• Title, Summary, Keyword: 체적비

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A CFD Analysis on the Gas-Liquid Ejector (가스-액체 이젝터에 대한 CFD 해석)

  • Jeong, H.M.;Utomo, Tony;Jin, Z.H.;Chung, H.S.
    • Journal of the Korea Society For Power System Engineering
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    • v.12 no.1
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    • pp.28-34
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    • 2008
  • 가스-액체 이젝터에 관한 수치해석은 3차원 CFD 모델로 수행하였다. 본 논문에서는 이젝터의 유동특성과 질량전달특성에 대한 작동조건과 이젝터의 기하학적 모형의 영향에 관한 연구를 수행하고자 한다. CFD 결과 실험 데이터에 의하여 검증되었으며, 유동 분석과 이젝터 성능의 예측 또한 실행되었다. 작동상태의 변화는 0.2 $\sim$ 1.2 범위에서 가스-액체 유량비를 변화시킴으로서 주어진다. 혼합관의 $L_M/D_M$이 4 $\sim$ 10의 범위에서 변화를 주었다. CFD 연구는 길이와 직경비가 5.5일 때 체적 유량전달계수는 가스 유량이 증가함에 따라 증가한다는 것을 나타낸다. 동시에 $L_M/D_M$가 4일 때 체적유량전달계수는 기체-액체 유량비가 0.6에서 최대치에 도달한다. 또한, 체적 유량전달계수는 혼합 튜브길이가 증가함에 따라 감소한다.

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Volume Integral Equation Method for Multiple Anisotropic Inclusion Problems in an Infinite Solid under Uniaxial Tension (인장 하중을 받는 무한 고체에 포함된 다수의 이방성 함유체 문제 해석을 위한 체적 적분방정식법)

  • Lee, Jung-Ki
    • Composites Research
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    • v.23 no.4
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    • pp.7-13
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    • 2010
  • A volume integral equation method (VIEM) is introduced for the solution of elastostatic problems in an unbounded isotropic elastic solids containing interacting multiple anisotropic inclusions subject to remote uniaxial tension. The method is applied to two-dimensional problems involving long parallel cylindrical inclusions. A detailed analysis of stress field at the interface between the matrix and the central inclusion is carried out for square and hexagonal packing of the inclusions. Effects of the number of anisotropic inclusions and various fiber volume fractions on the stress field at the interface between the matrix and the central inclusion are also investigated in detail. The accuracy of the method is validated by solving the single inclusion problem for which solutions are available in the literature.

Pseudo-Ductile Hybrid FRP Sheet for Strengthening Reinforced Concrete Beams (유사연성 하이브리드 FRP 시트를 이용한 RC 보의 휨 보강)

  • Ha, Sang-Su;Choi, Dong-Uk;Lee, Chin-Yong;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.20 no.2
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    • pp.239-247
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    • 2008
  • Use of both carbon fiber (CF) and glass fiber (GF) at the same time to strengthen existing flexural members was exploited. Using a proper volumetric GF / CF ratio, the CF can rupture first followed by subsequent rupture of GF at higher stress and strain showing a pseudo-ductile behavior. A theoretical study indicated that the ratio is 4.62 : 1 and higher where the pseudoductile effect can be shown. Flexural tests of plain concrete beams strengthened using fibers were first carried out. Hybrid FRP sheet using 8.8 : 1 ratio was then fabricated and the sheet was used to strengthen reinforced concrete beams. The RC beams strengthened using 1-ply and 2-ply hybrid sheets both revealed increased strength over a non-strengthened beam and ductile flexural behavior. A comparable beam strengthened using CF also showed increased strength but with limited ductility.

Evaluation of Permeability and Related Soil Characteristics Based on Pore Pressure Measurement during Consolidation by Radial Drainage (방사배수 압밀 중 위치별 간극수압 측정을 통한 투수계수와 관련물성치의 결정방법)

  • Yune, Chan-Young;Chun, Sung-Ho;Chung, Choog-Ki;Lee, Won-Tekg
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.1C
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    • pp.9-17
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    • 2008
  • In this research, an analytical solution for the coefficient of permeability of soils during consolidation is suggested. The pore pressure and the flow rate measurements at different locations during consolidation are utilized. The void ratio and volume compressibility of soils under consolidation are also estimated. A large consolidation testing device, possible in both vertical and radial drainage is designed and manufactured. And consolidation test with kaolinite soils were performed under radially inward drainage direction. Pore pressures in varying radial distances and flow rate with time were measured as well as vertical deformations. From the test results, the changes of permeability, volume compressibility and void ratio under consolidation and their spatial variations are estimated. Thus the proposed solution is verified by comparing with the experimentally estimated test results. In addition, it is confirmed that permeability, void ratio and volume compressibility decrease as consolidation and loading steps progress. Also, these soil characteristics increase with radial distant from drainage boundary, where lowest values observed, and slightly decrease as approaching undrained boundary.

