• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.937-942
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• 2000

The characteristics of spray combustion and dropsize of spray through twin-fluid atomizer was experimentally investigated. The distribution of flame temperature have an effect on the generation of NOx. To investigate there effects, flame temperature with different spray shape was observed. The spray shape was varied by various bluff-bodys. Mean temperature were measured by thermocouple respectively, and NOx concentration was measure by NOx analyser. Distribution of droplet sizes were measured by PMAS. The result showed that the flame with wide distribution has lower temperature and lower NOx emission compared with narrow.

• Journal of Advanced Marine Engineering and Technology
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• 제37권1호
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• pp.1-8
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• 2013

데칸에 물을 혼합하여 일정한 크기와 간격으로 액적을 형성하여 물과의 혼합비율, 분위기 온도, 액적의 크기와 간격 등이 유화액적의 점화와 미소폭발의 특성에 어떠한 영향을 주는가를 고온의 연소실에서 특성을 비교하였다. 점화가 시작하는 온도는 물의 비율이 낮을수록, 액적 크기가 클수록 낮아진다. 물의 혼합비율에 따른 수명시간은 단일 액적에서는 미소폭발의 영향으로 수명시간이 현저하게 짧아지나, 액적크기가 크고 분위기온도가 높을수록 미소폭발의 발생빈도는 자주 나타나게 된다. 퍼짐시간은 물의 혼합비율이 적을수록 더 빨라지고 서스펜더의 수가 많을수록 더 짧아짐을 알 수 있다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.186-191
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• 2004

The reactive flowfield of the transverse injecting combustor has been studied using Euler-Lagrange method in order to develop an efficient solution procedure for the understanding of liquid spray combustion in the transverse injecting combustor which has been widely used in ramjets and turbojet afterburners. The unsteady two-dimensional gas-phase equations have been represented in Eulerian coordinates and the liquid-phase equations have been formulated in Lagrangian coordinates. The gas-phase equations based on the conservation of mass, momentum, and energy have been supplemented by combustion. The vaporization model takes into account the transient effects associated with the droplet heating and the liquid-phase internal circulation. The droplet trajectories have been determined by the integration of the Lagrangian equation in the flow field obtained from the separate calculation without considering the iterative effect between liquid and gas phases. The reported droplet trajectories had been found to deviate from the initial conical path toward the flow direction in the very end of its lifetime when the droplet size had become small due to evaporation. The integration scheme has been based on the TEACH algorithm for gas-phase equation, the second order Runge-Kutta method for liquid-phase equations and the linear interpolation between the two coordinate systems. The calculation results has shown that the characteristics of the droplet penetration and recirculation have been strongly influenced by the interaction between gas and liquid phases in such a way that most of the vaporization process has been confined to the wake region of the injector, thereby improving the flame stabilization properties of the flowfield.

• 한국안전학회지
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• 제17권4호
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• pp.66-70
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• 2002

The transient soot distributions within the region bounded by the droplet surface and the flame were measured using a full-filed light extinction technique and subsequent tomographic inversion using Abel transforms. The soot volume fraction results for n-heptane droplets represent the first quantitative assessment of the degree of sooting for isolated droplets burning under microgravity condition. The absence of buoyancy(which produces longer residence times) and the effects of thermophoresis produce a situation in which a significant concentration of soot is produced and accumulated into a soot-cloud. Results indicate that indeed the soot concentration within the microgravity droplet flames(with maximum soot volume fractions as high as ~60ppm) are significantly higher than corresponding values that are reports for normal-gravity flames. This increase in likely due to longer residence times and thermophoretic effects that manifested under microgravity conditions.

• 한국분무공학회지
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• 제22권4호
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• pp.175-184
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• 2017

The numerical investigation on the effects of water-mist characteristics has been carried out for the fire suppression mechanism. The FDS are used to simulate the interaction of fire plume and water mists, and program describes the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The numerical model is consisted of a rectangular enclosure of $L{\times}W{\times}H=1.5{\times}1.5{\times}2.0m^3$ and a water mist nozzle that be installed 1.8 m from fire pool. In the present study, the parameters of nozzle for simulation are the droplet size and the spray velocity. The droplet size influences to fire flume on fire suppression more than the spray velocity because of the effect of the terminal velocity. The optimal condition for fire suppression is that the droplet size and the spray velocity are $100{\mu}m$ and 20 m/s respectively.

