선박용 디젤 기관의 축토크 변동에 관한 연구

Abstract

From a few decades, lots of researches have predicted that oil reserves are already passed the peak. We still rely on fossil fuel, but any energy can’t replace with fossil energy so far. China has recorded 10% economic growth every year and the growth of China has been leading world economy from global recession. However, the more China has grew up, the more increase oil consumption. The growth of China causes rising of oil price.

The efficiency of engine power began to take a growing interest because oil price was increased. Monitoring & diagnosis systems have been set up in almost all ships which were constructed lately in order to check the engine power and condition.

There are two methods to obtain engine power. One of them is to calculate indicated mean effective pressure by cylinder combustion pressure and another is to measure the strain from propulsion shaft like torque meter and dynamometer.

Low speed engine such like marine diesel engine has high combustion pressure. If combustion pressure of one cylinder is largely differed from the others, torque fluctuation become out of balance. Torque fluctuation brings on torsional vibration to caused of breakdown of propulsion shaft. Confirming and checking the torque fluctuation by monitoring and diagnosis system in real time can make the vessels safe and economical.

Controlling of emission from onboard ship as well as on land being more important issues. Especially, the CO2 gas is the biggest issue and many conferences about it have been held from 1997, the Kyoto Protocol to Dec of 2009, Copenhagen, in other to reduce CO2, but the conferences didn’t get a good result due to different opinion between developing countries and developed countries. In Cancun conference which was held in 2010, mutual agreement about reducing green house gas was reached. They were regulated and had been taken effect from 2005 in the name of ‘Prevention of air pollution from ships’ in the MARPOL 73/78 Annex VI. The air pollutants as NOx, SOx, VOCs can be reduce by several ways such as CR(Common Rail), EGR(Exhaust Gas Recirculation), SCR(Selective Catalytic Reduction), but the best way to reduce CO2 is to decrease rate of oil consumption.

This paper describes methods of measurement of cylinder pressure and shaft speed by using encoder which is set up on end of shaft in test engine A. This paper also describes methods of measurement of shaft speed by using pick up sensor set up on flywheel in test engine B. The torque fluctuation was calculated by combustion pressure measured in test engine A. The variation of shaft speed was measured in test engines A and B and then shaft torque was calculated by the shaft speed. This paper shows the results considered of shaft torque fluctuation which was measured by the variation of shaft speed in order to confirm torque fluctuation calculated by cylinder pressure.