2행정기관의 연료분사시기에 따른 연소특성 = Combustion Characteristics with Fuel Injection Timing Variation in Two-stroke Engines

국문 초록 (Abstract)

본 논문은 2행정 선박기관에서 분사시기가 연소과정과 배기 배출물에 미치는 영향을 해석하고 분석하였다. 보어와 행정이 각각 42 cm 및 136 cm이고, 엔진회전수가 180 rpm인 엔진에서, 분사시기를 상사점전 15도에서 상사점후 5도까지 변화시키며 연소실의 압력변화, 연료분포의 거동, 연소과정에서 OH 생성 및 소멸, 중간 생성물인 CO 생성 및 소멸, 그리고 대표적인 유해배출물인 NO 생성에 미치는 영향을 분석하였다. 상사점 10도 이전에 분사된 경우, 피스톤이 상승하는 동안 분사가 끝나기 때문에 고온 고압 상태에서 연료가 반응하여 연소가 빠르게 완료된다. 이로 인해 연소실에 매우 높은 온도가 형성되어 다량의 질소산화물이 생성된다. 반면, 분사시기가 지연되어 상사점 이후에 분사가 시작되면, 분사된 연료가 하강하는 피스톤과 함께 넓은 공간에 분포되어 고온의 연소영역이 크게 감소한다. 이로 인해 연소속도가 느려지고 미연소 연료가 증가된다. 반면 질소산화물의 생성량은 매우 감소하게 된다.

다국어 초록 (Multilingual Abstract)

This paper analyzes the effects of injection timing on the combustion process and exhaust emissions in a two-stroke marine engine. For an engine with a bore and stroke of 42 cm and 136 cm respectively, and a speed of 180 rpm, the study examines the impact of varying the injection timing from 15 degrees before top dead center (BTDC) to 5 degrees after top dead center (ATDC). The analysis includes cylinder pressure variation, fuel distribution behavior, OH radical formation and decay, intermediate product CO generation and decay, and the production of the harmful emission NO. When injection starts before BTDC 10, the injection ends with the rise of the piston that results in rapid combustion in a high-temperature and high-pressure environment. This creates a very high temperature in the combustion chamber and leads to significant formation of nitrogen oxides. When the injection timing is delayed and starts after top dead center (TDC), the injected fuel spreads across a wider space with the descent of the piston that significantly reduces the high-temperature combustion area. Consequently, the combustion rate slows down and unburned fuel increases while the production of nitrogen oxides decreases substantially.

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