• 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.

• International Journal of Fluid Machinery and Systems
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• 제5권2호
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• pp.60-64
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• 2012

The helical flow regime was investigated by using DPIV when the rotating Reynolds number is small. The wall slits were azimuthally located along the inner wall of outer cylinder and the slits number of each model was 9 and 18, another plain wall model was also studied for comparison purpose. The helical vortex flow regime can be observed in all the three models. The negative temperature gradients determine the direction of the rotation and movement of the helical vortex. But the helical wavy vortex flow can only be found in the plane and 9-slit models. And the result showed that the existence of slit wall accelerated the transition process.

• 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.

• 설비공학논문집
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• 제26권7호
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• pp.301-307
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• 2014

This paper presents a numerical study on the constrained melting of a phase change material inside various capsule containers, using water and HDPE (High Density Polyethylene) as a PCM and a capsule material, respectively. The computations are based on an iterative, finite-volume numerical procedure that incorporates a single-domain enthalpy formulation for simulation of the phase change phenomenon. Using the enthalpy method, various capsule configurations, such as a capsule from E company, an isochoric cylinder capsule, an equivalent diameter sphere capsule, and an isochoric sphere capsule, are used to investigate the effect of capsule configurations on the charging and discharging performance. A transient three-dimensional model is used for each case. The simulation results show that the capsule from E company results in a higher melting and solidification rate of the PCM, than the other capsule configurations considered in this research.