[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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This paper describes the development of the shear stress sensor for full-scale ship experiment carried out by the SR239 project of the Shipbuilding Research Association of Japan. The design concept and some preparatory experimental results have been shown. And the results of full-scale experiment are discussed compared with other measurement results. The effect of microbubbles to the local shear stress was discussed and the effect of the ship motion to the flow. field with microbubbles are also shown.

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The propulsion performance of an actual ship at sea deteriorates mainly due to the fouling of hull and propeller. If an on-board monitoring and analyzing system of propulsion performance could be realized, the system would be useful for planning the ship’s maintenance and management in order to perform the economical performance and safety through the ship’s service life. This research investigates the influence of the surface roughness on promotion performance with the model propeller of MAU 4-55 on the ship model basin and the training ship “Fukae-maru” of the Kobe University of Mercantile Marine (KUMM). The model experiment and numerical calculation of propeller performance with surface roughness effects were carried out. Using those researches, the relation of change of propeller torque coefficient K_Q and thrust coefficient could be shown by a simple estimation correlation, which can be presumed the surface roughness effects on the propeller performance. We believe that a monitoring system, which was developed by the method introduced in this paper, could be presumed the independent propeller performance change by surface rough and corruption; it can grasp the promotion performance of the ship on real time during a cruise.

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Numerical simulation of maneuvering of “Naniwa-maru” was performed to clarify the maneuver characteristics in particular with wearing operation. “Naniwa-maru” is a reconstruction of a sailing trader in the 18th to the mid-19th century in Japan. The rig was simple; single mast with a huge square sail. It was of totally wooden construction in a genuine Japanese manner. The sailing trial was performed in July and August of 1999. The steady sailing performance was measured and compared with the results of the VPP based upon tank tests and wind tunnel studies. The present paper shows the numerical simulation of her wearing operation, and the results compared with the measured data. The equations of motion dealt with coupled ship motions of surge, sway, roll and yaw with co-ordinate system using horizontal body axes. In order to obtain the hydrodynamic derivatives of the equations, the additional tank tests were carried out and the test data for the VPP were reanalyzed. The numerical simulation calculates ship response to the measured rudder angle, and shows the ship trajectory and the sailing state parameters such as velocity, leeway angle, heel angle and yaw angle. The calculated results coincided well with the measured data.

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[in Japanese]

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In previous works, the authors have developed the component-type mathematical model which can predict turning hydrodynamic forces by analyzing oblique hydrodynamic forces with in drift angle 90 degrees. In this paper, we have predicted maneuvering hydrodynamic forces by means of the mathematical model using principal particulars of a ship and using different analysis ranges of drift angles of oblique hydrodynamic forces. Then, we have simulated the steering motion by using these estimated hydrodynamic forces. As a results, it is found that the component-type mathematical model can predict turning hydrodynamic forces with large drift angles through oblique hydrodynamic forces and finally predict the maneuvering motion precisely.

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Numerical simulations of progressive waves and floating body’s motions with the particle method (MPS method) are examined. Availability of the particle method for strong nonlinear fluid phenomena has been considered through the comparison of flow patterns and fluid forces between simulations and experiments. When we study the steady problems like body motions in regular waves, we need to vanish wave reflection. This is very important to simulate waves and motions in finite region for practical problems. Therefore wave absorbing zone or system is discussed to be included in the MPS method. Based on these considerations, we show a numerical example of a large amplitude motion of the damaged floating body.

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When a ship with a wide immersed transom stern runs on a deeper draft, forward-oriented wave breaking often occurs just behind the transom stern. One of the most fundamental method to reduce the resistance is to optimize stern end form. In this paper, we take up stern bottom profile form as a component of stern end form to be studied. In design of the component, height of the lowest point at stern end is decided to keep necessary TKM on one side and height of the hull bottom just above a propeller is decided to lower propeller surface force under a required level on another side. With what form of curve should these two points be connected? Probably, most hull form designers have not paid so much attention to this limited part design. The authors’ studies on transom stern until now have suggested close relation between this part form and stern wave resistance. So, in this paper, we have compared three fundamental form of this part, ‘concave’, ‘flat’ and ‘convex’ by model test and have clarified the amount and characteristics of the effect of this part form on stern wave resistance.

