포트 마스킹이 엔진의 배기에 미치는 영향

김형식(Hyeongsig Kim),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2011 한국 자동차공학회논문집 Vol.19 No.3

LPG 가스분사엔진의 운전특성에 대한 연구

김형식(Hyeongsig Kim),장열성(Yeolsung Jang),우성동(Sungdong Woo),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

A gas injection system has an edge over the liquefied injection system in terms of durability and cost reduction. However, the engine performance of the gas system needs to be investigated to challenge that of liquefied injection system. In this work, measurements of operation characteristics were carried out to investigate the performance of gas injection system compared with liquefied injection system. The operation characteristics with gas injection shows much difference from that of liquefied injection. A gas injection system characteristics was investigated to adopt the system to a liquefied injection engine through idle test. It was also studied that operation characteristics for a engine speed fluctuation and the lambda fluctuation of gas injection system. As a result of LPGi engine experiment. overall engine speed fluctuation and lambda fluctuation was controlled bad. This work concludes that a gas injection system shows the performance comparable to the liquefied injection system, and as for the LPLi engine system a gas injection system is maladaptation.

포트마스킹이 엔진의 희박연소 한계와 연비에 미치는 영향

김형식(Hyeongsig Kim),권순태(Soontai Kwon),이재원(Jaewon Lee),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

To securing basic data for intake port design, effects of a port masking on the part load performance were investigated in a 4 valve SI engine. For this purpose, 9 kinds of masking, which have different shapes and masking ratio, are applied to the engine intake system. The characteristics of the performance were estimated through mixture response test at various engine load and speed. The results show that lean misfire limit is expanded considerably and fuel consumption is improved due to the stratification which is caused by unequal flow distribution between the two intake ports. The mechanism of stratification by masking is different from axial stratification and the fuel entering through masked port plays a very important role in this stratification process. In conclusion, the port masking method could be easily applied to engine intake system and be very effective for inducing the stratified charging without the change of port design.

반 쐐기형 연소실을 채택한 SI 기관에서 포트형상이 정상유동 특성에 미치는 영향 (1)

김형식(Hyeongsig Kim),엄인용(Inyong Ohm) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.7

본 논문은 반 쐐기형 연소실에서 포트 형상에 따른 정상유동 특성을 비교한 연구의 첫 번째로 통상적인 충격식 스월측정기 평가위치인 1.75B에서 입자영상유속계로 반 쐐기형 연소실에 직선형 포트와 나선형 포트를 적용하여 평면유속을 측정하고 비교하였다. 속도분포 분석 결과 직선형 포트에서는 밸브리프트 4 mm 이하, 그리고 나선형 포트에서는 2 mm 이하에서 두 개의 스월이 형성되고 이후 리프트가 증가하면 하나의 스월만 관찰된다. 리프트에 따른 유동체계의 천이점이 포트형상에 따라 상이하여 직선형 포트에서는 리프트 4 mm와 5mm를 경계로 유동 특성이 완전히 바뀌는 반면, 나선형 포트에서는 리프트 증가에 따라 점진적 변화만 관찰된다. 또한 모든 포트에서 1.75B 위치에서 편심도는 측정값이 왜곡되지 않는 범위에 들어오지 않고, 특히 직선형 포트의 편심도가 매우 크다. 동시에 포트형상에 관계없이 ISM 평가와 상응하는 실린더 중심 기준의 평균접선속도는 ISM 평가에서 가정한 속도보다 매우 낮고, 속도분포 특성도 ISM 평가의 가정과 매우 다르다. This paper is the first investigation of the steady flow characteristics of an SI engine with a semi-wedge combustion chamber as a function of the port shape. For this purpose, the planar velocity profiles were measured at the 1.75B position by particle image velocimetry. The flow patterns were examined with both a straight and a helical port. Two swirls were observed up to 4 mm valve lift with the straight port and up to 2 mm with the helical one; however, only one swirl was present after these lifts. The flow characteristics changed suddenly between 4 and 5 mm lift in the straight port; on the other hand, the change with lift was gradual with the helical port - the transition points between flow regimes were different with the port shapes. In addition, the centers of the swirls were relatively far from the cylinder center so that the effect of eccentricity may not be negligible at 1.75B, regardless the shape. The eccentricity values with the straight port were especially high - over 0.5 for all lifts. Finally, real velocities were found to be much lower than those predicted by the assumption of ISM evaluation, with the profiles differing qualitatively as well.

