• Title, Summary, Keyword: 축방향 유입

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Flow Analysis in a Rotating Container with Axial Injection and Radial Ejection (축방향 유입과 반경방향 유출이 있는 회전용기 내의 유동해석)

  • Park, Jun-Sang;Sohn, Jin-Gug
    • Journal of the Korean Society of Visualization
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    • v.9 no.1
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    • pp.49-54
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    • 2011
  • An investigation has been made of a viscous incompressible flow in a circular cylindrical tank. The flow is driven by the spinning bottom disk of tank together with/without central injection and radial uniform-ejection through the sidewall. Numerical solutions of steady and unsteady flows to 3-dimensional Navier-Stokes equation were obtained for several cases of injection strength. In a moderate flow rate of injection, the mass transfer occurs through the boundary layers but, as the flow rate increases, the inner region far from the container walls takes part in mass transfer.

Study and Evaluation of Sub Area Linkage Algorithm in COSMOS (COSMOS에서의 Sub Area 운영 알고리즘에 관한 연구 및 평가)

  • Lee, Young-Ihn;Kim, Sang-Yoon
    • Journal of Korean Society of Transportation
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    • v.22 no.2
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    • pp.109-119
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    • 2004
  • In COSMOS, an area for signal coordination is divided into subareas composed of several signalized intersections that share a common cycle time. Each subarea contains only one critical intersection having heavy traffic load. Subarea is a basic unit of control. The performance of COSMOS is highly dependent on the linkage rule between adjacent subareas. The purpose of this study is to provide an appropriate subarea linkage rule in COSMOS. This study developed a control strategy for Critical Intersection and Sub Area linkage. Critical Intersections calculate the Offset Pattern both East-West Axis and North-South Axis, and the coordination direction either East-West Axis or North-South Axis. Subarea can be combined with other one in all directions. The performance of the suggested linkage rule was evaluated on the real network in Gangnam-Gu. The result was that travel time was reduced by the suggested linkage rule.

The Effect of Trailing Wake Asymmetry on a Propeller Blade Forces in Inclined Inflow (비대칭 후류를 고려한 경사축 추진기의 유동해석)

  • Sang-Woo Pyo
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.1
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    • pp.24-31
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    • 1998
  • Unsteady propeller blade forces arising from shaft inclination have been found to be an important contribution tn total blade forces. The position of the wake relative to a blade oscillates with the first blade frequency, thus giving rise to unsteady blade forces which is significant relative to the forces produced directly by flow inclination. In order to find a wake geometry due to shaft inclination, a non-axisymmetric wake model is developed and applied to a specific case, which has experimental values. Predicted cavity shapes and unsteady forces acting on the blades of an inclined shaft propeller are compared to those predicted by other numerical methods, as well as those measured in experiments.

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Experimental Investigation on the Vortical Flows in a Single-Entry Swirl Mixing Chamber (단일공급 스월 혼합챔버 내의 와류유동에 대한 실험적 연구)

  • Kim, Hyung-Min;Yoon, Woong-Sup
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.445-450
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    • 2011
  • Swirling flows inside a swirl mixing chamber are investigated for simple configuration where swirl is produced by a tangential entry type swirl generator. The flow downstream of the swirl generator has been quantified by measurements two velocity components and their corresponding mean values along axial and radial direction using Particle Image Velocimetry(PIV). The mass flow rate of the tangential entry is increased in order to study their effect on the flow field. From the measurement profile of velocity and vorticity, flow mixing characteristics in a swirl mixing chamber are evaluated.

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Model testing of leakage effect due to multi-cell inflater of rapid protection system in subsea tunnel (해저터널 급속차폐시스템의 Inflater 분할구조에 따른 터널 내 차수효율에 대한 실험적 연구)

  • Yoo, Kwang-San;Lee, Ji-Hyun;Kim, Yeon-Deok;Kim, Sang-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.3
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    • pp.295-303
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    • 2015
  • This paper presents the study of leakage effect due to multi-cell inflater of rapid protection system to protect the possibilities of tunnel damages by flooding threats and unusual leakage to be occurred during and after subsea tunnel construction. Particularly, this protect system should be necessary in subsea tunnel. This research concentrates the physical model tests due to several multi-cell inflater to study protection capacity of leakage between the inflater and tunnel liner. A 27:1 small scale model are used in the model tests. The leakage rate, water pressure and axial displacement of inflater are measured during the model tests. According to the results, the minium leakage rate clearly shows in the case of two-cell inflater compared with in other cases. It is concluded that the results of this research will be very useful to understand the fundamental information of inflater structure design and development the technology of tunnel protection structures in the future.

