This paper presents some experimental results of the required time concerning to the combustion processes in diesel engines such as the illumination delay and the ignition delay. The experiments were carried out using a constant volume combustion chamber in the range of the initial pressure ρo up to 73 kgf/cm2, the initial temperature To up to 806K and the oxygen concentration φ up to 1.0. So called“ignition delay”is classified into heat release delay, illumination delay τi, pressure rise delay and ignition delay τid .In the range of higher initial temperature, the empirical relationships between the delays (τi, τid), and initial pressure ρo, initial temperature To and oxygen concentration φ can be presented the following form: τi=Apn0∅exp(B/T0), τid=A′pn′0∅c′exp(B/T0). In the range of ρo above 40 kgf/cm2, it is remarkable that ρo has no influence on τi and τid, that is, n and n' are almost zero.
In recent years, considerable attention has been given to the fatigue strength of ship propeller to establish a reasonable design standard. The authors carried out the strain measurement of high-speed twin-screw propeller in service condition, and conducted fatigue tests with the corroded fatigue specimens. The fatigue life of the propeller was discussed by using the stress-frequency curve and the fatigue results. The following conclusions may be drawn from the results of this work; (1) The blade stress conditions were as follows; mean stress and stress amplitude were 3.3±2.6 kg/mm2 in ordinary navigation, in transient state on turning, however, the stress amplitude became up to ±4.4 kg/mm2. (2) The stresses obtained in this measurement were good agreement with the stresses which were calculated under the load condition of blade estimated by using the torque and thrust taking account of axial wake distribution. (3) The fatigue results on corroded specimen under varying stress amplitude showed that the fatigue damage was caused by the stress amplitude being lower than the fatigue limit, and the S-N curve was on a partly shorter side of the fatigue lives explained by the modified Miner's rule. (4) The fatigue life of the blade was predicted by using the results of the fatigue test and the stress-frequency distribution from the measurements. It was known that the fatigue life using the modified Miner's rule on semi-logarithmic plotting of S-N diagram was nearly equal to the failed blade life.
In relation to the fact that barium compounds have a remarkable effect on the reduction of smoke level, the effect of barium compounds on soot formation is investigated in the combustion in diesel engine. Barium compound particles are either suspended in the inlet air or mixed with fuels. When barium compound particles are suspended in the inlet air, soot formation is suppressed less than its mixed with fuels. From the differences of size and form of soot and carbon particles between with and without barium compounds, it is suggested that barium compounds affect in the coagulation process of carbon particles, resulting in the reduction of smoke in the exhaust gas.
In general, it is widely recognized that the rate of fuel consumption of the vessel (output of main engine) is proportional with the“cube”of vessel speed (revolutions per minute of screw) . However, the vessel speed against a certain rate of fuel consumption is lowered little by little because of deterioration of hull's body, that is inevitable according to the passage of period of time, and soil, which occurs on hull's body. Therefore, was researched the relationship related with the individual stages on days after inauguration between the vessel speed (R.P.M. of screw) and rate of fuel consumption, while considering the vessel speed and rate of fuel consumption at the official trial operation on the sea, which was made immediately after her inauguration. On such a research, it was found that the amount of cube shown as the index of speed above is lowered in accordance as the time after inauguration is increased. So, presuming that such index of speed is“x”and also, presuming the primary function of‘days of passage’ (t), the relative formulas shown below between rate of fuel consumption and speed (R.P.M. of screw) were obtained for the individual vessels on research, “A-Maru”, “B-Maru”and“C-Maru”and by acquiring the amount “x”respectively on these vessels. “A-Maru”-------FtA=153×(rt/90)2.841-0.001153t “B-Maru”-------FtB=150×(rt/90)2.799-0.000533t “C-Maru”-------FtC=148×(rt/90)2.742-0.00104t By use of these formulas, the rate of fuel consumption (FtA, FtB and FtC) against the revolutions per minute of screw required at any optional time (t) after inauguration could be obtained. Although some problems still exist on the range of application by such revolutions per minute, the tendency of soils on hull's bottom area influenced by the vessel's age, voyage route, etc. can be supposed with these formulas.
Forecast of energy shortage were already stimulating the research and development of various saving energy systems, and the requirement of adequate analysis of energy consumption was emphasized. This paper notes the‘Energy Budget Method’for shipbuilding for the purpose of the evaluation of energy consumption. In general, the energy content of final products is made up of two parts; the direct energy content, the energy purchased by the firm for making and selling the products; and the indirect energy content, the energy used in the manufacture of supplies and in the service. And the‘Energy Budget Method’is one of the means for analysing the direct and indirect energy cost of products. In the shipbuilding field, our study shows the indirect energy, used for extracting and refining the materials and manufacturing the main engines and auxiliaries is far more than the direct energy which convert the materials into final ships in the shipyards. For the purpose of minimization of the energy required in the construction of ships, the wider systems optimization processes, in its industry's suppliers, and in its suppliers of materials, to be considered.