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가압경수로 핵연료집합체의 유동혼합과 열전달 실험 및 수치 해석
인왕기 대한기계학회 2021 기술과 교육 Vol.9 No.2
Experiments and CFD calculations were performed to investigate flow mixing and heat transfer in regular and tight-lattice rod bundles, which simulate cylindrical fuel assembly and dual-cooled annular fuel assembly for pressurized water reactor, respectively. The experiments and CFD calculations showed a large swirl in core region of subchannel and crossflow in gap region. The CFD prediction showed somewhat larger variation of rod temperature than the experimental result and significantly large discrepancy particularly in rod gap. The experimental and CFD results showed the decrease of rod temperature, i.e., the increase of heat transfer downstream of mixing-vane grid. 가압경수로 원통형 핵연료집합체와 이중냉각 환형핵연료집합체를 각각 모의한 표준 및 협소 4x4 봉 다발에서의 유동혼합과 열전달 특성을 실험과 CFD 방법으로 분석하였다. 실험 결과와 CFD 계산 결과 모두 부수로 중심 영역에서 큰 회전유동과 간극 영역에서 교차류가 발생하는 것을 알 수 있다. 표준봉 다발의 경우 CFD 결과들은 실험 결과에 비해 다소 큰 온도 변화를 예측하고 있으며, 특히 간극에서의 온도가 큰 차이를 보이고 있다. 혼합날개의 영향으로 지지격자 하류에서 봉 표면 온도가 감소하는즉 열전달이 증가하는 것을 실험 및 CFD 결과가 잘 보여주고 있다.
인왕기,이상용,Lee, Sang Yong 대한기계학회 1995 대한기계학회논문집 Vol.19 No.12
Hydrodynamic characteristics of a stratified flow at a Y-junction were examined analytically. Gas is supplied through the main horizontal channel and liquid is introduced into the gas stream from the Y-shaped bottom branch. Analysis was performed with irrational flow and inviscid fluid assumptions. The Stokes' inverse transformation technique was adopted to convert the real x-y plane into the x-.psi. plane. The potential flow equation was solved numerically in the transformed (x-.psi.) plane and the interface profile, pressure distribution and the streamlines were obtained. The effects of the inlet conditions, injection angle and the gravity on the flow characteristics were also examined. To check the validity of the present method, the previous resultant the two-dimensional obtuse wedge flow was compared. The inverse transformation technique turned out to be also very useful to predict the hydrodynamic characteristics of a stratified flow with the pressure variation at a Y-shaped mixing junction.
인왕기,이상용,송시홍,In, Wang-Kee,Lee, Sang-Yong,Song, Si-Hong 대한기계학회 1993 대한기계학회논문집 Vol.17 No.7
A simplified one-dimensional analysis has been performed to predict the local pressure distributions in Y-Jet twin-fluid atomizers. Fluid compressibility was considered both in the gas(air) and two-phase(mixing) ports. The annular-mist flow model was adopted to analyze the flow in the mixing port. A series of experiments also has been performed; the results show that the air flow rate increases and the liquid flow rate decreases with the increase of the air injection pressure and/or with the decrease of the liquid injection pressure. From the measured injection pressures and flow rates, the appropriate constants for the correlations of the pressure loss coefficients and the rate of drop entrainment were decided. The local pressures inside the nozzle by prediction reasonably agree with those by the experiments.