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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 3, Issue 2 - Dec 1998
Volume 3, Issue 1 - Jun 1998
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Effect of Acoustical Excitation and Flame Stabilizer on a Diffusion Flame Characteristics
Jeon, C.H. ; Chang, Y.J. ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 1~10
Lots of techniques are adopted for a flame stabilization and a high-load combustion. But the techniques being used were passive control method which have to change combustor shape like pilot flame, flame stabilizer, pressure profile, etc. Active control method which is not necessary to transform its shape is employed. Acoustical excitation is broadly used for its convenience in changing frequency and intensity. Both acoustical excitation and flame stabilizers were adopted to study their relationship. So, we investigated flammability limits. Flame visualization. And mean temperature in the condition of various frequencies, intensities, and flame stabilizers. As a consequence, flammability limit were advanced in acoustically excited flame at some frequencies. Coherent structure was extended to the downstream region through acoustical excitation and a size of vortice was curtailed. Also width of recirculation zone was magnified. In addition, Effects of acoustical excitation was stood out at 25mm flame stabilizer rather than another ones.
Effects of Oxidant Addition to Fuel on Soot Formation of Laminar Diffusion Flames
Lee, Won-Nam ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 11~19
The influence of oxidant addition on soot formation is investigated experimentally with ethylene, propane and mixture fuel co-flow diffusion flames. Oxidant addition into fuel shows the increase of integrated soot volume fractions for ethylene, ethylene/ethane and ethylene/methane mixture flames. However, the increase of integrated soot volume fraction with oxidant addition was not significant for propane and ethylene/propane mixture flames. This discrepancy is explained with
chemistry at the early stage of soot formation process. The oxidant addition increases the concentration of
in the soot formation region, and therefore, enhances soot formation process. A new soot formation rate model that includes both dilution effect and chemical effect of oxygen is suggested to interpret the increase of integrated soot volume fractions with oxidant addition into ethylene. Also, the role of adiabatic flame temperature for the chemical effect of oxygen addition into fuel was reviewed. The influence of oxidant or diluent addition into fuel on soot formation process are the fuel dilution effect, the adiabatic flame temperature altering effect and/or the chemical effect of oxygen. Their relative importance could change with fuel structure and adiabatic flame temperature.
Mathematical Modeling of Combustion Characteristics in HVOF Thermal Spray Processes(I): Chemical Composition of Combustion Products and Adiabatic Flame Temperature
Yang, Young-Myung ; Kim, Ho-Yeon ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 21~29
Mathematical modeling of combustion characteristics in HVOF thermal spray processes was carried out on the basis of equilibrium chemistry. The main objective of this work was the development of a computation code which allows to determine chemical composition of combustion products, adiabatic flame temperature, thermodynamic and transport properties. The free energy minimization method was employed with the descent Newton-Raphson technique for numerical solution of systems of nonlinear thermochemical equations. Adiabatic flame temperature was calculated by using a Newton#s iterative method incorporating the computation module of chemical composition. The performance of this code was verified by comparing computational results with data obtained by ChemKin code and in the literature. Comparisons between the calculated and measured flame temperatures showed a deviation less than 2%. It was observed that adiabatic flame temperature augments with increase in combustion pressure; the influence was significant in the region of low pressure but becomes weaker and weaker with increase in pressure. Relationships of adiabatic flame temperature, dissociation ratio and combustion pressure were also analyzed.
The Relationship between Soot Concentration and Operating Condition regarding Cavity Shapes in a D. I. Diesel Engine
Lee, Sang-Suk ; Lee, Tae-Won ; Ha, Jong-Yu1 ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 31~39
The local instantaneous flame temperature and soot concentration in a D. I. diesel engine were measured using a two-color method. The proposed method based on the continuous spectra! radiation from the soot particles in the flame is applicable to industrial Diesel engines without major modifications of their main characteristics because of simplicity and relative ease of application. Measurements were performed at two locations inside the combustion chamber of a D. I. diesel engine. Effects of different engine speeds and loads, fuel injection timings, combustion chamber shapes on flame temperature and KL factor, which is qualitatively proportional to soot concentrations, were examined. Flame temperature change were observed with increasing engine speed and load. The higher the flame temperature is, the lower the KL factor is.
A Numerical Study on Fuel Concentration Distribution in a FBC
Lee, D.I ; Park, S.H. ; Shin, D.S. ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 41~48
A numerical study on combustion in a fluidized bed is based on three dimensional mixing and dispersion phenomena in the bed owing to the bubble growth in the vertical direction. As fluidizing velocities increase, bubble diameters increase, which activates the fuel dispersion in the bed. The combustion rates, however, reduce due to the decrease of gas exchange rates between bubble and emulsion phases. Fuel distributions in the bed are dependent on fluidizing velocities, equivalence ratios, fuel particle diameters, fuel feeding points, and the number of fuel feeders.
An Experimental Study on High Temperature and Low Oxygen Air Combustion
Chung, D.H. ; Yang, J.B. ; Noh, D.S. ; Kim, W.B. ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 49~57
High temperature preheated and diluted air combustion has been developed as the technology to realize higher thermal efficiency. In this type of combustion, there are many interesting phenomena which cannot be observed in room temperature air combustion. The characteristics of the combustion, investigated using a 3500 kcal/h LPG fired test facility, are described. The flame is demonstrated to have a blue and green in color and has a large volume. As the preheated air temperature increased up to
, the NOx emission incrased exponentially over a few hundred ppm with 11%
correction. But, it drastically reducedabout 20ppm when the air was diluted from 21%
Control of Combustion Instabilities in a Gas Turbine Combustors Through Secondary Fuel Injection
Jeon, C.H. ; Santavicca, Domenic A. ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 59~69
The results of study on the active control of naturally occurring combustion oscillations with a single dominant frequency in an atmospheric dump combustor are presented. Control was achieved by an oscillatory infection of secondary fuel at the dump plane. A high speed solenoid valve with a maximum frequency of 250Hz was used as the actuator and a sound level meter, located at the combustor exit, measured the pressure fluctuations which served as the feedback signal for the control loop. Instability characteristics were mapped over a range of mean mixing section velocities from 6.7 m/s-9.3 m/s and with three mixing conditions. Different fuel/air mixing conditions were investigated by introducing varying percentages of primary fuel at two locations, one at the entrance to the mixing section and one 6 mixing tube diameters upstream of the dump plane. Control studies were conducted at a mean velocity of 9.3 m/s, with an air temperature of
, and from flame blowout to the stoichiometric condition.
A Study on the Combustion Characteristics of Turbulent Diffusion Flame Stabilized by Bluff Body
An, J.G. ; Song, K.K. ;
Journal of the Korean Society of Combustion, volume 3, issue 1, 1998, Pages 71~78
The flame stabilization and the combustion characteristics of diffusion flame formed in the wake of a cylindrical bluff body with fuel injection are studied. With the turbulence generator, the flame stability limits and ion currents were measured and analyzed. The results from this experimental study are summarized as follows. The region with highest average value of ion currents in the middle of flame is moved to the upstream side by the turbulent components of main stream. The flame mass with partially active reaction is moved fast for uniform flow and turbulence generator G3, but the flame mass with relatively slow reaction is moved slowly for turbulence generator G1. If the turbulence generator with strong turbulent component is installed, the turbulent time scale is increased with movement from main stream side to recirculation zone as well as the flame stability limits is deteriorated. Though the special dominant frequency is not appeared in the eddy which exists in flame, high frequency characteristics are appeared in uniform flow and turbulence generator G3, and low frequency characteristics are appeared in uniform flow, turbulence generator G3 and G1.