• 한국전산유체공학회지
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• 제8권1호
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• pp.30-37
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• 2003

The post-processor for two-dimensional flow visualization has been developed by using OOP(object-oriented programming) of Visual C++. User-friendly GUI(graphic user interface) has been built on the base of MFC(Microsoft Foundation Class). The number and order of variables can be specified by user because the input style is the free-format. The new variable can be defined and added to the variable list by using the various operators and functions.

• 대한기계학회논문집B
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• 제23권8호
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• pp.957-968
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• 1999

Performance tests of an airfoil fan and measurement of flow fields at the impeller exit are carried out to investigate the effects of the tip clearance between the rotor and inlet casing on the impeller performance. The impeller is twelve bladed of NACA 65-810 airfoils and tested with 3 different size of gap; 1, 2, 4mm. The relative decrease of pressure rising performance of the fan is 15 percent for the design flow rate when the gap size is 1 percent of the impeller diameter. The reduction of performance becomes large as the flow rate increases. The leakage flow through the clearance affects the through flow of the impeller, which results in decrease of the slip factor as well as the impeller efficiency. The data base obtained in the present study can be used for the design and flow analysis of the airfoil fans.

• 한국재료학회지
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• 제25권2호
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• pp.81-89
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• 2015

A strain-gradient crystal plasticity constitutive model was developed in order to predict the Hall-Petch behavior of a Ni-base polycrystalline superalloy. The constitutive model involves statistically stored dislocation and geometrically necessary dislocation densities, which were incorporated into the Bailey-Hirsch type flow stress equation with six strength interaction coefficients. A strain-gradient term (called slip-system lattice incompatibility) developed by Acharya was used to calculate the geometrically necessary dislocation density. The description of Kocks-Argon-Ashby type thermally activated strain rate was also used to represent the shear rate of an individual slip system. The constitutive model was implemented in a user material subroutine for crystal plasticity finite element method simulations. The grain size dependence of the flow stress (viz., the Hall-Petch behavior) was predicted for a Ni-base polycrystalline superalloy NIMONIC PE16. Simulation results showed that the present constitutive model fairly reasonably predicts 0.2%-offset yield stresses in a limited range of the grain size.

• Korea-Australia Rheology Journal
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• 제19권2호
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• pp.67-73
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• 2007

A finite volume method (FVM) base on the SIMPLE algorithm as the pressure correction strategy and the traditional staggered mesh is used to investigate steady, fully developed flow of Oldroyd-3-constant fluids through a duct with square cross-section. Both effects of the two viscoelastic material parameters, We and ${\mu}$, on pattern and strength of the secondary flow are investigated. An amusing sixteen vortices pattern of the secondary flow, which has never been reported, is shown in the present work. The reason for the changes of the pattern and strength of the secondary flow is discussed carefully. We found that it is variation of second normal stress difference that causes the changes of the pattern and strength of the secondary flow.

• 한국가시화정보학회지
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• 제5권2호
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• pp.48-55
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• 2007

Flow structure inside a refrigerating compartment of a scale-down display cooler model was investigated experimentally by using PIV (particle image velocimetry) method, a reliable velocity field measurement technique, in the present study. In addition, we also carried out flow visualization regarding flow structure and particle movement inside a display cooler by using a tracer method. As a result, the mean velocity field measurement shows a large scale vortical flow structure inside a refrigerating compartment due to strong entrainment flow, going through a base plate open gaps.

• 한국자동차공학회논문집
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• 제3권5호
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• pp.17-23
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• 1995

A numerical analysis on engine coolant is made by the use of FVM based general purpose 3 dimensional Navier-Stokes solver, TURB-3D. Numerical solutions are verified by comparison with the experimental data of Lotus model. The results show a good qualitative as well as quantitative comparison. Coolant flow rate control is attempted through adjusting the cross section area of passage base on the results of an original coolant passage. It is concluded from the results that the flow rate control is possible as attempted, and thus can be used in the real engine design.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.487-493
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• 2020

