• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.9-16
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• 2016

An experimental study was performed to investigate the combustion characteristics of the liquid hydrocarbon fuel atomized by an ultrasonic oscillator. Configuration of the flame was caught by the high-speed camera, and images were analyzed in detail through a post-processing. In addition, the fuel consumption was measured using the balance during the combustion reaction. As a result, the consumption of atomized fuel increased with the increasing flow-rate of carrier-gas, but any correlation between the air/fuel ratio and carrier-gas flow-rate was not found. The variation of flame area was dependent on the fuel consumption and input power of the ultrasonic oscillator. FFT (Fast Fourier Transform) analyses using the flame area were conducted in order to discuss flame flickering.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.6
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• pp.59-66
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• 2006

Acoustic cavity as a stabilization device to control high-frequency combustion instabilities in liquid rocket engine is adopted and its damping capacity is verified in atmospheric temperature. First, harmful resonant frequency in a modeling chamber can be damped effectively by the installation of properly-tuned acoustic cavity. Besides, geometric effects of acoustic cavity on damping characteristics are analyzed and compared quantitatively. Satisfactory agreements have been achieved with linear acoustic analysis and experimental approach. Results show that the acoustic cavity of the largest orifice area or the shortest orifice length was the most effective in acoustic damping of the harmful resonant frequency. Finally, it is proved that an optimal design process is indispensable for the effective control of combustion instabilities.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.26-30
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• 2011

Instantaneous water heater being not properly installed and not adequately maintained may produce fatal accidents due to carbon monoxide poisoning and suffocation. Insufficient supply of air into the gas appliance for complete burning of the fuel or blocking the outlet of the combustion gas could be a cause to increase carbon monoxide concentration in the exhaust gas of the gas appliance. In this work, the experiments are done with a collected instantaneous water heater using in domestic and the concentration of oxygen near the gas appliance and carbon monoxide in exhaust gas are observed to investigate the risk of instantaneous water heater. The concentration of oxygen near the gas appliance is reduced until 17.7% for the ratio of the ventilation area and floor area being 3.5%. If the outlet of combustion gas is blocked, the carbon monoxide concentration is steeply increasing more than 4,000ppm. Therefore, periodic checking the outlet of combustion gas is more important than vent area to reduce the risk of carbon monoxide poisoning.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.135-146
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• 2015

This paper is the fourth on the combustion characteristics of the landfill gas in a constant volume combustion chamber for a large displacement volume commercial engine and the second dealing with torch ignition. It discusses the combustion characteristics of torch ignition on the basis of the heat release and visualization. The results show that the jet and/or spout from the torch promote combustion by accelerating the flame front in the main combustion chamber. In addition, a hot gas jet exists when the orifice diameter is 4 mm, whereas the flame passes directly through the orifice if the diameter is 6 mm or greater. In addition, the effect of torch ignition differs according to the combination of the methane fraction, torch volume, and orifice size because various combustion processes occur as a result of the interaction of these parameters. Finally, it was found that the most suitable torch should have an orifice diameter of not less than 6 mm and an area ratio of not more than 0.15 to secure a consistent combustion process in a real engine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.293-298
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• 2011

The combustion and flow-rate control characteristics of fuel-rich gas generator which could be adopted to Ducted Rocket propulsion system are investigated. The gas generator is designed considering the design requirements of propulsion system and solid fuel for fuel-rich combustion is developed then adopted to ground test. The results of combustion test show the necessity of the special analysis tool for estimating the gas generator performance where multi-phase flow of fuel-rich gas exists. During the flow-rate control test, characteristics of gas generator pressure with the angle of valve are analyzed and, method to estimate the pressure of gas generator is suggested using the relation between the valve exit area and discharge coefficient.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.46-53
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• 2017

