• Journal of ILASS-Korea
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• v.10 no.4
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• pp.26-31
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• 2005

Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and air. We proved the interaction between vortex pairs and free surface on each condition that is created by the end of delta wings. Another purpose of this study is to investigate the effect of surface active material which call change the surface tension and we must consider when we refer to turbulent flow on surface tension. Therefore, this research examined the growth process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely but the vortex pairs in contaminated free surface and rigid, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid, no slip is stronger than before. and we can find the vortex shape which roll up more completely. However, these will disappear by the effect of wall.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.67-72
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• 2002

Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and air. We proved the interaction between vortex pairs and free surface on each condition that is created by the end of delta wings. another purpose of this study is to investigate the effect of surface active material which can change the surface tension and we must consider when we refer to turbulent flow on surface tension. therefore, this research examined the growth process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely but the vortex pairs in contaminated free surface and rigid, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid, no slip is stronger than before, and we can find the vortex shape which roll up more completely. However, these will disappear by the effect of wall.

• Journal of the Korean Society of Visualization
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• v.3 no.1
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• pp.51-57
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• 2005

Vertices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed fur the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.734-739
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• 2000

Vortices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface is totally different from the clean free surface case.

• Journal of the Korean Society of Visualization
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• v.9 no.3
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• pp.59-64
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• 2011

In this study the change of free surface vortex is expressed through the time volume fraction using multiphase unsteady condition in sump, because in previous studies of the pump sump did not represent the behavior of the free surface vortex exactly due to the reason it was calculated using single phase and steady condition. The reliability of the computational analysis is verified through comparing experimental results with that of present numerical analysis. Homogeneous free surface model is used to apply interactions of air and water. The results show that the free surface vortex can be identified on the isotropic surface at air volume fraction 1%~5%. The vortices make an air column from the free surface to the sump intake and are created and destroyed repeatedly. The behavior of free surface vortex at numerical analysis is quite similar to experimental test. The result of vortex motion according to time, works on a cycle.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.241-246
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• 2001

Vortices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Journal of ILASS-Korea
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• v.6 no.2
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• pp.29-36
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• 2001

Vortices terminating at free surface have been investigated extensively. however. are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LlF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Journal of the Korean Society of Visualization
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• v.9 no.4
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• pp.74-79
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• 2011

In this study the change of free surface vortex is represented at different times according to height of water and with or without curtain wall installation. The air volume fraction is investigated at each condition of water level and the influence about creation of vortex is analyzed. The height of sump intake is taken as 100mm and the water level is divided into 5 steps. The sump model is the TSJ model and the curtain wall is applied by HI standard of America. The results shows that the free surface vortex can be identified on the isotropic surface at air volume fraction 1%~5% and the vortices make an air column from the free surface to the sump intake and are created and destroyed repeatedly. In the higher water level, less air is absorbed into the intake pipe. After curtain wall installation, the suction rate of the air volume fraction is decreased by 6.7%. The result of the vortex motion according to time, works on a cycle.

• The KSFM Journal of Fluid Machinery
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• v.10 no.4
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• pp.39-46
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• 2007

In large pump station, vortex generation such as free-surface vortex and submerged vortex occurring around pump intake, or at bell-mouth inlet has been an important flow characteristics which should be considered always to keep away the suction of air-entrained or cavitated flow. In this study, a commercial CFD code was used to predict accurately the vortex generation for the specified intake design. These result shows the preliminary result of submerged vortex prediction for the Turbo-machinery Society of Japan Sump Test CFD standard model. At bottom wall, air volume fraction (red color) was found in a large scale to explain the submerged vortex generation at particular operation and configuration condition. And these indicate the free surface formation behind the bell mouth. Particularly, non-uniform approaching flow is a major parameter to govern the occurrence of the free-surface vortex. Futhermore the comparison between turbulence ($k-{\epsilon}$ & $k-{\omega}$ model) mode were executed in this study.

• Journal of Wetlands Research
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• v.24 no.3
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• pp.196-203
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• 2022

This paper contributed to the understanding of the effect of the blade relative position on performance of micro gravitational vortex turbine in free water surface. In a constant vortex flow, the rotation, voltage and current of micro vortex water turbine were measured according to the position change of the blade installed at the relative vortex height (y/h_v) ranging from 0 to 0.778 below the free water surface. The flow rate ranged from 0.0063 to 0.00662 m³/s. The results of the experiments showed that relative positions of the blade affected the performance of vortex water turbine because the distributions of incoming flow velocity and turbulence intensity were changed. The highest amount of the energy generated by the vortex water turbine occurred in the relative vortex height ranging from 0.111 to 0.222. The output power at the relative vortex height of 0.111 was about 2.4 times larger than the relative vortex height of 0.588 below the free water surface.