• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.169-172
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• 2005

A numerical analysis was made In investigate the pressure diminution of a silencer with baffles for high pressure blast flow fields. Reynolds-Averaged Navier-Stokes equations were solved for an axisymmetric computational domain constructed by multi block Chimera grids. A blast flow field was calculated for the silencers that are with one and three baffles. The evolution of high pressure blast flow fields was observed by depicting calculated contours of pressure. It was found that the tested silencer could achieve 97.7 percent pressure diminution.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.21-24
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• 2005

Numerical analysis were made for the unsteady flow fields of the rotor system of a Tilt-Rotor aircraft in cruise mode. The Reynolds-averaged thin-layer Wavier-Stokes equations were discretized by Roe's upwind differencing scheme and integrated in time by the LU-SGS algorithm. The computational domain of the rotor system was constructed by seven multi-block Chimera grids. Comparison of pressure coefficient on the surface of the main wing and blades were made for 3cases of advance ratio(0.325, 0.350, 0.375) and thrust and power coefficients for the rotor were compared with experimental data.

• Journal of computational fluids engineering
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• v.11 no.1 s.32
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• pp.16-20
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• 2006

The present study focuses on the flow analysis of a turbo pump inducer by performing both numerical and experimental methods. The head rise, efficiency and detailed flow fields such as outlet flow angles, pressure and velocity vectors are measured and compared with the computational data. Generally a good agreement is obtained between numerical and experimental results. However, some discrepancies are observed due to complex flow structures inside the inducer. Future calculations with an advanced turbulence model and a dense computational grid needs to be performed to obtain accurate numerical solution for the detailed flow fields.

• Journal of computational fluids engineering
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• v.20 no.4
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• pp.44-50
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• 2015

The computational efficiency of flow simulations with Multi-resolution analysis (MRA) was enhanced via the boundary treatment of the computational domain. In MRA, an adaptive dataset to a solution is constructed through data decomposition with interpolating polynomial and thresholding. During the decomposition process, the basis points of interpolation should exceed the boundary of the computational domain. In order to resolve this problem, the weight coefficients of interpolating polynomial were adjusted near the boundaries. By this boundary treatment, the computational efficiency of MRA was enhanced while the numerical accuracy of a solution was unchanged. This modified MRA was applied to two-dimensional steady Euler equations and the enhancement of computational efficiency and the maintenance of numerical accuracy were assessed.

• Journal of computational fluids engineering
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• v.20 no.4
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• pp.36-43
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• 2015

Accurate prediction of supersonic transition is required for the heat transfer estimation over supersonic double compression ramp flows. Correlation-based transition models were assessed for a supersonic double ramp problem. Numerical results were compared with experimental data from RWTH Aachen University. A parametric study on the nose bluntness was performed using a selected transition model. As the nose bluntness increases, the boundary layer thickness is increased and the triple point of shock interactions moves downstream. The peak magnitude of the heat transfer is consequently decreased with the nose bluntness.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.86-87
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• 2011

In this paper, a conjugate heat transfer around cylinder with heat generation was investigated. Both forced convection and conduction was considered in the present finite element simulation. A finite element formulation based on SIMPLE type algorithm was adopted for the solution of the incompressible Navier-Stokes equations. We compared the finite element solution with that of Ansys fluent 12.0, in which finite volume method was employed for spatial discretization. It was found that the finite element method gave more accurate solution than Ansys fluent 12.0. Further, it was found that the maximum temperature inside cylinder is positioned at the rear side due to the flow separation.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.572-578
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• 2011

The vane type air-motor hand-piece is used widely in the dental services. There are a lot of experimental studies about air-motor but eccentrically off not many numerical studies by using Computational Fluid Dynamics. An air-motor has rotor which rotates at the center of inner housing. The retractable vanes are installed on the rotor. As the rotor of the air-motor rotates, vanes move up and down straightly in the radial direction along the guide. Therefore we have to analyze the unsteady flow field by accurate time dependent marching technique. ANSYS 12.0 CFX is used to analyze unsteady vane-motor flow field Analysis of the changing control volume inside air-motor is implemented by user-defined functions and moving mesh options. Rotational speed of the rotor is approximately 23,000rpm.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.567-571
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• 2011

Air Starter motors are used for the start of medium-speed diesel engine. One of the main part of air starting motors is the axial turbine stage. In this study, design of 1-stage axial type turbine for 14kw class air starter motors has been performed. The turbine blade was designed based on mean-line analysis. 1-D design calculation and numerical analysis with CFD were conducted iteratively. The validation between 1-D design method and numerical analysis for axial clearance has been performed. It revealed that there is optimum axial clearance of turbine design.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.428-433
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• 2011

In this paper, a prediction method for dynamic stability derivatives is studied using steady state simulations in rotational coordinates. The simulations require the extension of a standard CFD formulations based on inertial coordinate. A new CFD code based on the method are developed. Flows induced by steady circular motions of airfoils with a constant pitch rate are simulated with the code. From the numerical simulations, the pitch rate derivatives are obtained at various Mach numbers, and the results are compared with other numerical results. The numerical simulations show that the new code are capable of predicting dynamic stability derivatives.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.112-116
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• 2011

In this paper, a preconverter of MCFC for an emergence electric power supplier is numerically simulated to increase the hydrogen production from natural gas (methane). Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). To get 10% fuel conversion rate in preconverter. the required external heat flux is supplied from outer wall of preconverter. The calculated results show that very nonuniform temperature distribution and chemical reaction happen near the wall of preconverter. These phenomena can be explained by the low heat conductivity of porous catalyst and the endothermic reforming reaction.