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Article type: Cover
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Published: March 30, 1983
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Article type: Index
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Article type: Appendix
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Published: March 30, 1983
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Takeaki MIYAZAKI, Hiromichi YOKOMIZO, Hitoshi HOTTA, Yukihisa WASHIO
Article type: Article
Pages
1-8
Published: March 30, 1983
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As one of improvement in air power on the wave power generator device "KAIMEI", the air flow phase-control is designed refering to the phase-control of a point absorption by K.Budal. As a first step of this study, the basic characteristics of air power in a fixed air chamber in regular waves are obtained by experimental and theoretical analisis by equivalent floating body approximation method. The results are summarized as follows; 1) It is accurated that the air flow phase-control method is efficacious for improving on performance of wave power absorption. 2) Some optimum condition for this control system which is phase-control start timing and valve opening time, is obtained by this paper. 3) The water column motion and wave power absorption ratio is explained by this theoretical analisis method (equivalent floating body approximation method) with nozzle loads, qualitatively and quantitatively.
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Shoichi NAKAMURA, Shigeru NAITO, Eizoh YAMAGUCHI, Ken TAKAGI
Article type: Article
Pages
9-13
Published: March 30, 1983
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It is necessary that the floating type wave absorber is supported by mooring lines. However, since the floating body has three degree of freedom when it is supported by mooring lines, the efficiency of it which is designed for heave or roll motion only, may be expected to decrease. Therefore it must be designed under the condition of three degree of freedom. This report shows a procedure of optimum design of the floating body supported by mooring lines. Furthermore, model tests on wave power absorption are carried out and the results of the test show that the complete wave power absorption is possible by using the present method.
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Osamu YAMAMOTO
Article type: Article
Pages
15-21
Published: March 30, 1983
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Complete wave power absorption is studied by using a two-dimensional floating body of symmetrical section, which oscillates in three degrees of freedom, and two kinds of energy absorbing mechanisms. One of the mechanisms is a single energy absorbing mechanism which exerts the reaction force on the floating body at a point away from the center line of the floating body. The other is a pair of single absorbing mechanisms which exert reaction forces on the floating body at the points symmetrical about the center line of the floating body. These power absorbing mechanisms are activated by the heaving motion at the points where the mechanisms are articulated with the floating body. The conditions, which the characteristics of the power absorbing mechanism and the floating body should satisfy for complete wave power absorption, are derived theoreti-ca11y for both configurations of the power absorbing mechanisms. Furthermore, a model test on wave power absorption in regular waves is carried out for the pair of single energy absorbing mechanism and the results of the test show that complete wave power absorption is possible by using a two-dimensional floating body of symmetrical section which oscillates in three degrees of freedom.
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Masatoshi BESSHO, Yusaku KYOZUKA
Article type: Article
Pages
23-29
Published: March 30, 1983
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This is a theoretical and experimental study on the wave-absorbing problem of a floating cylinder of symmetric section which oscillates vertically around a point of off-centerline. If we consider the time-reversed motion of this problem when the wave energy is completely absorbed, we have the radiation problem in which the radiating waves vanish on the one side of the cylinder. Hence, we study only the radiation problem which is simpler than the wave absorption problem. Then, we consider a symmetric cylinder which oscillates vertically and rotates freely around an arbitrary point and seek points such that the radiating waves vanish on the one side by the oscillation around them. The wave amplitudes radiating toward both sides of the cylinder are calculated on the basis of the linear water-wave theory and such points are found easily. Moreover, the maximum efficiency which could be achieved in the wave absorption problem is obtained by the wave amplitudes radiated to both sides. Experiments on a simple cylinder show the validity of the theoretical Predictions.
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Matao TAKAGI, Kimio SAITO, Hiroshi OKUBO, Minoru SAITO
Article type: Article
Pages
31-39
Published: March 30, 1983
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As a practical method to simulate the motion of a two-dimensional body with non-linear type mooring system in waves, the equation of motion described in frequency domain (F.D. method) is used. However this method is not exact since the frequency of motion can not be determined, a priori, when non-linear term is involved in the equation. In this paper, numerical simulation by using the equation of motion determined in time domain (T.D. method) is presented, and the results of simulation are compared with those of F.D. method and experimentl results. It is shown that the prediction by T.D. method show a more satisfactory coincidence with the measured values than those by F.D. method.
