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충돌분무의 액적 거동에 미치는 비등방성 난류특성의 영향에 대한 수치해석 연구
고권현(G. H. Ko),유홍선(H. S. Ryou) 한국전산유체공학회 2003 한국전산유체공학회지 Vol.8 No.4
It is an aim of this study to perform extensive numerical study for analyzing the anisotropic turbulence effects on spatial and temporal behaviors of droplet for impinging sprays. The turbulence model of Durbin is used for comparisons with the k-E model. The turbulence-induced dispersions of droplets are consider to describe the anisotropy of turbulence effectively and spray/wall interactions are simulated using the model of Lee and Ryou. Present study investigates the overall and the internal structures of impinging diesel sprays such as spray shapes, radius and height of wall sprays, Sauter mean diameter (SMD), local droplet velocity, and local gas velocity and compared the results with experimental data by two adopted turbulence models. When the anisotropy effect of turbulence is included, better predictions for both gas and droplet tangential velocities are obtained, compared to the k-ε model. It is concluded that anisotropic effect of turbulence should be considered for simulating impinging diesel sprays.
차량의 EEC시스템에서의 탄화수소 중기 발생량 예측을 위한 연구
김현수(H.S.Kim),김충익(C.I.Kim),유홍선(H.S.Ryou),손동연(D.Y.Son) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.11_2
The hydrocarbon(HC) emission from automotive vehicles has been named as a source of the ozone layer depletion. Therefore, the importance of Evaporative Emission Control(EEC) system which can reduce HC emission is brought forward. EEC system is composed of a fuel tank.a fuel-returning line. a roll-over valve. an orifice for pressure reguJatiolL tubes. and a canister. TIle canister is a centerpiece of EEC system that captures HC vapor escaping into the aunospllCre and its optimum capacity is decided by the amount of HC vapor generated during test periods. In this study, the mathematical model of the HC vapor generation in EEC system was constructed and solved accordingto testing conditions. TllC fuel vapor was considered as an ideal gas mixture of 35 different HC species .The pressure rise in the tank due to vapor generation causes the mixture of the fuel vapor and the air to pass through EEC system including the canister. The Reid Vapor Pressure(RVP) decrease of the remaining fuel was calculated and the amount of vapor generated in the lank and captured in the canister was predicted.!n addition,the obtained results were compared with <br/> . experimental results<br/>
[論文] 실린더 내부 유동장에 대한 흡입 밸브의 편심 효과에 관한 수치적 연구
양희천(H.C.Yang),최영기(Y.K.Choi),유홍선(H.S.Ryou),고상근(S.K.Kauh),허선무(S.M.Huh) 한국자동차공학회 1992 오토저널 Vol.14 No.4
Three dimensional numerical calculation carried out to investigate the eccentricity effect of intake valve on the in-cylinder flow fields for the intake stroke and the compression stroke.<br/> During the intake stroke, a corner vortex in the vicinity of the valve exit interacted strongly with a toroidal vortex in the case of axisymmetric valve. But a weak interaction between the corner vortex and the toroidal vortex occurred due to the eccentricity of the valve in the narrow region between valve and cylinder wall in the case of offset valve.<br/> During the compression stroke, it was found that a solid body rotation was maintained in the radial-circumferential plane in the case of axisymmetric valve. But a weak secondary vortex was formed in the radial-circumferential plane in the case of offset valve, because of the interaction between swirl flows and inward flows towards cylinder axis.<br/> The calculated turbulence intensity presented a similar trend with the experiental results but, in spite of using the modified k-ε model, it was found that the qualitative difference between the numerical results and experimental results was large in the region where the velocity gradient is substantial.
수정된 CIP 방법을 이용한 벽면 충돌 후 액적의 퍼짐 현상에 대한 수치해석 연구
손소연(S.Y. Son),고권현(G.H. Ko),이성혁(S.H. Lee),유홍선(H.S. Ryou) 한국전산유체공학회 2010 한국전산유체공학회지 Vol.15 No.4
Interface tracking of two phase is significant to analyze multi-phase phenomena. The VOF(Volume of Fluid) and level set are well known interface tracking method. However, they have limitations to solve compressible flow and incompressible flow at the same time. ClP(Cubic Interpolate Propagation) method is appropriate for considering compressible and incompressible flow at once by solving the governing equation which is divided up into advection and non-advection term. In this article, we analyze the droplet impingement according to various We number using improved ClP method which treats nonlinear term once more comparison with original ClP method. Furthermore, we compare spread radius after droplet impingement on the wall with the experimental data and original ClP method. The result using improved ClP method shows the better result of the experiments, comparison with result of original ClP method, and it reduces the mass conservation error which is generated in the numerical analysis comparison with original ClP method.
댐퍼 위치가 구획문의 유동분포에 미치는 영향에 관한 수치해석 연구
문효준(H.J. Moon),김홍진(H.J Kim),Andrey Burakov,고권현(G.H. Ko),유홍선(H.S. Ryou) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
The pressurized smoke control system is important for fire safety in building because it is directly concerned with egress time of people. Even though the damper plays an essential role in the pressurized smoke control system, the research for a position of damper effects on distribution of air flow at the compartment door is not performed. In this study, numerical simulation using FDS 5.0 was carried out to analyze the effect of the position of damper on flow distribution at the compartment door. To simulate real situation, effects of opening and closing of compartment door was considered. When the damper is on the opposite wall of the compartment door, the back flow to the lobby is large compared to the two other cases of damper position.
FDS_EVAC에 적용된 독성가스모델(FED)이 피난에 미치는 영향 분석 및 개선에 대한 연구
김홍진(H.J. Kim),배승용(S.Y. Bae),ANDRAY BURAKOV,최영기(Y.K. Choi),유홍선(H.S. Ryou) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
When fire occurs, the evacuation of human is very important. However, it is very difficult to evacuate human because of heat, toxic gas and smoke by fire. Especially toxic gas is important factor because it is significant parameter of death of evacuees. The effect of toxic gas which effects human motion is calculated using Purser’s Fractional Effective Dose(FED). The FDS_EVAC is used for evacuation. However, FED of FDS_EVAC has some problem of application because it dose not considers evacueess gender and age groups but using single subject. In this study, numerical analysis using modified FED which considers gender and age group of evacuees was performed. We investigate the effect of improved FED on the evacuation. We applied evacuation analysis to exhibition centre where the evacuees was set one thousand people. The FED is increasing with children 3%, male 26%, female 5%, adult 24% and elderly people 30%. Fatality is increasing due to increased FED.
수정된 CIP방법을 이용한 벽면 충돌 후 액적의 퍼짐 현상에 대한 수치해석 연구
손소연(S.Y. Son),고권현(G.H. Ko),이성혁(S.H. LEE),유홍선(H.S. Ryou) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
Interface tracking of two phase is significant to analyze multi-phase phenomena. The VOF(Volume of Fluid) and level set are well known interface tracking method. However, they have limitations to solve compressible flow and incompressible flow at the same time. CIP(Cubic Interpolate Propagation) method is appropriate for considering compressible and incompressible flow at once by solving the governing equation which is divided up into advection and non-advection term. In this article, we analyze the droplet impingement according to various We number using improved CIP method which treats nonlinear term once more comparison with original CIP method. Furthermore, we compare spread radius after droplet impingement on the wall with the experimental data and original CIP method. The result using improved CIP method shows the better result of the experiments, comparison with result of original CIP method, and it reduces the mass conservation error which is generated in the numerical analysis comparison with original CIP method.