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저레이놀즈수 레이놀즈응력모델을 이용한 난류선회류의 유동해석
김재한(J. H. Kim),김광용(K. Y. Kim) 한국전산유체공학회 2001 한국전산유체공학회지 Vol.6 No.4
In this study, numerical calculations are carried out in order to evaluate the performance of low- Re Reynolds stress model based on SSG model for a swirling turbulent flow in a pipe. The results are compared with those of k-ε model, GL model and the experimental data. The results show that low- Re Reynolds stress model and GL model give better results than k-ε model. In the region near the wall, low-Re Reynolds stress model improves the predictions. However, there is no large difference between the predictions with two Reynolds stress models.
김광용,장윤석,Kim, K.Y.,Chang, Y.S. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.1
Swirling turbulent flows downstream of an abrupt axisymmetric expansion in a pipe are analyzed numerically by a second-order turbulence closure. Predictions for the flows without swirl and with strong swirl are obtained. The governing differential equations are discretized by finite volume approach. The results show that the on-axis recirculation induced by the strong swirl is correctly reproduced. The predictions for mean velocity components and turbulent normal stresses agree well with experimental data far downstream of expansion, but show large discrepancies in wall-bounded recirculation zone.
김광용,윤장우,류원,Kim, K.Y.,Yoon, J.W.,Lyu, W. 한국전자통신연구원 2012 전자통신동향분석 Vol.27 No.5
멀티비전이라 함은 하나의 영상을 확대시키거나 축소할 수 있고 이것을 다수대의 영상표시기기 등 영상출력수단을 연결 디스플레이하는 시스템을 말한다. 이와 같은 멀티비전 시스템은 최근 각광받는 디지털 사이니지용 스크린을 이용한 광고, 전시 홍보에 널리 사용되며 N-스크린 서비스와 같이 다양한 스크린 단말에서의 연동 서비스로서 활용될 수 있다. 본고에서는 디지털 사이니지의 멀티비전 서비스나 감시 보안용 멀티비전으로 사용되는 서비스 시스템에 대해 유형별로 조사해보고 장 단점을 비교해 보고 이와 같은 멀티비전을 활용하는 국내외 서비스 동향에 대해 살펴본 뒤 보다 개선된 멀티비전 시스템의 나아갈 방향을 제시하고자 한다.
김광용,최재호,김태진,류호선,Kim, K.Y.,Choi, J.H.,Kim, T.J.,Rew, H.S. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.4
A Computational code has been developed in order to design axial fans by the numerical optimization techniques incorporated with flow analysis code solving three-dimensional Navier-Stokes equation. The steepest descent method and the conjugate gradient method are used to look for the search direction in the design space, and the golden section method is used for one-dimensional search. To solve the constrained optimization problem, sequential unconstrained minimization technique, SUMT, is used with imposed quadratic extended interior penalty functions. In the optimization of two-dimensional cascade design, the ratio of drag coefficient to lift coefficient is minimized by the design variables such as maximum thickness, maximum ordinate of camber and chord wise position of maximum ordinate. In the application of this numerical optimization technique to the design of an axial fan, the efficiency is maximized by the design variables related to the sweep angle distributed by quadratic function along the hub to tip of fan.
저레이놀즈수 레이놀즈응력모델을 이용한 난류선회류의 유동해석
김재한(J. H. KIM),김광용(K. Y. KIM) 한국전산유체공학회 2000 한국전산유체공학회 학술대회논문집 Vol.2000 No.10
Numerical calculations are carried out in order to evaluate the performance of low-Re Reynolds stress model based on SSG model for a swirling turbulent flow in a pipe. The results are compared with those of k- e model and GL model, and the experimental data. The finite volume method is used for the discretization, and the power-law scheme is employed as a numerical scheme. The SIMPLE algorithm is used for velocity-pressure correction in the governing equations.
최상철(S.C. Choi),김광용(K.Y. Kim) 한국전산유체공학회 2002 한국전산유체공학회 학술대회논문집 Vol.2002 No.-
The present work analyzed the effect of mixing vane shape on the flow structure and heat transfer downstream of mixing vane in a subchannel of fuel assembly, by obtaining velocity and pressure fields, turbulent intensity, flow-mixing factors, heat transfer coefficient and friction factor using three-dimensional RANS analysis. NJ15, NJ25, NJ35, NJ45, which were designed by the authors, were tested to evaluate the perlonnances in enhancing the heat transfer. Standard k- E model is used as a turbulence closure model, and, periodic and symmetry conditions are set as boundary conditions. The flow blockage ratio is kept constant, but the twist angle of mbdng vane is changed. The results with three turbulence models(k-ε, k-ω, RSM) were compared with experimental data.
김광용(K.Y. Kim),이기돈(K.D. Lee),문미애(M.A. Moon),허만웅(M.W. Heo),김현민(H.M. Kim),김진혁(J.H. Kim),Afzal Husain 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
This paper presents numerical analysis and design optimization of various turbine blade cooling techniques with three-dimensional Reynolds-averaged Navier-Stokes(RANS) analysis. The fluid flow and heat transfer have been performed using ANSYS-CFX 11.0. A fan-shaped hole for film-cooling has been carried out to improve film-cooling effectiveness with the radial basis neural network method. The injection angle of hole, lateral expansion angle of hole and ratio of length-to-diameter of the hole are chosen as design variables and spatially averaged film-cooling effectiveness is considered as an objective function which is to be maximized. The impingement jet cooling has been performed to investigate heat transfer characteristic with geometry variables. Distance between jet nozzle exit and impingement plate, inclination of nozzle and aspect ratio of nozzle hole are considered as geometry variables. The area averaged Nusselt number is evaluated each geometry variables. A rotating rectangular channel with staggered array pin-fins has been investigated to increase heat transfer performance and to decrease friction loss using KRG modeling. Two non-dimensional variables, the ratio of the eight diameter of the pin-fins and ratio of the spacing between the pin-fins to diameter of the pin-fins selected as design variables. A rotating rectangular channel with staggered dimples on opposite walls are formulated numerically to enhance heat transfer performance. The ratio of the dimple depth and dimple diameter are selected as geometry variables.