• Title/Summary/Keyword: flow separation

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Two-Phase Flow Distribution and Phase Separation Through Both Horizontal and Vertical Branches

  • Tae, Sang-Jin;Keumnam Cho
    • Journal of Mechanical Science and Technology
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    • v.17 no.8
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    • pp.1211-1218
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    • 2003
  • The present study investigated two-phase flow distribution and phase separation of R-22 refrigerant through various types of branch tubes. The key experimental parameters were the orientation of inlet and branch tubes (horizontal and vertical), diameter ratio of branch tube to inlet tube (1 and 0.61), mass flux (200-500 kg/㎡s), and inlet quality (0.1-0.4). The predicted local pressure profile in the tube with junction was compared and generally agreed with the measured data. The local pressure profile within the pressure recovery region after the junction has to be carefully investigated for modeling the pressure drop through the branch. The equal flow distribution case can be found by adjusting the orientation of the inlet and branch tubes and the diameter ratio of the branch tube to the inlet tube. The T-junction with horizontal inlet and branch tubes showed the nearly equal phase distribution ratio. The quality at the branch tube varied from 0 to 1 as the orientation of the branch tube changed, while it varied within${\pm}$50% as the orientation of the inlet tube changed.

Electrostatic Charging Measurement and PVC Separation of Triboeletrostatically Charged Plastic Particles using a Fluidized Bed Tribocharger

  • Shin, Jin-Hyouk;Lee, Jae-Keun
    • Journal of ILASS-Korea
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    • v.7 no.2
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    • pp.7-15
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    • 2002
  • A particle flow visualization, electrostatic charging measurement and separation of triboelectrically charged particles in the external electric field by a fluidized bed tribocharger are conducted for the removal of PVC particles from mixed waste plastics. The laboratory-scale triboelectrostatic separation system consists of the fluidized bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PET particles can be imparted negative and positive surface charges respectively due to the difference of triboelectric charging series between particles and particles in the fluidized bed tribocharger, and can be separated by passing them through an external electric field. To visualize these charged particles, He-Ne laser is used with cylindrical lenses to generate a sheet beam. In the charging measurement, the particle motion analysis system (PMAS), capable of determining particle velocity and diameter. is used to non-intrusively measure particle behavior in high strength electric field. The average charge-to-mass ratios of PVC and PET particles are $1.4\;and\;1.2{\mu}C/kg$, respectively. The highly concentrated PVC (91.9%) can be recovered with a yield of about 96.1% from the mixture of PVC and PET materials for a single-stage processing. The triboelectrostatic separation system using the fluidized tribocharger shows the potential to be an effective method for removing PVC from mixed plastics for waste plastic recycling.

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A Flow Characteristics for a Separation Behavior of Two-body Vehicle (비행 조건에 따른 비행체 단분리의 주위 유동장 해석)

  • Park, Geunhong;Kim, Kiun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.266-267
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    • 2017
  • A numerical investigation of the stage separation behavior of two-body vehicle focusing on its flow characteristics were carried out. For this simulation, separation of a booster from vehicle was modeled by a chimera grid system and calculated by using commercial code, CFD-FASTRAN$^{TM}$. Consideration of a spring force, gravity and relative acceleration of a booster was the essential factor that simulates the realistic situation. In this study, It was validated that the booster separation time decreases with increase in flight mach number and angle of attack. In view of the results so far achieved, it was expected that the dynamics modeling and boundary condition set up applied in this study will be helpful in a estimation of a safe stage separation and event sequence of flight test.

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Study of Energy Separation Mechanism in Vortex Tube by CFD (볼텍스 튜브의 에너지 분리 현상에 관한 수치해석 연구)

  • Choi, Won-Chul;Chung, Myung-Kyoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.2
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    • pp.92-99
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    • 2008
  • The "energy separation phenomenon" through a vortex tube has been a long-standing mechanical engineering problem whose operational principle is not yet known. In order to find the operational principle of the vortex tube, CFD analysis of the flow field in the vortex tube has been carried out. It was found that the energy separation mechanism in the vortex tube consists of basically two major thermodynamic-fluid mechanical processes. One is the isentropic expansion process at the inlet nozzle, during which the gas temperature is nearly isentropically cooled. Second process is the viscous dissipation heating due to the high level of turbulence in both flow passages toward cold gas exit as well as the hot gas exit of the vortex tube. Since the amount of such a viscous heating is different between the two passages, the gas temperature at the cold exit is much lower than that at the hot exit.

