• Title/Summary/Keyword: Dimensional characteristics

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FLOW CHARACTERISTICS AROUND A RUDDER IN OPEN LATER CONDITION (단독 타 주위의 유동 특성에 대한 연구)

  • Choi, J.E.;Kim, J.H.
    • Journal of computational fluids engineering
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    • v.13 no.1
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    • pp.14-20
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    • 2008
  • The flow characteristics around a rudder in open water condition is analyzed by the computational method. Reynolds averaged Navier-Stoke's equation is utilized for the computation. The computational hydrodynamic force coefficients are verified through comparing with the experimental results. The information of these flow characteristics is necessary to predict cavitation and maneuvering performances, to estimate steering gear capacitance, and to get the bending moment which is useful for the structural analysis. The pressure distribution, the three-dimensional flow separation, and the tip vortices are investigated. The pattern of the three-dimensional flow separation is analyzed utilizing a topological rule. The tip vortices are also investigated through a visualization technique.

Importance of the Settling Velocity on the Suspended Solids Diffusion in Osaka Bay (오사카만에서 부유토사의 확산특성에 대한 침강속도의 중요성)

  • 김종인
    • Journal of Ocean Engineering and Technology
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    • v.16 no.5
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    • pp.41-48
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    • 2002
  • Numerical experiments are conducted using a three-dimensional baroclinic equation model and a Lagrangian method for clarifying the effect of th settling velocity on the suspended solids diffusion caused by the dredging and the reclamination works. Diffusion characteristics of the neutral particles and the weighting particles is experimented by the Lagrangian particles trajectory model, The results show that the diffusion characteristics of the suspended solids is effected by the settling velocity classified by the particles size in the density layered semi-closed bay. To estimate exactly the diffusion characteristics of the suspended solids and the contaminant with weight the three-dimensional baroclinic equation model and the three-dimensional Lagrangian particles trajectory model considering the settling velocity of the particle in the density layered semi-closed bay must be used.

Investigation of Reducing Characteristics for the Spreading of Dredging Soil and the Diffusion of Contaminant by Silt Protector Curtain through Three Dimensional Numerical Model Experiment (3차원 수치모형실험을 통한 오탁방지막의 오염물질 및 준설토 확산 저감특성 조사)

  • Hong, Nam-Seeg
    • Journal of Ocean Engineering and Technology
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    • v.24 no.4
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    • pp.78-85
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    • 2010
  • This study investigates reducing characteristics for the spreading of dredged soil and the diffusion of contaminant by silt protector curtain through three dimensional numerical experiment. The numerical medel is modified by combining the sediment transport characteristics for cohesive sediment into the previously developed model. Several numerical experiments have been given in order to investigate the reducing effect of silt protector using two dimensional numerical channel model under various parameters such as upstream flow velocity, depth of silt curtain and the position of dumped materials. Through the evaluation of several simulation results, we knew that the careful design has to be given in the determination of depth and position of silt protector.

Characteristics of Propagating Tribrachial Flames in Counterflow (대향류 유동장에서 삼지 화염 전파 특성에 관한 연구)

  • Chung, Tae-Man;Ko, Young-Sung;Chung, Suk-Ho
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.422-427
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    • 2000
  • Propagation characteristics of tribrachial flames have been investigated experimentally in both two-dimensional and axisymmetric counterflows. Mixture fraction gradient at stoichiometric location is controlled by varying equivalence ratios at the two nozzles, one of which maintains rich while the other lean premixture. Tribrachial flames propagating through these mixtures are investigated. The propagation speed of tribrachial flames in two-dimensional counterflow decreases with fuel concentration gradient and has much higher speed than the maximum speed predicted previously in two-dimensional mixing layers. From an analogy with premixed flame propagation, this excessively large propagation speed can be attributed to the tribrachial flame propagating with respect to burnt gas. Corresponding maximum speed in the limit of small mixture fraction gradient is estimated and extrapolated experimental results substantiate this limiting speed. As mixture fraction gradient approaches zero, a transition in propagation characteristics occurs, such that the propagation speed of tribrachial flame approaches stoichiometric laminar burning velocity with respect to burnt gas. Similar behavior has been obtained for tribrachial flames propagating in axisymmetric counterflow.

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A Numerical Analysis of Flow and Beat Transfer Characteristics of a Two-Dimensional Multi-Impingement Jet(II) (이차원 다중젯트의 유동 및 열전달 특성의 수치적 해석(II) -돌출열원이 있는 경우의 유동 및 열전달 특성-)

  • 장대철;이기명
    • Journal of Biosystems Engineering
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    • v.20 no.1
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    • pp.66-72
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    • 1995
  • A numerical study for a two dimensional multi-impingement jet with crossflow of the spent fluid has been carried out. To study the flow characteristics especially in the jet flow region, three different distributions of mass flow rate at 5-jet exits were assumed. For each distribution, various Reynolds numbers ranging from laminar to turbulent flows were considered. Calculations drew the following items as conclusion. 1) A periodical fully developed flow was observed from the third protrusion. This was also observed from previous experimentally by Whidden at al. The Nessult number at the protrusion surface increased mildly as going downstream. 2) The low Reynolds number turbulence model of Launder and Sharma was found to be adequate for the prediction of fluid flow and heat transfer characteristics of two dimensional multi-jet configuration. 3) The Nusselt number at the protrusion surface was nearly proportional to the square root of the Reynolds number.

