• 대한기계학회논문집B
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• 제31권10호
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• pp.889-894
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• 2007

The effect of the axial slit of outer cylinder on Taylor-Couette flow was experimentally investigated. The radius ratio and aspect ratio of the model was 0.825 and 48, respectively. The depth of slits was 5mm and total 18 slits were azimuthally located along the inner wall of outer cylinder. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the axial slit did not affect the transition from laminar Couette flow to Taylor vortex. The effect of slit wall appeared when the Reynolds number is larger than Re=143 and the slit model shows the transition to turbulent Taylor vortex flow above Re=143.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3183-3186
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• 2007

Taylor-Couette flow may appear when the angular velocity is different between two concentric rotating cylinders. This kind of Taylor-vortex flow can be easily seen in lots of engineering problems. In general the geometries of rotating cylinders are generally complex in these cases. In this study, we investigated Taylor-Couette flow when the outer cylinder has the slit along the annulus. The radius ratio and aspect ratio of the experimental model used was 0.825 and 48, respectively. The depth of slits is 5mm and total 18 slits are azimuthally located along the inner wall of outer cylinder. We used PIV method to measure the flow and applied index matching method to resolve the complex geometry effect. The results show the model with slit has no stable wavy vortex region above Re=143.

• 한국가시화정보학회지
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• 제8권3호
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• pp.35-40
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• 2010

We have investigated different radial temperature gradient effect on the stability of Taylor-Couette flow. The radius ratio and aspect ratio of the model was 0.825 and 48, respectively. Two heating exchangers were used for generating different temperature gradient along the radial direction. The change of flow regime in the Taylor-Couette flow was studied by increasing the Reynolds number. The results showed that: as Gr is increased in helical vortex flow regime, the vortices with the same direction of convection flow increased in size, and the vortex moving velocity also increased. It is also shown that the presence of temperature gradient obviously increased the flow instability when the Richardson number is larger than 0.0045.

• 한국가시화정보학회지
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• 제6권2호
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• pp.33-38
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• 2008

The effect of the radial temperature gradient and the presence of slits in the wall of outer of two cylinders involved in creating a Taylor-Couette flow was investigated by measuring the velocity field inside the gap. The slits were azimuthally located along the inner wall of the outer cylinder and the number of slits used in this study was 18. The radius ratio and aspect ratio of the models were 0.825 and 48, respectively. The heating film wrapped around the inner cylinder was used for generating the constant heat flux and we ensured the constant temperature condition at the outer space of the outer cylinder. The velocity fields were measured by using the PIV(particle image velocimetry) method. The refractive index matching method was applied to remove image distortion. The results were compared with plain wall configuration of Taylor-Couette flow. From the results, the presence of slits in the wall of outer cylinder and temperature gradient increased the flow instability.

• 무역학회지
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• 제41권4호
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• pp.91-110
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• 2016

본 연구는 AEO 인증이 기업성과에 긍정적인 영향을 미칠 수 있을 것이며, 이로 인해 우리나라 기업이 국제경쟁력을 갖추기 위한 방안을 제시하기 위해 AEO 인증이 기업성과에 미치는 영향을 패널데이터를 이용하여 분석하였다. 변수간 내생성의 문제를 해결하는데 효율적인 Hausman-Taylor 추정법을 사용하여 AEO 인증이 기업성과에 미치는 영향을 분석한 결과, AEO 인증은 기업성과를 대표하는 주요 변수인 기업의 국내 매출액과 해외 매출액에 긍정적인 영향을 미치며, 특히 AEO 인증의 직접적인 혜택과 업무 프로세스 개선은 수출입 물류흐름을 향상시켜 매출액 증대에 긍정적인 영향을 미치는 것으로 나타났다. 결론적으로 본 연구는 AEO 인증이 기업성과에 미치는 영향을 보다 효율적인 패널데이터를 이용하여 분석함으로써 우리나라의 AEO 인증 정책에 대한 해법을 제시하였다.

• 공업화학
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• 제26권1호
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• pp.67-73
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• 2015

전산유체해석 기법을 이용하여, 테일러 반응기 내 유동특성과 입자의 체류시간에 대하여 연구하였다. 테일러 반응기는 반응기의 작동조건에 따라 내부 유동특성이 달라지므로, 입구주입속도와 반응기 회전속도 변화에 따른 테일러 반응기 내부의 유동특성 변화를 살펴보았다. 또한 테일러 와류(TVF)영역에서 리튬이온전지의 양극물질인 NMC입자의 반응기 내 체류시간을 측정하였다. 입구에서의 복잡한 화학반응은 고려하지 않았고 테일러 유동의 영향만 고찰하였다. 해석결과 반응기의 회전속도가 높고 반응물의 주입속도가 낮을수록 입자의 체류시간이 길어지는 것을 확인하였다.

• 대한기계학회논문집B
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• 제33권11호
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• pp.900-908
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• 2009

Numerical simulation has been carried out to investigate the influence of radial temperature gradient on the Taylor Vortex flow. Varying the Grashof number, we study the detailed flow and temperature fields. The current numerical results show good agreement with the experimental results currently available. It turns out that wavy spiral vortices are generated by increasing temperature gradient. We classify flow patterns for various Grashof numbers based on the characteristics of flow fields and spiral vortices. The correlation between Grashof number with wave number shows that the spiral angle and size of Taylor vortices increase with increasing temperature gradient. Temperature gradient does not have a great influence on the heat transfer rate of the cylinder surfaces.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.209-214
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• 2003

The Saffman-Taylor instability mechanisms in laminar premixed flames in a Hele-Shaw cell are investigated using two-dimensional numerical simulations with Poiseuille assumption for the viscous effect. The baseline calculations considering the Darrieus-Landau and diffusive-thermal instability modes show the results consistent with the classical linear instability theory. With the Saffrnan-Taylor instability mechanism. the overall effect is to enhance the destabilizing mechanism by providing an increased viscous force in the product gas. The linear instability behavior is found to qualitatively similar to the Darrieus-Landau mechanism. However, the results in the nonlinear range demonstrate that there may exist distinct characteristic time scales associated with Darrieus-Landau and Saffman-Taylor mechanisms, such that the latter effect sustains longer in time, contributing to a higher overall flame speed.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.123-127
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• 2007

The effect of axial slit wall of outer cylinder on Taylor-Couette flow was experimentally investigated. The axial slits were azimuthally located along the inner wall of outer cylinder and the number of slits was 6, 9 and 18. The radius ratio and aspect ratio of the experimental models was 0.825 and 48, respectively. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the effect of slit on the flow transition is increased as the number of slit increased. When the model has 6 slits, there were hardly the effect of axial slit wall and the flow transition happened at the same Reynolds number of plain smooth wall model case.

• 대한기계학회논문집B
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• 제30권7호
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• pp.630-637
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• 2006

The flow regimes for a Taylor-Couette flow with a stable, axial stratification in density are investigated using numerical simulation. The flow configuration identical to that in the experiment of Boubnov, et al. (1995) is considered in the present research. The main objectives of this investigation are to verify the experimental and numerical results carried out by Boubnov, et al. and Hua et al. (1997), respectively, and to further study the detailed flow fields and flow bifurcations. With increasing buoyancy frequency of the fluid (N), the stratification-dominated flow regime, called the S-regime, is observed. It is also confirmed that the important effect of an axial density stratification is to stabilize the flow field. The present numerical results are in good agreement with Boubnov, et al. and Hua et al.'s observations.