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Masaaki MINAMI, Takeo KOYAMA
Article type: Article
Pages
41-48
Published: March 30, 1983
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Dynamic positioning System (DPS) has been developed and operated for drilling rigs and work vessels in deep waters to keep position. In this paper the state feedback control based on multi-variable control system which takes the yaw-sway-suge coupling into account was compared with the conventional PID control system. Expressing the equation of motion in linear model, Linear Regulator Theory can be applied. Feedforward control is also effective in case the external forces can be mea-sured directly. Using the data of a typical drill ship, the computer simulations of state feedback control with feedforward were carried out comparing with that of PID control. From the results of simulation it was found that energy consumption of drill ships and lower-hull type semisubmersible rigs was remarkably reduced by state feedback control when the steady external forces like current exsist.
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Ryunosuke KAWAZUMI, Toshio KAWAI, Takehiko ABE, Seiichi NISHIMURA
Article type: Article
Pages
49-56
Published: March 30, 1983
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To avoid smoke nuisance, funnel must be protruded outside the turbulent zone gene-rated above compass bridge deck. Size of turbulent zone depends on the shape of wheel house and / or accommodation, and is different for each ship. Naval architects and researchers have carried out various systematic wind tunnel tests using models over years, and investigated many methods and formulas to estimate size of turbulent zone. However, because these methods and formulas are not applicable to recent less air resistance type deck houses, we carried out wind tunnel tests using their models and measured sizes of turbulent zones. In addition, we have investigated effects of fore and aft structures on turbulent zone. As a result, we have obtained a pair of experimental equations giving sizes of turbulent zones for less air resistance type deck houses and effects of fore and aft structures, and confirmed that these equations are applicable to actual ships.
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Sumitoshi MIZOGUCHI
Article type: Article
Pages
57-66
Published: March 30, 1983
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An invisid flow model based on the approximations of slender body theory is developed to calculate the flow with three-dimensional separation vorticities around ships at a small angle of attack. The vortex sheet can be represented by a number of free vortex-lines when it flow out from the thin boundary layer over the hull. Following the concept of this method, the two separation lines are defined from the pressure gradients on each side of the hull. Semi-infinite vortex-lines are emanated from the separation points at each section and extend downstream along a stream line. The force acting on a ship is analysed with the further development of the Newman's method and the new term of the force acting on the vortex-lines is found. The flow and the positions of the extended vortex-lines are calculated with a container ship and a tanker. From the calculated results, the followings are observed: 1) The vortex-lines emanated from the both sides of the tanker's bow flow down to the bottom but the vortex-lines near the bow of the container ship flow out far from the hull. 2) The vortex-lines are roll up near the lee side of the aft body. 3) Attachments of the vortex-lines emanated from the weather side of the mid-body are found.
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Iciiro TANAKA, Yasuyuki TODA
Article type: Article
Pages
67-77
Published: March 30, 1983
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In this paper, the authors propose a new hull form named the Under-Keel-Stern (UKS) Ship, whose stern has the under-keel portion of bulbous stern shape. The reason to propose this form is as follows. Firstly it adds more wake at the lower portion of propeller disc, so that the wake distribution will be more uniform. It may also increase the so-called wake gain due to increased mean wake. It also provides more flexibility for design of stern form, so that it may become possible to design low wake and low resistance form at the hull portion near load water line. Model experiments are performed at the water circulating tank for obtaining the resistance, propulsion and wake characteristics by using a normal-shaped tanker model and a newly proposed Under-Keel-Stern model. Results show that the Under-Keel-Stern form seems to have promising features in propulsive characteristics.
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Tomoo HANAWA, Yoshitaka HASHIMOTO, Ichiro TANAKA, Toshio SUZUKI
Article type: Article
Pages
79-94
Published: March 30, 1983
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In this paper, the effects of the following three appendages on fullship's stern are investigatied from the viewpoint of synthetic propulsive performance, i.e. propeller exiting force, propulsive performance and practical use. (1) Partial wake generator applied on the hull sur⊥ace directly be⊥ore the propeller (2) Under keel stern (U.K.S.) (3)Long fin applied along a potential stream line between S.S. 11/2 and S.S. 3/4 At first, tank tests, i.e. resistance, self-propulsion test and wake distribution mea-surement are carried out by using 1.92m and 4m models o⊥ SR 174B-4H ship with or without the above appendages. Using the tank test results, required horse power, bearing and surface forces are calculated and compared with each other. Consequenty, it is found possible to equalize the wake non-uniformity while improving propulsive performance at the same time, by properly applying such appendages to ship's stern.
