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원자로 냉각재 펌프의 과도 상태의 유동 및 열전달 해석 연구
허남건,김성원,유기풍,김승태,Hur, N.,Kim, S.,Yoo, K.-P.,Kim, S. T. 한국유체기계학회 2000 한국유체기계학회 논문집 Vol.3 No.2
The structural analysis of a reactor coolant pump(RCP) of a nuclear power plant is very important for the safety assessment of the plant. Accurate boundary conditions for the heat transfer coefficient are required for reliable thermal stress analysis of the pump casing, especially in transient operations of the pump since the coolant properties are largely dependent on operational conditions. In the present study, a 3D mixed flow type coolant pump was modeled from the RCP drawings and analyzed in the steady state and number of transient flow conditions by using a commercial code STAR-CD. From the result of the computation, it is seen that the average heat transfer coefficients for the cases considered are found to be the suggested values of the manufacturer, Westinghouse Energy System. The unevenness in local heat transfer coefficients, however, is found to be considerable so that the use of average heat transfer coefficients in all boundaries might not give reliable thermal stress predictions.
직교류 홴의 유동 해석: 깃 형상 변화가 성능에 미치는 영향
허남건,김욱,강신형,Hur, Nahm-Keon,Kim, Wook,Kang, Shin-Hyoung 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.1
Cross flow fans are used in various applications, especially in industrial ventilation applications and in room air conditioners, due to their superior performance characteristics. Unlike radial and/or axial fans, the design of cross flow fans have been mostly based on earlier experiences and experiments. In the present study, numerical computations of flow fields through a cross flow fan used in room air conditioner are performed to investigate the detailed flow fields and to study the effect of the blade shape on performance curves to aid better design of the fan. Despite some discrepancies between the two results, it is seen from the present study that the computational results agree quite well with the qualitative experimental results. It is also shown from the present study that by having a different shape of blade, it is possible to achieve about $15\%$ increase in flow rates. The stimulating results of the present study can be used in the design of high performance cross flow fans with the use of optimal design algorithm and experimental verifications.
허남건,원찬식,Hur, Nahm-Keon,Won, Chan-Shik 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.1
Transient flow inside a hollow shaft of a Gas Turbine engine during sudden engine stop may result in non uniform heat transfer coefficients in the shaft due to flow instability similar to steady Taylor vortex, which may decrease the lifetime of the shaft. In the present study, transient Taylor vortex phenomena inside a suddenly stopped hollow shaft are studied analytically. Flow visualization is also performed to study the shape and onset time of Taylor Vortices for various initial rotational speed.
허남건,김욱,김사량,차철현,Hur, Nahm-Keon,Kim, Wook,Kim, Sa-Ryang,Cha, Chul-Hyun 대한설비공학회 2001 설비공학 논문집 Vol.13 No.6
In the present study, the transient axi-symmetric numerical simulation of traffic ventilation induced by a train running through a 15.6km-long tunnel is performed by using over 100,000 computational cells. With train running, three cases of ventilation schemes are simulated, which are the case of ventilation fans turned on, the case of no fan but ventilation shafts open, and the case of no fan and no shaft. Results of the ventilation flow rate are pressure transients are compared for the cases considered.
허남건(N. Hur),윤성영(S. Y. Yoon),조원국(W. K. Cho),김광호(K. H. Kim) 한국자동차공학회 1992 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1992 No.11
Row fields in model engine cooling passages are studied numerically by using TURBO-3D program, a finite volume based 3-D turbulent flow program adopting a general body fitted coordinate system. The effects of exit position on mass flow rate at each gasket hole are examined for a model cooling passage in order to understand the flow distribution inside the water jacket. The results of the present study can be applied to the design of high performance, high reliability engine.
허남건(Nahmkeon Hur),원찬식(Chan-Shik Won),유홍선(Hong-Sun Ryou),손기헌(Gihun Son),김사량(Sa Ryang Kim) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
A general purpose program NUFLEX for the analysis 3-D thermo/fluid flow and pre/post processor in complex geometry has been developed, which consists of a flow solver based on FVM and GUI based pre/post processor. The solver employs a general non-orthogonal grid system with structured grid and solves laminar and turbulent flows with standard/RNG k-ε turbulence model. In addition, NUFLEX is incorporated with various physical models, such as interfacial tracking, cavitation, MHD, melting/solidification and spray model. For the purpose of verification of the program and testing the applicability, many actual problems are solved and compared with the available data. Comparison of the results with that by STAR-CD or FLUENT program has been also made for the same flow configuration and grid structure to test the validity of NUFLEX.
허남건(N. Hur),원찬식(C.-S. Won),손기현(G. Son),유흥선(H.-S. Ryou),신동신(D. Shin) 한국전산유체공학회 2004 한국전산유체공학회 학술대회논문집 Vol.2004 No.-
A general purpose program NUFLEX for the analysis of 3-D heat/fluid flow in complex geometry with pre/post processor have been developed, which consists of a flow solver based on FVM. and a dedicated pre/post processor. The program employs a general non-orthogonal grid system and solve laminar and turbulent flows with standard and RNG k-ε turbulence models. NUFLEX is capable of analysing two-phase flow with topologically complex interface, turbulent diffusion combustion, solidification problems and magnetic flow. For the purpose of verification of the program and testing the applicability, several practical problems are solved and compared with the available data. Comparison of the NUFLEX results with that by the STAR-CD program has been also made for the same flow configuration and grid structure.
허남건(Nahmkeon Hur),김욱(Wook Kim) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.4 No.1
Drag reduction on vehicles are the main concern for the body shape designers in order to lower the fuel consumption rate and to aid the driving stability. The drag of bluff bodies like transportation vehicles is mostly pressure drag due to the flow separation, which can be minimized by controlling the location and size of the separation bubble. In the present study, the TURBO-3D code is incorporated with optimal algorithm based on analytical approximation method to obtain an optimal after body shape of the MIRA Model corresponding to the lowest drag coefficient. For this purpose three mutually independent afterbody angles are chosen as design variables, while the drag coefficient is chosen as an objective function. It is demonstrated in the present study that an optimal body shape having the lowest drag coefficient which is about 6% lower than that of the original shape has been successfully obtained within number of iterations of the optima] design loop.