There are several problems regarding of the relation between maximum pressure variation in each cylinder and exhaust and scavenging process in the two-cycle marine diesel engine. In this type of diesel engine, it is not easy to test by the fired engine in practice. Therefore, it can not help to depend on a model test, or a simple test. In this paper it takes up basical problems associated with the scavenging, and which was discussed how to experiment by using a model. One cycle dynamic model which can be done one cycle scavenging process was made. By this model an experimental study regarding the scavenging carried out. It was found that dynamic effects, that is, the effect of revolution of a model in scavenging efficiency appear slightly, and the density difference of scavenging gas regarding to exhaust gas is affected considerably in the efficiency.
In recent years the capacity of electric power has grown larger with the increase of the scale in the tankers and container ships. The marine electric power systems will be more complicated by the superautomated ships, and the analytical method should be improved. In general marine electric power systems, the two-machine systems have been adopted and the analytical method, precisely simulated by the computer, has never developed. This paper describes the analytical method on the synchronous machine assumed one machine to infinite bus as the first step and the dynamic behaviour altogether, and it will contribute to improvement of the reliability and safety on the marine electric power systems. The accident modes are displayed by the three phase short circuits phenomena at the sending and receiving end on the transmission lines, further including the reclosing faults. The main parameter characteristics of the generators for a long period can be derived from the calculated results, and are available for the system operation and design.
The pitch, blade shape, etc. of ducted propeller are considerably different from those of conventional propeller. Combined with duct, such a special shape of propeller is assumed to have some effects on the torsional vibration of shafting on diesel ship. To investigate this matter, we have carried out the measurement on actual ships and have found the following. (1) The formulas for propeller entrained water calculation by Burill and Robson and also by Takaira and Yano are applicable to ducted propeller. (2) The damping effect on torsional vibration in ducted propeller is larger than that in conventional propeller.
In general, an actual data of marine use mechanical parts is not clearly classified in the failure replacement and the periodic replacement. This main reason is that a specified period of repair is sometimes disturbed and becomes random by several reasons, for example, ship's schedule, operational conditions, judgements of a maintenance crew and so on. In this note, the replacement data of valves of main diesel engine, i.e., the exhaust valve and the fuel oil valves, is chosen from such data which is gathered from four same type ships, and analyzed by using the Weibull chart, in which, in particular, we notice the shape parameter m. Next, the secular change and the characteristic of valve replacement on each ship is investigated through the shape parameter m. According to these obtained results, it is clear that m values have the range between 1.0 and 2.0, and as the time of using these parts increases, the maintenance method has a tendency to go to the specified replacement.