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Article type: Cover
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Cover1-
Published: June 30, 1984
Released on J-STAGE: March 30, 2018
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Article type: Index
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Published: June 30, 1984
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Article type: Appendix
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App1-
Published: June 30, 1984
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Hironori OHIWA, Tamaji IKEDA, Shuji KANDA, Akira HATTORI, Tateo NISHIM ...
Article type: Article
Pages
1-6
Published: June 30, 1984
Released on J-STAGE: March 30, 2018
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A Deep Diving System (DDS) has recently been completed after the successful shop test at Kobe Shipyard of Kawasaki Heavy Industries, Ltd. This system is planned to be mounted on a submarine tender (AS) for delivery to the Japan Defence Agency. The DDS consists of 1PTC (Personnel Transfer Capsule), 2DDC_s (Deck Decompression Chamber), 2MCC_s (Main Control Console) and supporting system. This system is designed to enable saturation diving up to 300m depth by total 12divers. The saturation diving is accomplished by the long term residence of divers under the high pressure of helium mixed gas corresponding to the diving depth. So, the environmental control inside the chambers are very important to keep the life and safety of the divers. Based on the knowledge on diving medicine and hyperbaric (high pressure) physiology, environment control system is designed and equipped. In the design of environmental control system, the special discussions are held about the environmental control criteria, adoption of external circulating system and temperature control responce. The various shop tests were carried out including unmanned operational test under 300m diving pressure and manned operational test under 60m diving pressure. Through the shop tests, fine environmental control performances are attained, as follows: pressure control accuracy: ±0.3m depth oxygen partial pressure control accuracy:±0.02 kgf/cm^2 temperature control accuracy:±0.5℃
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Hisayoshi TATANO
Article type: Article
Pages
7-16
Published: June 30, 1984
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In this 6th report the author shows some useful data for initial design of sailing yacht. The data are as follows; 1) Hydrodynamic derivatives of various type of sailing yacht models. 2) Effects of lead upon steady sailing performance. 3) Helm components in steady sailing condition. 4) On the power to carry sail and resistance-righting-moment ratio.
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Shigeru ASAI, Eiichi KOBAYASHI
Article type: Article
Pages
17-26
Published: June 30, 1984
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With trends of energy-saving ship design through lower-powered and lower-speed specifications, ship's manoeuvring characteristics are becoming more closely related with its propulsive performance. That is, under environmental forces due to wind, sea, and current, ship's course-keeping ability is unseparably connected with ahead resistance increase which can result in apparent drop in the service speed. It may be advised, therefore, that the mathematical models for simulation study on manoeuvring motions will be capable of dealing with propulsive performance as well. To cope with these demands, basic investigation is made on two mathematical models; a simplified one in which variations of longitudinal force and stern flow due to sway-yaw motions are simply expressed and MMG-type one in which expression of wake due to sway-yaw motions is modified. These models are derived so as to fully utilize experimental results about propulsive performance. In the present paper, various simulation including full-scale prediction is made to clarify applicability and effectiveness of the two mathematical models especially for manoeuvring motions. And it is shown that in spite of simple expressions mentioned above, simplified mathematical model is as effective as MMG-type one. It is considered that these mathematica1 models with assured reliability in prediction of manoeuvring motions will be effective for evaluation of ship manoeuvrability related with propulsive performance
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Eiichi KOBAYASHI, Shigeru ASAI
Article type: Article
Pages
27-37
Published: June 30, 1984
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In recent years, demands for computer prediction of harbour manoeuvring motions are increasing to evaluate ship handling safety under harbour environment. To carry out the task more efficiently, better mathematical model of harbour manoeuvring is necessary. In the present paper, two types of mathematical models were examined for low speed manoeuvring motions, including stopping, backing and large lateral drifting. The first simplified mathematical model dea1s with hydrodynamic characteristics of ships in such low speed conditions, following a conventional procedure. In the second advanced mathematical model, on the other hand, equations of motions for stopping and backing conditions were formulated taking the more detailed hydrodynamic characteristics into account, for example, hull-propeller interaction due to propeller reversing and drag to drifting in low speed condition. Using these two mathematical models, computer simulations were carried out and the results were compared with experimental ones. The obtained results are summarized as follows: (1) For estimation of stopping time only, simplified mathematical model will work fairly well with the effect of reversed propeller thrust. (2) For estimation of yaw and lateral deviations in stopping motions, hull-propeller interaction term due to reversed propeller rotation and drag to drifting in very low speed condition have significant effects. Taking them into consideration, the second mathematical model is found useful for computer simulation of harbour manoeuvring motions of ships.
