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H<sub>2</sub>-공기와 CO-공기 예혼합 화염 사이의 후류상호작용에 있어서 H<sub>2</sub>O 첨가 효과
박정,권오붕,김태형,박종호,Park, Jeong,Kwon, Oh Boong,Kim, Tae Hyung,Park, Jong Ho 한국연소학회 2015 한국연소학회지 Vol.20 No.1
Numerical study was conducted to clarify effects of added $H_2O$ for the downstream interaction between $H_2$-air and CO-air premixed flames in counterflow configuration. The reaction mechanism adopted was Davis model which had been known to be well in agreement with reliable experimental data. The results showed that both lean and rich flammable limits were reduced in increase of strain rate. The most discernible difference between the two with and without having $H_2O$ and/or $H_2$ addition into $H_2$-air and CO-air premixtures was two flammable islands for the former and one island for the latter at high strain flame conditions. Even a small amount of $H_2$, in which $H_2$-air premixed flame cannot be sustained by itself, participates in CO oxidation, thereby altering the CO-oxidation reaction path from the main reaction route $CO+O_2{\rightarrow}CO_2+O$ with a very long chemical time in CO-air flame to the OH-related reaction routes including $CO+OH{\rightarrow}CO_2+H$ with very short chemical times. This intrinsic nature alters flame stability maps appreciably. The results also showed that chemical effects of added $H_2O$ help lean flames at relatively low strain rate be sustained, and suppress the flame stabilization at high strain rates.
H₂-공기와 CO-공기 예혼합 화염 사이의 후류상호작용에 있어서 H₂O 첨가 효과
박정(Jeong Park),권오붕(Oh Boong Kwon),김태형(Tae Hyung Kim),박종호(Jong Ho Park) 한국연소학회 2015 한국연소학회지 Vol.20 No.1
Numerical study was conducted to clarify effects of added H₂O for the downstream interaction between H₂-air and CO-air premixed flames in counterflow configuration. The reaction mechanism adopted was Davis model which had been known to be well in agreement with reliable experimental data. The results showed that both lean and rich flammable limits were reduced in increase of strain rate. The most discernible difference between the two with and without having H₂O and/or H₂ addition into H₂-air and CO-air premixtures was two flammable islands for the former and one island for the latter at high strain flame conditions. Even a small amount of H₂, in which H₂-air premixed flame cannot be sustained by itself, participates in CO oxidation, thereby altering the CO-oxidation reaction path from the main reaction route CO + O₂ → CO₂ + O with a very long chemical time in CO-air flame to the OH-related reaction routes including CO + OH → CO₂ + H with very short chemical times. This intrinsic nature alters flame stability maps appreciably. The results also showed that chemical effects of added H₂O help lean flames at relatively low strain rate be sustained, and suppress the flame stabilization at high strain rates.
Variation of Liftoff height with diluents in Laminar Nonpremixed Lifted Flame
Suhyeon Oh(오수현),Kyu Ho Van(반규호),Chun Sang Yoo(유춘상),Oh boong Kwon(권오붕),Suk Ho Chung(정석호),Jeong Park(박정) 한국연소학회 2019 KOSCOSYMPOSIUM논문집 Vol.2019 No.11
With diluents (CO₂, N₂, and He) added to fuel or oxidizer stream, stationary lifted flame in non-premixed laminar coflow-jet has been studied. For CO₂ and N₂ diluted in oxidizer stream, liftoff height significantly increased with diluent mole fraction, while in He-diluted case liftoff height slightly increased. In fuel-diluted stream, liftoff height as adding He and N₂ slightly increased, but CO₂-diluted flame oscillated. To investigate change of liftoff height with diluent mole fraction, laminar burning velocity, effects of diluents, and buoyancy were considered.
배대석,권오붕,김현호,Bae Dae Seok,Kwon Oh Boong,Kim Hyun Ho 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.2
In an inclined enclosure with the upper part cooled and the lower part heated, quantitative data of the temperature and velocity are obtained simultaneously using thermo-sensitive liquid crystals. Experimental results are Presented for Pr=909. aspect ratios of 1/14. 2/14 and 3/14, angle of inclination, 0$\leq$$\theta$$\leq$45 to the horizontal line. The numerical results are obtained in the same conditions as experiments by the finite volume method and its results are compared with experimental results. It is found that the number of cell is decreased with increasing the angle of inclination. and a unicell is formed at nearby 6=30$^{circ}$ which is not affected by the aspect ratio.
상호작용 하는 H<sub>2</sub>-공기/CO-공기 예혼합화염에 미치는 H<sub>2</sub> 선호 확산 영향에 대한 수치적 연구
정용호,박정,권오붕,길상인,윤진한,Chung, Yong Ho,Park, Jeong,Kwon, Oh Boong,Keel, Sang In,Yun, Jin Han 한국연소학회 2013 한국연소학회지 Vol.18 No.4
The effects of preferential diffusion of hydrogen in interacting counterflow $H_2$-air and CO-air premixed flames were investigated numerically. The global strain rate was varied in the range $30-5917s^{-1}$, where the upper bound of this range corresponds to the flame-stretch limit. Preferential diffusion of hydrogen was studied by comparing flame structures for a mixed average diffusivity with those where the diffusivities of H, $H_2$ and $N_2$ were assumed to be equal. Flame stability diagrams are presented, which show the mapping of the limits of the concentrations of $H_2$ and CO as a function of the strain rate. The main oxidation route for CO is $CO+O_2{\rightarrow}CO_2+O$, which is characterized by relatively slow chemical kinetics; however, a much faster route, namely $CO+OH{\rightarrow}CO_2+H$, can be significant, provided that hydrogen from the $H_2$-air flame is penetrated and then participates in the CO-oxidation. This modifies the flame characteristics in the downstream interaction between the $H_2$-air and CO-air flames, and can cause the interaction characteristics at the rich and lean extinction boundaries not to depend on the Lewis number of the deficient reactant, but rather to depend on chemical interaction between the two flames. Such anomalous behaviors include a partial opening of the upper lean extinction boundary in the interaction between a lean $H_2$-air flame and a lean CO-air flame, as well as the formation of two islands of flame sustainability in a partially premixed configuration with a rich $H_2$-air flame and a lean CO-air flame. At large strain rates, there are two islands where the flame can survive, depending on the nature of the interaction between the two flames. Furthermore, the preferential diffusion of hydrogen extends both the lean and the rich extinction boundaries.
메탄-공기/합성가스-공기 예혼합화염의 후류 상호 작용에 대한 연구
박정(Jeong Park),권오붕(Oh Boong Kwon),길상인(Sang-In Keel),윤진한(Jin-Han Yun) 한국연소학회 2016 한국연소학회지 Vol.21 No.1
Downstream interactions between lean premixed flames with mutually different fuels of syngas and CH₄ have been numerically investigated particularly on and near lean extinction limits. The interaction characteristics between lean premixed (50% H₂ + 50% CO)-air and CH₄-air flames were shown to be quite different from those between the same hydrocarbon flames. The lean extinction boundaries were of slanted shape, thereby implying strong interactions. The weaker flames had negative flame speeds on the upper extinction boundaries, whereas the weaker flame speeds on the lower extinction boundaries were both negative and positive. The results also showed that the flame interaction characteristics did not follow the general tendency with the dependency of Lewis number in downstream interactions between the same hydrocarbon flames. Importance of chemical interaction in flame characteristics is discussed in the downstream interactions between lean premixed (50% H₂ + 50% CO)-air and CH₄-air flames.