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엇갈린 배열에서 미분탄 입자의 간극과 산소 농도가 연소 특성에 미치는 영향
서주형(Ju-Hyeong Seo),김호영(Ho-Young Kim),윤석구(Sukgoo Yoon),조상필(Sang-Pil Jo),김기덕(Ki-Duck Kim) 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-
The combustion characteristics of interacting pulverized coal particles in a convective flow are numerically investigated at various oxygen concentrations and particle spacing considering 2-dimensional particle staggered arrangement. The numerical simulation includes detailed interaction among the inter-spaced particles, undergoing devolatilization and subsequent char burning. Several parametric studies, which include the effect of oxygen concentration and variation in geometrical particle spacing on the volatile release rate along the char combustion rate, have been carried out. The particle spacing and the oxygen concentration level were varied from 4R? to 15R? and from 15% to 90%, respectively. The initial conditions of particle size and temperature were assumed to be 100㎛ and 600K. The predicted results show that the third particle is very highly influenced by the particle spacing and has the smallest particle life time at whole particle spacing. When O₂ concentration levels are 50% and 90%, volatile combustion and subsequent devolatilization burning rate are increased by 15% and 29% compared to 21% O₂ concentration level, respectively.
가솔린 직접분사식 엔진의 분무각에 따른 실린더 내 유동 및 연소 특성 해석
서주형(Ju Hyeong Seo),김호영(Ho Young Kim),윤석구(Sukgoo Yoon),이진휘(Jinhwi Lee) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
GDI(Gasoline Direct Injection) engine which is one among DISI(Direct Injection Spark Ignition) engine is one major approach in reducing Nox emission and increase the fuel efficiency. Numerical simulations for the GDI engine characteristics have been investigated from the effects of the spray cone angle on the process. In this study, a 3D unsteady Eularian-Langrangian two-phase model was used to account an optimal operating condition for a GDI engine using S/W STAR-CD (CD-adapco). Our simulation results indicate both flow field and mixture characteristics to obtain subsequent combustion and emission characteristics inside the cylinder. To improve mixing quality and evaporation rate, spray cone angle is commonly increased. As the spray cone angle increased, the uniformity index of the fuel has increased. With the variation of spray cone angle, Case BMwith spray cone angle 30 degree has the minimum NOx emission in the cylinder.
가솔린 직접분사식 엔진에서 연료온도와 피스톤 상면온도 변화가 연료 액막 형성에 미치는 영향
배진우(Jin Woo Bae),서주형(Ju Hyeong Seo),김호영(Ho Young Kim),윤석구(Sam Sukgoo Yoon),명차리(Cha Lee Myung) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
The subsequent behavior of the liquid fuel film has a strong influence on mixture preparation, combustion and emission. To achieve subsequent engine performance, liquid fuel film must be avoided after spray impingement. So evaporated fuel mass must be increase to reduce liquid fuel film. This study presents the CFD modeling using S/W STAR-CD to study the effect of the cylinder wall and piston crown temperature on the liquid fuel film quantity. Bai and Gosman’s model has been used for the liquid fuel film model. Results including liquid fuel film mass and thickness were obtained under transient condition and WOT (Wide Open Throttle). The result shows that Total liquid fuel film mass and average liquid fuel thickness tended to reduce when variables temperature increased more than certain range. But liquid fuel thickness on the piston wall tended to increased.
메탄올-가솔린 혼합연료를 사용한 DISI엔진에서 연료의 혼합비와 2단분사가 엔진 내부유동 및 연소특성에 미치는 영향
배진우(Jin-Woo Bae),서주형(Ju-Hyeong Seo),이재성(Jae-Sung Lee),김호영(Ho-Young Kim) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.43
Numerical studies were conducted to investigate the internal flow field and combustion characteristics of DISI engine with the fuel of low fraction methanol, M0 and M31, in gasoline and two stage injection at 4000rpm WOT (Wide Open Throttle). Mass flow of the injected fuel to cylinder was corresponded air-fuel ratio of each fuel for complete combustion. This study presents the CFD modeling using S/W STAR-CD v3.26. When M31 fuel was used, uniformity, equivalence ratio mean pressure and temperature in cylinder increase. When two stage injection was used, there was no significant change in uniformity and equivalence ratio. But mean pressure and temperature in cylinder increase. When M31 fuel and one stage injection was used, the engine emission of carbon monoxide (CO) and nitrogen oxides (NO) increased about 36%, 12% comparing with benchmarking case in cylinder prior to TWC (Three Way Catalytic converter). and also, when two stage injection was used, CO and nitrogen oxides NO increased.