포트 마스킹에 따른 엔진 부분부하 성능 특성

김형식(Hyeongsig Kim),김인옥(Inok Kim),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2011 한국 자동차공학회논문집 Vol.19 No.2

LPG 가스분사엔진의 시동특성에 대한 연구

장열성(Yeolsung Jang),김형식(Hyeongsig Kim),우성동(Sungdong Woo),박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Liquefied petroleum gas(LPG) is a popular and widely used alternative fuel, due mainly to its abundance and indigenous availability at attractive prices. A port injection type LPG fuel system characteristics were investigated to adopt the system to a LPLi engine. It was also studied the improvement of starting performance. The result in all the research was found using by V-6 LPLi engine, 2656㏄, mainly the performance of engine start. In this study, engine control variables such as injection pressure, fuel injection duration were changed by using injector driver(IC5160) at engine start to fine out the trends of engine speed variations and stability of engine start operation. Through the study, it is observed that the injection pressure affected to the stability of engine start operation and engine speed but the effects were insignificant on it. Increase in injection duration led to decrease of engine speed and improve of stability of engine start operation. On the other hand increase in ISA opening rate let to increase of engine speed and deterioration of stability of engine start operation. This result may offer the idea that how the work of improving engine start performance.

1/4 포트마스킹이 엔진의 부분부하 성능에 미치는 영향

이재원(Jaewon Lee),김형식(Hyeongsig Kim),권순태(Soontai Kwon),박찬준(Chanjun Park),엄인용(Inyong Ohm) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

To securing basic data for intake port design, effects of a masking on the part load performance were investigated in a SI engine. For this purpose, 3 kinds of masking, which have different shapes is applied to the engine intake system. The characteristics of the performance were estimated though mixture response test at various engine load and speed. The results show that lean misfire limits is expanded considerably and fuel consumption is improved and Nox emission increases in spite of retarded spake timing due to the stratification which is caused by unequal flow distribution between the two intake ports. The mechanism of stratification by masking is different from axial stratification, and the fuel entering though masked port plays a very important role in this stratification process. In conclusion, the port masking method could be easily applied to engine intake system and be very effective for inducing the stratified charging without the change of port design.

토치 점화 장치의 오리피스 직경에 따른 연소특성 파악

권순태(Kwon Soontae),김형식(Kim Hyeongsig),최창현(Choi Changhyeon),박찬준(Park Chanjun),엄인용(Ohm Inyoung) 한국에너지공학회 2010 한국에너지공학회 학술발표회 Vol.2010 No.4

토치 점화 장치의 연소 특성을 파악하기 위하여 7개의 각기 다른 토치 점화 장치를 설계하였다. 토치 점화장치의 오리피스 직경에 따른 특성을 파악하기 위하여, 토치 점화 장치의 체적과 높이는 고정하고, 오리피스 직경을 4㎜에서 16㎜까지 2㎜씩 증가시키며 실험하였다. 초기 화염 생성 및 전파는 절량 연소율과 연소 촉진율로 분석하였다. 질량 연소율과 연소 촉진율을 계산하기 위하여 정적 연소실 내의 평균 압력을 측정하였다. 또한 shadow graph법을 이용하여, 초기 화염 생성과 화염 전파과정 전 영역을 가시화하였다. 토치 점화 장치를 사용한 경우에는 일반적인 스파크 점화와 비교하여 질량 연소율의 기울기가 증가하였고, 연소 촉진율도 개선된것을 확인하였다. 또한 가시화된 이미지를 확인한 결과 토치 점화 장치를 사용하면 초기 화염 발달 단계에서 화염이 난류 화염으로 천이되어 연소가 촉진된것을 확인하였다. Seven different size of orifice were applied in a constant volume combustion chamber for evaluating the effects of torch-ignition on combustion. The initial flame development and flame propagation were analyzed by the mass fraction bum and combustion enhancement rate. The combustion pressures were measured to calculate the mass fraction burn and the combustion enhancement rates. In addition, the flame propagations were visualized by the shadowgraph method for the Qualitative comparison. The result showed that the combustion pressure and mass burned fraction were increased when using the torch-ignition device. The combustion enhancement rates of torch-ignition cases were improved in comparison with conventional spark ignition. Finally, the visualization results showed that the torch-ignition induced faster burn than conventional spark ignition due to the earlier transition to turbulent flame and larger flame surface, during the initial stage.

