over the weather side bulwark of the two-dimensional ship, provided waves are known along the ship side, the top of which is assumed higher enough than waves. This equation is proved appropriate for the fixed model ship and for the forcedly rolling model ship, and also, though a few experimental data, for the free oscillating model ship.
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Yoshiho IKEDA, Kiyoshi KOMATSU, Yoji HIMENO, Norio TANAKA
Article type: Article
Pages
31-40
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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The roll damping force of bilge keels consists of two components, one due to the normal force acting on bilge keels and the other due to the hull pressurecreated by bilge keels. Measurement of the hull pressure for several two dimensional cylinders with bilge keels were carried out. On the basis of these experimental results, a formula for roll damping coefficient due to the hull pressure component is proposed. And the estimated values of roll damping coefficient due to bilge keels which are derived from this formula together with the formula for the normal force component recently proposed by the authors, show fairly good agreements with experimental values for two dimensional cylinders and ship models with bilge keels.
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Masatoshi BESSHO
Article type: Article
Pages
41-48
Published: June 30, 1977
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A theory of a pulsating pressure distribution on a water surface of uniform flow is developed following Hanaoka's theory. They say this model simulates an oscillating gliding plank, but this may not be true because there exists no solution satisfying both Kutta's condition at trailing edge and the condition that a plank lies on a water surface. In this paper, a flat shallow-draft ship of them are treated in more detail. The principal aim is a mutual relation between the diffraction and radiation of wave. This knowledge, for example, solves directly a wave-energy absorption problem.
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Masatoshi BESSHO
Article type: Article
Pages
49-57
Published: June 30, 1977
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When a gliding plank on a water surface is oscillating, its wetted length varies also periodically. This phenomena is intrinsic in the theory too. This paper reports a linearized theory of this problem assuming that the variation of the wetted length is small enough, although this must be highly non-linear. An example calculated at high Froude number shows an interesting feature of this effect.
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Masatoshi BESSHO, Akio ISHIKAWA
Article type: Article
Pages
59-69
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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To clarify the water surface effect of a wing flying over water, both velocity potential of air and water flow are determined, so that the pressure might be continuous and both fluids might flow in the same direction at water surface. And its lift, water surface elevation and wave drag are also formulated. It is shown that the water surface effect of an air wing may be approximated as the rigid wall effect because of the density difference between air and water. Further, a numerical calculation is performed to investigate the effect of wing parameters, such as thickness ratio, attack angle and tail clearance upon the water surface effect of a two-dimensional wing section.
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Yoshihiro HTSUKA, Hiroshi ISSHIKI, Mitsunori MURAKAMI
Article type: Article
Pages
71-81
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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Launching from slip way being carried out into Onomichi Channel with breadth of about 240m, by using drag weight in our yard, it needs high technique of stopping ship's body within a tolerance of some 10m, according to the length of ship. There is a trend that actual launching travel is usually larger than estimated one, to some extent, the cause of which has not been revealed but may be considered to depend on the long peniodic wave motion in the channel, induced by launching ship. Authors calculated wave profiles for the simple simulation in order to know the mechanism of wave motion at launching, the result of which they applied for the launching, modifying the existing equation of motion, and got reasonable coincidence with the measured data. However, it is very difficult to estimate hydrodynamical force acting on the launching body exactly, and should be our main theme in future.
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Taketoshi KUNO, Yoji HIMENO
Article type: Article
Pages
83-94
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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Some measurements and theoretical considerations are made concerning the skin friction vectors and the velocity distributions in the three-dimensional turbulent boundary layers on ship models. The results of the measurements of the skin friction on the ship models show fairly good agreement with the boundary layer calculations. The limiting streamlines derived from the directions of the skin friction vectors on the hull and also observed using the oil film technique express that the three-dimensional separation at the stern of model belongs to the so-called open type. The velocity component measured, normal to the wall varies monotonously near the separation and attachment line. The cross plane flow near the stern calculated by the boundary layer theory has a similar tendency with that of the bilge vortices.
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Junkichi YAGI, Yasumitsu TOMITA
Article type: Article
Pages
95-103
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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Using the Miner's theory and the most probable largest load spectra in which the ship will experience during 10^8 wave encounters on the ocean sea, the fatigue criterion for ship structural members was proposed in order to secure against fatigue fracture. The following allowable tensile stress σAL may be given when mean results according to ordinary S-N_c curves for mild steel are used. σAL=σ_a+0.8/K_tσ_m=f_2 (1.5f+29/K_t) =f_2/K_t (8f+27) Kg/mm^2 where, K_t=stress concentration factor (K_t-values are not to be regarded as absolute values, but as relative values calibrated from experience for structural members) σ_a=stress amplitude (wave bending stress at a probability level of Q=10^-4) σ_m =mean stress (still water bending stress) f=usage factor defined as the cumulative fatigue damage ratio summed over a period of 20 years. f_2=σB/σBM (σBM; teusile strength of mild steel σB ; teusile strength) The above allowable stress for fatigue fracture was applited to the longitudinal and the transverse strength members.
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[in Japanese]
Article type: Article
Pages
105-119
Published: June 30, 1977
Released on J-STAGE: March 30, 2018
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[in Japanese]
Article type: Article
Pages
121-123
Published: June 30, 1977
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Article type: Appendix
Pages
125-127
Published: June 30, 1977
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Article type: Appendix
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Published: June 30, 1977
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Article type: Appendix
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Published: June 30, 1977
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Article type: Appendix
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Published: June 30, 1977
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Article type: Cover
Pages
Cover3-
Published: June 30, 1977
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Article type: Cover
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Published: June 30, 1977
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