Physical and Particle Flow Modeling of Shear Behavior of Non-Persistent Joints

  • Ghazvinian, A.;Sarfarazi, V.;Nejati, H.;Hadei, M.R.
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 2011.09a
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    • pp.3-21
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    • 2011
  • Laboratory experiments and numerical simulations using Particle Flow Code (PFC2D) were performed to study the effects of joint separation and joint overlapping on the full failure behavior of rock bridges under direct shear loading. Through numerical direct shear tests, the failure process is visually observed and the failure patterns are achieved with reasonable conformity with the experimental results. The simulation results clearly showed that cracks developed during the test were predominantly tension cracks. It was deduced that the failure pattern was mostly influenced by both of the joint separation and joint overlapping while the shear strength is closely related to the failure pattern and its failure mechanism. The studies revealed that shear strength of rock bridges are increased with increasing in the joint separation. Also, it was observed that for a fixed cross sectional area of rock bridges, shear strength of overlapped joints are less than the shear strength of non-overlapped joints.

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NUMERICAL INVESTIGATION ON THE SAFE SUPERSONIC AIR-LAUNCHING ROCKET SEPARATION FROM THE MOTHER PLANE (안전한 초음속 공중발사를 위한 삼차원 로켓 주위의 모선분리 유동 해석)

  • Ji Y.M.;Lee J.W.;Park J.S.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.10a
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    • pp.255-259
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    • 2005
  • An analysis is made of flow and rocket motion during a supersonic separation stage of air-launching rocket from the mother plane. Three-dimensional Euler and Navier-Stokes equations are numerically solved to analyze the steady/unsteady flow field around the rocket which is being separated from two cases of mother plane configuration: one is an idealized ogive-cylinder body and the other is a real F-4E Phantom. The simulation results clearly demonstrate the effect of shock-expansion wave interaction between the rocket and the mother plane. As a result, a design-guideline of supersonic air-launching rocket for the safe separation is proposed.

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A Mathematical Model Simulating A Grain-Straw Separation Process in an Axial-Flow Separator

  • Lee, Seung-Kyu-;Kim, Sung-Tae-;Park, Kyu-hong-
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 1993.10a
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    • pp.676-685
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    • 1993
  • A mathematical model was developed to quantify the separation process of threshed grain-straw mixtures. It was made to predict the separation loss from a separation unit consisted of stationary crimped sieve with rotating inner rotor. Experiments were performed to prove the mathematical model by changing various levels of pertinent variables for rice. Good Agreement between the simulated results and observed data under the various test conditions, such as inclination angle of the separator, vane pitch, rotor speed, MOG/G ratio, feed rate, and crop variety and moisture content, were confirmed.

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Center-of-Gravity Effect on Supersonic Separation from the Mother Plane (무게중심 변화에 따른 초음속 공중발사 로켓의 모선분리 연구)

  • Ji, Young-Moo;Lee, Jae-Woo;Byun, Yung-Hwan;Park, Jung-Sang
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.423-426
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    • 2006
  • An analysis is made of flow and rocket motion during a supersonic separation stage of air-launching rocket(ALR) from the mother plane. Three-dimensional compressible Navier-Stokes equations is numerically solved to analyze the steady/unsteady flow field around the rocket which is being separated from the mother plane configuration(F-4E Phantom). The simulation results clearly demonstrate the effect of shock-expansion wave interaction between the rocket and the mother plane. To predict the behavior of the ALR according to the change of the C.G., three cases of numerical analysis are performed. As a result, a design-guideline of supersonic air-launching rocket for the safe separation is proposed.

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Aeroacoustic Noise Generation in Unsteady Laminar Boundary-layer Separation (비정상 층류 경계층 박리에 의한 유동 소음)

  • Choi, Hyo-Won;Moon, Young-J.
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.300-305
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    • 2001
  • The unsteady flow structure and the related noise generation, which are caused by the separation of a two-dimensional, incompressible, laminar boundary-layer on the flat plate under the influence of local adverse pressure gradient, are numerically examined. The characteristic lines of the wall pressure are examined to understand the unsteady behavior of vortex shedding near the reattachment point of the separation bubble. Also, the generation and propagation of the vortex-induced noise in the separated boundary-layer are calculated by the method of computational aero-acoustics (CAA), and the effects of Reynolds number, Mach number and the strength of the adverse pressure gradient on the unsteady flow and noise characteristics are examined.

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An Experimental Study on the Energy Separation in a Low Pressure Vortex Tube for Engine (기관적용 저압용 vortex tube의 에너지 분리특성에 관한 실험적 연구)

  • 오동진;임석연;윤면근;류정인
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.235-241
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    • 2002
  • The process of energy separation in a low pressure vortex tube with air as a working medium is studied In detail. Experimental data of the temperature of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the inner surface of the vortex tube and the temperature distribution in the vortex tube provides useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. In this study Outer tube is used for the application of Diesel engine exhaust. The hot gas flow is fumed 180° and passes the outside of the vortex tube a second time heating it. From this geometric setup of a vortex tube the effects of energy separation and the prediction of the ignition of Diesel Soot is presented by experimental data.