The soot and OH radical distributions have been experimentally studied in ethylene and propane laminar diffusion flames. The integrated soot volume fraction was measured along the centerline of a flame using a laser light extinction method. Planar laser light scattering and PLIF techniques are employed for the soot and OH radical distribution measurements utilizing Nd:YAG laser and OPO, FDO system. The concentration of OH radical is rapidly decreased at the edge of sooting region, which implies the importance of OH radical species on the soot oxidation process. For ethylene flames, the addition of air in fuel moves the OH radical distribution towards the center line of a flame at the soot oxidation region, while the concentration of OH radical remains relatively high at the soot formation region. The interaction between soot particles and OH radicals becomes more active with fuel-air at the soot oxidation region. For propane flames, however, any indication of the increased interaction between soot particles and OH radicals with fuel-air was not noticed.

Excitations of eight pumping transitions for nitric oxide fluorescence imaging are analyzed under equivalent experimental conditions to determine the detection. Frequency mixed dye laser pumping, 1st anti-Stokes $H_2$ Raman of KrF excimer laser pumping and ArF excimer laser pumping show good sensitivities.

Characteristics of the lifted flame which is generated by issuing of the fuel through the miniature nozzle, d=0.164 mm, are studied using the planar laser induced fluorescence technique. OH radical is excited on the $Q_1$(8) line of the $A^2{\Sigma}\ ^+{\leftarrow}\ X^2{\prod}$ (1,0) band transition(283.55 nm) and LIF signals are captured at the bands of (0,0) and (1,1) transition(306-326 nm) using the filters and ICCD camera. Hydroxyl radical(OH) profile for nozzle attached flame shows that OH radical populations at the flame sides and flame tip are larger than those at the base. But for the lifted flame (tribrachial flame) case, those are larger at the flame base than at the flame tip and flame sides. The OH radical is more dense near the center line of flame base at the blowing out. This fact proves the Chung and Lee's blowout theory - blowout occurs when the flame is anchored at the flame axis.

연소상태의 온도를 이동하면서 측정할 수 있는 광대역 코헤런트 반스톡스 라만 분광기를 제작하였다. 분광기의 온도 측정 정확도를 향상시키기 위하여 무모드레이저를 제작하여 스톡스광으로 사용하였다. 이동형 CARS 분광기에 적합하도록 CARS신호 측정용 단색기를 제작하여 분광기 내부에 설치 하였다. CARS 분광기의 온도 측정의 정확도를 알아보려고 흑연관 전기로를 이용하여 표준 복사온도계와 CARS 분광기로 측정한 온도의 차이를 측정하였다. 장치의 온도 정확도는 1000 K - 2400 K 사이의 온도영역에서 2%이내 였다. 무모드 색소레이저의 출력 스펙트럼의 시간에 따른 안정도를 측정하여 온도측정에 미치는 오차를 조사한 결과 1500 K에서 5 시간 동안 1.5 %이내 였다. 평면 화염 버너에서 프로판공기 예혼합 화염의 온도 분포를 측정하여 이 장치의 응용 가능성을 확인하였다.

An experimental study on LII signal images from soot particles in a flame has been carried out in order to investigate the effect of the incident laser characteristics. By changing the wavelength of the incident laser beam, the LII signal was saturated at smaller laser power with 532 nm than 1,064 nm. This implies that the larger absorption coefficient of soot particles at 532 nm would influence the LII signal characteristic. Using the deconvolution technique, the projected LII line images were coverted to reconstruct the local LII signals inside the beam. The results show that the LII images at ICCD camera result from the integration of LII signal across the laser beam.

