모델연소실 내 압력 변화가 메탄/산소 이원추진제의 연소특성에 미치는 영향

최선(Sun Choi),김태영(Tae Young Kim),김희경(Hee Kyung Kim),권오채(Oh Chae Kwon) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5

메탄(CH4)/산소(O2) 액체이원추진제는 친환경성, 무독성, 경제성, 우수한 성능 등의 장점으로 최근 들어 차세대 친환경 이원추진제로서 각광을 받고 있다. 본 연구에서는 연소실 내 압력 변화에 따른 기체 메탄/산소 비예혼합 동축 화염의 연소안정한계를 측정하고, 화염 및 유동의 가시화를 통해 분사조건 및 압력 변화에 따른 화염의 구조와 특성을 파악하였다. 연소안정한계 측정 결과, 연료과농 조건에서 연소실 내 압력이 증가할 경우 연소안정한계가 확장되는 것이 확인되었고 연소(OH*) 강도 역시 크게 증가하는 것을 확인할 수 있었다. Liquid methane (CH4)/oxygen (O2) bipropellant have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance such as specific impulse and regenerative cooling capability. In this study, the combustion characteristics of gaseous CH4/O2 nonpremixed coflow flames in a model combustor with variation of internal pressure are investigated through measuring the combustion stability limits and visualizing flames and flow. Results show that the combustion stability limits are extended and reaction intensity (OH* intensity) is enhanced with increasing internal pressure of the combustion chamber for fuel-rich condition.

모델연소실 내 GCH₄/GO₂ 및 GH₂ /GO₂ 동축류 제트화염의 연소특성 기초 연구

최선(Sun Choi),김태영(Tae Young Kim),김희경(Hee Kyung Kim),권오채(Oh Chae Kwon) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12

로켓 엔진의 차세대 액체이원추진제로서 각광을 받고 있는 메탄(CH₄)/산소(O₂) 이원추진제의 기초연소특성 및 연소 안정화의 고유특성 확인을 위해 수소(H2)/산소 이원추진제 연소특성과 비교 연구를 수행하였다. 기초 연소특성 연구를 위한 모델연소실 내에서 기체 메탄(GCH₄)/기체 산소(GO₂) 및 기체수소(GH₂)/GO₂의 동축류 제트화염의 연소안정한계와 직접 사진, OH<SUP>*</SUP> 자발광 이미지를 측정한 결과, GCH₄/GO₂와 GH₂/GO₂ 모두 산소-연료 모멘텀비((O/F)mom)가 감소함에 따라 연소안정한계는 확장되는 경향을 보였으나 GH₂/GO₂ 화염에 비해 GCH₄/GO₂ 화염은 좁은 연소안정한계가 측정되었고, 또한 GCH₄/GO₂ 화염은 이론당량비 조건에서, GH2/GO₂ 화염은 연료과농 조건에서 최대 OH* 강도가 측정됨을 OH<SUP>*</SUP> 자발광 가시화를 통해 확인하였다. Liquid methane (CH₄)/oxygen (O₂) bipropellants have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance. To investigate the unique features of CH₄/O₂ bipropellants, the fundamental combustion characteristics of gaseous CH₄/O₂ and H₂/O₂ coaxial jet flames in a model combustor are investigated through measuring the combustion stability limits and visualizing flames. Results show that the combustion stability limits of GCH₄/GO₂ flames are reduced compared with the GH₂/GO₂ flames. The maximum OH<SUP>*</SUP> intensity of GCH₄/GO₂ flames is observed at near-stoichiometric condition, while the GH₂/GO₂ flames at fuel-rich condition.

Properties of inverse nonpremixed pure O₂/CH₄ coflow flames in a model combustor

Choi, Sun,Kim, Tae Young,Kim, Hee Kyung,Koo, Jaye,Kim, Jeong Soo,Kwon, Oh Chae Elsevier 2015 ENERGY Vol.93 No.1

