• 한국추진공학회지
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• 제3권1호
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• pp.95-103
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• 1999

혼합형 고체추진제의 저압하에서의 연소특성을 연소속도측정, 점화 및 정상 연소현상 관찰, 그리고, 소화표면의 구조 관찰의 측면에서 연구하였다. 이를 위하여 OVSB 장치를 제작하였으며, 저압 연소속도 측정기법을 정립하여 혼합형 고체추진제의 저압 연소속도를 측정하였고, OVSB의 연소실에 장착된 창을 통하여 추진제의 점화 및 연소현상을 비디오 카메라를 사용하여 초당 30 장의 속도로 촬영하여 분석하였다. 또한, 급속감압법을 이용하여 얻은 추진제의 소화표면의 구조를 주사전자현미경으로 분석하였다. 시험 대상 추진제들은 대기압 이하(2.0∼15psia)의 저압하에서 압력 지수가 0.6∼0.88로 높은 압력의존성을 보였으며, 추진제에 포함된 금속입자(Al) 함량이 연소속도와 압력 지수에 크게 영향을 주는 것으로 나타났다. 금속함량이 클수록 연소속도가 빨랐으며, 압력 지수는 작았다. 시험대상 추진제들은 2.0psia 부근에서 자체 소화되는 특성을 보였다. 그리고, 연소표면에서의 AP 입자의 분해속도가 바인더의 분해속도 보다 느렸으며, 낮은 압력으로 인해 바인더가 쉽게 기체상태로 승화하는 것으로 판단되었다. Al이 다량 함유된(17.5%) 추진제가 점화성이 우수하였다.

• 한국연소학회지
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• 제2권1호
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• pp.17-27
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• 1997

It is well known that NOx formation has a strong dependence on the maximum temperature and correspondingly with the maximum chamber pressure of a closed combustion system. However, in a case of impinging-jet-flame (IJF hereafter) combustion with opposed dual pre-chambers, low $NO_x$ formation with high pressure could be achieved, but its mechanism has not been clearly understood so far. In this study, a three-dimensional analysis is adopted to resolve time-variant local properties that might indicate the mechanism of IJF combustion. Numerical results are verified by comparing them with experiments. The IJF combustion in a vessel with no pre-chamber, with single pre-chamber, and with dual pre-chambers is studied. The orifice diameter and the volumetric ratio of pre-chamber are used as geometric parameters. The effects of main-chamber ignition delay time and combustion time of main-chamber, orifice exit velocity, orifice exit temperature, turbulent kinetic energy of main-chamber and spatial distribution of temperature in the latter stage of combustion are investigated. A longer main-chamber ignition delay and a shorter main-chamber combustion time suppress the formation of high temperature region with respect to mean temperature, which consequently results in less NO production.

• 대한기계학회논문집
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• 제9권5호
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• pp.548-554
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• 1985

본 논문에서는 디이젤기관의 연소소음의 저감을 최종목표로 하여 Wiebe의 연 소함수에 의해 근사시킨 열발생속도의 변화가 디이젤기관의 연소소음 및 도시열효율에 미치는 영향에 관하여 수치실험을 통하여 해석검토하였다.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.65-72
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• 2002

The closed cycle diesel system is operated in closed circuit system where there is non air breathing with working fluid consists of combination of oxygen, argon and recycled exhaust gas far obtaining underwater or underground power sources. Experimental apparatus using the MTU8V183SE92 high pressurized engine adapted for closed cycle running, capable of operating at the system pressure of maximum 5 bar is constructed with ACAP as data acquisition system in order to operate equally in the open cycle in surface or the closed cycle in submerged conditions. The general features and the characteristics of combustion of HP(high pressure) diesel engine, specially designed and manufactured only for CCDE, are investigated. The test results of performance of HP diesel engine in closed cycle system are presented with respect to power and boost pressure and compared with those of low pressure diesel engine. The oxygen concentration and specific heat ratio are investigated with its deviation

• 한국수소및신에너지학회논문집
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• 제32권1호
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• pp.53-62
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• 2021

Batch type reduction-oxidation tests were performed to check effects of temperature, pressure, gas velocity, and capacity on reduction characteristics of mass produced particle in a 0.5 MWth chemical looping combustion system. The fuel conversion and the CO2 selectivity increased as the temperature increased and as the gas velocity decreased. However the CO2 selectivity showed the maximum and decreased as the capacity increased because the CO emission increased. The results show that high temperature, low gas velocity and low inert gas concentration are preferable to ensure high reactivity of oxygen carrier in the fuel reactor.

