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이기돈(K.D. Lee),김광용(K.Y. Kim) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
In the present work, flow analysis has been performed for side channel type double stage ring blower by solving three-dimensional Reynolds-averaged Navier-Stokes equation. Shear stress transport model is used as turbulent closure. The commercial CFD code CFX 11.0 is used for the calculations. Each of two stage is calculated separately and the second stage inlet flow is same as the first stage outlet flow so that consecutive calculation is possible. Velocity and pressure fields have been analyzed at the midplane between blades. The numerical results are validated with experimental data for head coefficients at different flow coefficients.
이기돈(K.D. Lee),김광용(K.Y. Kim) 한국전산유체공학회 2007 한국전산유체공학회지 Vol.12 No.4
In the present work, flow analysis has been performed for side channel type double stage ring blower by solving three-dimensional Reynolds-averaged Navier-Stokes equation, Shear stress transport model is used as turbulent closure, The commercial CFD code CFX 11.0 is used for the calculations, Each of two stage is calculated separately and the second stage inlet flow is same as the first stage outlet flow so that consecutive calculation is possible, Velocity and pressure field, have been analyzed at the mid-plane between blades. The numerical results are validated with experimental data for head coefficients at different flail' coefficients.
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.
김선민(S.M. Kim),이기돈(K.D. Lee),김광용(K.Y. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
To protect the turbine blade, many cooling techniques has developed. With all other things, film-cooling has been widely used as the important alternative. In the present work, numerical analysis has been performed to investigate and to compare the film-cooling performance of various film-cooling hole schemes such as cylindrical, crescent, louver, and dumbbell holes. To analyze the turbulent flow and the film-cooling mechanism, three-dimensional Reynolds-averaged Navier-Stokes analysis has been performed with shear stress transport turbulence model. The validation of numerical results has been assessed in comparison with experimental data. The characteristics of fluid flow and the film-cooling performance for each shaped hole have been investigated and evaluated in terms of centerline, laterally averaged and spatially averaged film-cooling effectivenesses. The dumbbell shaped hole shows better film-cooling effectiveness than other shaped holes. And the louver and cylindrical shaped hole shows lower one, and concentrated flow on centerline only.
김선민(S.M. Kim),이기돈(K.D. Lee),김광용(K.Y. Kim) 한국전산유체공학회 2011 한국전산유체공학회지 Vol.16 No.4
In order to protect the turbine blade from working fluid of high temperature, many cooling techniques such as internal convection cooling, film cooling, impinging jet cooling and thermal barrier coating have been developed. With all other things, film-cooling has been widely used as the important alternative. In the present work, numerical analysis has been performed to investigate and to compare the film-cooling performance of various film-cooling hole schemes such as cylindrical, crescent, louver, and dumbbell holes. To analyze the turbulent flow and the film-cooling mechanism, three-dimensional Reynolds-averaged Navier-Stokes analysis has been performed with shear stress transport turbulence model. The validation of numerical results has been assessed in comparison with experimental data. The characteristics of fluid flow and the film-cooling performance for each shaped hole have been investigated and evaluated in terms of centerline, laterally averaged and spatially averaged film-cooling effectivenesses. Among the film cooling holes, the dumbbell shaped hole shows better film-cooling effectiveness than the other shaped holes. And the louver and cylindrical shaped hole show the worst film cooling performance, and concentrated flows on near the centerline only.
허만웅(M.W. Heo),이기돈(K.D. Lee),김광용(K.Y. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
In the present work, a numerical study of fluid flow and heat transfer on the concave surface with impinging jet has been performed by solving three-dimensional Reynods-averaged Naver-Stokes(RANS) equations. The constant temperature condition was applied to the concave impingement surface. The inclination angle of jet nozzle and the distance between jet nozzles are chosen as design variables under equivalent mass flow rate of working fluid into cooling channel, and area averaged Nusselt number on concave impingement surface is set as the objective function. Thirteen training points are obtained by Latin Hypercube sampling method, and the PBA model is constructed by using the objective function values at the trainging points. And, the sequential quadratic programming is used to search for the optimal point from the PBA model. Through the optimization, the optimal shape shows improved heat transfer rate as compared to the reference geometry.
엇갈리게 기울어진 충돌제트들에 의한 오목면 상의 열전달 성능해석
허만웅(M.W. Heo),이기돈(K.D. Lee),김광용(K.Y. Kim) 한국전산유체공학회 2011 한국전산유체공학회지 Vol.16 No.2
Numerical analyses have been carried out to analyze the three-dimensional turbulent heat transfer by impingement jet on a concave surface with variation of geometric configurations. Three-dimensional Reynolds averaged Navier-stokes equations have been calculated using the shear stress transport turbulent model. The numerical results for heat transfer rate were validated in comparison with the experimental data. The distance between jet nozzles and angle of inclined jet nozzle were selected as the geometric variables. Area-averaged Nusselt numbers on concave surface are evaluated to find the characteristics of heat transfer with the two geometric variables. The heat transfer increases as the distance between jet nozzles increases, and the inclined impinging jets show much better heat transfer performance than the vertical impinging jet.