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Takatsugu YOKOTA, Hiroshi SEKINE, Ryo TASAKI
Article type: Article
Pages
39-44
Published: June 30, 1984
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Our towing tank, IHI Ship Model Basin, has been afflicted for years with air bubbles which clung to the surface of a wax model and increased unsteadily the frictional resistance with roughing the surface. The phenomenon is a kind of tank storm, that is, the "positive" storm. T. Glen described his experience on a positive storm in the discussions to K.C. Barnaby's paper and concluded that the storm was biological in cause. The water of our towing tank is not so contaminated to be bacterized, as the water is purified with filters and the tank room has no window. The investigation of our positive storm showed that the air bubbles come from the supersaturation of air in the tank water which is brought on by the rapid rise of water temperature from the beginning of spring to summer. We have used a measure to prevent bubbles clinging which is to paint a wax model and jointly to sweep them off with the water jets before each running. Air bubbles however quickly collected, when the phenomenon is heavy, on the surface of the model even after sweeping completely them off. We have taken a radical measure directly to deaerate the tank water to keep it out of supersaturation. A deaerator capable of extracting daily 1.5% of the air contained in the tank water was put in August 1981 into the line from a filter to the tank. The air content of the tank water has decreased from 103% to 95% after operation of the deaerator for half a year and we have got through the seasons of 1982 and 1983 without any air bubble clinging. It is concluded that the large yearly variation of water temperature may quite possibly set up a positive storm due to air bubbles clinging in a towing tank and the deaeration of tank water is a practicable and effective measure to break up the storm.
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Hideaki MIYATA, Yasuaki DOI, Susumu TAKEUCHI, Hisashi KAJITANI, Makoto ...
Article type: Article
Pages
45-52
Published: June 30, 1984
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Some experimental results on the effects of stern configurations on both resistance and propulsion properties of simple hull forms are presented. Wave resistance is sensitively influenced by modification of stern configuration or attachment of an appended aft-body, which is attributable to the nonlinear free surface phenomena. Self-propulsion factors are also influenced by an appended aft-body which is located above a propeller.
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Akihiko FUJII, Kazuhiro FUKUDA, Hikaru YAGI
Article type: Article
Pages
53-60
Published: June 30, 1984
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This paper deals with the hull surface pressure of the full hull form ship under the action of a propeller. The distributions of the hull surface pressure were calculated by the potential theory in which the screw propelle was represented by the sink distribution on the actuator disk. It was shown that there were some discrepancies between calculated and experimented results. Flow visualization tests showed that these discrepancies were caused by the change of 3-dimensional separation regions due to the propeller action. By modifying such effect with the experimental function, the calculated thrust deduction coefficients by the present method agreed with the measured ones on the self-propulsion tests.
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Kiyoshi NEMA, Yoshio YAMAGAMI, Hodaka SHIMIZU, Tokio OHNISHI
Article type: Article
Pages
61-70
Published: June 30, 1984
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It is possible to calculate the hydrodynamic forces of vertical body of revolution in a very short CPU time considering its property of axisymmetry. In this paper, first, linear radiation and diffraction problems are formulated using three-dimensional Green's function of infinite water depth. The surface integral equation is transformed into a line integral equation analytically. Secondly, the radiation problem is solved numerically. Then, model tests are conducted to examine the accuracy of this calculation method. From the comparison with the test's results, it is confirmed that this method is useful for practical calculations.
