Since energy saving became an urgent problem, the constant pressure turbocharge system has been increasingly adopted especially in marine diesel engines because of its high thermal efficiency in the range of high mean effective pressure. Many cylinders are connected with one common exhaust pipe in this system. The exhaust pulsation is, therefore, so complicated that it gives adverse effect on some engines. However, it was difficult to take effective counter-measures when needed because the characteristics of the pulsation were not clear. The purpose of this study is, therefore, to clarify the characteristics of the exhaust pulsation in the constant pressure turbo-charge system and to establish a simulation system for it. As the result of the study, some of the characteristics have been made clear and a simulation system has been established. In this report the characteristic of flow at branch is to be firstly discussed and then it is presented that resonance can occur in the exhaust pulsation in this system in the range of ordinary revolutional speed of the engines.
The experimental results obtained from the effects of emulsified fuels, diesel oil and marine oil, on the soot formation and engine performances in the combustion of a marine low speed diesel engine are summarized as follows: (1) The emulsified fuels have a remarkable effect on the reduction of sooting ratio. The more we add water to the fuels, the more sooting ratio in the exhaust gas decreases. The minimum point of sooting ratio is being in this relation. (2) In the burning gases of emulsified fuels, the specific concentrations of carbon monoxide are more than in the original fuels. So it is suggested that the water in the emulsified fuels contributes on the water gas reaction. (3) Single soot particle measured with electron micrograph is a sphere of about 140Å in diameter and sizes are nearly same in a soot of both fuels. The swarm of soot particles is smaller in proportion to add water in emulsified fuels. (4) Ignition lags are longer in the burning of the emulsified fuels than in the original fuels, but the exhaust gas temperatures are lower. The consumptions per original fuels are little. (5) In the using of emulsified fuels, there is most fitting injection timing for the reduction of soot weight, fuel consumption and exhaust gas temperature. (6) Suction pressure has more influence in the using former fuels than latter fuels on the engine performance. (7) The volume of carbon sticked on the surface of the combustion chamber is little. From these experimental results, it is found that, in the burning of the emulsified fuels of a marine low speed diesel engine, there are remarkable effects on the reduction of sooting ratio, the consumption per original fuel and the dirt in combustion chamber. But there are problems of the corrosion of exhaust pipes and the dirt of lubricating oil by the water in emulsified fuels.
A study has been made on the fatigue limit of die forged crankshafts with 100 mm and 150 mm in journal diameter. It is found that the crankshaft shaped by die forging method has higher fatigue limit than those of the conventional forged ones, especially when the higher hardness layer than of their inner part is given on their outer layer by heat treatment. The required depth of this high hardness outer layer is estimated more than 0.2⋅R4 to increase fifty per cent in fatigue limit, where R4 is fillet radius. In the last part, a proposal for the estimation method of the fatigue limit of solid type forged steel crankshafts has been made based on our whole fatigue test results obtained on the actual sized crankshaft specimens with various dimensions and shaped by various methods.
In recent years, the quality of marine bunker fuel oil has been deteriorating and is anticipated to be poorer in the future. Although it is anxious that there must be happened many of considerable problems caused by degraded fuels, the more advanced technology of design and materials, including engine oil, on marine diesel engine is expected to solve such problems. This paper describes the influence of fuel deterioration against engine lubrication, and various charts and graphs show the effects of TBN and additive arrangement of engine oils on piston deposit and wear reduction. For this investigation, two types of test engine were applied, i.e. a Bolnes engine for cylinder lubricant of the crosshead diesel engine and a single cylinder Caterpillar test engine for the mediumspeed trunk piston diesel engine oil. And as for fuels in these engine tests, three grades of residual fuels in viscosity were burnt, i.e. IF 100, 180 and 380. In the last part of this paper, oxidative degradation tendency among three types of system oil; premium type, HD type and so-called mini-HD type in Bolnes engine test is discussed.