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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Combustion
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Journal DOI :
The Korean Society of Combustion
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Volume & Issues
Volume 5, Issue 2 - Dec 2000
Volume 5, Issue 1 - Jun 2000
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Experimental and Theoretical Study on the Effect of Pressure on the Surface Reaction over Platinum Catalyst
Kim, Hyung-Man ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 1~6
Surface reaction occurs at a certain surface temperature when a catalyst is heated up in a reactive mixture. If homogeneous ignition does not occur, a steady state is observed because the heat produced by the surface reaction is balanced with the heat loss caused by convection, conduction and radiation. The present paper treats the effects of pressure on the surface temperature at the steady state. Hydrogen and oxygen are used as reactants and nitrogen as an inert gas. A spherical platinum catalyst of 1.5 mm in diameter is sustained in the chamber with two wires of 0.1 mm in diameter. As results, there exists a maximum steady temperature at a certain relative hydrogen concentration which increases with total pressure. At the steady state, it can be approximated that the heat release is estimated by the mass transfer considering the effect of natural convection. The experimental results are explained qualitatively by the approximation.
The Influence of Strain Rates on the
Counterflow Nonpremixed Flames
Lee, Ki-Yong ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 7~18
Numerical simulations of counterflow non-premixed
flames added 8%(by volume) C2HCl3 on the fuel side are conducted at atmospheric pressure using a detailed chemical reaction mechanism in order to understand the effect of strain rates. A detailed sensitivity analysis is also performed in order to assess the relative influence of each reaction on the flame established at a strain rate of 200s-1. The structure of flames (i.e., temperature, velocity, and concentration of species) established at both a strain rate of 150s-1 and 300s-1 are investigated. As the strain rate increases, the "flame zone" is restricted to a narrower range and the position of maximum temperature is shifted to the fuel side. The concentrations of major species, H2O, CO, H2, HCl, Cl2, and Cl are decreased with increased strain rate. The reaction involving chlorine, CH4 + Cl
CH3 + HCl, instead of the reaction, CH4 + H
CH3 + H2 influences the consumption of methane. C2HCl3 + OH
CHCl2 + CHOCl and HCl + OH
H2O + Cl, are major reactions, through which OH radicals are consumed.
Analysis of NOx Emissions in Thrbulent Nonpremixed Hydrogen-Air Jet Flames with Coaxial Air
Park, Y.H. ; Kim, S.L. ; Moon, H.J. ; Yoon, Y.B. ; Jeung, I.S. ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 19~30
The characteristics of NOx emissions in pure hydrogen nonpremixed flames with coaxial air are analyzed numerically for the three model cases of coaxial air flames classified by varying coaxial air velocity and/or fuel velocity. In coaxial air flames, the flame length is reduced by coaxial air and can be represented as a function of the ratio of coaxial air to fuel velocity. Coaxial air decreases flame reaction zone, resulting in reducing flame residence time significantly. Finally, the large reduction of EINOx is achieved by the decrease of the flame residence time. It is found that because coaxial air can break down the flame self-similarity law, appropriate scaling parameters, which are different from those in the simple jet flames, are recommended. In coaxial air flames, the flame residence time based on the flame volume produces better results than that based on a cube of the flame length. And some portion of deviations from the 1/2 scaling law by coaxial air may be due to the violation of the linear relationship between the flame volume and the flame reaction zone.
Numerical Study of Regular Start and Unstart Process of Superdetonative Speed Ram Accelerator
Moon, G.W. ; Jeung, I.S. ; Choi, J.Y. ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 31~41
A numerical study was conducted to investigate the combustion phenomena of regular start and unstart processes based on ISL#s RAMAC 30 experiments with different diluent amounts in a ram accelerator. The initial projectile launching speed was 1800m/s which corresponded to the superdetonative speed of the stoichiometric
mixture diluted with
. In this study, it was found that neither shock nor viscous heating was sufficient to ignite the mixture at a low speed of 1800m/s, as was found in the experiments using a steel-covered projectile. However, we could succeed in igniting the mixtures by imposing a minimal amount of additional heat to the combustor section and simulate the regular start and unstart processes found in the experiments with an aluminum-covered projectile. The numerical results matched almost exactly to the experimental results. As a result, it was found that the regular start and unstart processes depended on the strength of gas mixture, development of shock-induced combustion wave stabilized by the first separation bubble, and its size and location.
