• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.91-101
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• 2004

With the mathematic linear model of a combustor which consists of a combustion chamber and injectors, the analysis of low frequency dynamic characteristics of a liquld-propellant rocket engine combustor was performed. Propellant mass flowrate was varied by combustion chamber pressure feedback, therefore low frequency oscillation was appeared. Increasing the time constant of a combustion chamber and injector pressure differences and decreasing combustion time delay increased the combustor system stability. The variation of injector time constant little affected stability. The system was always stable, when there was no combustion time delay. Increasing combustion time delay decreased oscillation frequency and damping ratio, and the system eventually became unstable.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.379-385
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• 2010

Mechanism of combustion frequencies occurring during combustion is experimentally investigated in a model combustor with V-gutter flameholder. The combustor has a long duct shape with a cross section area of $40{\times}40mm$. The v-gutter type flameholder with 10, 12, 14mm width is mounted at the side wall of combustor. CNG were used as fuel, and the fuel was injected transversely into air crossflow. It is found that combustion frequencies were considered as first longitudinal mode caused by combustor geometry. And it is found that flameholder length affects the flame holding range. Also, it is observed first longitudinal pressure oscillations make significant changes of flame structure.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.19-28
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• 2010

Generally, combustion instability is generated by the mutual coupling between the heat release and the acoustic pressure in the combustor. On the occasion, the acoustic pressure generates the oscillation of the mass flow rate of propellant injected from injector, and this oscillation again affects combustion in the combustor. So, the dynamic characteristics of the injector have been studied to control combustion instability using injector itself in Russia from 1970's. In order to study injector dynamics, a mechanical pulsator for forced pressure pulsation is produced and the method to quantify the mass flow rate of the propellant that is oscillating at the exit of the injector is developed. With the pulsator and the method, pulsating values of the mass flow rate, pressure, liquid film thickness, and axial velocity generated at the exit of the simplex swirl injector are measured in real time. And phase-amplitude characteristics of each parameter are analyzed using these pulsating values acquired at the exit of the simplex swirl injector.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.297-299
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• 2015

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.28-38
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• 2019

To investigate the relation between flame structure and combustion dynamic characteristics in bi-swirl coaxial injectors for a liquid rocket engine, combustion experiments were performed using gaseous methane and gaseous oxygen. CH* radicals and pressure fluctuations were simultaneously measured by changing the injector geometries such as recess length/orifice diameter and the flow conditions such as equivalence ratio/oxidizer mass flow rate. As the injector geometries affected the velocities and mixing of the propellants, the change in flame structures was observed. From a result of the frequency analysis, it was confirmed that combustion dynamic characteristics varied according to the injector geometry/flow condition and combustion instabilities could occur under specific recess length/flow conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.22-31
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• 2018

In this study, numerical simulations were performed to determine the dynamic characteristics of a pintle nozzle, with changes to the chamber boundary conditions. To apply movement, to the pintle, the nozzle and pintle were created separately by an auto-grid generation program using an overset grid method. The chamber boundary conditions were selected between a constant mass-flow rate condition and a propellant burn-back condition. The pressure and thrust characteristics of the constant mass-flow rate condition were determined by changing the ratio of the mass-flow rate in the inlet. The propellant burn-back condition was considered by formulation of the combustion rate. The burn-back conditions represented nonlinear phenomena, unlike the constant mass flow rate, and a small flow rate resulted in a large change in the chamber pressure.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.186.2-186.2
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• 2011

RDF 연료의 열이용은 2003 폐플라스틱 고형연료 사용에 관한 고시가 나온이후 생산과 이용이 꾸준히 증가하는 추세이며 최근에는 원주, 대구, 부산 등 각 지역의 RDF 생산시설 구축 및 열병합 보일러 건설사업의 추진으로 더욱 활발하게 진행되고 있다. 본 연구는 순환유동층 시범 연소로에서 RDF를 전용으로 연소하여 그 연소특성을 고찰하고 상용 보일러 설계를 위한 연소자료를 축적하는 데 있다. 본 연구는 실험을 위하여 자체로 건설한 순환유동층 보일러에서 수행하였다. 연소 연구에서는 연소특성과 더불어, 환경기술과 연소로의 부식방지에 관한 기술을 고찰하였다. 보일러의 스팀사양은 $300^{\circ}C$와 15ata 이상으로 하였다. 설치된 보일러는 장시간의 운전과 반복 실험을 통해 상용 규모 보일러의 설계에 적용할 연소자료를 확보하였다. 또한 연료특성을 파악하기 위하여 국내에서 생산되는 RPF와 RDF 각 일종을 입수하여 성분을 분석하고 그 특성 자료를 비교하였다. RDF는 순환유동층 보일러에서 뛰어난 연소 효율을 나타내었으며 배연특성도 연소하는 동안 일정하게 배출되었다. 온도나 압력등 연소 변수는 RDF는 연소실험 동한 안정적인 값을 나타내었다. 대부분의 배연물질은 환경기준을 충족할 수 있었다. 다만 HCl의 배출 특성은 환경 규제치를 넘어 섰으며 별도의 배가스 처리기술을 적용하여 환경기준을 맞출 수 있었다.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.19-20
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• 2014

Boiler design should be desinged to maximize thermal efficiency of the system under imposed load requirement and a boiler should be validated for transient operation. If a proper prediction is possible on the transient behavior and transient characteristics of a boiler, one may asses the performance of boiler component, control logics and operation procedures. In this work, dynamic modeling method of boiler is presented and dynamic simulation of load runback scenario was carried out on suprecritical oil-firing boiler.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.6-6
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• 2000

국가우주개발 중장기 계획에 의거, 독자 인공위성 발사체 개발에 필요한 필수기술을 확보하기 위하여 액체추진제 로켓엔진의 개발에 대한 필요성이 대두되었으며, 이에 따라 한국항공우주연구소는 과학로켓 3호(KSR-III)에 적용하기 위한 액체추진기관을 개발하고 있다. 이러한 목적으로 kerosine/LOx를 사용하며 13톤급의 추력을 낼 수 있는 시제엔진이 설계, 제작되었으며 이 엔진에 대한 연소시험이 실시되었다. 본 연구에서는 액체추진기관 시험을 위한 일련의 진행사항, 시험방법을 소개하며, 시험을 통하여 획득한 정특성 자료 및 동특성 자료에 대하여 분석하였다.(중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.263-266
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• 2009

The mainly objectives of this study was a combustion dynamics and instability characteristics in a model gas turbine dump combustor which is the scale down of GE 7FA+e DLN 2.6 gas turbine combustor. Model gas turbine injector has 2-stage swirl vane and it’s reduced 1/3 size of the original one. The shape of plenum and combustor were designed for similar acoustic characteristics. Inlet air was preheated to $200{\sim}400^{\circ}C$. The flow velocity at mixing nozzle was 30 to 75 m/s and equivalent ratio was 0.4 to 1.2. The combustor length was varied for different acoustic characteristics to $375{\sim}700\;mm$. As the result, this research have been show the combustion instability was observed at lower equivalence ratios ($\Phi$ < $0.5{\sim}0.6$) and higher equivalent ratios ($\Phi$ > $1.1{\sim}1.2$).