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Study on Rainfall infiltration Characteristics for Weathered Soils: Analysis of Soil Volumetric Water Content and Its Application (국내 풍화토의 강우 침투특성 분석을 위한 실험연구: 토양 체적함수비 분석 및 적용성 평가)

  • Kim, Man-Il;Chae, Byung-Gon;Cho, Yong-Chan;Seo, Yong-Seok
    • The Journal of Engineering Geology
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    • v.18 no.1
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    • pp.83-92
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    • 2008
  • In order to analyze infiltration characteristics of rainfall in soil, two laboratory experiments were conducted using an amplitude domain reflectometry (ADR) sensor and a pore water pressure meter (PWP) in this study. The first experiment is to understand the dependency of volumetric water content and temperature for standard sand and weathered granite soil. The second experiment is a laboratory flume test with changes of rainfall condition. As the results of the dependency experiment, the volumetric water content is increased with increase of the output voltage measured by the ADR sensor in both the standard sands and weathered granite soil. Furthermore, the results also indicate necessity of consideration of the temperature dependency under the condition of high volumetric water contents from 0.15 to 0.45. In the flume test, two measurement devices are detected to the variation of volumetric water content and pore water pressure at the installation point of the flume. In especial, the measured values of ADR4 and PWP3 installed on the lower part of slope are higher than those of the others. It means that the lower part of slope plays a role of a runoff face and a beginning point of slope failure.

The Volume Monitoring System of a Landfill Facility Using Stereo Camera Measurement (스테레오 카메라 측정을 이용한 매립장 체적 감시 시스템)

  • Cho, Sung-Yun;Lee, Young-Dae
    • Proceedings of the Korean Society of Computer Information Conference
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    • pp.5-8
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    • 2013
  • 이 논문에서는 쓰레기 매립의 표준화 및 고도화를 위한 일환으로 쓰레기 체적을 주기적으로 계산하는 알고리즘을 제시하였다. 카메라 캘리브레이션 이후에 대상체의 표면에 대한 포인트 클라우드(point cloud) 데이타를 얻을 수 있었으며 이것을 제시된 체적 계산 알고리즘의 입력이 된다. 균일(uniform) 및 비균일 삼각 격자 기반 메싱(non-uniform triangular meshing) 방법에 기초한 두 개의 체적 계산 알고리즘을 제안하였으며 알고리즘의 타당성을 시뮬레이션과 실제 현장 실험을 통해 입증하였다.

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Prediction of Elastic Constants and Attenuation Coefficients by the Analysis of Elastic Wave Propagation in Composite Material. (복합재료내의 탄성파 전파의 해석에 의한 탄성계수와 감쇠계수의 예측)

  • 김진연
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.96-99
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    • 1992
  • 섬유강화 복합재료의 동탄성계수와 감쇠특성을 규명하기 위하여 랜덤하게 분포된 무한 실린더 형상의 산란체를 가진 매질내에서, 조화운동을 하는 압축 및 SV탄성파의 전파에 관하여 연구하였다. 단일 실린더에 대한 산란계수로부터 La의 준결정근사법을 이용하여 다중산란에 관한 이론을 유도하였고, 매질내에서의 파동전파 특성을 내포하는 분산관계식을 얻었다. 수치적으로 분산관계식의 해를 구함으로써 2 차원 유효체적강성, 횡방향 유효전단강성 및 각 파동의 전파에 따른 감쇠계수를 주파수와 체적비의 함수로서 제시하였다.

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A Study on Combustion Characteristics of Fire Retardant Treated Pinus Densiflora and Pinus Koraiensis (난연처리된 육송과 잣나무의 연소특성 평가연구)

  • Choi, Jung-Min
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • pp.367-370
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    • 2011
  • 본 연구에서는 육송과 잣나무에 대한 연소특성을 비교 연구하였다. 두 수종은 한옥의 부재로 널리 사용되고 있으며, 그 체적밀도는 육송이 잣나무에 비하여 상대적으로 큰 값을 가지고 있다. 목재의 연소특성은 해당 수종의 체적밀도와 밀접한 관계를 갖고 있는데 본 연구에서 방염성능에 있어서는 뚜렷한 차이를 확인하기는 어려웠지만 콘칼로리미터 시험방법에 있어서는 총 방출열량, 평균 열방출률, 평균 질량손실률, 총 산소 소요량 비교를 통하여 목재 수종의 체적밀도의 상관성을 확인하였다.

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Measurements of Permeability Characteristics for Unsaturated Weathered Soils (불포화 풍화토의 투수특성 측정)

  • Ryu, Ji-Hyeop
    • Journal of Korea Water Resources Association
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    • v.33 no.1
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    • pp.133-142
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    • 2000
  • Series of tests were carried out to study permeability characteristics of unsaturated soils. The weathered soils taken from Inju, Sungwhan, and Kuri, were selected to have different amount of fine grained soils in order to find a possible correlation between the unsaturated permeability behavior and fine grained soils contents. Measurements of permeability for unsaturated soils were performed with a newly developed apparatus, which modeled after Klute's apparatus(1965a). The apparatus was designed to measure volumetric water content and permeability by applying incremental suction pressure. Permeability and volumetric water content of unsaturated soils generally decreased as density of the soil increased. The relationship between volumetric water content and permeability was not related to the fine grained soils contents because the plots scattered widely. By comparing volumetric water content with permeability, empirical parameters A and B could be determined, which made to be possible to predict unsaturated permeability from soil-moisture characteristics.

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Numerical Simulation of Surface Tension-Dominant Multiphase Flows by Using Volume-Capturing Method and Unstructured Grid System (비정렬격자계와 체적포착법을 사용한 표면장력이 지배적인 다상유동 수치해석)

  • Myong, Hyon-Kook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.7
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    • pp.723-733
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    • 2011
  • A numerical method of the CSF(Continuum Surface Force) model is presented for the calculation of the surface tension force and implemented in an in-house solution code(PowerCFD). The present method(code) employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with volume capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The application of the present method to a 2-D liquid drop problem is illustrated by an equilibrium and nonequilibrium oscillating drop calculation. It is found that the present method simulates efficiently and accurately surface tension-dominant multiphase flows.