최근 환경부의 강화된 규제로 건축물 아파트 등 산업시설을 도장함에 있어 페인트를 유압에 의해 자동으로 이송시켜 스프레이식으로 도장하는 기존 에어리스 방식의 사용을 금지하였다. 따라서 기존의 에어리스 도장장치에 스프레이 대신 부착하여 사용할 압송롤러개발이 필요한데, 현재 개발되어 판매 중인 압송롤러는 롤러를 구성하는 SUS배관 및 드럼베이스의 홀 설계에 대한 자세한 연구 사례가 없어 그 효율성이 의심이 되는 바이다. 특히, 롤러를 이용한 도장 시롤러 양단에 페인트가 충분히 공급되지 못하면 도장 후 붓을 이용한 재작업이 필요하게 되므로, 롤러 양단에 페인트가 잘 유입될 수 있도록 드럼베이스 홀을 분포시킬 필요가 있다. 본 연구에서는 SUS배관 및 드럼베이스에 가공되는 홀의 형태가 페인트의 유입양상에 미치는 영향을 알아보고 보다 효율적인 홀 설계 방안을 제시하기 위하여 SUS배관 및 롤러에 대하여 전산유체해석을 수행하였다. 해석결과 SUS배관에서의 홀 배치는 배관에 균일하게 배치하는 것이 균형 있게 페인트를 유입시키기에 좋고, 드럼베이스의 경우는 홀을 드럼베이스 양단에 밀집하여 가공하면 페인트가 롤러 양단에 더 잘 유입시킬 수 있음이 검증되었다.

• Korean Chemical Engineering Research
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• 제47권5호
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• pp.615-619
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• 2009

$Tr{\ddot{o}}ger$'s base 중 (+)-$Tr{\ddot{o}}ger$'s base는 항혈전제로 Thromboxane A2($T{\times}A2$) Synthase의 효소 활성을 저해하여 동맥경화의 치료제로 널리 사용되고 있다. 따라서 (+)-$Tr{\ddot{o}}ger$'s base를 라세미 혼합물로부터 순수하게 분리하는 것은 중요한 연구대상이다. 하지만 실험을 통한 (+)-$Tr{\ddot{o}}ger$'s base의 순수한 분리에는 많은 시간과 비용이 필요하게 되므로 분리 효율의 향상에 많은 어려움이 있다. 이러한 단점을 보완하고자 Aspen Chromatography 전산 모사는 여러 조건하에서 직접 실험을 하지 않는 효율적인 시뮬레이션 방법으로서 분리 효율 등을 예측할 수 있으므로 생산성 향상에 드는 시간과 비용을 절약할 수 있다. Aspen Chromatography simulator로 $Tr{\ddot{o}}ger$'s base의 주입량과 이동상 속도를 변화시켜 TB(-)와 TB(+)의 분리도, 수율 그리고 다양한 흡착식을 비교하였다. TB(-)와 TB(+)의 분리도와 순수한 수율은 이동상 속도 0.25 mL/min일 때 가장 높았다. 고정상과 이동상 농도사이의 관계식을 표시하는 등온흡착식을 변화하여 전산모사한 결과 Ideal Adsorbed Solution(IAS) Statistical Langmuir 등온흡착식이 분리 효율에 좋은 결과를 가져왔다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.65-70
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• 1999

Radiative heating of a liquid rocket base plane due to plume emission is numerically investigated. Calculation of flow and temperature fields around rocket nozzle precedes and thereby realistic plume shape and temperature distribution inside the plume are obtained. Based on the calculated temperature field, radiative transfer equation is solved by discrete ordinate method. The averaged radiative heat flux reaching the base plane is about $5kW/m^2$ at the flight altitude of 10.9km. This value is small compared with radiative heat flux caused by constant-temperature (1500K) plume emission, but it is not negligibly small. At higher altitude (29.8km), view factor between the babe plane and the exhaust plume is increased due to the increased expansion angle of the plume. Nevertheless, the radiative heating disappears since the base plane is heated to high temperature (above 1000K) due to convective heat transfer.

• Wind and Structures
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• 제29권1호
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• pp.1-13
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• 2019

A numerical investigation on forces and flow around three square cylinders in side-by-side arrangement is conducted at a Reynolds number Re = 150 with the cylinder center-to-center spacing ratio L/W = 1.1 ~ 9.0, where W is the cylinder side width. The flowat this Re is assumed to be two-dimensional, incompressible, and Newtonian. The flow simulation is conducted by using ANSYS-Fluent. The flow around the three side-by-side cylinders entails some novel flow physics, involving the interaction between the gap and free-stream side flows as well as that between the two gap flows. An increase in L/W from 1.1 to 9.0 leads to five distinct flow regimes, viz., base-bleed flow (L/W < 1.4), flip-flopping flow (1.4 < L/W < 2.1), symmetrically biased beat flow (2.1 < L/W < 2.6), non-biased beat flow (2.6 < L/W < 7.25) and weak interaction flow (7.25 < L/W < 9.0). The gap flow behaviors, time-averaged and fluctuating fluid forces, time-averaged pressure, recirculation bubble, formation length, and wake width in each flow regime are discussed in detail.