축대칭 곡면벽 제트 버너를 제작하여 화염의 안정화 특성을 실험적으로 연구하였다. 축대칭 곡면벽 제트 유동은 난류 강도의 증가와 더불어 버너 선단 부근에 재순환 영역을 형성하여 화염의 안정화를 촉진시킴으로서 기존의 튜브 버너에 비하여 화염의 안정화 특성이 향상되었다. 시간적으로 화염의 위치가 변동하는 난류 화염에서 화염의 안정화 특성과 밀접한 관계가 있는 OH 라디칼과 온도를 PLIF와 CARS를 각각 적용하여 측정하였다. 고유속으로 연소시키는 경우에 버너 선단에 형성된 재순환 영역에 OH 라디칼이 상당량 분포하고 있었으며 통계적으로 고온을 유지하였다. 이는 버너 선단에 형성되는 재순환 영역에 고온의 기연 가스가 점화원 역할을 하여 화학 반응이 활발하게 일어나고 있음을 의미한다. 이러한 결과로부터 고속의 출구유속에서 화염 안정화 특성은 재순환 영역에 의하여 영향을 받고 있음을 확인하였다.

The morphology and size distribution of chromium oxides and the concentration measurement of atomic arsenic have been studied in laminar diffusion flames. Nitrogen was added to vary flame temperatures in hydrogen flames. Ethene flames were used in order to investigate the potential for interaction between the soot aerosol that is formed in these flames and the chromium aerosol. Two sources of chromium compounds were introduced: chromium nitrate and chromium hexacarbonyl. A detailed investigation of the morphology was carried out by scanning electron microscopy (SEM). The amounts of Cr(VI) and total Cr were determined by a spectrophotometric method and by X-ray fluorescence spectrometry, respectively. Also, LIF was used for the measurement of atomic arsenic, which was excited at 197.2 nm and was detected at 249.6 nm. Results showed that the morphology of the particles varied with the flame temperature and with the chromium source. The particles were characterized by porous structures, cenospheres and agglomerated dense particles when chromium nitrate solution was added to the flames. At low to moderate temperatures, porous sintered cenospheric structures were formed, in some cases with a blow hole. At higher temperatures, an agglomerated cluster which was composed of loosely sintered submicron particles was observed. It was also found that the emission of Cr(VI) from the undiluted $H_2$ flame was more than 10 times larger than in the 50% $H_2$ / 50% $N_2$ flame on a mass basis. Single point LIF measurement of atomic arsenic indicated that arsenic exist only in the low temperature, fuel rich region.

Industrial-scale pulse corona process to remove $SO_2$ and $NO_x$ simultaneously from combustion flue gas has been studied. The pilot plant built in the present study treats 2,000 $Nm^3$/hr of flue gas from a boiler. The geometry of the pulse corona reactor is similar to that of an electrostatic precipitator commonly used in industry, A thyratron switch and magnetic pulse compressors, which can generate up to 130 kV of peak pulse voltage and up to 30 kW of average pulse power, have been used to produce pulsed corona. The removal efficiencies of $S0_2$ and $NO_x$ with the present process are maximum of 95 % and 85 %, respectively. Electrical power consumption to produce the pulsed corona, which has been one of the major difficulties to apply this process to industry, has been evaluated in the present study. The results showed that the power consumption can be reduced significantly by simultaneous addition of hydrocarbon injection and heterogeneous phase reactions to the process.

The axisymmetric Navier-Stokes model together with detailed chemical kinetics and variable transport properties has been applied to analyze the effects of the multidimensional flow on the flame characteristics in the nitrogen-diluted hydrogen counterflow nonpremixed flame. Computations are performed for two nozzle exit area-averaged velocities. Effects of multidimensional flow and strain rate on the near-extinction structure of the highly diluted hydrogen flames are discussed in detail.

대향류 확산 화염의 매연 생성 특성에 대한 실험적 연구가 수행되었으며, 그 결과 에틸렌 ($C_2H_4$)-프로판($C_3H_8$) 혼합 연료의 경우 매연 생성 상승 효과 (synergistic effect)가 관측되었다. 프로판과 에틸렌의 PAH 생성 양상이 상이하게 나타났으며, 소량의 프로판을 에틸렌 확산 화염에 첨가할 경우 순수 연료에 비하여 매연 및 PAH (다중 고리 방향족 탄화수소; polycyclic aromatic hydrocarbon) 생성이 증대되었다. 단조적으로 변화하는 아세틸렌($C_2H_2$) 농도와 단열 화염 온도를 고려할 때, 이러한 결과는 HACA (H-abstraction-$C_2H_2$-addition) 반응만으로는 확산 화염에서의 매연 발생 및 성장을 설명할 수 없음을 의미한다. 수치해석과 실험 결과의 비교로부터 초기 PAH의 생성 과정을 규명하였으며 이 과정에서 C3 화학종의 재결합 반웅이 매우 중요함을 확인할 수 있었다. 또한, 이러한 C3 화학종과 C2 화학종의 상호 보완적인 역할에 의하여 에틸렌-프로판 혼합 연료에서 매연 생성이 증대됨을 밝혔다.