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Norio TANAKA, Yoji HIMENO, Kimio NISHINO
Article type: Article
Pages
71-83
Published: June 30, 1984
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Mearsurements of unsteady hydrodynamic forces on a circular cylinder and a square cylinder are carried out. The motion of the cylinders are given by a forced oscillation mechanism with Reynolds numbers 35,000 to 50,000 and KC numbers 10 to 60. For the square cylinder attack angles are set to be 0, 30 and 45 degrees. For the analysis of the drag force, the authors attempt to clarify the magnitude of higher-order terms using Fourier expansions and a newly defined formula, in addition to the usual Morison's formula. It is found that there exists a considerable amount of the third-order force. The hydrodynamic lift is also found to be of the same order of magnitude as the drag. The lift frequency depends on the shape of the cylinder and the attack angle of the motion, although in the case of circular cylinder the frequency at high KC number is nearly equal to the value estimated from the steady-motion case.
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Minoru SAKAO
Article type: Article
Pages
85-101
Published: June 30, 1984
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In the case of a ship with wide beam and shallow draft, it is considered that a immersed transom stern has the advantage of a cruiser stern for ship resistance and stern structure. In this paper, making a ship with the ratio of beam to length B/L of about 0.15 and the ratio of draft to length d/L of about 0.03 the object of study, flow around her immersed transom stern was studied. The results are summarized as follows. 1. Flow around a stern of a high speed ship such as the flow separates at the lower edge of transom can approximate by the irrotational flow due to the pressure distribution on free surface which satisfies the linear water surface condition. For a ship of which B/L is nearly equal 0.15, the bottom pressure and the stern wave are expressed approximately by equation (19) and (18) respectively. For a ship of which B/L is smaller than 0.15, the stern flow is expressed approximately by equation (13) and the limit of application of it with B/L differs by the stern form. 2. Flow just after transom of a low speed ship is turbulent. For the estimation of pressure in the turbulent region, equation (30) may be available for the actual problem. The irrotational flow outside the turbulent region may analyse approximately by using the above mentioned equations for a high speed ship and flow analysis of a ship of which B/L is about 0.15 and smaller than it is not so difficult.
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Taiki TAKEDA, Yoji HIMENO
Article type: Article
Pages
103-113
Published: June 30, 1984
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The present paper concerns with a turbulence measurement in the stern flow field of a Series 60-0.6 C_B ship form. The measurement were carried out using a single channel slanted-wedge type hot-film velocimeter in a circulating water channel. The three components of mean velocity and six Reynolds-stress componets are obtained. It is found that the turbulence in ship stern is subject to a severe three dimensionality, and that the turbulence quantities show maximum values near the longitudinal vortex center. Also the turbulence intensities near water surface seem to be influenced by free surface effect. The distribution of mixing length at the stern indicates an influence of the longitudinal vortex. The Reynolds shear stress -<u'v'>^^^- is estimated by Cebeci and Smith's zero-equation model with a three-dimensional boundary layer calculation by Okuno's smethod. The comparison between the estimated result and the measured shows that the magnitudes are of the same order though the profiles in after-body sections show large difference.
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Masatoshi BESSHO, Yoji HIMENO
Article type: Article
Pages
115-125
Published: June 30, 1984
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An inverse procedure for minimizing the hydrodynamic drag of a body is proposed. The distribution of optimum body-deformation vectors is determined in each iterative step by solving an integral equation. The method is applied to two-dimensional Stokes flow. The basic equations with boundary conditions are converted into a set of integral equations. For the inverse procedure, another integral equation is introduced to obtain the distribution of an optimum body-deformation vector. The final optimum shape with the volume specified is obtained by an iterative scheme. Other various restrictions for length, beam, and/or moments are also taken into account. Numerical results and discussions on the optimum shapes are made. The present method can be applied to other flows like Oseen flow, cavity flow, and boundary-layer flow, and wll even be applied to the problem of ship viscousresistance optimization.
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Makoto KANAI
Article type: Article
Pages
127-135
Published: June 30, 1984
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A new photographic technique of wave analysis is developed The deformation of grid system projected on the water surface covered by aluminum powder film is photograhed by a 35mm camera. Two-dimensional wave profiles are analysed by use of a digitizer and a micro-computer. The details of the technique is described and it is applied to various wave problems, both steady and unsteady, such as wave making of an advancing ship, unsteady 2-D wave, diffraction of regular steep waves on a blunt-ended bow, and deformation of waves above a submerged mountainous obstacle.
