• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.244-249
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• 2002

It is known that tip clearance flows reduce the pressure rin, flow range and efficiency of the turbomachinery. So, the clear understanding about flow fields in the tip region is needed to efficiently design the turbomachinery. The Navier-Stokes code with the proper treatment of the boundary conditions has been developed to analyze the three-dimensional steady viscous flow fields in the transonic rotating blades and a numerical study has been conducted to investigate the detail flow physics in the tip region of transonic rotor, NASA Rotor 67. The computational results in the tip region of transonic rotors show the leakage vortices, leakage flow from pressure side to suction side and their interaction with a shock Depending on the operating conditions, the position of shock-wave on the blade surface are v8y different close to the blade tip of the transonic compressor rotor. The shock-wave position dose to the blade tip had the dose relationship with the starting position of leakage vortex and the direction of leakage flow.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.89-94
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• 2002

n general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank, is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, may introduce air into pump, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. Uneven flow distribution can also increase or decrease the power consumption with a change in total developed head. To avoid these sump problems pump station designers are considered intake structure dimensions, such as approaching upstream, baffle size, sump width, width of pump cell and so on. From this background, flow characteristics of intake within sump are investigated numerically to obtain the optimal sump design data. The sump model is designed in accordance with HI code.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1064-1072
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• 1998

The evaporation of sludge particles in a sludge dryer has been numerically investigated with commercial CFX4.1 code. Gas flow field, gas temperature field, sludge particle trajectories, and the moisture content variation of sludge particles are calculated fort various influencing factors, i. e., gas swirl velocity, initial particle distribution, gas temperature. Evaporation of sludge particles increases with gas swirl velocity, several supplying positions, and gas temperature, respectively due to increased residence time, increased contacting surface area, and increased temperature difference between gas and particle.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.8-14
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• 2018

In the present work, a numerical study is carried out to observe the characteristics of the flow and particle behaviors in a supersonic double Venturi abrasive blasting nozzle. Schlieren flow visualization and Pitot pressure at the nozzle downstream are also carried out, and those measurement results are compared to the numerical ones for code validation. Open and closed secondary holes on the double Venturi nozzle surface are tested for various nozzle pressures, and the results are compared with the ones observed for other similar supersonic Laval nozzles.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.7 s.262
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• pp.800-807
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• 2007

Autofrettage process is used for internal forming and sizing of cylinder designed to withstand high internal pressures. Once the tube is autofrettaged, it needs to be machined to its final dimensions both at the bore and its outer surface. This paper presents an analytical analysis and numerical analysis of machined compound cylinder using finite element code, ANSYS10.0. An analytical model for predicting the level of autofrettage following either inner, outer, or combined machining of the compound cylinder is developed for the autofrettage residual stress field is simulated by an autofrettaged pressure. The autofrettaged pressures are obtained by using trying-error method. As autofrettage percentage is 20 % and 40 %, the numerical results are found to be in almost agreement with the analytical ones. However, as autofrettage percentage is 60 %, the numerical results have a little difference with the analytical ones.

• Journal of Energy Engineering
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• v.8 no.2
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• pp.285-292
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• 1999

The design parameter of the reactor vessel insulation for the Korea Standard Power Plant has been studied numerically. The heat loss from the reactor vessel through the insulation is analysed by using the computational fluid dynamics code, FLUENT. Parametric study has been performed on the air gap width between the reactor vessel wall and the inner surface of the insulation, and on the insulation thickness. Also evaluated is the performance degradation due to the chimney effect caused by gaps between the panels during the installation of the insulation system. From the analysis results, the optimal air gap width and the optimal insulation thickness are obtained.

• International Journal of Korean Welding Society
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• v.5 no.1
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• pp.1-9
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• 2005

Multipass welds of 316L stainless steel have been widely employed to the pipes of Liquid Metal Reactors. Owing to localized heating and a subsequent rapid cooling by the welding process, residual stress arises in the weld of the pipe. In this study, the residual stresses in the 316L stainless steel pipe welds were calculated by the finite element method using the ANSYS code. Also, the residual stresses both on the surface and in the interior of the thickness were measured by the HRPD(High Resolution Powder Diffractometer) instrumented in the HANARO Reactor. The experimental data and the calculated results were compared and the characteristics of the distribution of the residual stress were discussed.

• The KSFM Journal of Fluid Machinery
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• v.9 no.2 s.35
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• pp.19-24
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• 2006

Nano fountain-pen is a novel device to make the constant patterning in micro process using new designed probe. Fountain-pen nanolithography (FPN) is applied for constant supply of liquid in conjunction of patterns and surface variation in the micro process. In this study, nuo fountain-pen is composed with reservoir, micro channels, tip and scondary chamber. Instead of traditional method only using capillary force, liquid can be definitely and exactly injected with membrane pumping by the repulse force of tip. It is dfficult to perform experiments in the micro range so that we carried out a numerical analysis for internal flow, using a commercial code, FlUENT, The velocity, pressure and flow rate are obtained under laminar, unsteady, three-dimensional incompressible flow with no-slip condition, and results are graphically described.

• Journal of the Korean Society of Visualization
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• v.4 no.1
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• pp.31-40
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• 2006

In this study a newly designed electro-osmotic micro-mixer is proposed. This study is composed of a channel and metal electrodes attached locally on the side wall surface ultimately to control the mixing effect. To obtain the flow patterns, numerical computation was performed by using a commercial code, CFD-ACE. The fluid-flow solutions are the cast into studying the characteristics of stirring in terms of the mixing index. It was shown that the local control of the electric potential can indeed contribute to the enhancement of mixing effect.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.154-159
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• 2004

Numerical simulations of supersonic impinging jet flows are carried out using the axisymmetric Navier-Stokes code. This paper focuses on the oscillatory flow features associated with the variation of the nozzle pressure ratio and nozzle-to-plate distance. Frequencies of the surface pressure oscillation from computational results are in accord with the measured impinging tones for various cases of nozzle-to-plate distance. The variation of this frequency with distance show a staging behavior. Computed results for the case of nozzle pressure ratio variation for a fixed nozzle-to-plate distance also demonstrate a staging behavior. These two seemingly different staging behaviors are found to obey the same frequency-distance characteristics when the frequency and the distance are normalized by using the length of the shock cell.