• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.14-17
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• 2008

Recently, several advanced flow visualization techniques such as Particle Image Velocimetry (PIV) including stereo PIV, holographic PIV, and dynamic PIV have been developed. These advanced techniques have strong potential as the experimental technology which can be used for verifying numerical simulation. In addition, there would be indispensable in solving complicated thermo-fluid flow problems not only in the industrial fields such as automotive, space, electronics, aero- and hydro-dynamics, steel, and information engineering, but also in the basic research fields of medical science, bio-medical engineering, environmental and energy engineering etc. Especially, NT (Nano Technology) and BT (Bio Technology) strongly demand these advanced measurement techniques, because it is difficult for conventional methods to observe most complicated nano- and bio-fluidic phenomena. In this paper, the basic principle of these advanced visualization techniques and their practical applications which cannot be resolved by conventional methods, such as flow in automotive HVAC system, ship and propeller wake, three-dimensional flow measurement in micro-conduits, and flow around a circulating cylinder will be introduced.

• Journal of the Korean Society of Visualization
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• v.3 no.1
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• pp.26-35
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• 2005

The combination of ultrasound echo images with digital particle image velocimetry (DPIV) method has resulted in a two-dimensional, two-component velocity field measurement technique appropriate for opaque flow conditions including blood flow in clinical applications. Advanced PIV processing algorithms including an iterative scheme and window of offsetting were used to increase spatial resolution. The optimum concentration of the ultrasound contrast agent used for seeding was explored. Velocity validation tests in fully developed laminar pipe flow and pulsatile flow showed good agreement with both optical PIV measurements and the known analytic solution. These studies indicate that echo PIV is a promising technique for the non-invasive measurement of velocity profiles and shear stress.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.102-103
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• 2004

Simultaneous CH and OH planar laser induced fluorescence(PLIF) and stereoscopic particle image velocimetry(PIV) measurements have been developed to investigate the local flame structure of turbulent premixed flames. The developed simultaneous two radical concentrations and three component velocity measurements on a two-dimensional plane was applied for relatively high Renolds number turbulent premixed flames in a swirl stabilized combustor. All measurements were conducted for methane-air premixed flames in the corrugated flamelets regime. Strong three-dimensional fluctuation implies that misunderstanding of the flame/turbulent interactions would be caused by the analysis of two-component velocity distribution in a cross section. Furthermore, comparisons of CH-OH PLIF and three-component velocity field show that the burned gases not always have high-speed velocity in relatively high Renolds number turbulent premixed flame.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.22-25
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• 2004

The present paper investigated the correlation between acoustic pressure and heat transfer augmentation in acoustic fields. The acoustic pressure predicted by numerical work and compared with the augmentation ratio of heat transfer coefficient was experimentally measured. Also, particle image velocimetry(PIV) was used for the visualization of velocity vectors and kinetic energy distribution inside liquid region. For the numerical work, SVS programed with Fortran language and based on a coupled FE-BEM was used. Results of the present study, the acoustic pressure is increased by $60\%$ and the largest augmentation of heat transfer about $28\%$ was measured. Finally, the profiles of acoustic pressure is consistent with that of augmentation of heat transfer. It is concluded that a correlation exists between the acoustic pressure and the heat transfer augmentation.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.44-47
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• 2004

Vortexing might occur during draining from tanks which reduces the rate of outflow. This phenomenon has practical relevance in the fuel feed system in space vehicles and rockets. Due to environmental disturbances rotational motion can be generated in the liquid-propellant tank, which in turn can affect the rate of outflow to the engines. The phenomenon is initialized by rotating the fluid In the experimental tank. The dip quickly develops into a vortex with an air core, which extends to the bottom port, reducing the effective cross-sectional area of the drain outlet and consequently the flow rate. Flow characteristics are investigated using SPIV(Stereoscopic Particle Image Velocimetry) method.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.99-102
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• 2003

PIV(Particle Image Velocimetry)was used to visualize the interaction of reed valve of the reciprocating compressor. The valve is the key part which governs the efficiency, noise and reliability of the compressor, so the development of analytical model about valve performance is necessary. As the valve reed is opened and closed by pressure pulsation, the flow characteristic of the refrigerant passing the valve is very important. In the present study, a circular disk with inclination is assumed to be the valve reed of a reciprocating compressor, The mean velocity shows the vortical characteristic of this flow. It is found that the back flow is affected by the height of reed valve of reciprocating compressor.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.48-51
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• 2004

Chemical Mechanical Polishing(CMP) is popularly used in production of semiconductor because of large area polishing ability probability of improvement for more integrated circuit. However, present CMP processing causes some non-uniformity errors which can be critical for highly integrated circuit. Previous studies predict that flow-field of slurry during CMP can create non-uniformity, but no quantitative measurement has conducted. In this study, using PIV, slurry velocity flow-field during CMP is measured by changing the ratio of RPM of pad and carrier with tuned PIV system adequate for small room in CMP machine and Cabot's non-groove pad Epad-A100. The result show that velocity of slurry is majorly determined by pad-rpm and the ratio of between carrier and pad rpm make some changes in streamlines.

• Journal of the Korean Society of Visualization
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• v.7 no.1
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• pp.21-28
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• 2009

The study of swirling flow is of technical and scientific interest because it has an internal recirculation field, and its tangential velocity is related to the curvature of streamline. The fluid flow for tubes and elbow of heat exchangers has been studied largely through experiments and numerical methods, but studies about swirling flow have been insufficient. Using the particle image velocimetry(PTV) method, this study found the time averaged velocity distribution with swirl and without swirl along longitude sections and the results appear to be physically reasonable. In addition, streamwise mean velocity distribution was compares with that of other. Furthermore, other experimental investigation was performed to study the characteristics of turbulent water flow in a horizontal circular tube by using liquid crystal. 2D PIV technique is employed for velocity measurement and liquid crystal is used for heat transfer experiments in water. Temperature visualization was made quantitatively by calibrating the colour of the liquid crystal versus temperature using various approaches.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.499-502
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• 2002

The present study has been carried out for understanding of flows over an evaporator in cooling system of water. Main emphasis is to decide the flow patterns in order to enhance the flow rate with low noise level. Two cases aye examined for comparison of flows; one is blowing system and the other is suction style with respect to Inn system. Present methodology for this work is PIV (Particle Image Velocimetry) techniques and Rot-wire anemometer for velocity measurements and wind tunnel for performance of the present fan. Consequently, it is found that flows passing evaporator and other components for cooling are more effective than the suction flows. Flow details with performance of fan system are also presented for proper explanation of the conclusion.

• Journal of Mechanical Science and Technology
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• v.19 no.2
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• pp.716-727
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• 2005

Comprehensive measurements for velocity and temperature fields have been conducted. A Micro PIV 2-color LIF system have been setup to measure the buoyancy driven fields in a 1-mm heated channel with low Grashof-Prandtl numbers [$86]. Fluorescence microscopy is combined with an MPIV system to obtain enough intensity images and clear pictures from nano-scale fluorescence particles. The spatial resolution of the Micro PIV system is $75{\mu}m\;by\;67{\mu}m$ and error due to Brownian motion is estimated $1.05\%$. Temperature measurements have achieved the $4.7\;{\mu}m$ spatial resolution with relatively large data uncertainties the present experiment. The measurement uncertainties have been decreased down to less than ${\pm}1.0^{\circ}C$ when measurement resolution is equivalent to $76\;{\mu}m$. Measured velocity and temperature fields will be compared with numerical results to examine the feasibility of development as a diagnostic technique.