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이차원발광화상계측에 의한 예혼합압축자기착화연소의 연소실내 혼합기의 불균질성에 관한 연구
임옥택(Ocktaeck Lim),노리마사 이이다(Norimasa Iida) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.12
HCCI엔진에는 농도성층화와 열적성층화가 존재하고, 이것들은 착화와 연소과정에 영향을 미치고 있다. 본 연구에서는 예혼합기의 불균질성이 HCCI연소과정에 미치는 영향에 대해서 조사하였다. 우선 4행정광학엔진을 이용하여 잔류가스가 있는 경우와 급속압축장치를 이용하여 잔류가스가 없는 경우의 예혼합기의 불균질성에 대하여 비교분석하였다. DME를 연료로 이용하고 프래밍카메라를 사용하여 2차원화학발광이미지를 취득하였다. 그 결과, 잔류가스가 있는 불균질 한 경우에 4행정엔진실험에서는 연소현상이 공간적으로 연소현상의 시간차이가 발생하였다. 잔류가스가 없는 급속압축장치의 실험에서는 4행정기관의 결과에 비해서 더 적은 공간적인 변화가 존재하는 것을 알 수 있었다. Fuel stratification and thermal stratification occur in the HCCI combustion chamber on a microscopic scale. They affect the ignition and combustion processes. In this study, the effect of the inhomogeneity in the mixture gas on the HCCI combustion process was investigated. Two-dimensional chemiluminescence images were captured using a framing camera to evaluate the flame structure. DME was used as the test fuel. First, the effect of inhomogeneity in the fuel distribution in the premixture was investigated for the four-stroke optically accessible engine. Then, by comparing the combustion of the homogeneous mixture in the rapid compression machine, which does not contain any residual gas, with the combustion in the four-stroke engine, the effect of inhomogeneity in temperature due to the residual gas was analyzed. The results showed that a time lag appears spatially in combustion under inhomogeneous conditions in the four-stroke engine. The spatial variation in the combustion without the residual gas in the rapid compression machine is less than that in the combustion in the four-stroke engine.
예혼합기의 열적성층화가 PRF연료의 예혼합압축자기착화에 미치는 영향
임옥택(Ocktaeck Lim) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.5
The HCCI combustion mode poses its own set of narrow engine operating by knocking. In order to solve this, inhomogeneity method of mixture and temperature is suggested. The purpose of this research is to get fundamental knowledge about the effect of thermal stratification on HCCT combustion of PRF-Air mixture. The temperature stratification is made by buoyancy effect in combustion chamber of RCM. The analysis items are pressure, temperature of in-cylinder gas and combustion duration. In addition, the structure of flames using the two dimensional chemiluminescence's images by a framing camera are analyzed. Under stratification, the LTR starting time and the HTR starting time are advanced than that of homogeneous. Further, the LTR period of homogeneous conditions became shorter than that of the stratified conditions. With the case of homogeneous condition, the luminosity duration becomes shorter than the case of stratified condition. Additionally, under stratified condition, the brightest luminosity intensity is delayed longer than at homogeneous condition.
예혼합기의 열적성층화가 PRE연료의 예혼합압축자기착화에 미치는 영향
임옥택(Ocktaeck LIM),이이다 노리마사(Norimasa IIDA) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The HCCI combustion mode poses its own set of narrow engine operating by knocking. In order to solve this. inhomogeneity method of mixture and temperature is suggested. The purpose of this research is to get fundamental knowledge about the effect of thermal stratification on HCCI combustion of PRF -Air mixture. The temperature stratification is made by buoyancy effect in combustion chamber of RCM. The analysis items are pressure, temperature of in-cylinder gas and combustion duration. In addition, the structure of flames using the two dimensional chemiluminescence's images by a framing camera are analyzed. Under stratification, the LTR starting time and the HTR starting time are advanced than that of homogeneous. Further, the LTR period of homogeneous conditions became shorter than that of the stratified conditions. With the case of homogeneous condition, the luminosity duration becomes shorter than the case of stratified condition. Additionally, under stratified condition, the brightest luminosity intensity is delayed longer than at homogeneous condition.
HCCI엔진연소에서 엔진회전수의 영향에 대한 수치해석연구
임옥택(Ocktaeck Lim),윤상진(Sangjin Yoon),박규열(Kyuyeol Park) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
HCCI combustion offers both high efficiencies and very low NOX and particulate emissions. However, operating range of HCCI engines is limited by an excessive pressure rise rate(PRR) during combustion in high load region which will lead engine knock. HCCI combustion is controlled by chemical reaction depending on thermal properties and fuel composition. Besides, engine speed also has significant effects on ignition timing, since it relates to the speed of compression. The engine speed is related to combustion robustness in expansion stroke because of changing expansion speed. The objective of this study is to investigate the influence of engine speed on combustion characteristics such as in-cylinder gas temperature, pressure at combustion start, combustion duration and combustion efficiency by using numerical analysis. Then, In order to investigate the mechanism of influence of engine speed, contribution matrix has been used. In results, DME which has negative temperature coefficient and methane which has not negative temperature coefficient were used as fuels.