This paper deals with an acoustic model for a lean premixed gas turbine combustor composed of three stages: premixing chamber, nozzle and flame tube. Our model is given as an acoustic transfer function whose input is a heat release rate perturbation and output is a velocity perturbation at a flame location. We have shown that the resonance frequencies are functions of three round-trip frequencies of acoustic wave in each stage, and area ratios between stages. By analyzing poles of the acoustic transfer function, we could characterize resonant frequencies and their dependency on various system parameters of a combustor. It was found that our analytic findings match with existing numerical and experimental results in literature.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.1-11
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• 2020

In this study, study on the internal ballistic analysis method for single-chamber dual-thrust rocket motors meeting a dual-thrust profile requirement by tailoring the grain burning area is presented. The analysis method, which can acquire variables required for the performance prediction, considering gradual change of burning rate correction factor and specific impulse in the transition phase, is proposed. Improvements compared to the analysis method in the previous study, which do not consider change in the transition phase, are verified through comparison between the newly proposed method and the method in the previous study. Internal ballistic variables are obtained for four different ground firing test conditions using the proposed method, and the performance prediction for each condition is conducted using these variables. These prediction results and the ground test data are in good agreement, so it is confirmed that the performance prediction of dual-thrust motors with same design geometries based on the proposed analysis method is available.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.45-51
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• 2001

Catalytic combustion is the environmental-friendly technology, which has been applied to a variety of areas for industrial and domestic use in recent years. Accordingly, this study performed the development of the catalytic manufacturing technology for the high temperature and of the catalytic combustor in priority, which were aimed to be aimed to a commercialized condensing boiler. Palladium(Pd) of a noble meta] was used as a catalyst for the high temperature and supported on $alumina(Al_{2}O_{3})\;and\;zirconia(ZrO_2)$ in constant weight ratio. Activity of Pd catalysts is compared and analysed in the catalytic combustion of natural gas. The ratio of $Pd/Al_{2}O_{3}\;=\;4$ was found to be better than any other weight ratios in activity and durability. The performance examination of catalysts and of combustion through the plate-type combustor made it possible to be developed the cylindrical-type combustor which has increased combustion area. Catalytic combustion condensing boiler of 25,000 kcal/hr class was also developed, which had the optimum combustion condition at the no221e of 5.95mm and the orifice of 21mm. This condition was determined through the performance experiments of catalytic combustion condensing boiler to which the cylindrical-type catalytic combustor was applied.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.633-638
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• 2011

Mn substituted La, Sr or Ba-hexaaluminate were prepared by $(NH_4)_2CO_3$ co-precipitate method and calcined at $1,200^{\circ}C$ for 5 h. Catalysts were characterized by X-ray diffraction and $N_2$ physisorption and scanning electron microscope (SEM). Compared to $SrMnAl_{11}O_{19}$ and $BaMnAl_{11}O_{19}$, $LaMnAl_{11}O_{19}$ in which La located at mirror plane showed better crystallinity and high surface area, 13 $m^2/g$. $LaMnAl_{11}O_{19}$ revealed well developed plate-like structure which is characteristic structure of hexaaluminate. The catalytic activity of methane combustion increased in the following order: $LaMnAl_{11}O_{19}$ > $SrMnAl_{11}O_{19}$ > $BaMnAl_{11}O_{19}$ and was dependent on surface area of catalysts. 60 wt% $CeO_2/LaMnAl_{11}O_{19}$ calcined at $700^{\circ}C$ showed enhanced methane activity and methane was oxidized completely at low temperature ($700^{\circ}C$). It was confirmed that addition of ceria seems to be effective for the low and middle temperature combustion of methane. But, after calcination at high temperature of $1,200^{\circ}C$, it lost the promoting effect of ceria due to increase of ceria particle size and it had a limit to applying to the high temperature catalytic combustion.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.66-73
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• 2005

Hydrogen linear power system is estimated as the next generation power system which can obtain a performance as same as fuel cell. In order to develop Hydrogen combustion power system with high thermal efficiency, it is very important to understand the basic characteristics of hydrogen combustion and establish combustion stabilization technique of its system. In this study, RICEM(Rapid Intake Compression Expansion Machine) for researching of hydrogen combustion linear power system was manufactured and evaluated, and the basic characteristics of linear RICEM were analyzed.