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성층희박연소 운전조건에서 분사시기에 따른 분무유도식 직접분사 가솔린엔진의 분무 및 화염특성
오희창(Heechang Oh),이민석(Minsuk Lee),박정서(Jungseo Park),배충식(Choongsik Bae) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.3
분무유도식 DISI엔진의 성층연소운전조건에서 분무 및 화염특성에 대한 실험적 연구가 수행되었다. 연소가시화를 통하여 성층연소 DISI의 연소는 희박 예혼합 연소와 확산연소의 성격을 모두 가지고 있는 것으로 확인되었다. 분사시기에 따른 혼합기 형성특성이 연소의 특성을 결정하는 중요한 인자임을 관찰하였다. 분무와 혼합기 가시화를 통해 낮은 분위기압에서의 over-mixing , 높은 분위기압에서의 under-mixing이 발생하는 것을 확인하였으며 이러한 혼합기 형성과정의 결과에 따라 화염특성, 연소효율 등의 연소특성이 결정되는 것을 살펴볼 수 있었다. 또한, NOx, IMEP도 분사시기에 따른 경향성을 보였으며, 분사시기에 따른 연소상의 변화에 의한 영향임을 확인하였다. An experimental study was carried out to investigate the effects of the injection timing on the spray and combustion characteristics in a spray-guided direct-injection spark-ignition (DISI) engine under lean stratified operation. An in-cylinder pressure analysis, exhaust emissions measurement, and visualization of the spray and combustion were employed in this study. The combustion in a stratified DISI engine was found to have both lean premixed and diffusion controlled flame combustion characteristics. The injection timing condition corresponding to the stratified mixture characteristics was verified to be a dominant factor for these flame characteristics. For the early injection timing, a non-luminous blue flame and low combustion efficiency were observed as a result of the lean homogeneous mixture formation. On the other hand, a luminous sooting flame was shown at the late injection timing because of an under-mixed mixture formation. In addition, the smoke emission and incomplete combustion products were increased at the late injection timing as a result of the increased locally rich area. On the other hand, the NOx emissions decreased and IMEP increased as the injection timing retarded. The combustion phasing produced by the injection timing was verified as the reason for this observation.
레이저시트광을 이용한 가시화 디젤엔진에서의 soot 계측
이명준,박태기,정성식 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.1
Recently the laser sheet technique has been developed to improve our limited understanding of the in-cylinder diesel combustion. The technique is capable of high temporal and spatial resolution, so that it is proved to be an adequate combustion diagnostics to finding out exhaust emission formation. These temporal and spatial sequences of LIS(Laser Induced Scattering), LII(Laser Induced Incandescence) images were made which show the extent of the soot distribution within the optically accessible diesel engine. And LIS, LII signal images of soot distribution provide new insight into where and when soot occurs in a diesel engine.
분사기공형상이 HSDI 디젤 엔진의 성능과 배기에 미치는 영향
공장식(Jangsik Kong),국상훈(Sanghoon Kook),이승원(Seungwon Lee),최욱(Wook Choi),배충식(Choongsik Bae) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the study, the influence of nozzle hole geometry, rail pressure and injection timing on combustion was analyzed in an optical access single-cylinder diesel engine equipped with a high pressure common-rail injection system. The K factor represents the taper ratio of the nozzle hole of the injector. The injection rate showed that tapered nozzle hole with bigger K factor result in a higher injection speed. A tapered nozzle produced some favorable results; a greater heat release and decreased THC (Total Hydrocarbon) and PM (Particulate Matter), despite an increase in NOx (Nitrogen Oxides) level.
직접 화염 가시화를 통한 직접분사식 가솔린 엔진의 성층연소과정 및 입자상 물질 배출 특성에 대한 연구
오희창(Heechang Oh),정진영(Jinyoung Jung),배충식(Choongsik Bae) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
An experimental study was carried out to investigate the combustion process and PM emission characteristics in a spray guided direct injection spark ignition (DISI) engine under lean stratified operation. In-cylinder pressure analysis, exhaust emissions measurement, and visualization of the spray and combustion were applied. Combustion process in a stratified DISI engine was found to be followed 3 major process; the premixed combustion which shows faster combustion speed and high intensity of heat release rate, mixing controlled combustion showing high intensity of luminous flame and lean premixed combustion of which combustion speed is low with smaller intensity of heat release rate. Luminous sooting flame during the combustion process is identified that it represents incylinder formation of PM. PM emission was verified that it is originated from the locally rich area in the stratified mixture which was not burned during the main combustion propagating. Result of incylinder spray visualization and PLIF mixture visualization in a constant volume chamber supported this explanation.
이중순 ( J. S. Lee ) 한국액체미립화학회 2000 한국액체미립화학회지 Vol.5 No.1
Recently the laser sheet technique has been developed to improve our limited understanding of the in-cylinder diesel combustion. The technique is capable of high temporal and spatial resolution, so that it is proved to be an adequate combustion diagnostics to find out exhaust emission formation. The optical signals of LIS(Laser Induced Scattering) and LII(Laser Induced Incandescence) images show informations for soot concentration within the optically accessible diesel engine. The LIS and LII signal images of soot concentration provide new insight into where and when soot occurs in a diesel engine.
SCV 형상에 따른 가솔린 기관의 실린더내 연소특성 연구
이석영(Sukyoung Lee),정구섭(Kuseob Jeong),전충환(ChungHwan Jeon),장영준(Youngjun Chang) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve SI optically accessible engine with swirl control valve(SCV). It adapted three different types of SCV(open ratio 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and in-cylinder mean gas velocity were calculated to explain combustion characteristics. Results indicate the superior of IMEP and an increase of 0.1 ㎧ to 0.2 ㎧ in maximum ensemble average mean gas velocity when SCVs are attached as compared to base-line engines. From acquired flame images, we inspected the flame propagation direction and flame centroid. Flame propagation direction showed different tendency between with/without SCV, It was possible to observe the flame propagation in the combustion chamber, and in a base-line engine, the flame propagated towards the exhaust valve, while flame propagation in SCV-attached engines propagated towards both the exhaust and intake valves due to the influence of intensified swirl flow.