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IRWST 환형관 실험장치 내의 수소화염 가속현상에 대한 CFD 해석 연구
강형석(H.S. Kang),하광순(K.S. Ha),김상백(S.B. Kim),홍성완(S.W. Hong) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.3
We developed a preliminary CFD analysis methodology to predict a pressure build up due to hydrogen flame acceleration in the APR1400 IRWST on the basis of CFD analysis results for test data of hydrogen flame acceleration in a scaled-down test facility performed by Korea Atomic Energy Research Institute. We found out that ANSYS CFX-13 with a combustion model of the so-called turbulent flame closure and a model constant of A = 5.0, a grid model with a hexahedral cell length of 5.0 mm, and a time step size of 1.0 × 10<SUP>-5</SUP> s can be a useful tool to predict the pressure build up due to the hydrogen flame acceleration in the test results. Through the comparison of the simulated results with the test results, we found out that the proposed CFD analysis methodology enables us to predict the peak pressure within an error range of about ±29% for the hydrogen concentration of 19.5%. However, the error ranges of the peak pressure for the hydrogen concentration of 15.4% and 18.6% were about 66% and 51%, respectively. To reduce the error ranges in case of the hydrogen concentration of 15.4% and 18.6%, some uncertainties of the test conditions should be clarified. In addition, an investigation for a possibility of flame extinction in the test results should be performed.
2층으로 성층화된 풀 내에서의 자연대류 열전달과 고화현상에 대한 연구
김종태(J. Kim),강경호(K. S. Kang),김상백(S. B. Kim),김희동(H. D. Kim) 한국전산유체공학회 2001 한국전산유체공학회지 Vol.6 No.1
The natural convection heat transfer and solidification in a stratified pool arc studied. The flow and heat transfer characteristics in a heat generating pool are compared between single-layered and double-layered pools. And local Nusselt number distributions on outer walls are obtained to consider thermal loads on a vessel wall. The cooling and solidification of Al₂O₃/Fe melt in a hemispherical vessel are simulated to study the mechanism of heat transfer and temperature distribution. A unstructured mesh is chosen for this study because of the non orthogonality originated from the boundaries of double-layered pool. Interface between the layers is modeled to be fixed. With this assumption mass flux across the interface is neglected, but shear force and heat flux are considered by boundary conditions. The colocated cell -centered finite volume method is used with the Rhie-Chow interpolation to compute cell face velocity- To prevent non- physical solutions near walls in case body force is large the wall pressure is extrapolated by the way to include body force. The numerical solutions calculated by current method show that averaged downward heat flux of the double-layered pool increases compared to single-layered pool and maximum temperature occurs right below the interface of the layers.
원자로 용기와 단열재 사이의 자연순환 유동에 관한 연구
하광순(K. S. Ha),박래준(R. J. Park),김상백(S. B. Kim),최지용(J. Y. Choi),김광용(K. Y. Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
To observe and evaluate the two-phase natural circulation phenomena through the gap between the reactor vessel and the insulation in the APR1400 under an external reactor vessel cooling, the T-HERMES program has been performed at KAERL. By a HERMES-HALF experimental study, the behaviors of the two-phase natural circulation flow in the insulation gap were observed, and the liquid mass flow rates driven by the natural circulation loop were measured by varying the air injection rate, the coolant inlet area and configuration, the outlet area and the water head condition of the coolant reservoir. And, three dimensional numerical analyses of the HERMES-HALF experiments using a CFX-5.7 commercial code have also been performed to evaluate the effects of ICI nozzles and shear keys on the natural circulation flows.
오픈 소스 OpenFOAM을 이용한 원자력 격납 건물용 피동형 촉매 재결합기 수치해석 모델 개발
김군홍(G.H. Kim),김상백(S.B. Kim),홍성완(S.W. Hong) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
In water-cooled nuclear power reactors, a large amount of hydrogen could be released following postulated severe accident leading to the melting of the core. In order to mitigate the risk of hydrogen combustion, nuclear reactor containments are equipped with passive autocatalytic recombiners(PAR), which preventively oxidize hydrogen for concentration lower than that of the flammability limit. This study is mainly motivated to develop reliable simulator to predict the main features of PAR in context of opensource ‘OpenFOAM’. Catalytic reaction of H<SUB>2</SUB>-Pt is utilized by a single step reaction rate expression based on experimental relation. In order to account for multi-component diffusion effects, Fickian model is employed for species transport equations. For the performance of PAR, the efficiency of H<SUB>2</SUB> conversion is crucially affected by catalytic surface temperature. The conjugate heat transfer between gas flow and catalytic plates is applied to improve the predictive capability of temperature. In present study, predicted mole fraction of H<SUB>2</SUB> and temperature have good agreements with experimental data of REKO-3 facility. The detailed discussions are made for the conversion characteristics of PAR, Numerical result indicates that the developed code has the capability to simulate the catalytic surface reaction of PAR.
원자로 용기 외벽 냉각을 통한 차세대 원전 관통부의 건전성 평가를 위한 지속 가열 실험 연구
강경호(K. H. Kang),박래준(R. J. Park),민병태(B. T. Min),김상백(S. B. Kim),이기영(K. Y. Lee),박종균(J. K. Park) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Under the same induction heating power histories, two tests named as KNGR-SUS-DRY and KNGR-SUS-EXT<br/> were performed varying the cooling conditions at the outer surface of the lower head vessel. The maximum heat flux<br/> imposed to the inner surface of the lower head vessel was about 0.35 MW/m2 in both the tests. In the KNGR-SUS-DRY<br/> test performed without the external vessel cooling, the inner surface of the lower head vessel was ablated by the<br/> thickness of 45 mm, which indicated the total ablation of the welding material. Although the welding material was<br/> ablated in all, the penetration tube was not ejected outside the lower head vessel due to the thermal expansion of the<br/> lower head vessel and the penetration tube. In the KNGR-SUS-EXT test performed with the external vessel cooling,<br/> however, the thickness of the ablation is about 10 mm at most.