• 한국대기환경학회지
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• 제16권6호
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• pp.653-663
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• 2000

A lot of hazardous wastes are discharged as by-products of working process by industrial development. Hazardous wastes is physical characteristics of difficult destruction at hight temperature. Numerical simulation and combustion experiment performed of dump incinerator for hazardous waste incineration. For the numerical simulation, the SIMPLEST algorithm was used to ensure rapid converge A K-$\varepsilon$ model was incorporate for the enclosure of turbulence flow. Combustion model was used by ESCRS (extended simple chemically reacting system) model available of CHEMKIN thermodynamic data for the source term of species conservation equation or energy equation. Radiation model is used by six flux model. A parametric screening studies was carried out through numerical simulation and experiment. Residence time and concentration in the incinerator was strongly dependent on the parameters of mixture velocity, mixture equilibrium ratio, surrogate velocity and surrogate equilibrium ratio.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.169-177
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• 1997

An experimental study has been conducted at an intermediate scale to study the effect of a cross flow on a purely buoyant fire. Video taping of the flame and post processing of the images by means of a novel technique provide a contour of a mean flame for all cases studied. This flame contour allows the determination of a mean flame length and a mean flame height. The mean flame length and height are recorded as functions of the forced flow velocity. Three dimensional flow patterns are formed in the flame trailing edge affecting both the mean flame length and height. The three dimensional patterns are studied systematically as functions of the cross flow velocity to quantify the effect of confinement on the flame geometry.

• 한국분무공학회지
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• 제28권3호
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• pp.134-142
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• 2023

Electric field assisted combustion is a method that reduces instability in lean combustion. In this study investigated the effects of electrode position on propane-air flame characteristic using a ring electrode. Results showed that burning velocity was not affected by electrode position, but positive voltage expanded the flammability limit while negative voltage contracted it. The effect of voltage polarity on the flammability limit decreased as the electrode position increased. Expanding the flammability limit with a positive voltage can reduce NOx emissions.

• 한국화재소방학회논문지
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• 제23권1호
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• pp.55-62
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• 2009

층류영역의 분출유량에서 큰 가진강도 효과를 얻기 위해 연료관 관 공명주파수로 가진된 비예혼합 분류 화염의 일반적인 가진 연소특성을 실험적으로 조사하였다. 화염 안정화 특성에서는 두 가지 형태의 부상 특성이 존재하는 사실을 알았는데, 화염이 부상되는 가진강도 크기에서 한 쪽은 감소, 다른 영역에서는 증가하는 것으로 나타나 각각 서로 다른 부상기구가 존재함을 확인할 수 있었다. 특히 부상되지 않고 노즐에 부착된 분출유량 영역에서의 가진 연소특성을 가진 강도에 따른 화염 길이와 형상, 유동장 응답 특성 그리고 노즐 출구에서의 유속 분포를 중심으로 집중 조사하였다. 특이한 현상으로는 가진 강도 증가에 따라 화염의 신장과 in-burning 현상 그리고 화염 내 거동 와동들의 말림방향이 서로 역전되는 현상 등이 발견되었다. 노즐 출구의 유속분포와 가시화 기법을 통해 이러한 현상들이 노즐관 관벽 안쪽서부터 음의 속도가 발생하기 시작함에 따라 주변 산화제인 공기가 노즐관 안으로 유입되는 현상과 관련되는 것으로 파악되었다.

• 항공우주시스템공학회지
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• 제16권5호
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• pp.17-25
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• 2022

액체로켓엔진의 중요한 특성인 연소 안정성, 연소효율 및 넓은 범위의 추력 조절 등에서 장점이 많은 핀틀 분사기를 설계 및 제작하여 초임계 조건에서 연소시험을 수행하였다. 핀틀 분사기는 추력 제어 및 제작성을 고려하여 직사각형의 1열 형상의 오리피스를 갖는 핀틀 분사기로 제작하였다. 핀틀 분사기의 연소성능 및 상용 분사기로써의 가능성을 검증하기 위해 TMR(Total Momentum Ratio)과 BF(Blockage Factor)를 변화하여 연소 특성을 분석하였다. 연소시험 결과 열유속은 TMR 증가에 따라 증가하는 경향이 나타났으며, 특성속도 효율은 TMR보다 BF에 영향을 받는 것으로 확인되었다. 따라서 TMR 변화에 둔감한 효율 특성을 갖는 1열 핀틀 분사기는 낮은 연료 차압 조건에서 높은 효율을 달성할 수 있다면, 가변 핀틀 분사기 설계 유연성이 높아질 수 있다.