• 한국연소학회지
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• 제21권3호
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• pp.7-15
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• 2016

The fuel in conventional liquid fuel combustor is atomized by spray method for high efficiency and low emissions. To improve the overall fuel efficiency and lower pollutant emissions in liquid fuel combustion systems, the effective spatial and temporal separation of droplet evaporation from normal spray process is needed. In this paper, the recuperation of high temperature burnt gas for fuel evaporation was proposed to develop a cylindrical premixed combustor. The recuperation process using U shaped tube is effective to evaporate the liquid fuel. The results show that the flame mode is changed into red radiation flame, blue flame and lift off flame with decreasing equivalence ratio as gas fuel combustion mode. In particular, the blue flame is found to be very stable at heating load 9.2 kW and equivalence ratio 0.731. NOx was measured blow 105 ppm ($O_2$ zero base) from equivalence ratio 0.705 to 0.835. CO which is a very important emission index in liquid fuel combustor was observed below 5 ppm ($O_2$ zero base) under the same equivalence region.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.829-835
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• 2011

A dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) has been developed as a new approach for the extraction of trace copper in water and beverage samples followed by the determination with flame atomic absorption spectrometry. In the DLLME-SFO, 8-hydroxy quinoline, 1-dodecanol, and methanol were used as chelating agent, extraction solvent and dispersive solvent, respectively. The experimental parameters related to the DLLME-SFO such as the type and volume of the extraction and dispersive solvent, extraction time, sample volume, the concentration of chelating agent and salt addition were investigated and optimized. Under the optimum conditions, the enrichment factor for copper was 122. The method was linear in the range from 0.5 to $300\;ng\;mL^{-1}$ of copper in the samples with a correlation coefficient (r) of 0.9996 and a limit of detection of $0.1\;ng\;mL^{-1}$. The method was applied to the determination of copper in water and beverage samples. The recoveries for the spiked water and beverage samples at the copper concentration levels of 5.0 and $10.0\;ng\;mL^{-1}$ were in the range between 92.0% and 108.0%. The relative standard deviations (RSD) varied from 3.0% to 5.6%.

• 한국항공우주학회지
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• 제30권4호
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• pp.70-76
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• 2002

가스터빈 연소기의 스월러와 노즐을 제작하여 스월러 형상 변화에 따른 비연소시 케로신 분무 특성과 연소시에 열유동장의 특성을 조사하였다. 액적의 크기(SMD)와 속도를 파악하기 위해서 위상도플러입자분석기(PDPA)를 이용하였고, 연소 온도를 조사하기 위해서 R-type 열전대(Platinum vs. Platinum-13%rhodium)를 이용하였다. 분무와 화염의 가시화는 스틸 카메라를 이용하였다. 스월러각이 커서 스월수가 큰 경우에 분무 및 화염이 반경방향으로 빠르게 발전하였다. 화염은 스월수가 작을 때는 원추형의 화염이 형성되지만 스월수가 커지면서 스월 모멘텀이 중심축으로 이송되고 혼합이 촉진되어 원통형으로 바뀌었다.

• 에너지공학
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• 제18권2호
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• pp.101-107
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• 2009

경유와 바이오 디젤이 혼합된 액적을 고온의 연소실에서 액적의 크기, 주위온도 그리고 각각의 혼합비율에 따라 연소특성에 미치는 영향에 대해 연구하였다. 경유에 0%, 20%, 50% 80%, 100%의 비율로 바이오 디젤을 혼합하여 다양한 크기의 액적을 만든 후 서스펜더에 매달고 970K에서 1070K까지 50K 간격으로 고온에서 자발화를 시키면서, 전체의 연소 과정을 고속 디지털 카메라로 촬영하여 점화지연, 수명시간, 전연소기간, 그리고 미소폭발 등의 연소 특성을 파악하였다. 액적의 크기가 증가하고 연소실 온도가 낮을수록 점화가 지연되었다. 경유에 대한 바이오 디젤의 혼합비율이 감소할수록 점화지연이 증가하였고 미소폭발 발생률도 증가하였다. 또한, 미소폭발이 발생하는 경우 전연소기간이 짧아짐을 확인하였다.

• 에너지공학
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• 제16권3호
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• pp.113-119
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• 2007

데칸에 물을 혼합하여 일정한 크기와 간격으로 유화액적배열을 형성하여 물과의 혼합비율, 액적의 수 그리고 액적 간격 등이 연소특성에 어떠한 영향을 주는가를 고온의 연소실에서 파악하였다. 각각 10%, 20%, 30%의 물을 혼합하여 유화액적을 만든 후 일정한 크기의 액적을 각각의 서스펜더에 매달아서 일정한 간격의 액적배열을 만들어 고온에서 자발화를 시켰을 때, 점화지연, 수명시간, 전연소기간 그리고 미소폭발 등의 연소특성을 비교하였다. 대기압에서 연소실의 온도를 920 K로 하고 서스펜더의 수를 3개와 5개로 하였으며 액적배열의 간격은 $3{\sim}7\;mm$ 범위에서 1 mm 간격으로 각각 실험을 수행하였다. 본 실험을 통하여 물의 혼합비율이 높을수록, 그리고 액적배열의 간격이 넓을수록 점화지연현상이 길게 나타났으며, 수명시간은 액적의 간격이 넓을수록 짧게 나타났으며 점화지연시간과 수명시간의 합인 전연소기간은 액적의 수량이 3개인 경우가 점화지연시간이 긴 관계로 5개에 비해 길게 나타남을 확인하였다.