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축류압축기의 Navier-Stokes설계를 위한 계산격자점 생성기법 연구
정희택(H.T. Chung) 한국전산유체공학회 1997 한국전산유체공학회 학술대회논문집 Vol.1997 No.-
A multiblock grid generation has been applied to a Navier-Stokes design procedure of a axial-flow compressors. A multiblock structure simplifies the creation of structured H-grids about complex turbomachinery geometries and facilitate the creation of a grid in the tip flow region. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The input module is made of the results of the preliminary design, I.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The final grids generated from each module of the system are used as the preprocessor for the performance prediction of the sectional blade, the blade-stacking process and the three-dimensional flow simulation inside the blade passage. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure of the turbomachinery cascades using the Navier-Stokes technique.
정희택(H.T. Chung),정향남(H.N. Jung),서영수(Y.S. Seo) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Numerical investigations have been performed to examine the effects of the computational grids on<br/> the prediction of the flow characteristics inside the turbine cascades. Three kinds of grid system based<br/> on H-type grid are applied to the high-turning transonic turbine rotor blades and comparisons with the<br/> experimental data and the numerical results of each grid structure have been done. In addition, the grid<br/> sensitivity on the estimation of the blade performances has been investigated.
정희택(H. T. Chung) 한국전산유체공학회 1996 한국전산유체공학회지 Vol.1 No.1
A multi block grid generation has been developed to be reliably used for a Navier-Stokes simulation of the turbomachinery flow-fields A multiblock structure simplifies the creation of structured H-grids about complex turbomachinery geometries and facilitate the creation of a grid in the tip flow region. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The grid refinement process is enhanced by developing strategies to utilized Belier curves and splines along with weighted transfinite interpolation technique and by formulating the grid-imbedding method for the viscous boundary-layer meshes. For purposes of illustration, the grid generator is applied to the high turning turbine rotor blades. Two different types of computational grids are provided to be compared with respect to the grid adaptation to the flow simulations. Extension to threedimensions was done to show the possibility of its application to the tip-flow simulations. The grid quality of the multiblock structure is good in the passages, with gloval orthogonality and adequate smoothness.
축류터빈 내부의 3차원 압축성 점성 유동특성에 관한 수치 시물레이션
정희택(H. T. Chung),정향남(H. N. Jung) 한국전산유체공학회 2004 한국전산유체공학회 학술대회논문집 Vol.2004 No.-
Numerical simulation of viscous compressible flow in turbomachinery cascade involves many problems due to the complex geometry of blade but also flow phenomena. In the present study, numerical investigations have been performed to examine the three-dimensional flow characteristics inside the transonic linear turbine cascades using a commercial code, FLUENT. Multi-block H-type grids are applied to the high-turning turbine rotor blades and comparisons with the experimental data and the numerical results have been done. In addition, the effects of turbulence models on the prediction of the endwall flows are analyzed in the sense of the flow compressibility.
정희택(H.T. Chung),정향남(H.N. Jung) 한국전산유체공학회 2005 한국전산유체공학회지 Vol.10 No.2
Numerical investigations have been performed to examine the effects of the computational grids on the prediction of the flow characteristics inside the turbine cascades. Three kinds of grid system based on H-type grid are applied to the high-turning transonic turbine rotor blades and comparisons with the experimental data and the numerical results of each grid structure have been done. In addition, the grid sensitivity on the estimation of the blade performances has been investigated.
Circular-to-Rectangular Transition Duct 내부의 3차원 유동장에 관한 연구
조수용(S. Y. Cho),정희택(H. T. Chung),손호재(H. J. Son) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.3 No.2
Predictive behaviors by the extended k-ε turbulence model and the standard k- e turbulence model are compared. Grid dependency is tested with the H-type grid as well as the O-type grid. Computations have been performed on a circular-to-rectangular transition duct. The Reynolds number is 390,000 based on the bulk velocity at the inlet. The computed axial velocity contours. transverse velocity profiles, static pressure contours, peripheral skin friction coefficient, peripheral wall static pressure distributions and turbulence kinetic energy have been compared with experimental results. The computed results obtained with the extended k-ε turbulence model show better agreement with experimental results than those obtained with the standard k-ε turbulence model. Comparing to the computed results obtained with the H-type grid and O-type grid, those with H-type grid seem to agree well with experimental results.
Circular-to-Rectangular Transition Duct 내부의 3차원 유동장에 관한 연구
조수용(S. Y. Cho),정희택(H. T. Chung),손호재(H. J. Son) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.3 No.2
Predictive behaviors by the extended k-ε turbulence model and the standard k- e turbulence model are compared. Grid dependency is tested with the H-type grid as well as the O-type grid. Computations have been performed on a circular-to-rectangular transition duct. The Reynolds number is 390,000 based on the bulk velocity at the inlet. The computed axial velocity contours. transverse velocity profiles, static pressure contours, peripheral skin friction coefficient, peripheral wall static pressure distributions and turbulence kinetic energy have been compared with experimental results. The computed results obtained with the extended k-ε turbulence model show better agreement with experimental results than those obtained with the standard k-ε turbulence model. Comparing to the computed results obtained with the H-type grid and O-type grid, those with H-type grid seem to agree well with experimental results.
정희택(H.T. Chung),류병식(B.S. Ryu) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.4 No.2
In the present paper, three types of the flow solvers were used to investigate the influence on the airfoil shape optimization. The adopted equations, i.e., Euler, thin layer Navier-Stokes and full Navier-Stokes ones, are solved using implicit LU-ADI decomposition scheme. The gradient projection method with the sinusoidal function was used as an optimization algorithm. The present numerical method was applied to the drag minimization problems under the initial shape of NACA0012 airfoils.
정희택(H.T. Chung),류병석(B.S. Ryu) 한국전산유체공학회 1999 한국전산유체공학회 학술대회논문집 Vol.1999 No.-
In the present paper, three types of the flow solvers were used to investigate the influence on the airfoil shape optimization. The adopted equations, i.e., Euler, thin layer Navier. Stokes and full Navier-Stokes ones, are solved using implicit LV-ADI decomposition scheme. The feasible direction algorithm with the sinusoidal function was used as an optimization algorithm. The present numerical method was applied to the drag minimization problems under the initial shape of NACA00l2 airfoils.