In the combustion of the pulverized coal compared with that of liquid fuel or gaseous fuel, serious pollutants such as ash, $NO_x$ and $SO_x$ are released to surroundings. The objective of this study is the reduction of such pollutants in the combustion process. The modeling of cyclone combustor which uses the method of two stage combustion was carried out. The main burner length, scattering angle and air/fuel ratio were considered as parameters. The results show that the shorter the main burner length is, the less the amounts of coals which exit the combustor directly are, but the scattered input of coal is required anyway in order to collect all ashes. It is recommended that the shorter the main burner length is, the less the scattering angle is. And in the case of the scattered input compared with no scattering, the temperature in the combustor is more uniform and the amount of volatile is more reduced.

The conditional moment closure formulation considering the molecular and turbulent diffusion is derived. A simplified solution procedure is proposed to reduce the computational burden due to the increased dimensionality of the conditionally averaged variables. A conditionally averaged variable is expressed as a linear weighted average of the two extremes, 'no reaction' and 'equilibrium' states. The modified elliptic-type conditional moment closure formulation is implemented to simulate a two dimensional nonpremixed mixing layer reacting flow. Results show good agreement for the conditional averages of the species concentration in Bilger et al.

The preliminary design and performance test for determining dimensions of gas turbine combustor were investigated. The combustor design program was developed and applied to design our combustor. and detailed design for determining of swirler. dome and liner holes were performed experimentally. The swirler. which govern the combustion characteristics of combustor, was determined $40^{\circ}$ as swirl angle at first performance test. After second performance test the swirler was re-determined by 24 mm i.d.. 34 mm o.d., and swirl angle of $45^{\circ}$. The geometry of liner holes were determined by considering the flame stability and recirculation zone size. It was found that flame can be more easily stabilized by adjusting the swirier dimensions rather than liner holes. The geometry of swirler and liner holes were re-determined by final performance test with dilution holes. Also. the performance of combustor was evaluated by analysis of exhaust gases.

The effects of tumble and swirl flows on the flame propagation were investigated experimentally in a 4-valve optical gasoline engine. The tumble flow patterns, generated by various intake ports of different entry angle; $25^{\circ}$ , $20^{\circ}$ and $15^{\circ}$ , were characterized under motored conditions with laser Doppler velocirnetry. Inclined tumble(swirl) flows were induced by three different swirl control valves. The initial flame propagation was visualized by an ICCD camera and its image were analyzed to compare the enflamed area and displacement of initial flames. It was found that there is a correlation between the stronger tumble during induction and turbulence levels at the time of ignition resulting in faster flame development. Inclined tumble was proved to be more beneficial than the pure tumble for faster and stable combustion under lean mixture conditions, which was confirmed by faster propagating flame images.

This article presents an application of a large-scale structural mixing model (Broadwell et al. 1984) to the blowout of turbulent reacting jets discharging perpendicularly into an unconfined cross air-flow. In an analysis of a common stability curve, a plausible explanation can be made that the phenomenon of blowout is related only to the mixing time scale of the two flows. The most notable observation is that the blowout distance is traced at fixed positions at all times according to the velocity ratio R. Measurements of the lower blowout limits in the liftable flame agree qualitatively with the blowout parameter ${\varepsilon}$, proposed by Broadwell et al. Good agreement between the results calculated by a modified blowout parameter ${\varepsilon}^'$ and experimental results confirms the important effect of a large-scale structure in specifying the stabilization feature of blowouts.