비정상 CH$_4$/공기 제트 확산화염에 관한 수치모사

이창언,오창보,Lee, Chang-Eon,O, Chang-Bo 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.8

The dynamic structures of unsteady CH$_4$/Air jet diffusion flame with a flame-vortex interaction were numerically investigated. A timed-dependent, axisymmetric computational model and a low mach number approximation were employed in the present calculation. A two-step global reaction mechanism which considers 6 species, was used to calculate the reaction rates. The predicted results including the gravitational effect show that the large outer vortices and the small inner vortices can be well simulated without any additional disturbances near nozzle tip. It was found that the temperature and species concentrations have deviated values even for the same mixture fraction in the flame-vortex interaction region. It was also shown that the flame surface is not deformed by the inner vortex in upstream region, while in downstream region, the flame surface is compressed or stretched by the outer vortex roll-up. The present unsteady jet flame configuration accompanying a flame-vortex interaction is expected to give good implications for the unsteady structures of turbulent flames.

수치계산을 이용한 LFG 혼합연료의 연소속도 상관식에 관한 연구

이창언,오창보,정익산,Lee, Chang-Eon,O, Chang-Bo,Jeong, Ik-San 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.11

In this study, the burning velocities of LFG and LFG mixed fuels have been numerically determined. C3 reaction mechanism involving 92 species and 621 reactions was adopted in the calculation. The computed burning velocities using C3 mechanism show good agreements with experimental data. Based on numerical results, the maximum burning velocities of LFG and LFG mixed fuels were correlated as a function of CH$_4$ and LFG component percentage at stoichiometric conditions. In addition, the correlations of burning velocities of LFG and LFG mixed fuels were obtained over a wide range of the equivalence ratio. The numerical results are well agreed with the burning velocity correlations. The burning velocity correlations for LFG and LFG mixed fuels suggested in this study can be applied to the practical utilization of LFG.

LFG 혼합연료의 화염 안정화 특성

이창언,황철홍,김선호,Lee, Chang-Eon,Hwang, Cheol-Hong,Kim, Seon-Ho 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.2

In this study, experiments were performed to investigate the characteristics of flame stabilization of the LFG mixing gas. LFG has merely half heating value compared with liquified natural gas but can be greatly utilized as a commercial fuel. In order to use LFG in practical combustors, Webbe Index and heating value of LFG mixing gas were adjusted by mixing LPG with LFG. The comparisons were conducted between CH$_4$and LFG mixing gas for searching the region of flame stabilization based upon the flame blowout at maximum fuel stream velocity. As a result, the flame stability of LFG mixing gas was not improved with that of CH$_4$in non-swirl and weak swirl diffusion flame. However, LFG mixing gas had wide flame stabilization region rather than CH$_4$with increasing ambient flow rate in strong swirl. It was also found that flame stability was affected by included quantity of inert gas such as CO$_2$in the weak swirl but by heating value of fuel in strong swirl.

산화제 제어 확산화염의 화염구조 및 NO 생성 특성에 관한 수치해석적 연구

이창언,한지웅,Lee, Chang-Eon,Han, Ji-Ung 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.5

Numerical Study with detailed chemistry has been conducted to investigate the flame structure and NOx formation characteristics in oxygen -enhanced(CH$_4$/O$_2$-$N_2$) and oxygen-enhanced-EGR(CH$_4$/O$_2$-$CO_2$) counter diffusion flame with various strain rates. A small amount of $N_2$is included in oxygen-enhanced-EGR combustion, in order to consider the inevitable $N_2$contamination by $O_2$production process or air infiltration. The results are as follows : In CH$_4$/O$_2$-$CO_2$flame it is very important to adopt a radiation effect precisely because the effect of radiation changes flame structure significantly. In CH$_4$/O$_2$-$N_2$flame special strategy to minimize NO emission is needed because it is very sensitive to a small amount of $N_2$. Special attention is needed on CO emission by flame quenching, because of increased CO concentration. Spatial NO production rate of oxygen-enhanced combustion is different from that of air and oxygen-enhanced-EGR combustion in that thermal mechanism plays a role of destruction as well as production. In case CH$_4$/O$_2$-$CO_2$flame contains more than 40% $CO_2$it is possible to maintain the same EINO as that of CH$_4$/Air flame with accomplishing higher temperature than that of CH$_4$/Air flame. EINO decreases with increasing strain rate, and those effects are augmented in CH$_4$/O$_2$flame.

열교환기 위치에 따른 NOx 및 CO 생성특성

김종민(Jong-Min Kim),이승로(Seungro Lee),금성민(Sung-Min Kum),이호연(Ho-Yeon Lee),윤희중(Hee-Jung Yun),이창언(Chang-Eon Lee) 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.38

Recently, strict pollutant regulations of NOx emission and increasing awareness of the environmental damage stimulated interest in research to obtain useful information regarding CO and NOx reductions at the same time. In this study, Premixed flame was experiment to reduce CO and NOx emission level by heat exchanger location in which burner and first heat location distance(L₁) and first and second heat location(L₂) changed. To reduce the NOx emission, first heat exchanger location(L₁) was decided near the flame. After first heat exchanger(L₁) was decided for the optimal NOx emission(about 30 ppm), in order to decide the optimal CO emission(about 30ppm), seocond heat exchanger location(L₂) was tested and decided for several cases. Finally, the optimal location of heat exchanger for minimal CO and NOx emission simultaneously was determined and suggested.