Determination of Ignition Squence and Estimation of Injector Life Extension Technique in Liquid Rocket Engine
Park, Jeong ; Kim, Yong-Wook ; Kim, Young-Han ; Moon, Il-Yoon ; Lee, Jae-Yong ; Kang, Sun-Il ; Chung, Yong-Gahp ; Cho, Nam-Kyung ; Oh, Seung-Hyup ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 43~53
Experimental studies on determination of the supply leading time of propellants to combustion chamber have been made to stably and efficiently guarantee the ignition process with liquid rocket engine. The propellant used is a Jet A-1 as fuel and a liquid oxygen as oxidizer. Unlike impinging FOOF type of injectors are arranged radially and the designed O/F ratio is 2.34. The present experiment program also includes the stability on the quadlet type of ignitor using the triethylalumimum as an ignition source and injector life tests. Experimental results clarifies that the propellant supply through LOx leading to combustion chamber is proper for stable ignition and combustion processes based on the fuel and oxidizer manifold pressures, combustion chamber pressure, and the variation of flame length from the nozzle exit with lapse time, and shows that the leading supply time of propellants affects the engine performance little. The effect of positioning cooling holes is remarkable to protect the injector face.
Simulation of Axisymmetric Flows with Swirl in a Gas Turbine Combustor
Shin, Dong-Shin ; Lim, Jong-Soo ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 55~66
A general purpose program for the analysis of flows in a gas turbine combustor is developed. The program uses non-staggered grids based on finite volume method and the cartesian velocities as primitive variables. A flow inside the C-type diffuser is simulated to check the boundary fitted coordinate. The velocity profiles at cross section agree well with experimental results. A turbulent diffusion flame behind a bluff body is simulated for the combustion simulation. Simulated results show good agreement with experimental data. Finally, a turbulent flow with swirl in a gas turbine combustor was simulated. The results show two recirculating region and simulated velocity fields agree well with experimental data. The distance between two recirculating regions becomes shorter as swirl angle increases. Swirl angle changes angular momentum and streamlines in flow fields.
A Study on Combustion Characteristics of Turbulent Spray Flame by the Dual Swirler
Lee, Kang-Yeop ; Hwang, Sang-Soon ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 67~79
An Experimental study was conducted on spray combustion using dual swirlers at different outlet angle; co-swirl and counter-swirl. To understand the characteristics of turbulent spray combustion of dual swril flow(DSF), the axial helical annular vaned swirlers with various swirl ratios and combination of angle and direction were designed. and temperature measurements of a rapidly thermocouple insertion and measurements of soot volume fraction and microstructure using thermophoretic sampling particle diagnostic(TSPD) as TEM were carried out. The NOx,
, etc. was analyzed using emission gas analyzer. The results show that flame stability were maintained under very lean condition. for both co-swirl and counter-swirl case. And though Counter-swirl case kept the higher temperature region compared to co-swirl case, Counter-swirl combustion represented less NOx emission and soot formation than co-swirl case.
An Experimental Study on Vaporization and Combustion Behavior for Single Droplets of Water-in-Oil Emulsified Fuels
Park, M.C. ; Kim, B.S. ; Oh, S.H. ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 81~89
An experimental study has been carried on single fuel droplets of water-in-light oil emulsions in an electric furnace to elucidate the dominant factor for the occurrence of micro-explosions. The tests were carried out by changing the following four parameters; the surfactant, the ratio of water to light oil, ambient temperature in electric furnace, and four kinds of fuels having different viscosity(light-oil, kerosene, iso-octane, bunker fuel). The result shows that micro-explosion phenomena is dominated without surfactant and below 30% of water content. Explosion-time is affected by ambient temperature and viscosity of used fuel.
Study on the Partially Premixed Flames Produced by a Coflow Burner as Temperature Calibration Source
Park, Chul-Woung ; Hahn, Jae-Won ; Shin, Hyun-Dong ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 91~98
We investigated a uniform temperature zone, produced by double flame structure of a co flow CH4/air partially premixed flame, to be used as a temperature calibration source for laser diagnostics. A broadband N2 CARS(coherent anti-Stokes Raman spectroscopy) system with a modeless laser was used for temperature measurement. When the stoichiometric ratio was 1.5, we found the uniform temperature zone in radial direction of the flame of which the averaged temperature was 2110 K with standard deviation 24 K. In the stoichiometric ratio range between 2.0 and 2.5, we found very stable temperature-varying zones in vertical direction at the center of the flame. The size of the zone was approximately 15 mm and it covered a temperature range from 300 K to 1900 K. We also suggest that this zone can be used as a calibration source for 2-D PLIF(planar laser induced flurescence) temperature measurement.
An Experimental Study on Combustion Characteristics of Regenerative Gas Burner
Yang, J.B. ; Kim, W.B. ; Noh, D.S. ;
Journal of the Korean Society of Combustion, volume 5, issue 1, 2000, Pages 99~108
Regenerative burner is a product of new combustion technology for realizing higher thermal efficiency and lower emissions, moreover utilizing very high preheated air temperature up to
. In this study the experimental study was carried out to find out a combustion characteristics breaking the old combustion concept. From the variation of configuration of gas nozzle and hot test on the temperature distribution and NOx, CO, it was found out that the performance of regenerative burner was better than that of existing burner, mainly due to the effect of internal gas recirculation.