The present study is begun with the idea based on the propulsive method by oscillating a caudal fin, as a result of examining conventional propulsion systems of a ship in terms of safety, energy saving and environmental integrity. The purpose of this study is experimentally to pursue the problem which an oscillating wing is practically applied to the propulsion system of a ship. In this work, a simple two-dimensional oscillating wing model is analysed macroscopically; the basic experiment is carried out by use of both an apparatus oscillating a wing harmonically and a circular stream water tank. Consequently, experimental results are in good agreement with numerical analysis for low reduced frequency; the relationship between wing's motion and its thrust has been clarified; the optimum value of phase lag ψ= 60°causing a maximum coefficient of thrust is present; when the optimum value of phase lag is ψ=90°and that of reduced frequency isΩ=0.6-0.8, an efficiency of propulsion of a single wing indicates the value of about 53%.
Luwa TLT eliminator is a kind of the eliminators constructed by zigzag bended thin-plates. A bending angle of this eliminator is 60°, a bending number of 3, and a thickness of plate made of CPVC is about 2 mm. The each bending corner of this is round more or less, and the each bending plate has a few zigzag parts. Luwa TLT eliminators used here have two different dimensionless pitches, one is 0.64 (pitch of 24 mm) which the other is 1.07 (pitch of 40 mm) . In this paper, separation of water droplets from air including water droplets by Luwa TLT eliminators is investigated through experiments, and obtained separation performances are considered as compared with the results predicted by theoretical analysis which has been presented by one of the authors of this paper. And furthermore resistance coefficients of these eliminators are also investigated. The test section is the vessel made of 10 mm thick transparent acrylic sheet (same material used in the existing horizontal duct), and Luwa TLT eliminator is incased in it. Experiments have been made varying from 2.0 to 10.0 m/s in mean air velocity and varying from 0.085 to 0.95 mg/ (mm2·min.) in mass flow rates of water droplets at inlet of the test section, respectively. The water droplets have been obtained in various sizes from about 5 to 170μm.
Most of the icebreaking vessels employ electric propulsion systems which utilize diesel engine prime-movers, ac generators, rectifiers, do motors and fixed pitch propellers. The nature of the icebreaking process imposes certain unique loads on the propulsion systems of ships applied to such service. These systems are subject to inefficient operation in addition to possible failure of propellers, shafting or other system components. To estimate the static and dynamic performances of the proposed AC-R-DC electric propulsion system applied to the icebreaking ship, a brief description of the icebreaking process is presented and a method for calculating load torques in function of the advance coefficiency is developed. An introduction is given to methods which utilize steady state and dynamic technique for synthesizing the AC-R-DC electric transmission system which meets given performance requirements. Transient characteristics of the system are calculated in cases of step and impulse ice loading. Effects of torsional vibration of shafting are also evaluated.
From the thermodynamic point of view, an evaluation of energy flow is very important for energy saving. In this paper, the mathematical regularity of available energy is examined such that a value of parameters is influenced by the neighborhood of environment. A part of available energy is disappeared or produced by a variation of outer system. These phenomena are explained by a transposition from available energy to unavailable energy induced by a variation of environment. This study deals with these transposition of available energy for ideal gas change and polytropic change. The purpose of this paper is to investigate the transposition from available energy to unavailable energy or vice versa in more detail.
In our country, general cargo transportation is shared progressively by the autotruck, and, at present, which is going to conquer completely the cargo vessel and the railroad. In order to recapture the transportation demand of general cargo, therefore, the marine tranporter is forced to devise countermeasures coping with the autotruck. When the shipper can use several transportation measures, he chooses one from them to minimize his shipping cost. Among many factors influencing the shipper's cost two factors are considered to be important. The one is the transportation performance which is expressed as the energy consumption per a unit transport, that is, kcal/ton·km, and the other is the total transport time, that is, the door-to-door time. From the viewpoint of above shipper's cost, this paper proposes the catamaran ferry as one of such countermeasures. Because the catamaran has a wide deck area which makes it possible to ameliorate the transportation performance, and the ferry can transport general cargo with high speed enough to compete with the autotruck. A case study is carried out to reveal these merits. In the case study, the transportation performance and the total transportation time of the catamaran ferry are compared with those of the autotruck and the container vessel in regard to model routes in the SETONAIKAI region.
In the burning of low grade fuel droplets in which contain much high carbonized carbon residue and sludge, the squre low (-dD2/dt=const.) of droplet diameter (D) does not come into existence. Therefore, the new method of burning rate which is measured by the pressure changes of combustion chamber in the buring of marine them was studied experimentally. It was found to answer this purpose roughly.
The reduction in fuel consumption and NOxemission have been confirmed with burning of emulsified fuels in diesel and boiler plant so far. Fuel savings from four to seven per cent have been achieved, when burning water-in-heavy oil emulsions in marine diesel engines. In the evaluations of emulsified fuel combustion, the following parameters should have been considered: water content, particle size, distribution, stability, viscosity, specific gravity. These fundamental data with emulsified fuel have been lacked. Thus investigations have been given to these parameters which affect conditions of combustion.