<P><B>Abstract</B></P> <P>In order to evaluate the potential of oxy-combustion of inverse nonpremixed coflow flames using a clean fuel to improve the combustion and emission characteristics compared with the normal coflow flames using air, the fundamental properties of inverse nonpremixed pure oxygen (O<SUB>2</SUB>)/methane (CH<SUB>4</SUB>) coflow flames in a model combustor are experimentally investigated. The combustion stability (extinction) limits, structure and nitrogen oxide (NO<SUB>x</SUB>) emissions of the inverse coflow flames in the quartz-windowed combustion chamber with a single shear coaxial injector and a fully opened exhaust nozzle are measured using OH<SUP>∗</SUP> chemiluminescence, a schlieren imaging system and a gas analyzer. Results show four distinct stability regimes and limits: the attached flame regime, the near-blowout flame regime, blowout limits and blowoff limits. The direct flame and OH<SUP>∗</SUP> chemiluminescence images confirm the cooling effects of chamber walls that cause no steady liftoff flame and only the near-blowout flame. The extinction limits of the inverse CH<SUB>4</SUB>/O<SUB>2</SUB> coflow flames are extended compared with the normal CH<SUB>4</SUB>/air coflow flames and reasonable levels of NO<SUB>x</SUB> emissions are observed, which supports that oxy-combustion of the inverse nonpremixed coflow flames using the clean fuel is acceptable for practical application, providing a useful database for modeling the flames in the confined chamber.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Extended stability limits of inverse nonpremixed O<SUB>2</SUB>/CH<SUB>4</SUB> coflow flames are found. </LI> <LI> Stable, attached flames and oscillating, near-blowout flames are observed. </LI> <LI> Direct flame and OH<SUP>∗</SUP> chemiluminescence images indicate no steady liftoff flame. </LI> <LI> Reasonable levels of NO<SUB>x</SUB> emissions are observed. </LI> <LI> Inverse nonpremixed O<SUB>2</SUB>/CH<SUB>4</SUB> coflow flames are acceptable for practical applications. </LI> </UL> </P>

모델연소실 내 산소-메탄 비예혼합 역확산화염의 연소특성 연구

최선(Sun Choi),김태영(Tae Young Kim),김희경(Hee Kyung Kim),권오채(Oh Chae Kwon) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5

지구온난화로 인한 기후변화에 대응하기 위해 다양한 노력이 요구되는 가운데 연소효율을 증가시키고 공해물질의 배출을 저감할 수 있으며 연소 후 이산화탄소 포집이 용이한 산소-메탄 비예혼합 역확산화염의 연소특성에 대한 연구를 수행하였다. 모델연소실 내에서 산소-메탄 비예혼합 역확산화염의 연소안정한계를 측정하고, 화염구조 파악을 위해 OH* 자발광 기법을 통해 반응영역을 확인하였다. In response to the concern over global warming, there has been substantial interest in either developing high-efficiency or low-emission combustion devices. The use of inverse nonpremixed oxygen (O₂)-methane (CH₄) flames as one possible technology for achieving the high-efficiency and low-emission is considered and thus the combustion characteristics of the oxy-fuel inverse flames in a model combustor are experimentally investigated. The combustion stability limits and structure of O₂-CH₄ inverse flames are measured using OH* chemiluminescence.

Combustion characteristics of gaseous inverse O₂/H₂ coaxial jet flames in a single-element model combustor

Kim, Tae Young,Choi, Sun,Kim, Young Hoo,Ahn, Yeong Jong,Kim, Hee Kyung,Kwon, Oh Chae Elsevier 2018 ENERGY Vol.155 No.-

<P><B>Abstract</B></P> <P>To effectively design hydrogen (H<SUB>2</SUB>)/oxygen (O<SUB>2</SUB>) liquid rocket engines through understanding the combustion characteristics of H<SUB>2</SUB>/O<SUB>2</SUB> bipropellants, fundamental studies for the bipropellants in different phases are needed. This study is focused on the combustion characteristics of inverse gaseous O<SUB>2</SUB>/H<SUB>2</SUB> coaxial jet flames in a single-element model combustor as a preliminary step for succeeding studies of injection at different phases in the combustor, visualizing flame structure by direct imaging, OH<SUP>∗</SUP> chemiluminescence and OH planar laser-induced fluorescence. With increasing Reynolds number (Re), the frequency of occurrence of the local flame extinction increases and the length of the disconnected OH reaction zone is extended. The OH layer thickness increases downstream, while it is almost constant where the local flame extinction occurs and decreases with increasing Re due to the enhanced strain and scalar-dissipation rates. The excessive flame wrinkledness increases the local flame strain rate and results in the local flame extinction, exhibiting the tendency of increasing and then decreasing flame surface density with increasing Re. The probability density function of OH intensity quantifies the fluctuation intensity of OH radicals and the possibility of the local flame extinction. A useful database is provided for modeling the combustion of H<SUB>2</SUB>/O<SUB>2</SUB> bipropellants under different phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A useful database for modeling the H<SUB>2</SUB>/O<SUB>2</SUB> bipropellant combustion is provided. </LI> <LI> Local flame extinction frequently occurs at high Reynolds number (<I>Re</I>). </LI> <LI> OH probability density function indicates the possibility of local extinction. </LI> <LI> Flame surface density increases and then decreases with increasing <I>Re</I>. </LI> <LI> Strong burning of O<SUB>2</SUB>/H<SUB>2</SUB> causes laminar-like combustion near the injector lip. </LI> </UL> </P>

