• 한국자동차공학회논문집
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• 제8권2호
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• pp.64-71
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• 2000

In order to clarify the characteristics of soot formation and oxidation in-cylinder of a diesel engine, it is necessary to diagnose accurately for combustion of in-cylinder. The past techniques for soot measurement have limitations in providing the characteristics of soot in a diesel engine, whereas, laser-based 2D imaging diagnostics have the potential to provide better temporally and spatially resolved measurements of the soot distribution. We rebuilt an optically accessible diesel engine which is similar to the conditions of a conventional engine and tried to measure soot distribution in a cylinder of the diesel engine using laser induced scattering(LIS) and laser induced incandescence(LII). Some results were acquired in this study. LIS and LII signal that show soot distribution of a in-cylinder were taken by ICCD properly. The signal of LIS was intenser than that of LII. Although they have some differences of signal intensity in early combusion period, both of signals show that they are generally similar in late combustion period, after ATDC 50 degree.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.486-491
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• 2008

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomizer internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD(Sauter Mean Diameters) distribution by using PLLIF(Planar Liquid Laser Induced Fluorescence) technique. The objectives of this research are getting a droplet distribution and drop size measurement of each condition and compare with the other flows effect. As the result, This research have been showed the droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects and normalized distance from the injector exit length.(x/d, y/d)There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.16-19
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• 2011

고성능의 다단연소 사이클 액체로켓 엔진에 사용되는 Gas-centered swirl coaxial injector(GCSCI)의 분무특성에 대한 연구가 상압수류시험을 통해 이루어졌다. 시험은 물과 질소를 사용하였고, 고속카메라를 이용하여 분무형상을 측정하였고 이미지 프로세싱으로 데이터 처리에 활용하였다. 본 연구에서는 분사기의 리세스 길이와 액체노즐과 기체노즐의 간격과 같은 형상에 따른 영향과 기체와 액체의 운동량비에 따른 분무특성을 알아보았다.

• 한국추진공학회지
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• 제15권3호
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• pp.22-30
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• 2011

추력변화를 위한 방법에는 여러 가지가 있는데, 고압력 강하 시스템, 이중 매니폴드 분사기, 가스 분사, 다중 챔버, 펄스 추력, 움직이는 분사기 구성요소 등이 있다. 이 중에서 이중 매니폴드 분사기의 경우에는 하나의 분사기 구조에 서로 다른 두 개의 매니폴드를 가지는 분사기를 결합하는 방식의 분사기인데, 각 분사기는 각각의 연료 공급시스템을 독립적으로 가지고 있어 각 매니폴드마다 독립적으로 유량을 조절 할 수 있다. 본 논문에서는 이중 매니폴드 분사기를 사용하여 넓은 추력범위에서 연료분사의 안정성을 판단하기 위하여 각 매니폴드의 접선방향 유입구 넓이의 비와 분사압력에 따라 분사 형상을 측정하고, 분사기 오리피스 끝단에서 액막 두께를 측정하였다.

• 한국추진공학회지
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• 제17권2호
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• pp.16-23
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• 2013

정상초음파장이 개재하는 메탄/공기 예혼합화염의 전파특성에 대한 당량비의 영향을 실험적 연구결과로 제시한다. 화염구조 가시화는 슐리렌 기법을 이용하였으며, 이미지 후처리를 통해 화염 전파 거동을 면밀히 관찰하였다. 정상초음파에 의한 화염 구조 변화가 연소반응을 촉진시켜 화염 전파속도를 증가시키는 것을 알 수 있었으며, 당량비가 증가할수록 정상초음파에 의한 화염전파속도의 증분은 감소하게 되고, 속도변화가 미미한 당량비 구간이 존재한다는 사실을 확인할 수 있었다.

