http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
축류형 유체 기계에서 팁 누설 유동 해석을 위한 난류 모델 성능 비교
이공희(Gonghee Lee),백제현(Jehyun Baek) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
It is well-known that high anisotropic characteristic of turbulent flow field is dominant inside tip leakage<br/> vortex. This anisotropic nature of turbulence invalidates the use of the conventional isotropic eddy viscosity<br/> turbulence model based on the Boussinesq assumption. In this study, to check whether an anisotropic<br/> turbulence model is superior to the isotropic ones or not, the results obtained from steady-state Reynolds<br/> averaged Navier-Stokes simulations based on the RNG k-e and the Reynolds stress model in two test cases,<br/> such as a linear compressor cascade and a forward-swept axial-flow fan, are compared with experimental data.<br/> Through the comparative study of turbulence models, it is clearly shown that the Reynolds stress model,<br/> which can express the production term and body-force term induced by system rotation without any modeling,<br/> should be used to predict the complex tip leakage flow, including the locus of tip leakage vortex center,<br/> quantitatively.
기계적 환기 장치가 설치된 단일 룸에서 연료 저장조 화재 거동에 대한 수치적 연구
이공희(Gonghee Lee) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
According to the international fire safety analysis studies, fire contributes significantly to the overall core damage frequency (CDF) for both existing and new nuclear power plants. Fire simulation models have been developed as analytical tools for a performance-based fire safety assessment The use of calculated predictions could be considered, on the one hand, for improvements and upgrades of the fire protection by the licensees and, on the other hand, as a tool for reproducible and clearly understandable estimations in assessing the available and/or foreseen fire protection measures by the regulatory authority. However, there are still a lot of challenges in the use of validated fire simulation models that can reasonably predict the consequences of a fire in the nuclear power plants. In this study, in order to examine the characteristics of fuel pool fire behavior in a single room with mechanical ventilation facility, calculations were conducted with Fire Dynamic Simulator (FDS) 6.4. The predicted results were compared with the measured data (PRS-SI-D1) obtained from PRISME SOURCE test series.
칼란드리아 내부의 감속재 열유동 해석을 위한 난류 모델 성능 평가
이공희(Gonghee Lee),방영석(Youngseok Bang),우승웅(Swengwoong Woo) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
It is experimentally well-known that the thermal flow in the CANDU calandria is generally complex and highly turbulent due to the interaction of buoyancy force with inlet jet inertia. In this study, to assess the prediction performance of turbulence models, the results obtained with the commercial flow solver, FLUENT<SUP>(1)</SUP>, is compared with experimental data for Sheridan Park Engineering Laboratory (SPEL) test vessel<SUP>(2)</SUP>. Through this comparative study of turbulence models, it is concluded that turbulence models including the source term to consider the effects of buoyancy on the turbulent flow should be used to predict reliably the thermal flow inside the CANDU calandria.
분할 형태 혼합날개가 장착된 연료집합체 내부 난류유동 분포 수치해석
이공희(GongHee Lee),정애주(AeJu Cheong) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
In general, the turbulent flow inside PWR (Pressurized Water Reactor) fuel assembly depends on the mixing vane configuration and the pattern of the mixing vane arrangement on the strap of the spacer grid. In addition, this flow consists of the swirl flow in a subchannel and the cross flow between the rod gaps. The swirl flow improves the heat removal at the rod surface by mixing the hot water near the rod surface with the relatively cold water at the center of the subchannel, while the cross flow mitigates the peak temperature by exchanging the hot and cold water between subchannels. In this study, in order to examine the turbulent flow structure inside fuel assembly with the split-type mixing vanes, simulations were conducted with the commercial CFD software, ANSYS CFX R.14. The predicted results were compared with the measured data from the MATiS-H (Measurement and Analysis of Turbulent Mixing in Subchannels-Horizontal) test facility. Although there were locally differences between the prediction and the measurement, ANSYS CFX R.14 predicted the time averaged velocity field in the reliable level. The predicted horizontal and vertical velocity components were more in agreement with the measured data than the axial velocity component.
선회 형태 혼합날개가 장착된 연료집합체 내부유동 분포 수치해석
이공희(Gonghee Lee),신안동(Andong Shin),정애주(Aeju Cheong) 대한설비공학회 2016 설비공학 논문집 Vol.28 No.5
As a turbulence-enhancing device, a mixing vane installed at a spacer grid of the fuel assembly plays a role in improving the convective heat transfer by generating either swirl flow in the subchannels or cross flow between fuel rod gaps. Therefore, both configuration and arrangement pattern of a mixing vane are important factors that determine the performance of a mixing vane. In this study, in order to examine the flow distribution features inside 5×5 fuel assembly with swirl-type mixing vanes used in benchmark calculation of OECD/NEA, simulations were conducted with commercial CFD software ANSYS CFX R.14. Predicted results were compared to data measured from MATiS-H (Measurement and Analysis of Turbulent Mixing in Subchannels-Horizontal) test facility. In addition, the effect of swirl-type mixing vanes on flow pattern inside the fuel assembly was described.