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엄인용(Inyong Ohm) 한국가시화정보학회 2004 한국가시화정보학회지 Vol.2 No.2
Initial flame development and propagation were visualized under different fuel injection timings to relate the initial flame development to the engine stability in a port injection SI engine. Experiments were performed in an optical single cylinder engine modified from a production engine and images were captured through the quartz window mounted in the piston by an intensified CCD camera. Stratification state was controlled by varying injection timing. Under each injection condition, the flame images were captured at the pre-set crank angles. These were averaged and processed to characterize the flame. The flame stability was estimated by the weighted average of flame area, luminosity, and standard deviation of flame area. Results show that stratification state according to injection timing did not affect on the direction of flame propagation. The flame development and the initial flame stability are strongly dependent on the stratified conditions and the initial flame stability governs the engine stability and lean misfire limit.
엄인용(Inyong Ohm),명차리(Chalee Myung) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_1
A PlV (Particle Image Yelocimetry) was applied to measure in-cylinder velocity field according to intake flow characteristics that were defined by steady flow bench. Two engines, one is conventional DOHC 4 valve and the other is high swirl lean combustion., were used to compare real swirl and tumble flow. Swirl and tumble ratios were also calculated from the velocity by momentum and energy method.<br/> The results show that the swirl flow patterns become more and more complicated as the measuring plane is far from the TDC and the tumble flow is more clearly observed under the one port deactivation condition. In high swirl condition, unexpected reverse tumble flow is observed during compression. The swirl ratio has higher value at BDC timing and the strength of tumble steadily decreases from the early stage of intake.
엄인용(Inyong Ohm),박찬준(Chanjun Park),우성동(Sungdong Woo),장열성(Yeolsung Chang) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake stroke. Two engines, one is conventional DOHC 4 valve and the other is narrow valve angle. were used to compare real intake flow. The results show that the intake flow pattern of conventional engine is more complicated than that of narrow angle one in horizontal plane and the vertical component of in-cylinder flow is rapidly decayed at the end stage of intake. On the other hand, the flow pattern of narrow angle one is relatively well arranged in horizontal plane and the vertical velocity component remains so strongly that forms large-scale strong tumble. Two engines also form commonly three tumble; two are small and bellow the intake valve and one is large-scale. The center of large scale tumble moves to bottom of cylinder as the vertical velocity increases.
흡입 밸브 각도에 따른 압축 행정 중 실린더 내 유동 특성
엄인용(Inyong Ohm),박찬준(Changjun Park),장열성(Sungdong Woo),우성동(Yeolsung Jang) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during compression stroke. Two engines, one is conventional DOHC 4 valve and the other is narrow valve angle, were used to compare real compression flow. The results show that the flow patterns are well arranged compared with intake flow and the basic tumble flow structures are maintained until end compression stage regardless valve angle. Also the results shoe that the tumble motion is intensified by momentum conservation during compression in normal engine. In the normal engine, the bulk shape of flow pattern is "Y" type at the top of cylinder and reverse "Y" type at the bottom of cylinder and weak reverse flow exists at the top of cylinder along cylinder center line. Otherwise, the other engine's flow pattern changes from "Y" type to "T" type at the top of cylinder during compression.
[가솔린엔진부문] 공연비 계산법에 대한 고찰 : Part 5 - 계산방식의 총괄 평가
엄인용(Inyong Ohm),이원근(Won Geun Lee) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.11_1
This paper is the last of 5 companion papers which compare the method of Air-Fuel ratio determination. In the previous work, various AFR calculations were performed for various fuels and the results were compared with each other. The comparison, however, were limited to numerical value and estimation of each equation or method was insufficient.<br/> In this paper, the overall estimation of the methods was attempted. Also, the method of trouble shooting of instrumentation was presented.<br/> Through the estimation of methods, it is concluded that the Eltinge method contains inherently the most perfect thermal dissociation model as far as the exhaust composition is concerned; therefore, this might be regarded as the most general equation of AFR determination among the existing ones. The others might be considered as approximate form. In addition, the mal-distribution factor in Eltinge method is qualitatively equivalent to thermal dissociation chemical equilibrium constant K. Lastly, it is illustrated that all instrumentation error, including the sampling line leakage, can be easily detected through the analyzing the exhaust component on the Eltinge chart<br/>
밸브 각이 큰 나선형 포트 엔진의 실린더 내 흡입 유동 특성
엄인용(Inyong Ohm),박찬준(Chanjun Park),김형식(Hyeongsik Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Two wide valve-angle engines, which are same ones and have slightly different rig swirl number, were used to compare the characteristics of cylinder-flow. One intake port is deactivated to induce swirl flow. A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field during intake stroke. The results show that the intake flow component passing through valve area near the cylinder wall is not negligible in helical port engine with wide valve angle contrary to conventional one. The effect of this velocity component on in-cylinder increases as the swirl ratio rises and intake process progresses. Consequently, this component interferes the formation of in-cylinder swirl flow resulting in lower actual swirl.