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KSTAR(Korea Superconducting Tokamak Advanced Research) 냉각 시스템에 대한 열해석 연구
김홍원(H. W. Kim),하지수(J. S. Ha),김대순(D. S. Kim),이종석(J. S. Lee),최창호(C. H. Choi) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
A study on the engineering design and numerical thermo-hydraulic analysis for KSTAR TF coil structure<br/> cooling system has been conducted. The numerical analyses have been done to verify the engineering design<br/> of cooling using the commercial code, FLUENT and in-house code for calculating helium properties which<br/> varies with cooling tube’s heat transfer. Through the engineering design process based on the steady heat<br/> balance concepts, the circular stainless steel tube with inner diameter of 4 mm for TF coil has been selected as<br/> cooling tube. From normal operation mode analysis results, total 28 cooling tubes were finally chosen. Also,<br/> three dimensional cool down analysis for TF coil with designed cooling tube was satisfied with next three<br/> design criteria. First is cooling work termination within a month, second is maximum temperature difference<br/> within 50 K in TF coil structure and third is exit helium pressure above 2 bar. Consequently, these cool down<br/> scenario results can afford to adopt as operating scenario data when KSTAR facilities operate.
Incompressible Turbulent Flow Simulation of the Rotor-Stator Configuration
김홍원(H.W. Kim),박원규(W.G. Park),정영래(Y.R. Jung),김기섭(K.S. Kim),문성균(S.G. Moon) 한국전산유체공학회 1995 한국전산유체공학회 학술대회논문집 Vol.1995 No.-
터빈익렬내부의 유동해석을 위해 비압축성 점성유동해석을 이용한 수치 해석 프로그램을 개발하였다. 지배방정식으로는 2차원의 비정상 비압축성 Navier-Stokes 방정식을 일반화된 곡선좌표계로 전환하여 암시적으로(implicitly) 반복적인 시간진행방법을 이용하여 유동해석을 하였다. 지배방정식의 각항들은 시간에 대해 1차의 정확도 그리고 영역에 대해서는 2차의 정확도, 대류항에 대해서는 3차의 정확도를 가지는 Upwind기법을 적용하였다. 특히, 실험적 접근이 매우 어려운 터빈의 정익과 회전하고 있는 동익과의 상호운동을 멀티블럭기법과 데이터 interface를 통해 보다 쉽게 해석할 수 있었다. 본 연구결과는 정익만을 계산한 타 연구자의 결과와의 비교시 매우 일치하였으며 물리적인 유동을 잘 파악 할 수 있었다. 난류유동 해석을 위해서 Baldwin-Lomax 모델을 적용하였다.
측풍영향을 고려한 고속전철 주위의 비압축성 점성 유동 해석
정영래(Y.R. Jung),박원규(W.G. Park),김홍원(H.W. Kim),하성도(S.D. Ha) 한국전산유체공학회 1995 한국전산유체공학회 학술대회논문집 Vol.1995 No.-
The flow field around a high-speed train including cross-wind effects has been simulated. This study solves 3-D unsteady incompressible Navier-Stokes equations in the inertial frame using the iterative time marching scheme. The governing equations are <br/> differenced with 1st-order accurate backward difference scheme for the time derivatives. 3th-order accurate QUICk scheme for the convective terms and 2nd-order accurate central difference scheme for the viscous terms. The Marker-and-Cell concept was applied to efficiently solve continuity equation. which is differenced with 2nd-order accurate central difference scheme. The 4th-order artificial damping is added to the continuity equation for numerical stability. A C-H type of elliptic grid system is generated around a high-speed train including ground. The Baldwin-Lomax turbulent model was implemented to simulate the turbulent flows. To validate the present procedure, the flow around a high speed train at constant yaw angle of 45°and 90°has been simulated. The simulation shows 3-D vortex generation in the lee corner. The flow separation is also observed around the rear of the train. It has concluded that the results of present study properly agree with physical flow phenomena.