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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of computational fluids engineering
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Journal DOI :
Korea Society of Computational Fluids Engineering
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Volume & Issues
Volume 5, Issue 3 - Dec 2000
Volume 5, Issue 2 - Sep 2000
Volume 5, Issue 1 - May 2000
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Numerical Calculations of Compressible Flows using a SIMPLE Algorithm
Ahn Hee-Sub ; Sohn Chang-Hyun ; Moon Su-Yeon ;
Journal of computational fluids engineering, volume 5, issue 2, 2000, Pages 1~8
A well-known pressure correction method, a SIMPLE algorithm, is extended to treat compressible flows. Collocated grids are used and density is linked to pressure via an equation of state. The influence of pressure on density in the case of compressible flows is implicitly incorporated into the extended SIMPLE algorithm. The first-order Upwind and high-order Quick scheme are compared with respect to an accuracy and convergence time at all speeds. The extended method is verified on a number of test cases and the results are compared with other numerical results available in the literature. The calculated results show that the Quick scheme improves accuracy at all speed and also reduces the calculation time at supersonic flows, compared with the Upwind scheme.
Numerical Study on Transient Aerodynamics of Moving Flap Using Conservative Chimera Grid Method
Choi S. W. ; Chang K. S. ; Kim I. S. ;
Journal of computational fluids engineering, volume 5, issue 2, 2000, Pages 9~19
Transient aerodynamic response of an airfoil to a moving plane-flap is numerically investigated using the two-dimensional Euler equations with conservative Chimera grid method. A body moving relative to a stationary grid is treated by an overset grid bounded by a 'Dynamic Domain Dividing Line' which has an advantage for constructing a well-defined hole-cutting boundary. A conservative Chimera grid method with the dynamic domain-dividing line technique is applied and validated by solving the flowfield around a circular cylinder moving supersonic speed. The unsteady and transient characteristics of the flow solver are also examined by computations of an oscillating airfoil and a ramp pitching airfoil respectively. The transient aerodynamic behavior of an airfoil with a moving plane-flap is analyzed for various flow conditions such as deflecting rate of flap and free stream Mach number.
Parallelization of an Unstructured Implicit Euler Solver
Kim J. S. ; Kang H. J. ; Park Y. M. ; Kwon O. J. ;
Journal of computational fluids engineering, volume 5, issue 2, 2000, Pages 20~27
An unstructured implicit Euler solver is parallelized on a Cray T3E. Spatial discretization is accomplished by a cell-centered finite volume formulation using an upwind flux differencing. Time is advanced by the Gauss-Seidel implicit scheme. Domain decomposition is accomplished by using the k-way n-partitioning method developed by Karypis. In order to analyze the parallel performance of the solver, flows over a 2-D NACA 0012 airfoil and 3-D F-5 wing were investigated.
Computational Grid Generator for Flow Analysis of Single Stage Axial Turbomachinery with Its Applications
Chung H. T. ; Park J. Y. ; Baek J. H. ;
Journal of computational fluids engineering, volume 5, issue 2, 2000, Pages 28~37
An integrated grid generation has been developed for a Navier-Stokes simulation of flow fields inside multistaged turbomachinery The internal grids are generated by the combination of algebraic and elliptic methods. The interactive mode of the present system is coupled efficiently with the design results and flow solvers. Application to several types of axial-flow turbomachines was demonstrated to be reliable and practical as the pre-processor of the computational fluid engineering for gas turbine engines.
2-D Inviscid Analysis of Flow in One Stage of Axial Compressor
Kim HyunIl ; Park JunYoung ; Baek JeHyun ; Jung HeeTaek ;
Journal of computational fluids engineering, volume 5, issue 2, 2000, Pages 38~46
It has been indicated that the rotor/stator interaction has distinct causes of unsteadiness, such as the viscous vortex shedding, wake/stator interaction and potential rotor/stator interaction. In this paper, the mechanism of unsteady potential interaction in one stage axial compressor is numerically investigated for blade row ratio 1:1 and 2:3 at design point and for blade row ratio 2:3 at off-design point in two-dimensional view point. The numerical technique used is the upwind scheme of Van-Leer's Flux Vector Splitting(FVS) and Cubic spline interpolation is applied on zonal interface. In this study the flow unsteadiness due to potential interaction are found to be larger in blade row ratio 2:3 than in 1:1. The total pressure rise in blade row ratio 2:3 is closer to the real value in design point than that in 1:1. The change of unsteady pressure amplitude according to the variation of stator exit pressure is very small.
Hypersonic Chemical Nonequilibrium Flow Analysis with HLLE+ and LU-AF
Park Soo-Hyung ; Kwon Jang Hyuk ;
Journal of computational fluids engineering, volume 5, issue 2, 2000, Pages 47~54
A robust Navier-Stokes code has been developed to efficiently predict hypersonic flows in chemical nonequilibrium. The HLLE+ flux discretization scheme is used to improve accuracy and robustness of hypersonic flow analysis. An efficient LU approximate factorization method is also used to solve the flow equations and species continuity equations in fully coupled fashion to implicitly treat stiff source terms of chemical reactions. The HLLE+ scheme shows lower grid dependency for the wall heating rates than other schemes. The developed code has been used to compute chemical nonequilibrium air flow through expanding hypersonic nozzle and past two and three dimensional blunt-nosed bodies. The results are in good agreement with existing numerical and experimental results.
Ram Accelerator Optimization Using the Response Surface Method
Jeon Kwon-Su ; Jeon Yong-Hee ; Lee Jae-Woo ; Byun Yung-Hwan ;
Journal of computational fluids engineering, volume 5, issue 2, 2000, Pages 55~63
In this paper, the numerical study has been done for the improvement of the superdetonative ram accelerator performance and for the design optimization of the system. The objective function to optimize the premixture composition is the ram tube length, required to accelerate projectile from initial velocity V/sub 0/ to target velocity V/sub e/. The premixture is composed of H₂, O₂, N₂ and the mole numbers of these species are selected as design variables. RSM(Response Surface Methodology) which is widely used for the complex optimization problems is selected as the optimization technique. In particular, to improve the non-linearity of the response and to consider the accuracy and the efficiency of the solution, design space stretching technique has been applied. Separate sub-optimization routine is introduced to determine the stretching position and clustering parameters which construct the optimum regression model. Two step optimization technique has been applied to obtain the optimal system. With the application of stretching technique, we can perform system optimization with a small number of experimental points, and construct precise regression model for highly non-linear domain. The error compared with analysis result is only 0.01% and it is demonstrated that present method can be applied to more practical design optimization problems with many design variables.