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Characteristic Analysis of High Speed Coaxial Magnetic Gear by Two-Dimensional Finite Element Analysis (2차원 유한요소 해석을 이용한 고속용 마그네틱 기어의 형상에 따른 특성 해석)

  • Lee, Jeong-In;Shin, Kyung-Hun;Bang, Tae-Kyoung;Lee, Sang-Hwa;Choi, Jang-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.68 no.1
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    • pp.36-43
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    • 2019
  • In this paper, the characteristics of the coaxial magnetic gear according to the shape of the same gear ratio are analyzed using the two - dimensional finite element analysis. The rotor shape is SMCMG, CPCMG and RCMG. After this we analyzed the characteristics according to three shapes. Also, the amount of permanent magnet used in each shape was compared. Next, characteristics analysis of the magnetic gear according to the shape at the same torque was performed. And the total weight and efficiency of the magnetic gears were compared and verified.

In-plane Natural Vibration Analysis of a Circular Plate by Using finite Element Method (유한요소법을 이용한 원형 평판의 면내 고유진동 해석)

  • Kim, Chang-Boo;Kwak, Dong-Hee
    • Proceedings of the KSR Conference
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    • 2009.05a
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    • pp.1083-1087
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    • 2009
  • We present an 1-dimensional annular disk element with which natural vibration of a circular plate can be analyzed accurately and facilely. The natural vibration characteristics of a circular plate with free outer boundary are analyzed by using the presented I-dimensional element. Its results are compared with the results obtained by utilizing 2-dimensional 8-node quadrilateral plane element and cyclic symmetry of the circular plate. And also, by comparing with the theoretical results of previous researchers, the accuracy and facility of the presented I-dimensional element are verified.

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Multi-dimensional Development Type and Plan for Railway Facility Site - Focus on the Gyeongbu Line Railway Multi-Dimensional Project in Busan (철도시설 부지 입체개발 유형 및 개발 방안 - 경부선 철도 입체화 사업을 대상으로 -)

  • Keum, Yun Jeon ;Kim, Jong Gu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.43 no.4
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    • pp.525-533
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    • 2023
  • Due to the topographical characteristics of Busan, which has many mountainous areas, there is a shortage of available land, and even the Gyeongbu Line railroad crosses the city center, hindering the disconnection of living areas and urban development. Accordingly, the need for multi-dimensional development has been raised to secure land, and recently, interest has been increasing in connecting cities divided by the undergroundization of the Gyeongbu Line railway and making efficient use of land. In this study, the development type was analyzed through the case of multi-dimensional development of land, and the development direction for each three-dimensional development type was set based on the results of the multi-dimensional development of four areas (Sasang Station, Gupo Station, Gaya Station, and Busanjin Station). In addition, reflecting the regional characteristics of the target area and the ongoing urban regeneration project, we will propose a design plan for horizontal and vertical space utilization of the railway site through multi-dimensional development through the efficient land use.

A Study on the Three Dimensional Statistical Turbulent Flow Characteristics Around a Small-Sized Axial Fan for Refrigerator (냉장고용 소형 축류홴의 통계학적 3차원 난류유동 특성에 관한 연구)

  • Kim, Jang-Gwon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.6
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    • pp.819-828
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    • 2001
  • The operating point of a small-sized axial fan is strongly dependent upon the system resistance. Therefore, the turbulent flow characteristics around a small-sized axial fan may change significantly according to the operating point. This study represents three-dimensional turbulent flow characteristics around a small-sized axial fan measured at the ideal design point $\phi$=0.25, which is equivalent to the maximum total efficiency point, by using three dimensional fiber-optic type LDA system. This LDA system is composed of a 5 W Argon-ion laser, two optics in back-scatter mode, three BSAs, a PC, and a three-dimensional automatic traversing system. A kind of paraffin fluid is used to supply particles by means of fog generator. Mean velocity profiles downstream of a small-sized axial fan along the radial distance show that the streamwise and the tangential components exist in a predominant manner, while the radial component has a small scale distribution and shows the inflection which its flow direction is inward or outward. Moreover, the turbulent intensity profiles show that the radial component exists the most greatly among turbulent energies.

A Study on Noise Identification of Compressor Based on Two Dimensional Complex Sound Intensity (Two Dimensional Complex Sound Intensity를 이용한 압축기 소음원 규명에 관한 연구)

  • 안병하;김영수
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.1
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    • pp.83-92
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    • 2000
  • Sound intensity method is well known as a visualization technique of sound field or sound propagation in noise control. Sound intensity or energy flux is a vector quantity which describes the amount and the direction of net flow of acoustic energy at a given position. Especially two dimensional sound intensity method is very useful in evaluating periodic characteristics and acoustic propagation mode of noise source. In this paper, we have studied the noise source Identification, acoustic sound field analysis, and characteristics of noise source of rotary compressor and scroll compressor for air conditioner using complex sound intensity method. Also we proposed a now method of time domain analysis which is used in evaluating of position of noise source in rotary and scroll compressor in this paper This paper presents the advantage, simplicity and economical efficiency of this method by analysing the characteristics of noise source with two dimensional complex sound intensity simultaneously.

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