부상 예혼합화염이 있는 확산화염의 매연 생성 및 산화 메커니즘

문두성(Dusung Moon),남연우(Younwoo Nam),이원남(Wonnam Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40

The soot formation and oxidation mechanisms of laminar ethylene diffusion flames have been experimentally studied at the presence of inner flames. The inner flame was either an inverse diffusion flame (IAF) that is attached at the center nozzle or a lifted premixed flame (ILF). The soot volume fraction profiles were obtained by a laser light extinction technique with an Abel inversion. The soot particle temperature profiles were measured by a modulated LII technique. The flame/soot particle temperatures were increased due to the presence of inner flames for both IAF and ILF cases. However, soot volume fraction at the center region was increased at the presence of an IAF while they were decreased with an ILF. The additional soot particles and PAH's that are supplied due to the nature of an inverse diffusion flame of IAF and the increased temperature for the soot formation region could be main reasons for the increase soot volume fraction. The additional soot oxidation region due to the nature of a premixed flame of ILF at the center region and the increased temperature at the soot oxidation region could be responsible for the decreased soot volume fraction.

다중 동축류 화염의 구조와 특성

문두성(Dusung Moon),이원남(Wonnam Lee) 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.39

A multi-concentric co-flow burner was designed and constructed in order to study the flame-flame interaction in a diffusion flame scheme. A variety of multiple ethylene diffusion flames could be obtained up to a quadruple flame that contains two inverse diffusion flames and two normal diffusion flames. Flames may be either merged together or separated each other. A lifted inner flame was formed with relatively higher air flow rate while an attached inner flame was formed with lower air flow rate. The amount of soot in a flame decreases with a lifted inner flame although the apparent flame temperature seems to be increased. An attached inner flame, however, increases the amount of soot in a diffusion flame until that the size of inner flame becomes very small. The possibility of experimental investigations for the flame-flame interaction has been demonstrated.

환형 화염이 있는 다중 에틸렌 확산화염의 PAH 및 매연분포

문두성(Dusung Moon),남연우(Younwoo Nam),이원남(Wonnam Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41

The distributions of PAH and soot particles were measured for multi-concentric ethylene diffusion flames with an annular flame inside and with an inverse diffusion flame attached at the center nozzle in addition to an annular flame. Temperatures of soot particles in flames were also measured by a modulated LⅡ technique. The presence of an annular flame inside increased the flame temperature at the soot formation region and resulted in the increase of PAH and soot concentrations. The maximum soot volume fraction, however, was decreased mostly due to the rapid oxidation of soot particles at the soot oxidation region. The addition of an inverse diffusion flame inside of an annular flame significantly decreased PAH and soot concentrations all over the flame. The oxidation of soot precursors including PAH as well as significantly increased flame temperature due to the flame-flame interaction could be the primary reason for the decreased soot volume fraction with annular and inverse diffusion flames inside.

내부로 공급되는 공기 유량에 따른 에틸렌 확산화염의 매연 방출 현상

남연우(Younwoo Nam),문두성(Dusung Moon),이원남(Wonnam Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41

The characteristics of soot formation with air addition have been studied experimentally using a concentric co-flow diffusion burner, which provides the stratified air mixture through an inner nozzle. Integrated soot volume fraction, temperature and scattering images of diffusion flames were measured using a laser light extinction method, two-color pyrometry and 2-D laser light scattering technique, respectively. An ethylene diffusion flame started to emit soot with a small amount of air flow through an inner nozzle, which could be explained with the enhanced soot formation process due to the oxygenated species assisted pyrolysis. The increase of air flow rate up to 250 sccm transformed a soot emitting flame into a non-emitting flame without inner flame. Further increase of air flow rate created an inner flame and changed the flame into a soot emitting flame. When air flow rate was decreased again, the flame was changed back to a emitting flame; however, the presence of an inner flame altered the soot formation and oxidation characteristics of the flame and enhanced the soot formation process. The oxygenated species assisted pyrolysis, the radiation heat loss and the temperature effect of inner flames would determine the characteristics of soot production/oxidation of an ethylene diffusion flame with air flow inside.

프로판 확산화염의 불안정성에 대한 내부화염의 역할

남연우(Younwoo Nam),문두성(Dusung Moon),이원남(Wonnam Lee) 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.39

The instability of laminar propane diffusion flames due to the existence of an inner inverse diffusion flame has been investigated using a concentric co-flow burner. A stable laminar propane diffusion flame started to oscillate with a small amount of air flow through an inner nozzle. Further increase of air flow rate changed the flame into a stable non-sooting, an oscillating and sooting, an oscillating non-sooting, and a stable non-sooting flame in sequence. Starting from high air flow rate, the decrease of air flow rate changed the flame back to a stable non-sooting flame via an oscillating non-sooting, an oscillating sooting and an oscillating non-sooting flame. The increased or decreased soot formation and oxidation rates, radiation heat loss, and heating by an inner flame are most likely to be responsible for the characteristics of a propane diffusion flames on instability and soot production.

Karman 와류 흘림과 층류 예혼합화염의 상호작용

이원남(Wonnam Lee),문두성(Dusung Moon) 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-

Flame oscillation and self-induced noise via interaction with a Karman vortex street have been investigated using a slot burner. The wrinkled flame surface showed the same pattern and frequency to those produced by Karman vortex street at the downstream of a circular cylinder. The measured flame oscillation frequency is very similar to the twice of estimated Karman vortex shedding frequency with Strouhal number of 0.2. This result could be a clear evidence of the interaction between laminar pre-mixed flame and a Karman vortex street. As Reynolds number increases with the increase of cylinder diameter from 1.67 ㎜ to 3.01 ㎜, the measured. oscillation frequency decreases from 334 ㎐ down to 175 ㎐ and the self-induced noise level increases from 64 ㏈ to 68 ㏈. The flame is more severely wrinkled with 3.01 ㎜ cylinder. The increased sound level and more severly wrinkled flame suggest that the flame/vortex interaction becomes more intense with the increase of Reynolds number.

연속제어 가변오일펌프 시스템 개발

이성하(Sungha Lee),문두성(Dusung Moon),방성훈(Sunghun Bang),강호균(Hogyoun Kang),배상수(Sangsoo Pae),조성문(Sungmun Cho) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11

Fuel economy of the engine can be improved by reducing output pressure of the engine oil pump. This paper presents electronic pressure feedback control system which controls oil pressure of the engine lubrication system. We developed oil pressure feedback control system which runs according to engine operating condition by integrating variable oil pump, sensors and control logic. Dual-chamber type variable oil pump is controlled by proportional solenoid valve using hydraulic pressure of the engine oil. Evaluation result showed that fuel economy was improved by reducing oil pressure using developed continuously controlled variable oil pump system.