Analysis of Short Circuit Characteristics for 1MVA Power Transformer (1MVA 전력용 변압기의 단락특성 해석)

  • Lee, Byuk-Jin;Ahn, Hyun-Mo;Hahn, Sung-Chin
    • Proceedings of the KIEE Conference
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    • pp.1109-1110
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    • 2011
  • 본 논문에서는 선간단락 시 단락전류에 의한 전력용 변압기의 단락특성을 해석하였다. 변압기 사양은 1[MVA], 6,600/660[V] 단상 내철형 배전용 변압기를 사용하였으며, 변압기에 유입되는 단락전류를 회로방정식을 이용해 계산하였다. 단락전류에 의해 발생되는 누설자속 밀도는 유한요소법을 이용해 계산하였고, 계산된 단락전류와 누설자속 밀도에 의해 권선에서 발생하는 축 방향과 반경방향 단락전자력을 계산하였다.

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Comparison of Aerodynamic Loads for Horizontal Axis Wind Turbine (I): with and without Turbulent Inflow (수평축 풍력터빈의 공력 하중 비교 (I): 난류 유입 유·무)

  • Kim, Jin;Kang, Seung-Hee;Ryu, Ki-Wahn
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.5
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    • pp.391-398
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    • 2016
  • This study focused on the aerodynamic loads of the horizontal axis wind turbine blade due to the normal turbulence inflow condition. Normal turbulence model (NTM) includes the variations of wind speed and direction, and it is characterized by turbulence intensity and standard deviation of flow fluctuation. IEC61400-1 recommends the fatigue analysis for the NTM and the normal wind profile (NWP) conditions. The aerodynamic loads are obtained at the blade hub and the low speed drive shaft for MW class horizontal axis wind turbine which is designed by using aerodynamically optimized procedure. The 6-components of aerodynamic loads are investigated between numerical results and load components analysis. From the calculated results the maximum amplitudes of oscillated thrust and torque for LSS with turbulent inflow condition are about 5~8 times larger than those with no turbulent inflow condition. It turns out that the aerodynamic load analysis with normal turbulence model is essential for structural design of the wind turbine blade.

A Study on Performance Characteristics of Horizontal Axis Tidal Turbine Considering Nose Shape, Angle of Inflow and Tower Structure (수평축 조류발전 터빈의 노즈 형상 및 유입각도, 타워 구조물의 영향을 고려한 터빈 성능특성 분석)

  • Heo, Man-Woong;Kim, Dong-Hwan;Yi, Jin-Hak
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.1
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    • pp.17-25
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    • 2020
  • In this study, three-dimensional fluid flow analyses have been performed in order to investigate the performance characteristics of a horizontal axis tidal turbine (HATT) by solving three-dimensional Reynolds-averaged Navier-Stokes equations utilizing the shear-stress-transport turbulence model. The computational domain for the flow analysis has been composed of hexahedral grids, and the grid dependency test has been carried out so as to determine the optimum grid size. Performance characteristics of the HATT have been investigated in consideration of the effects of hub nose geometry, inflow angle, and the tower. It has been found that the power output can be enhanced along with an increase of the ratio of the length to the diameter of the turbine nose, and the power of HATT has been reduced by approximately 10% when the primary fluid flow had an inflow angle of 15°. The power output of downstream HATT is found to be lower than that of the upstream HATT by about 1%.

Flow Analysis of the Plain Seal with Injection (분사를 수반하는 평씨일 내의 유동해석)

  • 이관수;김우승;김기연;김창호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.4
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    • pp.795-802
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    • 1992
  • A numerical analysis is performed on the turbulent flow in the plain seal with injection. The parameters used in this study are as follows : Reynolds number, rotation speed, injection speed, clearance ratio, injection angle, and axial injection location. Flow pattern and leakage performance due to the variation of parameters are investigated. SIMPLER algorithm is used to solve the Navier-Stokes equation governing steady, incompressible turbulent flow and standard K- .epsilon. turbulent model is used to consider the turbulence effects. The leakage performance is significantly enhanced with injection. The increases of the injection flow rate and be rotation speed of the shaft cause the leakage performance to the increased. With the increase of the Reynolds number the leakage performance is diminished. At the injection angle of 90deg, the leakage coefficient has a minimum value. The pressure drop has a maximum value at axial center location but the injection location has little effect on the pressure drop. Clearance ratio has a significant effect on the pressure drop.

The development of LVI tester for application of transformers winding deformation diagnosis (변압기 권선변형 진단에 적용하기 위한 LVI 시험기 개발)

  • 조국희;김광화
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.5
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    • pp.97-103
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    • 2002
  • The assessment of the condition of a transformer winding which is suspected of having suffered short circuit damage can be difficult. Conventional test such as winding resistance, magnetic current or insulation resistance will only detect damage if a permanent electrical fault exists. Visual inspection of windings necessitates the removal of oil and in many cases only a very small proportion of the winding can be seen. We describe the characteristic of LVI test system and methods to detect the deformation of windings in the power transformers. As the front rise time of recurrent-surge generator pulse less than 1000 ㎱ and the peak value of pulse is about 500 V, we have the good results of detecting winding deformation in the LVI test of transformers.