A theoretical investigation of misfiring effects on the crankshaft torsional vibration of diesel engine

디젤기관 착화실패가 크랭크축계 비틀림 진동에 미치는 환경의 이론적 고찰

Since the oil shock of '70s the engine makers have developed new types of diesel engine with low fuel consumption. There is an obvious tendency towards the use of poorer quality fuels, such as the residual oil from chemical processes of refinery. The shaft driving generators is also widely adopted on behalf of the auxiliary diesel engines, which are driving on the expensive diesel oil and have high fuel oil consumption rates, and some mania propulsion diesel engines are equipped with reduction gear systems to get better propulsive efficiency by slower propeller revolutions. The propulsion shafting system equipped with the shaft driving generator or the geared diesel engine shafting system has flexible couplings, and it requires extensive investigations of the torsional vibration and torque fluctuation in order to ensure the acceptable operation range in service. The characteristics of misfiring must be especially examined for the high viscosity fuels to be used. Both torsional vibration and fluctuating torque resulted from misfiring, should be examined for thier effects on the flexible coupling and propulsion shafting system. This paper is to investigate and solve the above mentioned problems which must be predicted on the design-stage of marine propulsion shafting system. A computer program is developed to calculate the indicated diagram, fluctating torque and torsional vibration for both normal and misfiring conditions.