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Recently, the shape optimisation methods using CFD techniques, are being applied to the fluid-dynamic design problems. However, since CFD analysis requires lots of CPU time-consuming, the performance of optimisers must be carefully investigated. In the present work, hydrodynamic ship shape optimisation system with two optimisers, that is a genetic algorithm(GA) and a gradient based method(GM), has been developed and the comparison & evaluation of the performance for the two optimisers are conducted. As a result, GA is found to be better optimiser, because it was able to reduce more drag than GM and consumed almost same computational time as GM.

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Low-level noise propellers with a higher performance are required lower incipient cavitation number of tip vortex cavitation and even if tip vortex cavitation is developed, to depress the underwater noise level. In this study, the author provided some highly skewed propellers that were modified propeller geometry to influence low-noise performance and then the incipient cavitation numbers and the underwater noise were measured at a cavitation tunnel by using the propeller models. From the results, we found that the propeller with lower incipient cavitation number does not always have low-level underwater noise even if the cavitation is generated. Also the author shows a guideline in design of low-level noise propellers by referring to the results from the measurements and CFD analysis.

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The window covering the recess of the ADCP (Acoustic Doppler Current Profiler) equipped at the bottom of a large ocean research vessel “Mirai” was broken sometimes. This paper reports about the investigated results of the reason of this breaking mainly by carrying out model experiments and by theoretical calculation of ship motions in regular and irregular waves. Some caution about the consideration of pressure distribution were found and some prevention methods were proposed. Those results will be some help to the similar situations.

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Waves statistics are important for the evaluation of a service performance of a ship. In general, waves statistics are given as a scattering table of significant wave height and mean wave period based on observation results. To make it easy to treat the table, researchers have proposed analytical distribution of wave statistics. They have been often applied by lognormal distribution and Weibull distribution. However, theoretical grounds of lognormal distribution and Weibull distribution are not so clear. Authors propose new stochastic models of wave statistics based on the regression to equilibrium condition. The models are expressed by stochastic differential equation with Gaussian process, and the distribution of wave statistics are obtained theoretically. The validity of the distribution is evaluated by the observation results of significant wave height and mean wave period. In addition, the time series simulation of significant wave height and mean wave period is shown.

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In this research, at first, Bow-Diving phenomena of planing craft is measured in model test and the relative position between the hull and water surface at the time of Bow-Diving phenomena occurrence is investigated. The results show that the hull, which dropped the bow by a certain disturbance, begins to sink and Bow-Diving phenomena occurs. Next, the steady hydrodynamic forces due to the displacements of ship motions are measured, and the characteristics of the forces are investigated. Consequently, it became clear that the hydrodynamic forces, which return to the steady running attitude, do not act on the hull that dropped the bow greatly by a certain disturbance. Furthermore, the simplified estimation method that Bow-Diving phenomena occurs based on the forces is proposed.

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In the present study, a methodology for planning, evaluating, and measuring an advanced marine transportation system is proposed, which consists of four steps, planning, selecting, evaluating, and measuring. In the methodology, firstly, internal and external factors of an advanced marine transportation system are identified using Internal and External Factors Analysis Summary (IFAS and EFAS) models. Then, strategies for planning an advanced marine transportation system are formulated using Strength Weakness Opportunities Threat (SWOT) model. After that, an alternative advanced marine transportation system is selected using Priority model based on index value of each alternative in which the highest index value of alternatives is selected. The selected advanced marine transportation system is evaluated using Life Cycle Value Chain model by measuring value of each stage in its life cycle. The methodology is applied for planning, selecting, and evaluating an advanced LNG tanker in Arun, Indonesia-Osaka, Japan route. The obtained results are discussed and compared with the conventional one.

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A theoretical study on psychological energy of a captain operating in conflict sea is made from the view point of thermodynamics. A relationship which corresponds to the PVT system of thermodynamics is found among P the blockage pressure, V the wide of the territory of a ship and T the temperature of menace in sense of her captain. Feeling of efficacy of a captain is defined effectively by the thermodynamic work. A model of psycho-engine in a captain is proposed keeping the conservation low of psychological energy. The psycho-engine change his willpower in motivation pool to his feeling of efficacy which is pooled in satisfactory experience. The psycho-entropy low which represents that the quality of motivation degenerates is applied to obtain a equilibrium velocity in operation in a straight narrow canal. The obtained velocity is proportional to square root of the width of the canal.

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