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HYDRODYNAMIC SOLVER FOR A TRANSIENT, TWO-FLUID, THREE-FIELD MODEL ON UNSTRUCTURED GRIDS
J.J. Jeong(정재준),H.Y. Yoon(윤한영),J. Kim(김종태),I.K. Park(박익규),H.K. Cho(조형규) 한국전산유체공학회 2007 한국전산유체공학회지 Vol.12 No.4
A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed for a 3D component of a nuclear system code and a component-scale analysis tool. A two-fluid three-field model is used for the two-phase flows. The three fields represent a continuous liquid. an entrained liquid. and a vapour field. An unstructured grid is adopted for realistic simulations of the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been applied to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the modified numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing very well.
김종태(J. Kim),박익규(I.K. Park),조형규(H.K. Cho),윤한영(H.Y. Yoon),정재준(J.J. Jeong) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstuctured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.
비정렬 격자계에서의 물-기체 2상 유동해석코드 수치 기법 개선
이희동(H.D. Lee),정재준(J.J. Jeong),조형규(H.K. Cho),권오준(O.J. Kwon) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
A thermal-hydraulic code, named CUPID, has been developed for the analysis of transient two-phase flows in nuclear reactor components. A two-fluid three-field model was used for steam-water two-phase flows. To obtain numerical solutions, the finite volume method was applied over unstructured cell-centered meshes. In steam-water two-phase flows, a phase change, i.e., evaporation of condensation, results in a great change in the flow field because of substantial density difference between liquid and vapor phases. Thus, two-phase flows are very sensitive to the local pressure that determines the phase change. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new numerical scheme to evaluate the pressure gradient at cell centers on unstructured meshes. The results of the new scheme for a simple test function, a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the CUPID code.
비정렬 격자 기반의 물-기체 2상 유동해석기법에서의 압력기울기 재구성 방법
이희동(H.D. Lee),정재준(J.J. Jeong),조형규(H.K. Cho),권오준(O.J. Kwon) 한국전산유체공학회 2010 한국전산유체공학회지 Vol.15 No.2
A thermal-hydraulic code, named CUPID, has been developed for the analysis of transient two-phase flows in nuclear reactor components. A two-fluid three-field model was used for steam-water two-phase flows. To obtain numerical solutions, the finite volume method was applied over unstructured cell-centered meshes. In steam-water two-phase flows, a phase change, i.e., evaporation or condensation, results in a great change in the flow field because of substantial density difference between liquid and vapor phases. Thus, two-phase flows are very sensitive to the local pressure distribution that determines the phase change. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new reconstruction method to evaluate the pressure gradient at cell centers on unstructured meshes. The results of the new scheme for a simple test function, a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the CUPID code.
CUPID 코드를 이용한 CANDU 감속재의 열-유동 예비해석
박상기(S.G. Park),이재룡(J.R. Lee),윤한영(H.Y. Yoon),정재준(J.J. Jeong) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
The objectives of this study are to predict CANDU moderator temperatures by using the CUPID code and to validate the CUPID against STERN 2D experimental data. In this study, both single and two phase flows in the Calandria vessel were calculated by using the CUPID code. KAERI has been developing the CUPID Code. It adopts three-dimensional, transient, two-phase and three-field model, and includes various physical models and correlations of the interfacial mass, momentum and energy transfer for the closure relations of the two-fluid model. The CUPID code validated using the single-phase flow experimental data that were performed in the STERN Lab.
수평관 기포유동 실험 데이터를 이용한 3차원 2상유동 해석코드 CUPID 평가
이동훈(D.H. Lee),이승준(S.J. Lee),윤한영(H.Y. Yoon),정재준(J.J. Jeong) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.1
Bubbly flows may occur in horizontal pipes during an accident in a nuclear power plant. Horizontal bubbly flows are characterized by asymmetric distribution of main parameters, such as void fraction and velocity, and slip ratio less than 1. Thus, three-dimensional simulation capability is needed for horizontal bubbly flows. In this study, horizontal bubbly flows were simulated using the CUPID code. The model evaluation results showed that the particle based 2-fluid momentum equation simulated more physically reasonable slip ratio than standard 2-fluid momentum equation and the turbulent dispersion force was the most important factor in the prediction of void fraction. In the quantitative assessments, it was shown that the CUPID code predicted well the axial pressure drop within the error range of 10%. Also, the code estimated well axial development process of void fraction. However, it was found that the code can not simulate asymmetric distribution of flow parameters and phenomena which gas phase moves slower than liquid phase. To improve the prediction ability, the modification of turbulence model such as turbulent shear stress, bubble induced turbulence, and so on, or the additional term in momentum equation are needed.