스파크 점화 엔진에서 초기화염 발달의 가시화

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.

밸브 각이 큰 나선형 포트 엔진의 실린더 내 압축 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 compression process progresses. Consequently, this component destroys in-cylinder swirl flow completely during compression resulting in no actual swirl at the end stage of compression.

PIV를 이용한 실린더 내 유동 측정

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.

흡입 밸브 각도에 따른 실린더 내 흡입 유동 특성

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.

흡입밸브 각이 실린더 내 와류 발생 특성에 미치는 영향(Ⅰ)

엄인용(Inyong Ohm),박찬준(Chanjun Park) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.19 No.6

This paper is the first of 2 companion papers which investigate in-cylinder swirl generation characteristics according to inlet valve angle. Two DOHC 4 valve engines, one has wide intake valve angle and the other has narrow valve angle, were used to compare the characteristics of swirl motion generation in the cylinder. One intake port was deactivated to induce swirl flow. A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake stroke. The results show that the stronger swirl motion is observed in wide valve angle engine at the early intake stage; however, the swirl motion is gradually distorted by the intake flow component passing through valve area near the cylinder wall as the stroke proceeds. The tumble motion also does so in wide angle. On the contrary, the swirl and tumble motions, which are not clear at the initial stage, become better and better arranged as the piston goes down and up again after bottom dead center.

가솔린 엔진에서 연료분사시기와 포트특성에 따른 실린더 내 연료거동 : Part Ⅱ - 저/중 와류의 경우

엄인용(Inyong Ohm),조영석(Yongseok Cho) 한국자동차공학회 2001 한국 자동차공학회논문집 Vol.9 No.3

This paper is the second of 3 companion papers which investigate axial stratification process. In-cylinder fuel behavior has been investigated in the port injected SI engine by visualizing for the purpose of understanding stratification. Planar laser light sheet from an Nd:YAG laser has been illuminated through the transparent quartz cylinder of the single cylinder optical engine and the Mie scattered light has been captured through the quartz window in the piston head with an ICCD camera, Fuel has been replaced with an air-ethanol mixture to utilize atomized fuel spray for the visualization purposes. This results have been compared with steady flow concentration measurement.<br/> For low/medium swirl port, the early injection makes such a fuel distribution state that is upper-rich, middle-lean and lower-rich along the combustion chamber and cylinder by tumbling motion. On the other hand, the late injection induces upper-rich, middle-lean and lower-rich state due to the short fuel penetration.<br/> <br/>

가솔린 엔진에서 연료분사시기와 포트특성에 따른 실린더 내 연료거동:Part I-와류가 없는 경우

엄인용(Inyong Ohm),조용석(Yongseok Cho) 한국자동차공학회 2001 한국 자동차공학회논문집 Vol.9 No.2

This paper is the first of 3 companion papers which investigate axial stratification process. In-cylinder fuel behavior has been investigated in the port injected SI engine by visualization for the purpose of understanding stratification. Planar laser light sheet from an Nd:YAG laser has been illuminated through the transparent quartz cylinder of the single cylinder optical engine and the Mie scattered light has been captured through the quartz window in the piston head with an ICCD camera. Fuel has been replaced with an air-ethanol mixture to utilize atomized fuel spray for the visualization purposes. This results have been compared with steady flow concentration measurement.<br/> For no swirl port, the axial penetration depends on the fuel injection timing. The fuel tends to remain in the upper region of the cylinder far from the spark plug and the distribution is not affected by the injection timing except 90 ATDC.

나선형 포트를 적용한 광각엔진에서 실린더 내 압축 유동 특성

엄인용(Inyong Ohm),박찬준(Chanjun Park) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.1

This paper is the second of 2 companion papers which investigate in-cylinder swirl generation characteristics in helical port engine with wide valve angle. 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 compression process progresses. Consequently, this component destroys in-cylinder swirl flow completely during compression resulting in no actual swirl at the end stage of compression.

흡입밸브 각이 실린더 내 와류 발생 특성에 미치는 영향(Ⅱ)

엄인용(Inyong Ohm),박찬준(Chanjun Park) 한국자동차공학회 2009 한국 자동차공학회논문집 Vol.17 No.2

This paper is the second of 2 companion papers which investigate in-cylinder swirl generation characteristics according to inlet valve angle. Two DOHC 4 valve engines, one has wide intake valve angle and the other has narrow valve angle, were used to compare the characteristics of swirl motion generation in the cylinder. One intake port was deactivated to induce swirl flow. A PIY (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake stroke. The results show that the flow patterns of narrow valve engine are much more stable and well arranged compared with the normal engine over the entire intake and compression stroke except early intake stage, and very strong swirl motion is generated at the end of compression stage in this engine nevertheless using straight port which is unfavorable for swirl generating. In the wide valve angle one, however, strong swirl motion induced during intake stroke is destroyed as the compression progresses.