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이성재(Sung-Jae Yi),장근식(Keun-Shik Chang) 한국전산유체공학회 1996 한국전산유체공학회 학술대회논문집 Vol.1996 No.-
Density wave propagation phenomenon has been theoretically studied in this paper for inhomogeneous, non-equilibrirum two-phase flow. Basic assrunption used in this model is that a nearly quasi-linear relation exists between the interfacial area and the void fraction in all the flow regimes. The model equations developed by the authors consist of seven equations such as the continuity equation, momentum equation, energy equation for each phase, and modified interfacial area transport equation. By introducing new independent parameters, the classical two-phase equation system was changed to hyperbolic type while they causes virtually no quantitative effect on the given basic equations. The new hyperbolic equation system has three complete sets of eigenvectors, each of which having seven real eigenvalues. Three sets of them are identified with the typical flow regimes such as the dispersed, slug, and separated flows. The wave propagation properties(speed of sound) have good agreement with both the experimental data and the earlier theory in the two-phase flows. This studies suggests that the newly proposed parameters truly play an important role in stabilizing the equation system, it turns out that the characteristics of the system equation could produce as well chaos in some parameter range.
이성재(Sung-Jae Yi),장근식(Keun-Shik Chang),박래준(Rae-Joon Park) 한국전산유체공학회 1996 한국전산유체공학회 학술대회논문집 Vol.1996 No.-
The two-phase model developed by the authors consists of seven equations such as equations of separated continuity, momentum, energy, and modified interfacial area transport. By introducing new independent parameters in the momentum equations, the classical two-phase equation system was changed to hyperbolic type while they causes virtually no quantitative effect on the given equations. A hyperbolic solution method for twophase flow is presented in this paper using the assumption that nearly quasi-linear relation exists between interfacial area and the void fraction in all the flow regimes. The hyperbolic equation system has three complete sets of eigenvectors, each of which having seven real eigenvalues. Each set of the eigenvalues is identified with the represents typical flow regime such as the dispersed, slug, and separated flows. This feature of the model allows to apply the numerically higher-order upwind technique in the characteristic directions. The newly proposed parameters play an important role in stabilizing the equation system. It turns out that the characteristics of the equation system could also produce chaos in some parameter regions. To validate the new model, the two-phase flow in a closed vertical pipe was solved by using Flux Vector Splitting(FVS) method. The results show that the characteristics of the equation system mathematically describe all the known flow regimes and the FVS solution clearly demonstrates the phenomenological behavior of the two-phase flows.
SMART-ITL 1 계열 피동안전계통을 이용한 안전주입배관 파단 소형냉각재상실사고 모의에 대한 실험적 연구
류성욱(Sung Uk Ryu),배황(Hwang Bae),유효봉(Hyo Bong Ryu),변선준(Sun Joon Byun),김우식(Woo Shik Kim),신용철(Yong-Cheol Shin),이성재(Sung-Jae Yi),박현식(Hyun-Sik Park) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.3
노심보충탱크(Core Makeup Tank, CMT), 안전주입탱크(SafetyInjection Tank, SIT)와 자동감압계통(Auto Depressurization System, ADS)로 구성된 1 계열의 SMART 피동안전주입계통의 주입특성을 파악하기 위한 소형냉각재상실사고(SBLOCA) 모의에 대한 실험적 연구가 수행되었다. SBLOCA 모의시험은 0.4 인치 안전주입수 배관파단에 대해 수행되었으며, 정상상태 조건은 실험요건서에 제시된 시험 초기 조건을 만족시키도록 746초 동안 운전되었다. 노심 출력 및 안전주입 유량 등의 경계 조건도 적절히 모의되었으며, 안전주입계통 배관에서의 파단, 히터 트립 및 잔열곡선 인가, 원자로냉각재펌프 관성서행(Coastdown), 급수 중단, CMT 및 SIT의 주입, ADS #1 개방이 SBLOCA 시나리오에 따라 적절히 모의되었다. 노심지지원통 내부의 액체환산수위는 파단 초반에 감소하다가 CMT와 SIT가 주입되면서 서서히 회복되었으며, 피동안전주입계통의 주입유량이 노심 수위를 회복하기에 충분한 것으로 판단할 수 있다. An experimental study of the thermal-hydraulic characteristics of passive safety systems (PSSs) was conducted using a system-integrated modular advanced reactor-integral test loop (SMART-ITL). The present passive safety injection system for the SMART-ITL consists of one train with the core makeup tank (CMT), the safety injection tank, and the automatic depressurization system. The objective of this study is to investigate the injection effect of the PSS on the small-break loss-of-coolant accident (SBLOCA) scenario for a 0.4 inch line break in the safety-injection system (SIS). The steady-state condition was maintained for 746 seconds before the break. When the major parameters of the target value and test results were compared, most of the thermal-hydraulic parameters agreed closely with each other. The water level of the reactor pressure vessel (RPV) was maintained higher than that of the fuel assembly plate during the transient, for the present CMT and safety injection tank (SIT) flow rate conditions. It can be seen that the capability of an emergency core cooling system is sufficient during the transient with SMART passive SISs.
박막 열유속센서 내부 온도분포에 대한 수치해석 기초연구
류성욱(Sung Uk Ryu),김유나(Yu Na Kim),이성재(Sung-Jae Yi) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Thin film heat flux sensor proposed by Yi et al.(2018) is a technique in which two contacts are formed in a sensor in a surface direction and a heat transfer rate in a thickness direction can be calculated using a temperature difference in the surface direction. The heat transfer rate in this method can be calculated by using a thermopile like as a typical layered-type heat flux sensor. In order to examine the applicability of the theoretical methods of the new technology, numerical study is reported on the temperature distribution inside the heat flux sensor in the present work. Analysis was performed under three different conditions to identify the effect of the thickness and thermal conductivity of the film on the temperature distribution inside the sensor. These numerical results can be used basic research data for the detailed design of the prototype heat flux sensor.