• 한국추진공학회지
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• 제24권6호
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• pp.53-60
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• 2020

액체연료 분무 연소에서 화염 외부에 정상초음파 가진을 통해 압력장을 조절함으로써 초음파 무화액체연료 화염에 미치는 초음파 가진의 영향을 관찰하는 실험을 수행하였다. 초음파에 의해 미립화된 케로신 에어로졸화염은 초고속카메라, DSLR 그리고 슐리렌 촬영기법을 이용하여 가시화하였다. 연소시 소모된 연료량은 정밀유량측정법으로 계측하였고, 이를 통해 수송기체 공연비를 구할 수 있었다. 실험결과, 2차화염영역에 정상초음파를 가함에 따라 액체연료 에어로졸의 연소반응률이 증대되는 것을 관찰할 수 있었다.

• 한국추진공학회지
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• 제26권1호
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• pp.60-67
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• 2022

본 연구는 정상초음파 가진 유무에 따른 초음파 무화 케로신 화염의 거동변이를 분석하기 위해 수행되었다. Slit-jet 노즐을 통과하며 생성된 연소영역은 DSLR, ICCD 및 초고속카메라와 슐리렌 기법을 통해 가시화되었고, 연료소모량은 정밀저울을 통해 측정하였다. 그 결과, 정상초음파 가진시, OH 라디칼의 강도가 증가하는 것이 관찰되었고 정상파장 상단부에서 최적 연소 조건이 형성됨을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제16권7호
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• pp.935-941
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• 2002

This work is to investigate the combustion characteristics and flame propagation of the LPG (liquified petroleum gas) and gasoline fuel. In order to characterize the combustion processes of the fuels, the flame propagation and combustion characteristics were investigated by using a constant volume combustion chamber The flame propagation of both LPG and gasoline fuels was investigated by the laser deflection method and the high-speed Schlieren photography. The result of laser deflection method show that the error of measured flame propagation speed by laser method is less than 5% compared with the result of high-speed camera. The flame propagation speed of the fuel is increased with the decrease of initial pressure and the increase of initial temperature in the constant volume chamber. The results also show that the equivalence ratio has a grate effect on the flame speed, combustion pressure and the combustion duration of the fuel-air mixture.

• Advanced Composite Materials
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• 제18권4호
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• pp.395-413
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• 2009

Impact tests on high-strength membrane materials under biaxial loads were experimentally conducted in order to evaluate influence of biaxial loads on impact fracture of the membrane materials for the inflated applications. Cruciform specimens of the membrane materials were fabricated for applying biaxial loadings during the impact test. A steel ball was shot using a compressed nitrogen gas gun, and struck the membrane specimen. Impact tests on uniaxial strip specimens were also conducted to obtain the effect of specimen configuration and boundary condition on the impact fracture. The results of the measured crack length and the ultra-high speed photographs indicate the impact fracture properties of the membrane fabrics under biaxial loadings. Crack length due to the impact increased with applied tensile load, and the impact damages of the cruciform membrane materials under biaxial loadings were smaller than those of under uniaxial loadings. Impact fracture of the strip specimen was more severe than that of the cruciform specimen due to the difference of boundary conditions.

• 한국환경과학회지
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• 제16권9호
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• pp.1091-1098
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• 2007

Activated carbon was prepared from waste citrus peels by chemical activation with $ZnCl_2$. The optimal condition of carbonization was at $300^{\circ}C$ for 1.5 hr. Activation experiments with carbonized samples prepared at optimal carboniztion condition were carried out under various conditions such as activation temperature of 400 to $900^{\circ}C$, activation time of 0.5 to 2.0 hr, and $ZnCl_2$ ratio of 100 to 300%. In order to investigate the physical properties of the activated carbons prepared, iodine adsorptivities and specific surface areas were measured and their morphologies were observed from scanning electron microscopy. As $ZnCl_2$ ratio increased, activation yield decreased, while iodine adsorptivity and specific surface area increased. The optimal condition of activation was at 300% $ZnCl_2$ ratio and $300^{\circ}C$ for 1.5 hr, and then iodine adsorptivity and specific surface area was measured as about 862 mg/g and $756m^2/g$, respectively. SEM photography showed that the surface morphology was changed and many active pore were produced by chemical activation.