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WSGGM-RG를 이용한 임의의 형상을 갖는 3차원 공간 내의 비회색 복사열전달 해석 연구
윤경범(Kyung-Beom Yoon),장희철(Hee-Chul Chang),박원희(Won-Hee Park),박리진(Lee-Jin Park),김태국(Tae-Kuk Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The weighted sum of gray gases model with a gray gas regrouping(WSGGM-RG) has been successfully developed to nonhomogeneous and nonisothermal combustion gases. The WSGGM with gray gas regrouping technique is then applied to model the radiative transfer within some three-dimensional irregular enclosures to examine the applicability of the WSGGM-RG for different geometrical variations. In this study some radiative transfer problems through nongray gases are successfully solved by using the discrete ordinates interpolation method(DOIM) with the regrouped WSGGM and with nonorthogonal grids generated for a cubical enclosure and for some skewed hexahedral enclosures.
가스상과 입자상의 유입비율에 따른 가스 입자 혼합특성 연구
윤경범(Kyung Beom Yoon),장희철(Hee Chul Chang),김태국(Tae Kuk Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The purpose of this research is to study numerically the gas-particle two phase mixing characteristics for different inflow rates of gas and particle phases. A computer code is developed for numerical study by using the k-ε-a<SUB>p</SUB> two-phase turbulent model. The k-ε-a<SUB>p</SUB> two phase turbulent model assumes both of the gas and particle phases as continua and the transport phenomenon is expressed by the Eulerian point of view. A 3-dimensional rectangular furnace is considered for the numerical study and the inlet ports for gas and particle are provided at the bottom of the furnace. Numerical results show that the larger velocity slips between the gas and particle phases result in the wider dispersion of the particle phase from the centerline of the jets.
최적화기법을 이용한 철도차량 바닥재의 화염 열유속 및 방사율 예측
박원희,윤경범,Park. Won-Hee,Yoon. Kyung-Beom 한국방재학회 2014 한국방재학회논문집 Vol.14 No.3
철도차량 바닥재로 사용되는 합성 고무를 시편으로 하여 콘 칼로리미터 실험을 수행하고 시편의 표면온도, 발화시간 및 질량감소율을 측정하였다. 측정된 결과를 이용하여 임계열유속 및 발화온도를 산출하고, 반발 입자 군집 최적화 알고리즘을 이용하여 시편 표면에서의 화염에 의한 열유속을 예측하였다. 본 연구에서 최적화된 열유속을 이용하여 계산된 표면온도는 실험에서 측정한 표면 온도와 잘 일치하였다. 본 연구에서 제안한 화염에 의한 열유속을 구하는 방법은 철도차량의 화재 시뮬레이션의 신뢰성 확보에 유용한 도구로 활용될 수 있다. Surface temperatures, ignition times and mass loss rates of the synthetic rubber for railway vehicle flooring are measured for different external heat fluxes by the cone calorimeter. The flame heat flux on the surface can reach the better value by applying the repulsive particle swarm optimization algorithm. During optimization process the critical heat flux and ignition temperature are calculated using measured results. Finally we estimated the optimized flame heat flux. The calculated surface temperatures obtained by using optimized flame heat flux on the surface in this study are matched well with those from the test. The suggested process of determining flame heat flux proposed might be a very useful engineering method for ensuring the validity of a fire simulation for railway vehicles.
지하철 터널 내 운행 중 객차에서 화재발생시 제연풍량에 따른 열 및 연기 확산 예측 연구
장희철,윤경범,박리진,김태국,박원희,김동현,Chang. Hee-Chul,Yoon. Kyung-Beom,Park. Lee-Jin,Kim. Tae-Kuk,Park. Won-Hee,Kim. Dong-Hyeon 한국방재학회 2007 한국방재학회 학술발표대회논문집 Vol.2007 No.1
The purpose of this research is focussed on the numerical predictions of the heat and smoke propagations for a passenger train fire in an underground subway tunnel for different air supply and extraction flowrates. The analysis is performed for one of the stations on subway line #5 in Seoul under the emergency operation mode for different air supply and extraction flowrates. Five different the air supply and extraction flowrates are considered for the numerical analyses. The numerical results show that the air supply and extraction flowrates affect the smoke control performance significantly by improving the smoke removal performance for the balanced control of air supply and smoke extraction and for the unbalanced control with lager smoke extraction than air supply.
당량비 변화에 따른 복사 특성이 3차원 난류 연소에 미치는 영향 연구
김태국(Tea-Kuk Kim),윤경범(Kyung-Beom Yoon),민동호(Dong-Ho Min),장희철(Hee Chul Chang),김진수(Jin-Soo Kim) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
Radiative heat transfer is very important in many combustion systems since they are operated in high temperature. Fluid flows in most of the combustion systems are turbulent to promote fast mixing of the hydrocarbon fuel and oxidant. Major combustion products are CO₂ and H₂O. The turbulent flow is modeled by using the standard k-? model and the radiation transfer is modeled by using the discrete ordinates method where the radiative gas properties are calculated by using the weighted sum of gray gases model with a gray gas regrouping(WSGGM-RG). Effect of the radiation on the combustion characteristics in a three-dimensional rectangular enclosure is studied by changing the equivalence ratio. Results show that the radiation plays a significant role on the heat transfer in the combustion systems by resulting in a temperature drop of 16% as compared to that obtained without radiation. The equivalence ratio also affects the combustion by different contribution of the radiative transfer with different gas compositions.
박원희(Won-Hee Park),윤경범(Kyung-Beom Yoon) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.1
고온환경의 복사열유속을 측정하기 위하여 판열유속계를 제작하였다. 열유속은 스테인리스스틸로 제작된 판열속계 뒷면에서 측정된 온도를 이용하여 계산되어진다. 스미트-볼터계로 측정된 열유속을 기준값으로 이용하였다. 단열재로의 열손실, 판열유속계 두께방향으로의 전도 및 평판의 위치에 따라 온도가 상이하여 발생하는 열전달 등을 고려하기 위하여 전도상수를 도입하였다. 이 상수는 반발입자군집 최적화법으로 구하였다. Plate thermometers are used for measuring the radiative heat flux in high-temperature surroundings. The heat flux is calculated from the temperature measured at the back surface of the stainless steel surface of the meter. Heat fluxes from a Schmidt-Boelter gauge are measured as reference heat fluxes. A combined conductive coefficient is introduced to consider the heat loss to insulation, conduction through the stainless plate depth, and conduction from the non-uniform temperature of the plate of the plate thermometer. This coefficient is obtained using the repulsive particle swarm optimization.
지하철역사 화재시 주변온도 및 기류의 영향에 대한 수치적 연구
장희철(Chang Hee-Chul),윤경범(Yoon Kyung Beom),김태국(Kim Tae-Kuk),박원희(Park Won-Hee),김동현(Kim Dong-Hyeon) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this study effects of the environmental temperature and air flow are studied numerically to examine the fire characteristics on the platform of a bank type underground subway station. Two different air flow velocities through the tunnel and four different environmental temperatures are considered in the numerical simulations. Distributions of heat, smoke and visible range are compared at a height of 1.5m meters above the platform. The numerical results show that the environmental air temperature causes to increase the densities of the heat and smoke with a significant decrease in the visibility. The numerical result also show that air flow causes a rapid spread of the heat and smoke over the platform into the air flow direction.