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원영호(Y. H. Won) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.11_2
A fluorescence/scattering image technique for droplet sizing was applied to measure the droplet diameter distribution in non-evaporating gasoline fuel sprays of S.I. engines. The 2-D fluorescence and scattering lights are imaged simultaneously by the visualization system composed of a laser sheet, a doubling prism and optical filters. Semi-Quantitative droplet size distributions were extracted from evaluating the ratio of the two light densities. The technique also gives the information of the characteristics of droplet impingement on a inclined wall.
디젤분무의 모델에서 액적의 형상 및 수밀도의 영향에 관한 연구
원영호 ( Y. H. Won ) 한국분무공학회 2002 한국액체미립화학회지 Vol.7 No.2
N/A A number of droplet breakup models have been developed to predict the diesel spray. The capabilities of droplet deformation and breakup models such as TAB, ETAB, DDB and APTAB models are evaluated in modeling the non-evaporating diesel sprays injected into atmosphere. New methods are also suggested that take into account the non-spherical shape of droplets and the reduced drag force by the presence of neighbouring droplets. The KIVA calculations with standard ETAB, DDB, and APTAB models predict wellthe spray tip penetrations of the experiment, but overestimate the Sauter Mean Diameter(SMD) of droplets. The calculation with non-spherical droplets injected from the nozzle shows very similar results to the calculation with spherical droplets. The drag coefficient which is linearly increased with the time after start of injection during the breakup time gives the smaller SMD that agrees well with the experimental result.
원영호(Y.H.Won) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.11_1
The soot formation processes of unsteady spray flames in a rapid compression machine was investigated using the multi-dimensional model calculation(KIVA-II) which is modified for the combustion and soot formation submodels. The rate of reaction is assumed to be controlled by the characteristic time scale of turbulent mixing. In order to access the convection of soot particles, the soot particles are treated as tracer particles which have no effects on the ambient gas flow and combustion, and have the same velocity as the gas velocity. The mass of soot particles is changed by absorbing soot formed by the ambient gas. The comparison between calculated results and measured heat release rates and soot distribution show that the proposed simple submodels can predict the experimental results well.<br/>
김태완(T.W. Kim),원영호(Y.h. Won) 한국자동차공학회 2000 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Most gasoline engines employ a port injection system to achieve the better fuel-air mixing. A part of injected fuels adheres to the wall or intake valve and forms a film of liquid fuel. The other is secondarily atomized by the spray-wall interaction. A better understanding of this interaction will help in designing injection systems and control the strategies to improve engine performance and exhaust emissions.<br/> In the present research, the spray-wall interaction was investigated by laser sheet visualization method, the shape of sprays was pictured at various impinging velocities and angles. The fuel dispersion was estimated by fluorescence light, and the atomization was evaluated by the enlarged images of droplets.<br/> The experimental results were compared with model predictions which are based on OPT and TAB method. The models have been modified to have the better agreement with the experimental results, and are implemented in the KIVA-II code.
[디젤엔진] 이색법을 이용한 직접 분사식 디젤엔진의 화염 온도 및 Soot 분포 측정에 관한 실험적 연구(Ⅱ)
정수훈(Chung S.H.),박정규(Park J.k.),원영호(Won Y.H.) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Two dimensional flame temperature and KL value distribution from the luminous flames containing soot in a DI diesel engine were measured by the two-color method using two different wavelengths of the flame image. The combustion chamber of a DI diesel engine was visualized by elongating the piston and cylinder and the flame in the combustion chamber was photographed on a nega-color film using a high speed camera. In this study, color CCD camera was used to digitize the three color density of the film exposed to the flame and standard lamp. The accuracy of the measuring method depends on the calibration line of film made from a high temperature standard tungsten lamp. The formation and oxidization of soot in the diesel engine were studied by observing measured time history of KL factor and flame temperature. Also, effects of various shapes of combustion chamber and fuel injection on flame temperature and KL value distribution were examined.
간헐 가솔린 분무의 충돌에 의한 미립화 촉진에 관한 연구
임치락(C.R.Lim),원영호(Y.H.Won) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_1
An experimental and analytical study is presented to characterize the break-up mechanism and atomization process of the intermittent-impinging-type nozzle. Gasoline jets made by the circular nozzle which has the outlet diameter of 0.4 mm and the injection duration of 10 ms were impinged on each other. The impingement of fuel jets formed a thin fuel sheet, and the atomization of the sheet produces liquid ligaments and droplets.<br/> The shape of a fuel sheet was visualized using planer laser induced fluorescence (PLIF) technique. Prediction of the droplet size is obtained through the measured dimension of the fuel sheet and the theoretical analysis of the sheet disintegration by the growth of Kelvin-Helmholtz instability waves. The mean diameter of droplets was calculated theoretically by the sheet thickness at the edge and the wavelength of the fastest growing wave. Comparisons of theoretical results with the experimental results show favorable agreement.<br/>