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Hideo ONO, Toshiyasu TSUNENARI
Article type: Article
Pages
137-145
Published: June 30, 1984
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The fatigue crack propagation tests under K-controlled program loading and under random loading are executed on two kinds of steels and an aluminum alloy in order to establish the crack propagation life estimation method for actual structures, machines and so on. As for the K-controlled program test, transitional behavior of crack propagation after the acceleration or retardation was observed in order to improve the crack propagation model proposed previously by the authors. Subsequently, the quasi-random loading tests where the stress ratio is constant and the amplitude varies randomly every ΔN, cycles were performed to investigate the effects of stress distribution, ΔN, and truncate level of load on three kinds of materials. As a result, it was made clear that the fatigue crack propagation life under the random loading is roughly calculated by means of the linear estimation method using the constant amplitude test results. In addition, when the life estimation is made by means of either crack propagation model which takes into consideration the crack closure behavior or acceleration-retardation model obtained by the K-controlled tests, the estimated lives are more accurate than those by linear estimation method.
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Ken-ichi KITAURA, Hiroo OKADA, Yoichiro OKAMURA
Article type: Article
Pages
147-154
Published: June 30, 1984
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In this study, as a basic study on the impact fatigue of ship structural members under random load induced by sea waves, effects of mean stress on impact fatigue strength of mild steel are investigated experimentally. Low-cycle impact fatigue tests on four kinds of round bar specimens having stress concentration factor K_t=1∼4.7 under alternating axial load of systematically varying stress ratio are carried out. Ordinary fatigue tests are also carried out on the same specimens to make comparison with the above results. The results are summarized as follows: (1) The process of fracture for smooth specimens is a creep type and that for notched specimens having large K_t-values is a crack type independent of the stress ratio R defined by the ratio minimum stress σ^^-_<ca> to maximum stress σ^^-_<ta>. That for specimens having small K_t-values is different depending on magnitude of stress and stress ratio. (2) In the case of the creep type, the relation between permanent strain rate Δε_c and impact fatigue life N_f does not depend on R but the relation between stress amplitude σ^^-_a (=σ^^-_<ta> (1-R)/2) and N_f depends largely on R. In other cases, the relations between σ^^-_a and crack initiation life N_c and fracture life N_f depend largely on R, too. (3) From the above results, it is found that the relation between stress amplitude σ^^-_a and mean stress σ_m for each specimen except the notched specimen having very large K_t-value is given in the following form: [numerical formula] where σ^^-_<-0.8> : stress amplitude for stress ratio R=-0.8 σ'_B : ultimate stress for each specimen. (4) The fatigue behaviour for ordinary fatigue tests is almost similar to that for impact fatigue tests but the degree of effects of stress ratio on the fatigue behaviour is less than that for impact fatigue tests.
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[in Japanese]
Article type: Article
Pages
155-157
Published: June 30, 1984
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[in Japanese], [in Japanese]
Article type: Article
Pages
159-163
Published: June 30, 1984
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The world's slimmest "Water bus", 4.9 metres wide, 27.45 metres long, 1.2 metres depth and only 1.6 metres high from water level, has gone into service in Osaka carrying 116 (140) Passengers on each of its 3 sea mile runs along the city's waterfront. Four of the alternative transport vehicles are operated by a private company for scheduled runs in the morning and evening rush hour. At other time the unusual commuter vehicle is available for sightseen services. The air conditioned water craft has a clear grass roof, designed to lower automatically by more than 0.3 metres in order to pass under the major bridges in case of rising water levels. The water bus negotiates its scheduled run in 30 minutes, round trip fares are \500 for adults, with half-price fares for children and senior citizens.
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Article type: Appendix
Pages
165-167
Published: June 30, 1984
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Article type: Appendix
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App2-
Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Appendix
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Published: June 30, 1984
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Article type: Cover
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Published: June 30, 1984
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Article type: Cover
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