A measuring method for the transfer matrix parameters of acoustic systems by using 3 microphones is described in this report. The acoustic characteristics of engine intake systems are usually analyzed by the transfer matrix method. However, there are some intake subsystems for which there is still no adequate theoretical representation. By using the 3 microphones method, the matrix parameters of unknown systems can be determined experimentally. Furthermore, this 3 mirophones method was applied for measurement of the acoustic charastristics of sound absorbing materials. The propagation constants and the characteristic impedance of some materials were measured and compared with measured values by using the 2 microphones method
A ship is equipped with a large engine that increases ship vibrations. Particularly, it may give rise to the serious large vibration problems due to the coupling effect of the large engine and the hull. So, it is important for us to grasp vibration characteristics of each support point of a large engine. However, a measuring method of vibration char-acteristics of support points of a large engine has not been established until now because a ship engine is too large. Therefore, we tried to apply Mechanical Impedance Method to prediction of mechanical impedance at each support point by the former paper. This paper confirms utility of the experimental analytic method for measuring impedance characteristics of support points of a large engine that we suggested. And we showed the effectiveness of Mechanical Impedance Method by using the experimental results of the engine and hull models on prediction coupling vibration.
Steel plates are generally used as a member of structures and machines. But they often cause a serious vibration and noise trouble. Against these troubles, there is a way to use damping steel plates in the structure element as a effective measure. Yet about one of the kind of the damping steel plate, the ferromagnetic damping steel plate is not well clear of its effects. They say damping characteristics goes down when it is structured. In this paper, we are invest the damping characteristics of these To make clear these reasons, we investigated the damping characteristic of these constructed structures, using S.D.E. (specific damping energy) method. And we introduce a method to predict damp-ing performance of structure at a design stage.
Recently, computer technologies are being introduced very rapidly into the marine machinery. As for the boiler control, a new technique of PLC (Programmable Logic Control/ Controller) is being introduced and effectively used for sequential control of boiler machinery. By the introduction of PLC, which is composed of power-supply unit, CPU and I/O units, the control system is greatly simplified and become reliable. The PLC is used not only for controlling a BMS (Burner Management System) but also for a ACC (Automatic Combustion Control) system and a FWC (Feed Water Control) system in the latest boiler control. It could be expected that the introduction of PLC would decrease boiler troubles. But actual situation is not so, and boiler troubles caused by handling mistake are now increasing. Main reason for such trouble increase seems to be that marine engineers are given little chance to learn the internal structure of PLC, and the PLC is therefore an untouchable black box for them. Further they can not be given any chance for sufficient explanation on the PLC in OJT (on-the-job-training on board) . It is demanded, therefore, marine engineers should be educated for the knowledge of boiler control and PLC. Responding to the demand, the authors developed a simple boiler control simulator introduced a PLC system, and, using it, marine engineer's training is being carried out in the author's institute. This paper shows a training method using the simulator, and considers a future MET (E) (Maritime Education and Training for Engineers) method.
A gas turbine is well known as a clean thermal engine system, and it has an advantage of availability for multi-kinds fuels as a continuous combustion system. But it has not been popularized so much by its own low thermal efficiency. Recently, arranging the co-generation and the combined cycle, the gas turbine system has been reconsidered. In this report, we have investigated the availability of vegetable oils as a blender to a fuel for making good use of a gas turbine. After all, a waste oil (vegetable oil) was a good blender to a A -heavy fuel. The performance has good con-ditions.
Vegetable oils such as alcohol, rape-seed oil, etc., are well-known as alternative fuels in the near future. But they have low performance, especially long ignition delay and low calorific value, for use as a fuel of diesel engines. So we tried to improve better performance by mixing with petroleum. This report shows the application availability of the Laser speckle interferometry to the fixed combustion chamber in the former, and the ignition difference about each fuel's droplet by use of this interferometry in the latter. The performance analysis was something made clear, but the specification of temperature field in each combustion process was not clear by the disturbance of ignition ray, smoke and soot.
A feasibility study was made on the use of the waste edible oil used for cooking as an alternative fuel for diesel engines. If the waste edible oil is proved to be of use in diesel engines, the consumption of the fossil fuel would be reduced. In the experiment described in this paper, kerosene was mixed with the waste edible oil in order to improve some of the characteristics of the vegetable oil. The mixing ratios were varied from 20 to 80% in weight. The lower calorific value, density, surface tension and kinematic viscosity of the waste edible oil-kerosene mixture were measured. It was found that the mixing of kerosene improved the thermophysical properties of the waste edible oil. In addition, the ignition temperature and the ignition lag were measured and found to be improved by mixing kerosene more than 60% in weight with the waste edible oil. Finally the waste edible oil-kerosene mixture was burned in a conventional 273-cc diesel engine. Although the thermal efficiency was a little lower, the smoke level in the exhaust gas was confirmed to be almost the same level as the gas oil.
We propose a new reasoning method of crankshaft alignment in 2-stroke diesel engine for installing an engine on a vessel and for maintain the engine in good condition. The crankshaft alignment has not been reasoned qualitatively with practical measurement methods in 2-stroke diesel engine. In this study, a crankshaft alignment reasoning method is considered by using a measurement method, crankshaft deflection measurement method. Firstly, a model of a crankshaft and bearing support system of diesel engine is developed to calculate crankshaft deflection under assumed uneven crankshaft alignment. The model is solved by using transfer matrix method. Secondly, for the purpose of to calculate the crankshaft alignment by a measured crankshaft deflection result, it is necessary to solve the inverse problem. Therefore, genetic algorithm is applied for this solution. In this solution, each bearing height is changed until to fit the calculated crankshaft deflection under the assumed alignment for measured crankshaft deflection result. Finally, the developed algorithm is evaluated with actual measurement results in an engine. As a result, the developed algorithm is good correspondence with the difference height between adjacent bearings and also with the engine bedplate sag curves in several vessel conditions.
This paper describes a novel high frequency induction heating system to reduce particulate matters (PM) exhausted from diesel engine. In the first place, the optimum structure of a metal filter which traps PM is investigated. Secondly, ZCS characteristics of the multi-resonant ZCS high frequency inverter as the power supply of the high frequency induction heating system are analyzed in relation to load equivalent circuit. On the basis of the analysis, the high frequency high power supply with high efficiency for induction heating system has been estimated by experimental results in the treatment of diesel engine generator.