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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Visualization
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Journal DOI :
The Korean Society of Visualization
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Volume & Issues
Volume 9, Issue 4 - Dec 2011
Volume 9, Issue 3 - Sep 2011
Volume 9, Issue 2 - Jun 2011
Volume 9, Issue 1 - Mar 2011
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Effects of Stroke Change on Turbulent Kinetic Energy for the In-Cylinder Flow of a Four-Valve SI Engine
Yoo, S.C. ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 16~21
DOI : 10.5407/JKSV.2011.9.4.016
The effects of stroke change on turbulent kinetic energy for the in-cylinder flow of a four-valve SI engine were studied. For this study, the same intake manifold, head, cylinder, and the piston were used to examine turbulence characteristics in two different strokes. In-cylinder flow measurements were conducted using three dimensional LDV system. The measurement method, which simultaneously collects 3-D velocity data, allowed a evaluation of turbulent kinetic energy inside a cylinder. High levels of turbulent kinetic energy were found in regions of high shear flow, attributed to the collisions of intake flows. These specific results support the more general conclusion that the inlet conditions play the dominant role in the generation of the turbulence fields during the intake stroke. However, in the absence of two counter rotating vortices, this intake generated turbulent kinetic energy continues to decrease but at a much faster rate.
Visualization of Unsteady DC Electro-osmotic flow by using Methods of Coupling Fortran and CFX Codes
Heo, Young-Gun ; Jeong, Jong-Hyeon ; Suh, Yong-Kweon ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 22~27
DOI : 10.5407/JKSV.2011.9.4.022
In this study, we present methods of coupling a commercial code, ANSYS CFX, and the user Fortran codes for solving an unsteady electro-osmotic flow around a pair of electrodes, receiving DC, attached to the top and the bottom walls of a two-dimensional cavity. We developed a module of Fortran programs for solving the ion-transport equations as well as the Poisson equations for the potential to be used in coupling with the CFX. We present how the developed codes are applied to solving the transient DC electro-osmotic flow problem within a simple cavity. We also address various problems encountered during the development process and explain why such problems are raised.
Numerical Simulations of Cavitation Flow in Volumetric Gear Pump
Lee, Jung-Ho ; Lee, Sang-Wook ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 28~34
DOI : 10.5407/JKSV.2011.9.4.028
A volumetric gear pump is often used in extensive industrial applications to provide both high pressure and sufficiently high flow rate by physical displacement of finite volume of fluid with each revolution. Template mesh function in commercial CFD software, PumpLinx, by which 3-D meshes in the complex region between rotor and housing can be readily generated was employed for 3-D flow simulations. For cavitation analysis full cavitation model was included in 3-D simulations. The results showed high pulsation in pressure and flowrate which is implicated in pump vibration and noise. A model test for cavitation visualization was conducted and the results showed good qualitative agreement with numerical prediction.
A Study on the Mixing Capacity of Lifted Flame by the Nozzle Hole-tone of High Frequency in Non-premixed Jet Flames
Jo, Joon-Ik ; Lee, Kee-Man ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 35~40
DOI : 10.5407/JKSV.2011.9.4.035
An experimental investigation of the characteristic of non-premixed lifted flames with nozzle hole-tone of high-frequency has been performed. Before the fuel was supplied to nozzle, the fuel was supplied through a burner cavity which was located under the nozzle. The fuel passed through the excitation cavity under the influence of the high-frequency affects the lifted flame characteristics. The measurements were performed in flow range that occurs lifted flame and blow out. When the high-frequency is generated from burner cavity, the lifted length became shorter, and noise reduced comparing to unexcitation case. Additionally, operating flow range was increased and diameter of flame base became smaller with high-frequency effect. Through this experiments, it's ascertained that the high-frequency excitation can be adopted with effective method for flame stability and noise reduction.
Fabrication of Oxygen Sensitive Particles and Characteristic Analysis
Jeong, Won-Taek ; Yi, Seung-Jae ; Kim, Hyun-Dong ; Kim, Kyung-Chun ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 41~46
DOI : 10.5407/JKSV.2011.9.4.041
Oxygen sensitive functional particles(OSParticle) were fabricated by three different methods for using the particles as oxygen sensors and PIV tracers. The used methods were a physical coating method, an ion-exchange method and a dispersion polymerization method. The physical coating method is dipping
hollow particles into dye solution then drying. This method is very simple, but particles are not uniform in diameter and luminescence. The particles fabricated by the ion-exchange method have very uniform diameter and well doped. However, it can not be used in water since the particles are hydrophobic. In case of the dispersion polymerization method, the diameter of OSParticles is quite uniform. The diameter of OSParticles can be changed by controlling the quantity of AIBN (2,2'-azobis isobutyronitrile). For the purpose of dissolved oxygen concentration measurement in micro scale water flows, the dispersion polymerized OSParticles turn out to be the most superior functional particles. The luminescent intensity of OSParticles was tested with the variation of dissolved oxygen concentration in water samples. As a result, the luminescent intensity of OSParticles is monotonically decreased with increasing DO (Dissolved oxygen) concentration of water.