GT-POWER를 이용한 신형 로터리 엔진의 1D 해석 모델 개발

박영준(Youngjoon Park),박태준(Taejoon Park),이창언(Chang-Eon Lee) 한국연소학회 2020 KOSCOSYMPOSIUM논문집 Vol.2020 No.9

This study develops 1D CFD simulation models for a new rotary engine originated from a three-lobes Gerotor pump(GP3 RTE). The models consider unique characteristics of GP3 RTE such as effective-area variations. The models are compared to identify each parameter effect and validated by comparing to 3D CFD result. The most advanced model well predict the performance indexes. The model may allow as a convenient tool for getting basic informations on optimizing design parameters of GP3 RTE without time-consuming 3D design change.

산지별 천연가스들의 열 물성치 및 연소 정보 검토

이창언(Chang-Eon Lee),현승호(Seung-Ho Hyun),황철홍(Cheol-Hong Hwang),이성민(Sung-Min Lee),하영철(Young-Cheol Ha),이강진(Kang-Jin Lee) 한국연소학회 2007 한국연소학회지 Vol.12 No.1

The diversification of import districts of natural gas is trying to prepare an increase in the demand and price. The interchangeability of natural gases should be examined prior to supply to gas appliances, although compositional differences among natural gases are not large. The object of this study is to investigate numerically the thermodynamic and transport properties as well as information on combustion of 6 natural gases. Comparing the properties of BOG1 with those of standard gas, the maximum differences of heating value, Wobbe index, air-fuel ratio, and specific heat are 10%, 4%, 10% and 5.54%, respectively. That is, the BOG1 is required careful application. However, all gases except for BOG1 show the similar properties with standard gas. Finally, the combustion information such as flame temperature and burning velocity are examined. These results will provide the useful information related to the interchangeability of various natural gases in practical combustion appliances.

가스호환성 환청에 편리한 새로운 화염안정영역의 도시법의 제안 및 유용성 검토

이창언(Chang-Eon Lee),김종민(Jong-Min Kim),황철홍(Cheol-Hong Hwang),김종현(Jong-Hyun Kim) 한국연소학회 2008 한국연소학회지 Vol.13 No.3

A flame stability diagram in a partially premixed flame is typically expressed using the axis coordinates of heat input rate and equivalence ratio. These diagrams are inadequate for identifying changes in combustion conditions and flame stability when a reference fuel is substituted with other fuels under identical operating conditions. This study proposes a new type of diagram and validates it experimentally. In this new diagram, the axis coordinates are air flow rate and Wobbe fuel flow rate, defined as the fuel flow rate multiplied by the square root of the relative density. The diagram was validated in trials using various fuels, including CH₄, C₃H8 and LFG-C₃H8 mixed fuels, in a domestic gas-range and an gas interchangeability test burner. The results of these trials show that the new diagram can provide information useful for assessing gas interchangeability of combustion conditions and flame stability when one fuel is substituted with another under identical operating conditions.

재순환류가 존재하는 난류확산화염에 관한 연구

이창언(Chang-Eon Lee),오수철(Su-Cheol Ohu) 한국항공우주학회 1994 韓國航空宇宙學會誌 Vol.22 No.5

산돌배나무(Pyrus ussuriensis) 잎 분획물의 항산화 효과

이창언 ( Chang Eon Lee ),김영훈 ( Young Hun Kim ),이병근 ( Byung Guen Lee ),이도형 ( Do Hyung Lee ) 한국산림과학회 2010 한국산림과학회지 Vol.99 No.6

This study was conducted to confirm the application as ingredients of cosmetics through an examination of the function for anti-oxidant activity of the fraction isolated from Pyrus ussuriensis leaves. The dried leaf of Pyrus ussuriensis were extracted with acetone-H2O (6:4, v/v), concentrated and fractionated with the upper layer of acetone on a separatory funnel. Each fraction was freeze dried, then a portion of acetone soluble powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol as eluents and also used the MIC-gel using a series of aqueous methanol as developing solvent. The isolated compounds were identified by silica-gel TLC. The concentration of total phenolic compound of Pyrus ussuriensis acetate soluble fraction was high, 914 mg/g. The results obtained from the analyses of the anti-oxidanat effects of Pyrus ussuriensis acetate fraction can be summarized as follows: In the result of DPPH scavenging radical activity, Pyrus ussuriensis acetate soluble fraction showed more than 80% at 100 ppm. SOD-like activity of one of Pyrus ussuriensis acetate soluble fractions was 77% at 1000 ppm. Xanthine oxidase inhibition of Pyrus ussuriensis acetate soluble fraction was 38% at 100 ppm. From these results, we confirmed that acetate fraction of Pyrus ussuriensis has a great potential as a natural ingredients with a natural antioxidant and antimicrobial source.