레이저 Rayleigh 산란을 이용한 연료농도의 계측

권순태(Soontae Kwon),김형식(Hyeongsig Kim),이재원(Jaewon Lee),박찬준(Chanjun Park),엄인용(Inyoung Ohm) 한국에너지학회 2008 한국에너지공학회 학술발표회 Vol.2008 No.-

본 연구는 정상 상태의 유동에서 Rayleigh 산란을 이용하여 연료의 농도를 측정하는 방법에 대해 것이다. 실험 장치는 연료의 농도 변화를 시간적, 공간적으로 측정함과 동시에 정확한 농도 측정을 위한 보정도 가능하도록 구성하였다. 실험 장치를 우선 보정 용기에 적용하여 프로판, 부탄, 아세틸렌, 프레온 가스의 산란단면적을 구하였다. 이후 내연기관을 상사한 실린더 헤드, 인젝터, 흡기매니폴드, 투명 실린더로 구성된 정상유동 장치를 구성하여 분사된 연료의 시간적, 공간적 농도 변화를 측정하였다. Mie산란의 간섭을 제거하기 위하여, 산란 신호의 상승 기간과 증배관-앰프의 시정수에 바탕을 둔 소프트웨어 필터를 개발하여 적용하였다. 실험 결과 LRS는 연료 농도 계측에 매우 유용하게 이용될 수 있고 소트프웨어 필터는 Mie 간섭을 효과적으로 제거할 수 있음을 확인하였다. In this study, a system to measure continuously the fuel concentration in a steady flow rig on the basis of Rayleigh scattering is presented. The system can be employed to measure both the temporal and the spatial distribution. Also, it is possible to calibrate the system for the measurement of accurate absolute concentration. Firstly, the system was tested at a calibration chamber for the determination of scattering cross section from propane, butane, acetylene, Freon-12 and Genetron 143a. After this, the system was adapted to a steady flow rig to measure the temporal and spatial fuel concentration. The rig is composed of cylinder head, intake manifold, injector, and transparent cylinder which can simulate internal combustion engine. To cope with the problem of Mie scattering interference, a software filter was developed, which is based on the rise time and the time constant of the photomultiplier-amplifier system. The results show that LRS can provide useful informations about concentration field and the software filter is very effective method to remove Mie interference.

토치 점화 장치의 체적에 따른 연소특성 파악

권순태(Kwon Soontae),김형식(Kim Hyeongsig),최창연(Choi Changhyeon),박찬준(Park Chanjun),엄인용(Ohm Inyoung) 한국에너지공학회 2010 한국에너지공학회 학술발표회 Vol.2010 No.4

토치 점화 장치의 연소 특성을 파악하기 위하여 6개의 각기 다른 토치 점화 장치를 설계하였다. 토치 점화장치의 체적이 메탄의 연소특성에 미치는 영향을 파악하기 위하여, 토치 점화 장치의 높이(h)와 오리피스 직경(De)는 10㎜와 6㎜로 고정하고, 입구 직경(D)을 12㎜에서 22㎜까지 2㎜씩 증가시키며 토치 점화 장치를 설계하였다. 초기 화염 생성 및 전파는 질량 연소율과 연소 촉진율로 분석하였다. 질량 연소율과 연소 촉진율을 계산하기 위하여 정적 연소실 내의 평균 압력을 측정하였다. 또한 shadow graph법을 이용하여, 초기 화염 생성과 화염 전파과정 전 영역을 가시화하였다. 토치 점화 장치를 사용한 경우에는 일반적인 스파크 점화와 비교하여 질량 연소율의 기울기가 증가하였고, 연소 촉진율도 개선된것을 확인하였다. 토치 점화 장치의 체적이 증가할수록 연소가 개선되었으며, 넓은 점화 표면을 제공하였다. Six different size of torch-ignition device were applied in a constant volume combustion chamber for evaluating the effects of torch-ignition on combustion. The torch-ignition device was designed six different volumes and same orifice size. The combustion pressures were measured to calculate the mass bum fraction and combustion enhancement rate. In addition, the flame propagations were visualized by shadowgraph method for the Qualitative comparison. The result showed that the combustion pressure and mass bum fraction were increased when using the torch ignition device. And the combustion duration were decreased. The combustion enhancement rates of torch-ignition cases were improved in comparison with conventional spark ignition. Finally, the visualization results showed that the torch-ignition device the torch-ignition induced faster bum than conventional spark ignition due to the earlier transition to turbulent flame and larger flame surface, during the initial stage. And the initial flame propagation was effected torch-ignition volume.