• 한국연소학회지
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• 제15권1호
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• pp.12-21
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• 2010

The main objective of this study was investigation of combustion instability characteristics in a lean partially premixed gas turbine dump combustor. Dynamic pressure transducers were located on combustor and inlet section to observe combustion pressure oscillation and difference at each measurement places. Also flame shape and $CH^*$ chemiluminescence were measured using a high speed ICCD camera. The combustor length was varied in order to have different acoustic characteristics from 800 to 1090 mm. The first section of this paper shows the stability map in model gas turbine combustor. And the effects of combustor length, mixture velocity in the mixing section and equivalence ratio were studied by the pressure perturbation and heat release oscillation. Also, the instability frequency and mode analysis were studied in last two sections. We observed two dominant instability frequencies in this study. Lower frequencies were obtained at lower equivalence ratio region and it was associated with a fundamental longitudinal mode of combustor length. Higher frequencies were observed in higher equivalence ratio conditions. It was related to secondary longitudinal mode of combustor and mixing section. In this instability characteristics, pressure oscillation of mixing section part was larger than pressure oscillation of combustor. As a result, combustion instability was strongly affected by acoustic characteristics of combustor and mixing section geometry.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.853-858
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• 2001

The knowledge of flame structure is essential for control of combustion instability phenomena. Some results of an experimental study on mechanism of naturally occurring combustion oscillations with a single dominant frequency are presented. Tests were conducted in a laboratory-scale dump combustor at atmospheric pressure. Sound level meter was used to track the pressure wave inside the combustor. The observed instability was a longitudinal mode with a frequency of $\sim341.8Hz$. Instability map was obtained at the condition of inlet temperature of $360^{\circ}C$, mean velocities of $8.5\sim10.8m/s$ and well premixed mixture. It showed that combustion instability was susceptible to occur in the lean conditions. In this study, unstable flame was observed from stoichiometric to 0.7 in overall equivalence ratio. At selected unstable conditions, phase-resolved OH chemiluminescence images were captured to investigate flame structure with various mean velocities. As mean velocity is increased, the flame grows and global heat release was changed. Due to these effects, combustion instability can be maintained at more lean air-fuel ratio. Also, these results give an insight to the controlling mechanism for an increasing heat release at maximum pressure.

• 한국분무공학회지
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• 제15권3호
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• pp.131-139
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• 2010

Gas motion within the engine cylinder is one of the major factors controlling the fuel-air mixing and combustion processes in diesel engines. In this paper, a special swirl-chamber is designed and applied to a DI (direct injection) diesel engine to generate a strong swirl motion thus enhancing gas motion. Compression, combustion and expansion strokes of this DI diesel engine with the swirl-chamber have been simulated by CFD software. The simulation model was first validated through comparisons with experimental data and then applied to do the simulation of the spray and combustion process. The velocity and temperature field inside the cylinder showed the influences of the strong swirl motion to spray and combustion process in detail. Cylinder pressure, average temperature, heat release rate, total amount of heat release, indicated thermal efficiency, indicated fuel consumption rate and emissions of this DI diesel engine with swirl-chamber have been compared with that of the DI diesel engine with $\omega$-chamber. The conclusions show that the engine with swirlchamber has the characteristics of fast mixture formulation and quick diffusive combustion; its soot emission is 3 times less than that of a $\omega$-chamber engine; its NO emission is 3 times more than that of $\omega$-chamber engine. The results show that the DI diesel engine with the swirl-chamber has the potential to reduce emissions.

• 한국분무공학회지
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• 제21권1호
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• pp.37-46
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• 2016

For the SI engines, at only full load, the pumping loss has a negligible effect, while at part load conditions, the pumping loss increases. To avoid the pumping loss, the spark-ignited engines are designed to inject gasoline directly into the combustion chamber. In the spark-ignited direct-injection engines, ignition probability is important for successful combustion and the flame propagation characteristics are also different from that of pre-mixed combustion. In this paper, a visualization experiment system is designed to study the ignition probability and combustion flame characteristics of spark-ignited direct-injection CNG fuel. The visualization system is composed of a combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. It is found that ambient pressure, ambient temperature and ambient air flow velocity are important parameters which affect the ignition probability of CNG-air mixture and flame propagation characteristics and the injected CNG fuel can be ignited directly by a spark-plug under proper ambient conditions. For all cases of successful ignition, the flame propagation images were digitally recorded with an intensified CCD camera and the flame propagation characteristics were analyzed.

• 한국연소학회지
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• 제20권1호
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• pp.32-42
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• 2015

The combustion instability was experimentally investigated in model gas turbine combustor with dual swirl burner. When such instability occurs, a strong coupling between pressure oscillation and unsteady heat release excites a self-sustained acoustic wave which results in a loud sound, and can even cause fatal damage to the combustor and entire system. In present study, to understand the combustion instability with a premixed mixture, the detailed periods of pressure and heat release data in unstable flame mode were investigated by various measurement methods at relatively rich condition and lean condition near flammable limits. Also, to prepare the utilization of synthetic natural gas (SNG) fuel in gas turbine system, an investigation was conducted using a simulated SNG including methane as a reference fuel to examine the effects of $H_2$ content on flame stability. These results provide that the instability due to flash-back behaviour like CIVB phenomenon occurred at rich condition, while the repetition of relighting and extinction caused the oscillation of lean condition near flammable limit. From the analysis of $H_2$ content effects, it is also confirmed that the instability frequency is proportional to the laminar burning velocity at both rich and lean condition.