• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.367-376
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• 2012

연소불안정 현상을 제거하거나 효과적으로 제어하기 위해서는 화염구조에 대한 이해가 매우 중요하다. 이에 본 연구에서는 OH 자발광 및 He-Ne 레이저 광흡수 계측기법을 이용하여 연소불안정과 화염구조사이의 상관관계에 대한 실험적 연구를 다양한 실험조건에서 수행하였다. 실험에서는 673K로 가열되어진 swirl 형태로 공급되는 건조한 공기와 LNG(CH4) 연료를 사용하였으며 전체 당량비는 1.2 조건에서 속도를 25 ~ 70 m/s까지 바꾸어가며 실험을 수행하였다. 이를 통하여 연소불안정 현상이 낮은 속도조건과 높은 속도조건에서 발생하는 것을 확인할 수 있었고, 낮은 속도조건의 불안정에서는 화염의 와동구조가 연소불안정현상에 영향을 끼친다는 것을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제25권1호
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• pp.47-58
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• 2014

The characteristics of flame shape, laminar burning velocity, emissions and heat flux of stagnation point in premixed impinging jet flame of syngas fuel with 10% hydrogen content were experimentally investigated. Also, the adiabatic temperature and burning velocity are calculated by Chemkin package with USC-II mechanism. The equivalence ratios(0.8~5.0) and dimensionless separation distance(2.0~5.0) with fixed Reynolds number(1800) are main parameters in this work. Different flame shapes and colors were observed for different impingement conditions. The experimental results of burning velocity by flame surface area have a consistent with previous works and numerical simulation of this work. The inner flame length could be predicted with the ratio of mixture velocity and burning velocity from a simple formulation by the laminar burning velocity definition. It has been observed that the heat fluxes at stagnation point are directly affected by the flame shape including the separation distance. The emission results in impinging flame of syngas fuel show that the characteristics of $NO_x$ emission traced well with adiabatic temperature trend and CO emission due to fuel rich condition increased continuously with respect to the equivalence ratio.

• 대한기계학회논문집
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• 제13권3호
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• pp.517-527
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• 1989

본 연구에서는 국내 난방용 주연료인 연탄의 연소특성의 규명을 위한 기본 모델로서 일차적으로 형상을 단순화한 중공 원통형 고체연료의 연소모델을 개발하여 고체연료의 열분해 및 열분해 가스의 연소현상을 이론적으로 고찰하여 고체연료의 연속특성을 규명한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3062-3067
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• 2007

HVOF thermal spray guns are now being widely used to produce protective coatings, on the surfaces of engineering components. HVOF technology employs a combustion process to heat the gas flow and melt the coating materials which are particles of metals, alloys or cermets. Particle flow which is accelerated to high velocities and combustion gas stream are deposited on a substrate. In order to obtain good quality coatings, the analysis of torch design must be performed. The reason is that the design parameters of torch influence gas dynamic behaviors. In this study, numerical analysis is performed to predict the gas dynamic behaviors in a HVOF thermal spray gun with various torch shapes. The CFD model is used to deduce the effect of changes in nozzle geometry on gas dynamics. Using a commercial code, FLUENT which uses Finite Volume Method and SIMPLE algorithm, governing equations have been solved for the pressure, velocity and temperature distributions in the HVOF thermal spray torch.

• Journal of Advanced Marine Engineering and Technology
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• 제18권1호
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• pp.81-91
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• 1994

Combustion noise involved with chemical heat release and turbulent process in turbopropulsion systems, gasturbine, industrial furnaces and internal engines is indeed noisy. The experimental study reported in this paper is made to identify a dominant combustion noise in jet flames. Gaseous propane and kerosene fuel have been used with air as the oxidizer in a different jet combustion systems. Combustion and aerodynamic noise are studied through far field sound pressure measurements in an anechoic chamber. And also mean temperature and velocities and turbulent intensities of both isothermal and reacting flow fields were measured. It is shown that axial mean velocity of reacting flow fields is higher about 1 to 3m/sec than that of cold flow in a gaseous combustor. As the gaseous fuel flow rate increases, the acoustic power increases. But the sound pressure level for the spray flame decreases with increasing equivalence ratio. The influence of temperature in the combustion fields due to chemical heat release has been observed to be a dominant noise source in the spray flame. The spectra of combustion noise in gaseous propane and kerosene jet flame show a predominantly low frequency and a broadband nature as compared with the noise characteristics in an isothermal air jet.

