• Title/Summary/Keyword: CFD 유동해석

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Numerical Analysis of Fluid Flow and Filtering Efficiency in Centrifugal Oil Filter (원심 오일필터 유동 해석을 통한 필터링 효율 분석)

  • Bang, Kwang-Hyun;Kim, Kyung-Kyu;Song, Young-A;Kim, Pyung-Su
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.6
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    • pp.867-872
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    • 2009
  • In centrifugal oil filters particles are forced to move toward the filter casing wall by centrifugal force in the rotating oil flow and the particles are trapped and removed on the filter paper installed at the wall. In the present study, flow field of oil and particle motion in a centrifugal oil filter has been numerically calculated in order to estimate the filtering efficiency for various operating conditions. Fluent code was used for the numerical calculations. Uncoupling the oil flow and the particle motion and the use of particle tracking trajectory enabled the estimation of filtering efficiency for various particle sizes, particle density and the filter rotational speed. Higher filtering efficiency was observed for heavier and larger particles as well as higher filter rotational speed. For the typical case of the particle density of 6000kg/m3 and the particle size of 10μm at 3500 RPM, the calculated filtering efficiency per passage was 0.31.

A Numerical Analysis on the Outside Pressure Distribution by Outdoor Wind Effect in a High-rise Residential Building (수치해석을 이용한 초고층 주거건물에서 외풍영향에 의한 외벽 압력 분포 분석)

  • Kim, Chi-Wan;Yang, Soon-Chang;Ahn, Young-Chull
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.10
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    • pp.639-645
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    • 2011
  • The object of this study is to analyze and evaluate outdoor wind pressure effect in a high-rise residential building when seasonal wind blow on coast area. The target building consists of 3 tower buildings over 250m in height. For the evaluation of the outdoor wind effect, CFD simulation was performed. The results of the simulations are as follows : 1) In that case of high-rise building, horizontal stream is more affected than vertical stream. 2) In case of summer season northeasterly wind, building pressure distributions are unstable and surface pressures of outside are effected respectively. 3) In case of winter season westerly wind, building preassure differentiations are not so much because of screening effects of the B, and the C buildings. 4) In case of winter season northwesterly wind, front wind affects on the A building directly because of no obstacles.

A Numerical Study on Passenger Evacuation in a Subway Station in Case of Fire Occurrence (화재 발생 지하철 역사에서의 여객 대피 해석에 관한 연구)

  • Kim, Chi-Gyeom;Lee, Sung-Won;Hur, Nahm-Keon;Nam, Seong-Won
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.8
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    • pp.509-514
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    • 2010
  • A numerical simulation of passenger evacuation in a subway station was performed by coupling the passenger flow analysis and the fire simulation. The algorithm of the passenger flow analysis was based on a DEM (Discrete Element Method) using the potential map of the direction vector for each passenger. This algorithm was improved in the present study as to use finer grid smaller than a passenger in order to resolve detailed geometry of the station and to resolve the behavior of passengers in the bottleneck at the ticket gate considering the collision of passengers to a wall or with other passengers. In the fire simulation, the CO distribution predicted by using CFD was used to take into account the effect of toxic gases on the passengers' mobility. The methodology proposed in the present study could be used in designing safer subway station in case of fire occurrence.

An Investigation into the Three-dimensional Design of Turbine Rotor Blade for Turbopump (터보펌프용 터빈 로터 블레이드의 3차원 설계 연구)

  • Jeong, Sooin;Choi, Byoungik;Lee, Hanggi;Kim, Kuisoon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.1038-1044
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    • 2017
  • We are working on improving the performance by applying the three-dimensional design element to the rotor blades of high pressure supersonic impulse turbine that drives turbo pump of liquid rocket engine. In this paper, based on the shape of a rotor blade of a turbopump turbine designed in the past, a three-dimensional shape is applied to a rotor blade through a stacking line change such as sweep and dihedral. After performing the flow analysis, the changes in the turbine performance characteristics for each design element were carefully examined and the results were summarized.

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A Numerical Analysis on the Indoor Air Ventilation by Stack Effect and Outdoor Wind in a High-rise Residential Building (초고층 주거건물에서 굴뚝효과와 외풍영향에 인한 실내 환기 기류해석 및 평가에 관한 연구)

  • Kim, Chi-Wan;Lim, Tae-Kun;Ahn, Young-Chull
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.12
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    • pp.828-835
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    • 2011
  • The purpose of this study is to analyze and evaluate the 3 types of indoor ventilation methods such as natural, mechanical, and hybrid ventilation in high-rise building which is affected by stack effect and outdoor air pressure. For the evaluation of the ventilation capacity, CFD simulation was performed in a typical high-rise residential building. The results of the simulations are as follows: 1) Natural ventilation method is not enough to the regulation. 2) In case of mechanical ventilation, congested area is occurred but meets the regulation. 3) In case of hybrid ventilation with stack effect, all the areas of indoor meet the regulation and congested area is reduced. 4) In case of high-rise building, the differences of ventilation rate among houses in the building are not large because the mechanical ventilation is main factor.

