Effect of Reentrant Type Bowl Geometry on Combustion Characteristics in Diesel Engine -Effect of Reentrant Angle and Cupola Height of Bowl Center-

리엔트런트형 연소실 형상이 디젤기관의 연소특성에 미치는 영향 -리엔트런트 각도 및 중앙돌기부 높이의 효과-

Effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.I. diesel engine. The main factor was the cupola height of bowl center and the reentrant angle of combustion chamber, and the cylinder pressure, engine performance and emissions of the engine using the total 11 kinds of the combustion chamber were measured by test. The results are as follows. The NOx decreases by increasing the cupola height of bowl center because it makes the decreasing of maximum combustion pressure by the heat loss and smooth combustion from good airflow. The smoke increases by increasing the reentrant angle at high speed range of the engine, but decrease at low and medium speed range until the reentrant angle becomes $15^{\circ}$.