• 설비공학논문집
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• 제9권2호
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• pp.221-228
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• 1997

A strong combustion-driven sound from a surface burner made of a perforated metal fiber plate for premixed gas was investigated to clarify the physical mechanism of its generation. A simple model was developed for the acoustic power generation in terms of the heat transfer response function and the acoustic impedance of the burner. The acoustic impedance of the perforated metal fiber placed on the open exit was measured and the heat release response of the burner to the oscillating flow associated with the acoustic disturbance was expressed in terms of a response function. It was found that the power is generated by the heat release in response to the downstream particle velocity, in contrast to the upstream velocity in the case of the Rijke oscillation driven by a heater placed in the lower half of a columm with upstream flow. The measured frequencies of the oscillation were in agreement with the estimated resonance frequencies and their excitation was varied with the combustion conditions. For the same fuel rate, the excited frequency increases with the air ratio if it is low but decreases with the ratio if not so low. Such frequency characteristics were explained by assuming a heat release response function with a time constant and it was shown that the excited frequency decreases as the time constant increases.

• 한국추진공학회지
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• 제17권4호
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• pp.73-80
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• 2013

장거리 극초음속 비행체에 적용 가능한 유일한 냉각방안으로 알려져 있는 흡열연료 적용기술을 개발하기 위하여 흡열반응에 의해 분해된 연료의 분사 및 연소특성에 대한 연구사례를 살펴보았다. 흡열반응을 거친 연료가 연소실에 분사될 때 처해지는 초임계 상태의 분사 특성, 초임계 연료가 초음속 유동장에 분사될 때의 공기혼합 특성 등에 관한 연구사례를 살펴보았고, 연소특성으로서 점화지연시간 및 화염전파 속도에 미치는 영향, 초음속 연소실에서 연소될 때의 연소효율 상승 연구사례 등을 살펴보았다. 국내에서 수행된 흡열연료 관련 연구동향을 살펴보았다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
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• pp.119-124
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• 2001

Propane coflow diffusion flames have been experimentally studied to investigate the liftoff and reattachment characteristics. Flame properties such as velocity and density distribution were measured by LDV and shadowgraphy, respectively. It is shown that as the velocity of coflowing air increases, liftoff velocity decreases nonlinearly in turbulent jets and linearly in laminar jets, while reattachment velocity decreases nonlinearly. Meanwhile, as inner nozzle tip thickness increases, liftoff velocity increases with the reattachment velocity nearly unchanged. Liftoff phenomena in these flames can be categorized into three classes as a function of coflow velocity, such as laminar liftoff, turbulent liftoff, and transient liftoff.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.136-145
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• 1995

The aim of this study is to gain a better understanding of the effect of a flow motion on the flame development by means of an optically-accessible constant-volume combustion chamber and the visualization technique of a combustion flame. At first, the characteristics of a flame propagation are investigated in the combustion field of the two kinds of flow conditions such as a quiescent and a flowing condition, and methane-air mixture is used as fuel. Then the same investigation is performed in two flow configurations : bulk flow motion type and turbulence generating type. In this study, the combustion phenomena are analyzed by measuring the combustion pressure, flame propagation speed, mean velocity, turbulent intensity, and mass fraction burned.

• 한국추진공학회지
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• 제25권6호
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• pp.45-52
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• 2021

본 연구에서는 액체 추진제 소형로켓엔진의 개발을 위한 선행연구로 연료과농 조건의 기체메탄-기체산소 연소시험 결과를 제시한다. 다양한 당량비에 대한 연소특성을 비교하기 위해 산소 공급 유량을 12 g/s로 설정하고 메탄 공급 유량을 변화시켰다. 시험 결과, 연소시험 중 형성되는 정상상태 특성속도가 후반에서 급작스럽게 증가하는 현상이 관측되었으며, 그 변화량은 당량비에 비례하여 커지는 경향을 확인할 수 있었다. 이를 바탕으로 특성속도의 변이특성에 종속하는 당량비 구간을 총 3가지 연소 범주로 구분하였다.