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Mitsuhisa IKEHATA
Article type: Article
Pages
95-100
Published: March 30, 1983
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It is reported in this paper that the propulsive performance of a ship is surely im一proved by the aid of a wheel of stators installed behind the propeller. This new apparatus converts the rotational motion of the water induced in the rear of the screw propeller into the accelerative motion effectively so as to generate the additional thrust. The principle of the action of it is the same of the old "Star-Contra-Propeller", but it is of a new mode refined by the modern technology. The results of the model tests of one example in the experimental tank showed us that the advantage to be gotten by the stators was five percents up of the propeller efficiency in the open condition and seventeen percents up of the propulsive efficiency in the self-propelled tanker model 6 metres long. From these test results we can predict that the power of the actual ship with the length of 216m will be 10-12 percents down provided with the stators.
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Nobuo NAGAMATSU
Article type: Article
Pages
101-109
Published: March 30, 1983
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The purpose of this paper is to propose the total design method for Highly Skewed CPP (HSCPP) which takes into account such several factors as performance, spindle torque, cavitation and surface force. Concerning a performance, the applicability of wake adapted propeller theory to HSCPP is investigated. On a spindle torque, computer program was developed and skew distribution which gives small spindle torque is studied using this program. Surface force is estimated by Vorus' theory. To confirm this design method, cavitation tests and measurements of fluctuating pressure for model propellers designed by this method were performed.
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Shozo OKAZAKI, Kiyoshi HASEGAWA
Article type: Article
Pages
111-122
Published: March 30, 1983
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On the design for the strength of carburized gears, it is necessary to take the fatigue strength of gear teeth into consideration especially. It is not yet clear which formulas, such as AGMA's, DIN's, JGMA's etc., are the most useful for the fatigue strength design of gears. So, this report presents a design formlula for the fatigue strength of marine carburized gears on basis of our experimental results. The basic equation in a gear is calculated as follows; St≦β_1・β_2・β_3・β_4・β_5・β_6・S_<αo>/fm where, St =maximum actual tooth bending stress (kg/mm^2) Sαo = bending stress obtained by the pulsating fatigue test results of gear under optimum carburizing conditions (kg/mm^2) fm = factor of safety (=2) β_1 = carburizing conditions factor β_2 = hardening ratio factor β_3 = size factor β_4 = surface roughness factor β_5 = load stress form factor β_6 = carburizing process factor Estimating the safety of some actual marine carburized gears by equation above, it turned out to be. fm≧2 and safe enough.
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Hiroshi KAWABE, Masatoshi BESSHO
Article type: Article
Pages
123-132
Published: March 30, 1983
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In the present paper the singularity method or so-called the boundary element method is applied to the two-dimensional elastodynamic problems. Various representations of the displacement field are introduced, the one of which is very much useful to compute the stress concentration around a cavity or rigid inclusion during passage of plane harmonic waves in an infinity extended plate. Analyzing the property of kernel functions near the origin, an accurate method of integration of kernel function is proposed. To verify its usefullness and accuracy, some numerical examples are shown for circular cavity and rigid inclusion and crack and the calculation gives good values especially near or on the boundary compared with the former results.
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[in Japanese], [in Japanese]
Article type: Article
Pages
133-137
Published: March 30, 1983
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[in Japanese], [in Japanese]
Article type: Article
Pages
139-143
Published: March 30, 1983
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[in Japanese]
Article type: Article
Pages
145-173
Published: March 30, 1983
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Article type: Appendix
Pages
175-176
Published: March 30, 1983
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Article type: Appendix
Pages
177-182
Published: March 30, 1983
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Article type: Appendix
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Published: March 30, 1983
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Article type: Appendix
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Published: March 30, 1983
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Article type: Appendix
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Published: March 30, 1983
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Article type: Appendix
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Article type: Appendix
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App6-
Published: March 30, 1983
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Article type: Appendix
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Published: March 30, 1983
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Article type: Cover
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Published: March 30, 1983
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Article type: Cover
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Published: March 30, 1983
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