• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.103-109
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• 2017

An increase in acoustic energy in a combustion chamber coupled with heat fluctuations from flame results in the occurrence of combustion instability. The assessment of combustion stability requires the prediction of acoustic energy variation by understanding the acoustical characteristics of flow boundaries in a combustion chamber. The present paper discusses about the characteristics of acoustic impedances at boundaries in terms of Strouhal number and summarizes theoretical analyses on the acoustic characteristics of injector-head-like configurations. Also, the details of the two-microphone measurement technique have been presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.3
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• pp.70-77
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• 2014

In this paper, the development of unique model of the 2.75 inch rocket propulsion system is described. Recently developed korean 2.75 inch rocket propulsion system shows the improvement of a flame stability resulted from a change in the configuration of propellant grain, and of an incidental ignition protection function using the EMI(electromagnetic interference) filter on ignition system. Moreover it is shown that a directional flight stability is improved by increasing the number of fins and changing the nozzle configuration. Static firing test and thermal shock test were conducted for the validation before flight, and flight test of 210 rounds of rockets was conducted to verify the trajectory uniformity. In addition, intellectual property issues can be overcome with the unique korean 2.75 inch rocket motor as well as the performance improvement.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.144-151
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• 2004

Stabilization and reduction of combustion noise and NOx emission from dry low NOx combustor of GE MS7001F gas turbine were achieved. Dry low NOx gas turbines that adopt the lean premixed combustion technology frequently generate the flame instability and high NOx emissions if not adequately tuned. Dynamic pressure oscillation during the combustion mode transfer increased as ambient temperature decreased with frequency of 80㎐ and magnitude of 4-9 psi. Effects of both combustor tuning for uniform fuel flow with burner nozzles and fuel pre-filling into transfer fuel valves on stabilisation of the dry low NOx combustor were very significant. Dynamic pressure oscillation during the combustion mode change was decreased up to 2.5 psi. Also, NOx emission from GE7F DLN-1 combustor can be maintained as low as 35-43ppm (15% O$_2$) in base load operation of 150 MW.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.492-497
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• 2015

VOCs (Volatile Organic Compounds) are generally generated in the painting process, or at the company and laundry where use organic solvents. The VOCs consist of various hydrocarbons and has low calorific value due to its dilution with atmospheric air. Therefore, the VOCs are difficult to burn by a conventional fuel combustor. In this study, a novel plasma dump combustor was proposed for the treatment of low calorific VOC gases. This combustor was designed a combination of the characteristics in a plasma burner, a dump combustor and a 3D matrix burner. The combustor has good structure for maintaining enough residence time and reaction temperature for stable flame formation and VOC destruction. For investigating the performance characteristics of the plasma dump combustor, an experiment was achieved for VOC feed rate, VOC injector position, etc. Toluene was used as a surrogate of VOC. The novel combustor gave better performance than a conventional combustor, showing that VOC destruction rate and energy efficiency were 89.64% and 12.27 kg/kWh respectively, at feeding rate of 450 L/min of VOC of 3,000 ppm of toluene concentration.

• Journal of Forest and Environmental Science
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• v.13 no.1
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• pp.153-165
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• 1997

Hydroxyl radicals were detected and their qualitative yields were estimated by using chemiluminescence method and $\gamma$-irradiation technique in oxygen or chlorine dioxide radicals bleaching conditions. The correlation of hydroxyl radical formation and lignin model(Apocynol) or carbohydrate model($\alpha$-D-glucopyranose and methyl-$\beta$-D-glucopyranoside) degradation was studied in the presence of metal ion or without metal ion. The results showed that the presence of metal ions efficiently affected the formation of hydroxyl radicals in oxygen bleaching process, in the order of $Cu^{2+}$ > $Mn^{2+}$ > $Mg^{2+}$ > $Fe^{2+}$, and these metal gave also rise to the degradation of carbohydrate. But it was found that the addition of $100{\mu}m\;Mg^{2+}$ gave an efficient protection against carbohydrate degradation and suppressed the hydroxyl radical formation under oxygen bleaching conditions. And the presence of $Cu^{2+}$ had a detrimental effect on the stability of carbohydrates, whereas the addition of $3{\mu}m\;Mn^{2+}$ surprisingly had a small protective effect on methyl--$\beta$-D-glucopyranoside. In the $ClO_2$ radical bleaching conditions the hydroxyl radical expected to generate from water or substrates was not detected in the presence of metals.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1079-1089
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• 2013

The flow characteristics in a solid particle incinerator are investigated numerically for high burning rate of wastes. The studied incinerator employs both a swirl flow used in the furnace of powerplants and a design concept applied to a rocket combustor. As the first step, the non-reactive flow field is analyzed in the incinerator with primary and secondary injectors through which solid fuel and air are injected. The deflection angle of a primary injector, inclination angle of a secondary injector, and gap between the two types of injectors are selected as design parameters. The swirl number is adopted for evaluating the degree of swirl flow and estimated over wide ranges of three parameters. The swirl number increases with deflection angle, but it is affected little by inclination angle. Recirculation zones are formed near the injectors, and their size affects the swirl number. The swirl number decreases with the zonal size of recirculation. From the numerical results, the design points can be found with strong swirl flow.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.22-28
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• 2015

In order to keep the competitiveness of LPG fuel for transportation fuel, the difference in fuel consumption with gasoline and cost for an aftertreatment system should be reduced with continuous development of technology for LPG engine. In the present study, spray-guided type direct injection combustion system, whose configuration is composed of direct injector in the vicinity of spark plug, was employed to realize stable lean combustion. A certain level of nitrogen oxides($NO_x$) emits due to a locally rich mixture regions in the stratified mixture. With the application of EGR system for the reduction of $NO_x$, 15% of $NO_x$ reduction was achieved whereas fuel consumption and hydrocarbon emission increased. By the application of EGR, the combustion speed reduced especially appeared at initial flame development period and peak heat release rates and increasing rates for heat release rate decreased as EGR rate increased due to the dilution effect of intake air.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.72-86
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• 2006

A technical review of current ramjet propulsion is presented. In addition to summarize the current status of ramjet technology, new key techniques like Boosting technique easily adapting total impulse of booster, flame stabilization technique with minimized ramjet combuster length, variable nozzle-inner-surface technique realizing wide flight-envelop, and thermal protection technique for long operating time are identified. Actually various Ramjet propulsion technology has been matured and expanding to both military and combined cycle application. Yet many opportunities remain to be challenged by future generations of explorers to utilize s typical ramjet propulsion system for multi-purpose(multi-platform and multi-target) missiles, for example, American JSSCM and Russian Yakhont missiles, improving both reliability of techniques and downsizing development cost of new propulsion system.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.11-18
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• 2023

This study explained the need for ammonia fuel and the value chain as a hydrogen carrier. The basic concept of ammonia combustion characteristics and the development of flame stability and low NOx combustion technology were introduced. In addition, through the trend of ammonia combustion technology, the characteristics of ammonia combustion technology in the power generation and industrial sectors were examined, and the author's opinions were included. Through this paper, the author intends to give some overview of basic knowledge about ammonia fuel and its future development direction and meaning.