조기위함에서 침윤, 유형 및 분화도에 따른 p53, bcl-2의 발현

권오선,조현득,오미혜,김의한,양승하 순천향대학교 의학연구소 2006 Journal of Soonchunhyang Medical Science Vol.12 No.2

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한국어와 몽골어의 어음대조

권오선 서울대학교 어학연구소 1990 語學硏究 Vol.26 No.3

In this paper I will compare the phonetic systems of modern Korean and Mongol. There are 21 vowels in Korean and 37 in Mongol, among which 3 pairs are alike, while the rest different. Mongol has its written and spoken language, its long and short vowels. Korean, however, has no such differences. There are 19 consonants in Korean and 26 in Mongol, among which 9 pairs are alike and all are plosive and nasal sounds, whereas the rest different. Both Korean and Mongol have some phonemes of their own and both have various sound changes. Here I will also compare the difference of syllables and stresses between the two languages.

대학병원의 외래진찰실 및 수술실 활용도 조사방법에 대한 연구 : 지방소재 J대학교 사례조사를 중심으로 Case study in J university hospital

오종희,권순정,김광현 대한건축학회 2004 대한건축학회논문집 Vol.20 No.3

The purpose of this study is to develop the survey method for the proper, effective space utilization and to analyze the utilization rate of the outpatient's consulting room and the operating room in the university hopsital. The utilization rate of the outpatient's consulting room could be got by the survey to investigate the outpatient's consulting room session utilization, doctor's behavior, time delay, special medical department's behavior etc. The utilization rate of the operating room could be got by the survey to investigate the every part of the process in the operation, that is operation time, preparation time, cleaning & arrangement time, eating time etc. Finally it was suggested that the department of internal medicine & rehabilitation medicine need to have more consulting room and surgery, othopedic surgery, neurosurgery need to reduce the number of consulting room. About the operating room, it was suggested that if the present utilization of the operating room got down to 90%, at least 3 more operating room would be needed.

汚染된 河川底泥로부터 營養鹽 溶出에 關한 硏究

權五億,徐承敎,姜善泰 대구산업정보대학 1992 논문집 Vol.6 No.-

Past dicharges of settleable and colloidal organic solids into natural waterways have resulted in appreciable accumulations of sediment in the botton of many lakes, estuaries and river stretches over the years. Under such conditions, bottom sediments, when present, may be come one of the most important factots influencing the quality of natural water. Thus, this study was performed to investigate the nutrients release through chamber experimentation at Gangchang bridge which one of polluted places in Kumho River. The coefficients of sediment oxygen demand for aerobic and anaerobic conditions were 0.864, 5.04 day^(-1), respectively. Also, the release rate of NH₃-N and PO₄-P for aerobic conditions were 0.242g/m²·day, 0.029g/m²·day, and the released rate of NH₃-N and PO₄-P for anaerobic condition were 0.665g/m²·day, 0.186g/m²·day, respectively.

工團地域 小河川의 底泥中 重金屬 含量

權五億,梁成鎬,姜善泰 대구산업정보대학 1992 논문집 Vol.6 No.-

This study was carried out to investigate the contents of six heavy metals (Cd, Cr, Cu, Mn, Pb and Zn) in sediment collected at seven sites of 3-Gongdan stream receiving industrial wastewater. The mean Zn, Cu, Mn, Pb, Cr and Cd contents in sediment of all sites investigated was 1496.6mg/kg, 764.4mg/kg, 562.0 mg/kg, 231.6 mg/kg, 37.3 mg/kg and 9.5 mg/kg, respectively. It can be esteimated that the high amount of heavy metals is possibly due to the industrial wastewater, and alkaline pH water when most of the heavy metals are precipitated.