Numerical Analysis and Flow Visualization Study on Two-phase Flow Characteristics in Annular Ejector Loop
Lee, Dong-Yeop ; Kim, Yoon-Kee ; Kim, Hyun-Dong ; Kim, Kyung-Chun ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 47~53
DOI : 10.5407/JKSV.2011.9.4.047
A water driven ejector loop was designed and constructed for air absorption. The used ejector was horizontally installed in the loop and annular water jet at the throat entrained air through the circular pipe placed at the center of the ejector. Wide range of water flow rate was provided using two kinds of pumps in the loop. The tested range of water flow rate was 100
/min to 1,000
/min. Two-phase flow inside the ejector loop was simulated by CFD analysis. Homogeneous particle model was used for void fraction prediction. Water and air flow rates and pressure drop through the ejector were automatically recorded by using the LabView based data acquisition system. Flow characteristics and air bubble velocity field downstream of the ejector were investigated by two-phase flow visualization and PIV measurement based on bubble shadow images. Overall performance of the two-phase ejector predicted by the CFD simulation agrees well with that of the experiment.
Water-Simulant Facility Installation for the Sodium-Cooled Fast Reactor KALIMER-600 and Global Flow Measurement
Cha, Jae-Eun ; Kim, Seong-O ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 54~62
DOI : 10.5407/JKSV.2011.9.4.054
KAERI has developed a KALIMER-600 which is a pool-type sodium-cooled fast reactor with a 600MWe electric generation capacity. For a SFR development, one of the main topics is an enhancement of the reactor system safety. Therefore, we have a long-term plan to design the large sodium experimental facility to evaluate the reactor safety and component performance. In order to extrapolate a thermal hydraulic phenomena in a large sodium reactor, the thermal hydraulics phenomena is under investigation in a 1/
water-simulant facility for the KALIMER-600. In this paper, we shortly described the experimental facility setup and the measurement of the isothermal global flow behavior. For the flow field measurement, the PIV method was used in a transparent Plexiglas reactor vessel model at around
Measurement of Liquid-Metal Flow with a Dynamic Neutron Radiography
Cha, Jae-Eun ; Saito, Yasushi ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 63~68
DOI : 10.5407/JKSV.2011.9.4.063
The flow-field of a liquid-metal system is very important for the safety analysis and the design of the steam generator of liquid-metal fast breeder reactor. Dynamic neutron radiography (DNR) is suitable for a visualization and measurement of a liquid metal flow and a two-phase flow in a metallic duct. However, the three dimensional DNR techniques is not enough to obtain the velocity information in the wide channel up to now. In this research, a high speed DNR technique was applied to visualize the heavy liquid-metal flow field in the narrow channel with the HANARO-beam facility. The images were taken with a high frame-rate neutron radiography at 250 fps and analyzed with a Particle Image Velocimetry(PIV) method. The images were compared with the results of the commercial CFX code to study the feasibility of DNR technique for the measuring the heavy liquid-metal flow field. The PIV images could discern the turbulent vortex flow in the two-dimensional narrow channel.
In vivo visualization of liquid-feeding phenomena of a butterfly
Lee, Seung-Chul ; Kim, Bo-Heum ; Lee, Sang-Joon ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 69~73
DOI : 10.5407/JKSV.2011.9.4.069
Butterflies have been known to suck viscous liquids through a long, cylindrical proboscis using the large pressure difference formulated by the cyclic expansion and contraction of a muscular pump located inside their head. However, there are few studies on the liquid-feeding phenomena in a live butterfly, because it is hard to observe the internal morphological structures under in vivo condition. In this study, the dynamic motion of the pump system in a butterfly was in vivo visualized using synchrotron X-ray micro-imaging technique to analyze the liquid-feeding mechanism. The period of the liquid-feeding process is about 0.3sec. The expansion stage is about two times larger than the contraction stage in one cycle. The cyclic variation of pump volume generate large negative suction pressure and the pressure difference inside the long proboscis of a butterfly is estimated to be larger than 1atm.
A Study on the Change of Free Surface Vortex according to Intake Conditions in the Pump Sump
Park, Young-Kyu ; Li, Kui-Ming ; Choi, Yoon-Hwan ; Lee, Yeon-Won ;
Journal of the Korean Society of Visualization, volume 9, issue 4, 2011, Pages 74~79
DOI : 10.5407/JKSV.2011.9.4.074
In this study the change of free surface vortex is represented at different times according to height of water and with or without curtain wall installation. The air volume fraction is investigated at each condition of water level and the influence about creation of vortex is analyzed. The height of sump intake is taken as 100mm and the water level is divided into 5 steps. The sump model is the TSJ model and the curtain wall is applied by HI standard of America. The results shows that the free surface vortex can be identified on the isotropic surface at air volume fraction 1%~5% and the vortices make an air column from the free surface to the sump intake and are created and destroyed repeatedly. In the higher water level, less air is absorbed into the intake pipe. After curtain wall installation, the suction rate of the air volume fraction is decreased by 6.7%. The result of the vortex motion according to time, works on a cycle.