Minoru Kamata

Study on Arrangement of Fire Detectors in Engine Room of Ships (1 st Report)

In ships engine room, many fire detectors are positioned for rapid detection of the onset of fire, and most of them are smoke detectors. The purpose of this study is to present a guidance for the arrangement of smoke detectors under the actual ventilating condition in engine room. As the 1st report, this paper shows the performance results of smoke detectors in some fire tests based on the combustion of marine fuel oils. In the tests, the effects of height of detectors above fire source and the speed of ventilation air were investigated.In addition, considering fire alarm tests on board, we proposed the method of fire test using smoke signals for automobiles which is equivalent to fire test using marine fuel oils.

Sound Power Measurement Method of Marine Diesel Engines

Sound power evaluation methods are investigated numerically and experimentally. Sound measurement in ships engine room is under very inferior condition because the engine is installed in such a small place. There are two methods to evaluate sound power; sound pressure based method and sound intensity method. The investigation shows that the former method has a inferiority in the precision, especially in the decision of environment correction factor, and the latter method is not practical for a large marine engine. As a result, the hybrid method which has both precision and practicality is proposed.

Torsional Vibration Characteristics of Marine Diesel Propulsion System Installed with Highly -Elactic Rubber Coupling

Rubber is applied to highly-elastic couplings installed in geared diesel propulsion system. Taking advantage of its high elasticity and large damping effect, torque fluctuations transmitted to gear can be diminished. However, the dynamic behaviour of the shafting system including rubber is not comprehended exactly because of their complex characteristics and scant examples of detailed measurement under actual operation.In order to make clear the dynamic characteristics, the authors did comprehensive full-scale measurement on two ships and have been analizing the results. The aim of this study is to show the actual torsional vibration of rubber damping system and to present a practical calculation method by modal analysis applicable to the system. This paper, which is the 1 st report of the study, is devoted to the illustration of the results of the full-scale measurement. At first, the framework of the measurement is explained. Then the dynamic response at each parts of rubber couplings is showed as well as general features of the rubber damping system.