• 대한기계학회논문집A
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• 제28권7호
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• pp.877-884
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• 2004

In this paper, structural analysis is performed to investigate the deformation of porous media in a proton exchange membrane fuel cell (PEMFC). Structural deformation of air plate of the fuel cell causes the change in configuration and cross sectional area of the channel. The distributions of mass flow rate and pressure are major factors to decide the performance of a PEMFC. These factors are affected by channel configuration of air plate. Two kinds of numerical air plate models are suggested for flow analyses. Deformed porous media and undeformed porous media are considered for the two models. The Numerical flow analysis results between deformed porous media and undeformed porous media have some discrepancy in pressure distribution. The pressure and velocity distribution under a working condition are numerically calculated to predict the performance of the air plates. Pressure and velocity distributions are compared for two models. It is shown that structural deformation makes difference in flow analysis results.

• 한국융합학회논문지
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• 제5권2호
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• pp.19-23
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• 2014

본 연구에서는 자동차 차체의 형상에 따른 차체 주위의 유동해석을 이용하여 공기 저항을 연구하였다. 입구평면에서 들어가는 공기 유동 속도가 70km/h과 100km/h인 2가지 경우이다. 승용차의 고속 주행 시(100km/h) 정속 주행(70km/h)보다 큰 항력이 나타나는 것을 알 수 있고 차체의 전방 단면적이 넓은 차가 단면적이 좁은 차보다 항력이 더 크게 나타나는 것을 알 수 있다. 본 해석 결과를 이용하여 공기 저항을 줄일 수 있는 자동차 차체의 형상 설계를 효율적으로 할 수 있다고 사료된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.461-462
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• 2009

• 한국융합학회논문지
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• 제11권5호
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• pp.159-164
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• 2020

본 연구에서는 자동차에서의 공기의 유입구에 따른 자동차 내부에서의 유동 해석을 하였다. 공기가 들어오는 유입구로서 쾌적성이 좋은 조건으로서는 유입구가 자동차의 상단 중간이나 전방위치임을 확인할 수 있었다. 차량 내부에 공기 유동의 고르게 분포가 안되는 경우는 자동차의 하단 위치가 유입구의 모든 조건들 중에서 가장 저조한 조건하다. 본 연구 결과를 통하여 탑승자의 기호나 상황에 맞게 공기의 유입이 되도록 그 유입구의 위치를 조절하므로서 자동차 내부의 상태를 쾌적하게 유지할 수 있는데 도움이 될 것이다. 본 연구의 설계 및 해석 결과는 실제적으로 자동차에서의 공기의 유입구의 위치를 조절하는 데에 효율적으로 적용할 수 있다. 자동차에서의 공기의 유입구에 따른 유동해석을 적용함으로서, 본 논문이 미적인 설계에 부합된 융합 연구라고 보여진다.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.252-258
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• 1999

As an effective means to convey crushed materials from seabed to on board ship and to raise hazardous or abrasive liquids air-lift pump provides a reliable mechanism due to its simple config-uration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newto-nian liquids. it is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates and furthermore attachment of downcomer gives little effects on riser performance the conveyed liquid flow rate increases with larger submergence rate.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.515-516
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• 2008

• 대한기계학회논문집A
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• 제24권9호
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• pp.2159-2166
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• 2000

Recently, high performance machining center requires special type of sealing mechanism that prevent a leakage of oil jet or oil mist lubrication system. Sealing of oil-air mixture plays important r oles to have an enhanced lubrication for performance machining center. Current work emphasizes on investigations of the air jet effect on the protective collar type labyrinth seal. To improve sealing capabilities of conventional labyrinth seals, air jet is injected against the leakage flow. In this study, an adapted model is introduced to improve sealing capability of conventional non-contact type seals. It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. The sealing effects of the leakage clearance and the air jet magnitude aic studied in various parameters. Gas or liquid has been used as a working fluid for most of nori-contact types seals including the labyrinth seal. However, it is more reasonable to regard two-phase flows because oil mist or oil jet are used for high performance spindle's lubrication. In this study, working fluid is regarded as two phases that are mixed flow of oil and air phase. Both of turbulence and compressible flow model are also introduced in a CFD analysis to represent an isentropic process. Estimation of non-leaking property is determined by amount of pressure drop in the leakage path. Results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effect of the sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger

• 한국항공운항학회지
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• 제23권3호
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• pp.8-17
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• 2015

In this research, low fidelity air/heat load analysis was conducted for the intake of high speed vehicle. For air/heat load calculations, aerodynamic properties at the surface and the boundary layer edge were estimated using Taylor-Maccoll equation for conical flow, shockwave relation and Prandtl-Meyer expansion equation for internal and external flow. Couette flow assumption and Reynolds analogy were used in order to calculate convective heat transfer coefficient. In order to calculate skin friction coefficient for heat transfer coefficient analysis, Van Driest method II and Reference Enthalpy method were considered. An axis symmetric SCRAMJET model was selected as a reference configuration for verifying the proper implementation of the present method. Comparison of the results using the present method and Computational Fluid Dynamic analysis showed that the present method is valuable for efficiently providing pressure and heat loads for air-intake structure design of the high speed air vehicle.

• 한국가시화정보학회지
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• 제9권4호
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• pp.47-53
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• 2011

A water driven ejector loop was designed and constructed for air absorption. The used ejector was horizontally installed in the loop and annular water jet at the throat entrained air through the circular pipe placed at the center of the ejector. Wide range of water flow rate was provided using two kinds of pumps in the loop. The tested range of water flow rate was 100${\ell}$ /min to 1,000 ${\ell}$/min. Two-phase flow inside the ejector loop was simulated by CFD analysis. Homogeneous particle model was used for void fraction prediction. Water and air flow rates and pressure drop through the ejector were automatically recorded by using the LabView based data acquisition system. Flow characteristics and air bubble velocity field downstream of the ejector were investigated by two-phase flow visualization and PIV measurement based on bubble shadow images. Overall performance of the two-phase ejector predicted by the CFD simulation agrees well with that of the experiment.

• Design & Manufacturing
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• 제14권2호
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• pp.28-33
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• 2020

Recently, as the income level and quality of life have improved, the desire for a pleasant environment has increased, and a deodorization plan is required through thorough prevention and diffusion of odorous substances in waste treatment facilities recognized as hateful facilities, appropriate collection, and selection of the right prevention facilities. In this study, a waste disposal facility was modeled and computerized analysis for odor and ventilation analysis was conducted. Numerical analysis of the waste treatment facility was performed at the size of the actual plant. CATIA V5 R16 for numerical model generation and ANSYS FLUENT V.13 for general purpose flow analysis were used as analysis tools. The average air-age of the internal was 329 seconds, and the air-flow velocity was 0.384m/s. The odor diffusion analysis inside the underground pump room showed congestion-free air circulation through streamline distribution and air-age distribution. This satisfies the ASHRAE criteria. In addition, the results of diffusion analysis of odorous substances such as ammonia, hydrogen sulfide, methyl mercaptan and dimethyl sulfide were all expected to satisfy the regulatory standards. Particularly in the case of the waste loading area, the air-flow velocity was 0.297m/s, and the result of meeting the regulatory standards with 0.167ppm of ammonia, 0.00548ppm of hydrogen sulfide, 0.003ppm of methyl mercaptan, and 0.003ppm of dimethyl sulfide was found.