• 한국추진공학회지
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• 제3권1호
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• pp.41-47
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• 1999

고체 추진제의 연소율(burning rate)은 연소의 동적 거동과 추진제의 성능을 판단할 수 있는 중요한 변수이다. 특히 AP계의 고체추진제 표면에서는 발열반응인 분해반응(decomposition) 이외에도 기체로 증발되는 증발반응(evaporation or sublimation)이 존재하므로 이를 고려한 연소 반응율의 해석은 매우 중요한 의미를 갖는다. 본 연구에서는 분해반응과 증발반응이 존재하며 외부로부터 고체추진제 표면으로 입사하는 복사열전달이 있는 경우, 응축영역에서 에너지 방정식과 화학 종 보존식을 사용하여 정상상태의 연소반응율에 관한 이론 해석을 수행하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.69-72
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• 2015

Computational fluid dynamics (CFD) modeling of large-scale coal-fired boilers requires a complicated set of flow, heat transfer and combustion process models based on different degrees of simplification. This study investigates the influence of coal devolatilization, char conversion and turbulent gas reaction models in CFD for a tangential-firing boiler at 500MWe capacity. Devolatilization model is found out not significant on the overall results, when the kinetic rates and the composition of volatiles were varied. In contrast, the turbulence mixing rate influenced significantly on the gas reaction rates, temperature, and heat transfer rate on the wall. The influence of char conversion by the unreacted core shrinking model (UCSM) and the 1st-order global rate model was not significant, but the unburned carbon concentration was predicted in details by the UCSM. Overall, the effects of the selected models were found similar with previous study for a wall-firing boiler.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.9-12
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• 2012

In this study, opposed flow combustion was re-visited in a narrow channel. Various flame behaviors were observed. Due to the confined structure of the combustor in this study, flame structures at very narrow strain rate could be stabilized and their characteristics were investigated. This study will be helpful to understand overall flame behavior of non-premixed flame in a narrow combustion space, and will also be useful to develop small combustors.

• 대한기계학회논문집
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• 제17권10호
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• pp.2611-2623
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• 1993

To construct the design back data for a lean-burn gas engine, we investigated the combustion characteristics in the main chamber using a constant volume combustion chamber with subchamber. The combustion characteristics with configuration change of the critical passageholes have been studied by taking pressure data, schlieren photograph, ion current and light emission signal of flame. Heat release rate with various critical passageholes also have been analysed by using the combustion model of a prechamber diesel engine. It was found that combustion characteristics in the main combustion chamber were greatly influenced by the geometric configurations of critical passagehole.

• 대한기계학회논문집B
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• 제22권11호
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• pp.1582-1590
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• 1998

Combustion-driven oscillations in a surface burner have been investigated to clarify their characteristics. A model combustor is made and the oscillation frequencies are measured for various dimensions of the combustor. It is found that there are two modes of oscillations; one is the 'acoustic mode' at high frequencies, associated with the acoustic mode of the combustion system and the other is the 'combustion mode' at low frequencies around 100 Hz, associated with the instability of the flame. Acoustic mode is excited when the surface burner is placed where the phase of particle velocity leads that of acoustic pressure by $90^{\circ}$, for all the combustion conditions. Combustion mode is driven at high combustion rate by the lift of unstable flame near the lower limit of the combustible equivalence ratio. Combustion mode is greatly influenced by the inlet temperature of the premixed gas. When the inlet temperature is very high, the combustion mode does not occur.

• 항공우주시스템공학회지
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• 제1권2호
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• pp.37-42
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• 2007

This paper proposes a numerical modeling approach to simulate the hybrid combustion phenomena. From the physical understandings of hybrid combustion, the computational domain was separated into three regions: the solid fuel, gas phase reactive flow, and the interface between solid and fluid. Moreover, for the accurate calculation, computational grids for these regions was generated at every time step considering the instantaneous moving interface which are governed by the balance equations using thermal pyrolysis. In the domain of reactive flow, by virtue of diffusion flame structure, turbulent combustion modeling was introduced using either mixture fraction approach or mean reaction rate approach.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.89-92
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• 2004

This work describes a model development and numerical simulation of detailed combustion mechanisms of RDX/GAP/BTIN propellants. The analysis is based on the conservation equations of mass, energy, and species concentrations for both the condensed and gas phases, and takes into account finite-rate chemical kinetics and variable thermophysical properties. The model has been applied to study the combustion wave structures and burning characteristics of RDX/GAP/BTIN propellants over a broad range of pressures. Reasonably good agreement is achieved between the calculated and measured burning rate at atmospheric pressure. But the model calculation does not result in dark zone experimentally observed.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.237-240
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• 2006

Hybrid propulsion systems provide many advantages in terms of stable operation and safety. However, classical hybrid rocket motors have lower fuel regression rate and combustion efficiency compared to solid propellant rocket motor. Accordingly, the recent research efforts are focused on the improvement of engine efficiency and regressionrate in the hybrid rocket engine. The present study has numerically investigated the combustion processes and the flame structure in the hybrid rocket engine. The turbulent combustion is represented by the flamelet model and Low Reynolds number $k-{\varepsilon}$turbulent model is employed to reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect. Numerical results suggest that the present approach is capable of realistically simulating the combustion characteristics of the hybrid rocket engines.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3381-3386
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• 1996

The engine performance and combustion characteristics of methanol blended fuel in spark ignition engine were discussed on the basis of experimental investigation. The effects of methanol blending fuel on combustion in cylinder were investigated under various conditions of engine cycle and blending ratio. The results showed that the engine performance was influenced by the methanol blending ratio and the variations of operating conditions of test engine. The increase of fuel temperature brought on the improvement of combustion characteristics such as cylinder pressure, the rate of pressure rise and heat release in an engine. The burning rate of fuel-air mixture, the exhaust emissions and the other characteristics of performance were discussed also.

• 대한기계학회논문집
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• 제11권5호
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• pp.819-827
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• 1987

본 연구에서는 예혼합화염에 물을 촘가하였을 때의 물/연료 체적비에 따른 화 염온도, 불완전가스농도(CO, THC, H$_{2}$), soot 농도를 측정하여 물이 연소효율에 미치는 영향을 고찰하고자 한다.