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전기적인 열원을 가진 변압기 내부에서 층류 자연대류의 수치해석
오건재,하수석 慶南大學校 附設 工業技術硏究所 1998 硏究論文集 Vol.16 No.-
본 논문은 20KVA 유입자냉식 변압기 내부의 공간에서 일어나는 층류 자연대류에 대하여 수치해석 하였다. 변압기 내부의 코어부분은 일정한 열원을 가지는 원통형 실린저로 가정하였고, 계산은 Rayleigh수가 10³-10?인 경우에 대하여 수행하였다. 계산 결과로부터 내부실린더의 평균 Nusselt수와 Rayleigh수에 대한 상관 관계식을 얻을 수 있었으며, Rayleigh수의 변화에 따라 대류영역과 전도영역은 내부실린더의 벽면에서 잘 나타났다. Numerical analysis of the laminar natural convection in an enclosure of the 20KVA oil-immersed transformer model is presented. The core in the transformer is modeled as a cylinder with a heat source. Calculations are carried out for Ra=10³-10?. The correlating equation between the inner cylinder mean Nusselt numbers and Rayleigh numbers can be obtained. The conduction and convection regimes for the variation of Rayleigh numbers are well represented in the temperature distributions along the side wall of the inner cylinder.
크기가 다른 두개의 동심원형 실린더 내에서 층류 자연대류의 수치해석
오건제,하수석 慶南大學校 附設 工業技術硏究所 1997 硏究論文集 Vol.14 No.2
Numerical analysis of the laminar natural convection in an enclosure of the 20KVA oil-immersed transformer model is presented. The core in the transformer is modelled as a circular cylinder and calculation is carried out for Ra= . The correlating equation between the inner cylinder mean Nusselt numbers and Rayleigh numbers can be obtained. The conduction and convection regimes for the variation of Rayleigh numbers are well represented in the temperature distributions along the side wall of the inner cylinder.
2차원 공동내에서 저레이놀즈형 난류모델을 이용한 난류 자연대류의 수치해석
오건제,하수석 慶南大學校 附設 工業技術硏究所 1997 硏究論文集 Vol.15 No.1
본 논문은 한쪽 수직벽면이 가열되는 2차원 밀폐공간내의 난류자연대류 현상을 Rayleigh수가 ??인 경우에 대해서 수치해석 하였다. 본 논문에서 사용한 난류모델은 Davidson의 저 레이놀즈 모델을 사용하여 기존의 실험치와 비교 연구하였다. 수치해석하여 얻은 결과는 실험 측정하여 얻은 실험치와 잘 일치됨을 알 수 있었다. The turbulent buoyancy-driven flow in a 2-dimensional enclosed cavity heated from the vertical side is numerically calculated at Ra= ??. Calculation results using the Davidson's low-Reynoldys-number k-εmodel show good agreement with the experimental data.
변압기를 모델링한 두 개의 동심 원형 실린더 내에서 난류 자연대류의 수치해석
오건제,하수석 대한설비공학회 1999 설비공학 논문집 Vol.11 No.2
Numerical calculations of turbulent natural convection in an enclosure of the 20 kYA oil-immersed transformer model are presented. The transformer is modelled as two concentric cylinders with different heights and diameters. The thermal boundary layers are well represented in the temperature distributions along the wall of the transformer model. The flow stratification between the hot and cold walls can not be seen in the transformer model. The turbulence eddy viscosity has its maximum at the center of the core and its maximum values at the top of the core are larger than those at the bottom of the core.
이공훈(Kong Hoon Lee),하수석(Su Seok Ha),김욱중(Ook Joong Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
Temperature distribution and heating characteristic of the panel heater for infrared heating have been investigated. The temperature variation with time is firstly measured with the thermocouple to figure out the response time of the heater to the power input. The heater reaches faster to the steady state in comparison to the ceramic heater. The infrared thermal imaging system is utilized to investigate the temperature distribution over the heater surface. The measured thermal images show that the thermal boundary layer induced by the free convection near the heater surface affects the temperature distribution on the surface. The images also show the fairly good uniformity of the temperature distribution in the core region of the surface.
이공훈(Ko ng H oon Lee),김욱중(Oo k Joo ng K im),하수석(Su seok H a),강새별(Sae By ul Kan g),이준식(Joon Sik L ee) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Analysis has been carried out to investigate the temperature variation and the uniformity of the<br/> temperature distribution of the glass panel by infrared radiant heating. Halogen lamps are used to heat<br/> the panel and located near the top and bottom of the rectangular chamber. The thermal energy is<br/> transfered only by radiation and the radiation exchange occurs only on the solid surfaces and is<br/> considered by using the view factor. The results show that the uniformity of the temperature<br/> distribution of the panel is improved but the time for heating increases as the wall reflectivity is large.<br/> The temperature difference reaches a maximum in the early stage of the heating process and then<br/> decreases until it reaches the uniform steady-state value.