A Study on Internal Flow Characteristics of T Branch using CFD Analysis (대구경 고압 T형 분기관의 지관 형상에 따른 내부 유동 영향성 해석)

  • JO, CHUL HEE;KIM, MYEONG JOO;CHO, SEOK JIN;HWANG, SU JIN
    • Journal of Hydrogen and New Energy
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    • v.26 no.5
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    • pp.438-444
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    • 2015
  • This study describes the effect of T branch shape on internal flow characteristics inside itself. Continuity and three-dimensional Reynolds-averaged Navier-Stokes equation have been used as governing equations for the numerical analysis. The T branch was modeled assuming that it is used for Alaska pipeline project which was planned to provide reliable transportation of natural gas from ANS to Alaska-Yukon border. Therefore the characteristics of T branch and operating condition of pipeline were from report of Alaska pipeline project. The nine T branch shapes were analyzed and the mass flow rate ratio between mainline and branch was assumed to be 0.95 : 0.05, 0.9 : 0.1, 0.85 : 0.15. The results shows that there are typical flow patterns in T branch and the shape of T branch makes some differences to the internal flow of branch rather than mainline.

Numerical Analysis of Flow Characteristics in Swirl Chamber Type Diesel Engine (연락공 형상에 따른 와류실식 디젤기관의 유동 특성 수치해석)

  • Kwon Taeyun;Choi Gyeungho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.4
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    • pp.49-57
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    • 2005
  • In this study, in-cylinder flow of the swirl chamber type diesel engine numerically simulated by VECTIS code. The flow fields during the intake and compression process were also investigated in detail. Numerical results revealed that the generation and distortion of the swirling, tumbling vortices and those influences on turbulence kinetic energy by shape of the jet passage, angle and area. It was also found that flow characteristics were affected by inflow velocity that depends on change of the jet passage shape. Swirl ratio was increased according to decrease of jet passage area, and was affected by piston motion according to increase of jet passage angle. Tumbling vortices had the similar in various cases, but tumble ratio was increased with the inflow velocity. The generation of turbulence kinetic energy was considerably influenced by complex effects of swirling and tumbling vortices.

Flow/Heat Transfer Analysis and Shape Optimization of a Heat Exchanger with Internally Finned Tube (내부휜이 부착된 원형관 열교환기의 열/유동 해석 및 최적설계)

  • Lee Juhee;Lee Sanghwan;Lim Hyo-Jae;Park Kyoungwoo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.4 s.235
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    • pp.460-468
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    • 2005
  • Analyses of flow and heat transfer characteristics and shape optimization of internally finned circular tubes have been performed for three-dimensional periodically fully developed turbulent flow and heat transfer. CFD and mathematical optimization are coupled in order to optimize the shape of heat exchanger. The design variables such as fin widths (d1,d2) and fin height (h) are numerically optimized by minimizing the pressure loss and maximizing the heat transfer rate for limiting conditions of d1=0.2\~1.5mm,d2=0.2\~1.5mm, and h=0.2\~1.5mm. Due to the periodic boundary conditions along main flow direction, the three layers of meshes are considered. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by means of the sequential quadratic programming (SQP) method which is widely used in the constrained nonlinear optimization problem.

The measurement and analysis of Regenerative Pump Noise (재생펌프 소음특성의 측정 및 해석에 관한 연구)

  • Kim, Tae-Hoon;Seo, Young-Soo;Jeong, Weui-Bong;Jeong, Ho-Kyeong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.1067-1071
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    • 2004
  • In this paper, the characteristic of the regenerative pump is reviewed by the measurement and the analysis. The dominant noise sources are harmonic components of the rotating impeller frequency. The acoustic characteristics and the noise source position at the dump are identified. In order to reduce the high-level peak noise, the interior flow of the pump chamber is analyzed by CFD (Computational Fluid Dynamics). Acoustic pressure is calculated with Ffowscs Williams and Hawkings equation. As the result of the analysis new design of the pump chamber is recommended. The recommended pump is compared with original pump by evaluating the RMS value of a interior static pressure and the sound pressure level. The new pump chamber recommended by analysis results is proved by a process of the measurement. The overall SPL of a recommended pump is reduced about 3 dBA.

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A numerical study on the flow characteristics and condensed water inflow in the Venturi tube with T-branch tube (T-분지관이 부착된 벤튜리관의 유동특성과 응축수 유입에 대한 수치해석 연구)

  • Kim, S.I.;Park, S.H.;Hwang, J.G.
    • Journal of the Korean Society of Industry Convergence
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    • v.22 no.2
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    • pp.173-181
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    • 2019
  • This study was carried out numerically to investigate the flow characteristics in the Venturi tube with 90 T-branch tube and the inflow of condensed water into the Venturi tube from the branch tube. In this study, the diameter of the branch tube(1, 2, 3mm) and the neck diameter of the Venturi tube(0.3, 0.9, 1.5mm) were varied. The flow rate of the water at the Venturi tube inlet is 80cc/min and the water temperature is 288K. The condensed water temperature at the branch tube inlet is 355K. It was found that the velocity and pressure of the fluid near the branch point in the Venturi tube were more dependent on the diameter of the Venturi tube than the diameter of the branch tube. The temperature of the mixed water at the exit of the Venturi tube was the highest when the Venturi tube's neck diameter is 0.9mm and the branch tube diameter is 2mm. This means that the condensed water is flowing well through the branch tube.