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초소형 압축기용 초고속 전동기 내부의 복합 열전달 해석
김태균,허남건,정시영,전승배,Kim, T. G.,Hur, N.,Jeong, S.,Jeon, S. B. 한국유체기계학회 2001 한국유체기계학회 논문집 Vol.4 No.1
In a small centrifugal compressor system, a high-speed motor needs to be developed to drive impellers directly. Heat is generated by both electrical heating due to copper coil resistance and aerodynamic heating in the gap between the rotor and stator in a high-speed motor. Removal of the heat is essential to the design of such motors since most magnetic materials are brittle and can be easily fractured by the heat. In the present study the cooling flow fields and temperature distributions are analyzed by using computational fluid dynamics simulation for a high-speed motor which has air cooling system as well as water cooling system. In the analysis, a conjugate heat transfer problem is solved by considering both convective heat transfer in the cooling system and conduction heat transfer in solid parts. Based on design drawings of a motor, air cooling system and water cooling system are analyzed to obtain temperature field and thus to check the coiling system performance. Also the cooling performance are studied for various flow rates of cooling air and water at the inlets.
유체$\cdot$구조물 상호 작용 기법을 이용한 오일 펜스의 변형 예측
김태균,김욱,허남건,Kim T. G.,Kim W.,Hur N. 한국전산유체공학회 2000 한국전산유체공학회지 Vol.5 No.3
In the present study a method of computing fluid-structure interaction is presented to simulate the deformation shape of an oil fence which is used to contain or to divert the split oil in sea water. The computation is performed by taking into account of the force and moment balance in each computational element of the oil fence. The forces and moments acting on each element of the structure is computed from the flow analysis, which in turn is used to predict deformed shape of the structure until the procedure converges. The flexibility of the oil fence was also considered in the analysis. It is shown from the present study that the predicted deformed shapes agree quite well with the available experiment data.
초소형 압축기용 초고속 전동기 내부의 복합 열전달 해석
김태균(T. G. Kim),허남건(N. Hur),정시영(S. Jeong),전승배(S. B. Jeon) 한국유체기계학회 2000 유체기계 연구개발 발표회 논문집 Vol.- No.-
In a small centrifugal compressor system, a high-speed motor needs to be developed to drive impellers directly. Heat is generated by both electrical heating due to copper coil resistance and aerodynamic heating in the gap between the rotor and stator in a high-speed motor. Removal of the heat is essential to the design of such motors since most magnetic materials are brittle and can be easily fractured by the heat. In the present study the cooling flow fields and temperature distributions were analyzed by using computational fluid dynamics simulation for a high-speed motor which has air cooling system as well as water cooling system. In the analysis a conjugate heat transfer problem is solved by considering both convective heat transfer in the cooling system and conduction heat transfer in solid parts. Based on design drawings of a motor, air cooling system and water cooling system were analyzed to obtain temperature field and thus to check the cooling system performance. Also the cooling performance are studied for various flow rates of cooling air and water at the inlets.
원형 Cylinder 주위의 Vortex Shedding에 관한 수치 해석 연구
김태균(T. G. Kim),허남건(N. Hur) 한국전산유체공학회 2000 한국전산유체공학회 학술대회논문집 Vol.2000 No.5
A Numerical study of laminar vortex-shedding past a circular cylinder has been performed widely by many researchers. Many factors, such as numerical technique and domain size, number and shape of grid, affected predicting vortex shedding and Strouhal number. In the present study, the effect of convection scheme, time discretization methods and grid dependence were investigated. The present paper presents the finite volume solution of unsteady flow past circular cylinder at Re=200, 400. The Strouhal number was predicted using UDS, CDS, Hybrid, Power-law, LUDS, QUICK scheme for convection tenn, implicit and crank-nicolson methods for time discretization. The grid dependence was investigated using H -type mesh and O-type mesh. It also studied that the effect of mesh size of the nearest adjacent grid of circular cylinder. The effect of convection scheme is greater than the effect of time discretization on predicting Strouhal. It has been found that the predicted Strouhal number changed with mesh size and shape.