• 대한기계학회논문집B
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• 제21권11호
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• pp.1527-1537
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• 1997

Extinction characteristics and acoustic response of hydrogen-air diffusion flames at various pressures are numerically studied by employing counterflow diffusion flame as a model flamelet in turbulent flames in combustion chambers. The numerical results show that extinction strain rate increases linearly with pressure and then decreases, and increases again at high pressures. Thus, flames are classified into three pressure regimes. Such nonmonotonic behavior is caused by the change in chemical kinetic behavior as pressure rises. The investigation of acoustic-pressure response in each regime, for better understanding of combustion instability, shows different characteristics depending on pressure. At low pressures, pressure-rise causes the increase in flame temperature and chain branching/recombination reaction rates, resulting in increased heat release. Therefore, amplification in pressure oscillation is predicted. Similar phenomena are predicted at high pressures. At moderate pressures, weak amplification is predicted since flame temperature and chain branching reaction rate decreases as pressure rises. This acoustic response can be predicted properly only with detailed chemistry or proper reduced chemistry.

• 한국추진공학회지
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• 제21권1호
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• pp.63-71
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• 2017

메탄($CH_4$)/산소($O_2$) 액체이원추진제는 친환경성, 무독성, 경제성, 우수한 성능 등의 장점으로 최근 들어 차세대 친환경 이원추진제로서 관심을 받고 있다. 본 연구에서는 연소실 내 압력 변화에 따른 기체 메탄/산소 비예혼합 동축 화염의 연소안정한계를 측정하고, 화염 및 유동의 가시화를 통해 분사 조건 및 압력 변화에 따른 화염의 구조와 특성을 파악하였다. 연구 결과 연료과농 조건에서 연소실 내 압력이 증가할 경우 연소안정한계가 확장되고 반응 영역이 증가하는 것을 확인할 수 있었다.

• 대한기계학회논문집B
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• 제29권2호
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• pp.180-188
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• 2005

It is well known that a lean burn engine caused by stratified mixture formation has many kinds of advantages to combustion characteristics, such as higher thermal efficiency and lower CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can achieve low fuel consumption technology, it produces much unburned hydrocarbon and soot because of heterogeneous equivalence ratio in the combustion chamber. Therefore, the stratified mixture formation technology is very important to obtain the stable lean combustion. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The local effect of mixture formation according to control air-fuel distribution in the chamber was examined experimentally. In addition, the effect of turbulence on stratified charge combustion process was observed by schlieren photography. From this study, we found that the flame propagation speed increase with swirl flow and the swirl promotes the formation of fuel and air mixture.

• 한국대기환경학회지
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• 제12권2호
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• pp.131-139
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• 1996

The developent of ceramic combustor is being increased beca- use of the excellent physical properties of ceramic material, that is, high-resistant strength, high emissivity power and high corrosin-resistance. Ceramic combustor has been interested in the application of ultra-lean combustion for low NO$_{x}$ emission and gaseuos waste incineration with good combustion. This experimental study was conducted to investigate the combustion and emission characteristics of wall recess type ceramic combustor with equivalence ratio, mixture flow velocity and wall recess depth as parameters. The results in this study are as follows: 1. Wall recess played a important role to extend flame stability region. 2. The peak temperature of gas was peoportional to equivalence ratio, mixture flow velocity and wall recess depth. 3. The static pressure of mixing chamber and inlet temperature depended on the position of flame zone. 4. NO reduction was achieved by lean mixture without lower combustibility.y.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.472-474
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• 2012

축소형 가스발생기를 제작하여 연소시험을 성공적으로 수행하였으며 분사기의 형상 변화에 따른 유량계수의 영향을 파악하였다. 연소시험 결과 산화제 분사기의 유량계수는 이전 결과보다 향상되었지만 저압 및 설계압 시험조건에서 저주파 섭동이 발생하였다.