• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.505-514
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• 1998

Flow pattern of air-water two phase flow depends on the conditions of pressure void fraction and channel geometry. We classify the flow pattern by measuring the output signal of the conductivity probe. under the classified flow pattern we mount a visualization equipment on the test section and take pictures. We vary the concentration of pure solvent and polymer to measure local void fraction. We know that the maximum point position of local void fraction distribution move from the center of the pipe to the wall of the pipe as JSL increase when JSA is constant in two phase flow. But we find that the maximum point position of local void friction move from the wal of the pipe to the center of the pipe when polymer concentration increase.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2619-2627
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• 2012

The electronic float flow pattern system can predict a rate of flow of river by monitoring a location of float in remote with location measurement technology and a variety of communication technology. Now, to analyze the flow pattern of the natural streams, we use the manual floats in many forms. The measurement of a rate of flow using a manual float measures the distance and time of the manual float directly and uses it. It is inefficient for measurement method and exact a rate of flow of river. To overcome this problems, we designed and implemented the electronic float using CDMA, GPS, and RF module. Then, to get the location information and a rate of flow information, we designed and implemented the monitoring system for the electronic float flow pattern. The short life cycle of electronic float using the battery decreases the utility of the electronic float flow pattern system. Then, we design the power saving method to reduce the power of the electronic float in electronic float flow pattern system.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.2
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• pp.96-101
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• 2000

In machining with cutting tool inserts having complex chip groove shape the flow curl and breaking pattern of the chip are different than in flat-face inserts. In the present work an effort is made to understand the three basic phe-nomena occurring in a chip since its formation in machining with groove type and pattern type inserts. These are the ini-tial chip flow the subsequent development of up and side curl and the final chip breaking due to the development of tor-sional and bending stresses. in this paper chip flow angle in a groove type and pattern type inserts. The expres-sion for chip flow angle in groove type and pattern type inserts is also verified experimentally using high speed filming techniques.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.939-946
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• 2009

Wettability is a critical parameter in micro-scale two-phase system. Several previous results indicate that wettability has influential affect on two-phase flow pattern in a microchannel. However, previous studies conducted using circular microtube, which was made by conventional fabrication techniques. Although most applications for micro thermal hydraulic system has used a rectangular microchannel, data for the rectangular microchannel is totally lack. In this study, a hydrophilic rectangular microchannel was fabricated using a photosensitive glass. And a hydrophobic rectangular microchannel was prepared using silanization of glass surfaces with OTS (octa-dethyl-trichloro-siliane). Experiments of two-phase flow in the hydrophilic and the hydrophobic rectangular microchannels were conducted using water and nitrogen gas. Visualization of twophase flow pattern was carried out using a high-speed camera and a long distance microscope. Visualization results show that the wettability was important for two-phase flow pattern in rectangular microchannel. In addition, two-phase frictional pressure drop was highly related with flow patterns. Finally, Two-phase frictional pressure drop was analyzed with flow patterns.

• Journal of Advanced Marine Engineering and Technology
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• v.4 no.1
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• pp.23-31
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• 1980

The fluid static pressure has been generally measured by means of a small hole leading to a measuring instrument. In case of viscoelastic fluids, however, it has been shown experimentally that a systematic error exists in measuring the static pressure by means of the small hole becuase viscoelasitc fluids have many properties that can not be observed in Newtonian fluids. In this paper, in order to examine the mechanism of the errors in measuring the static pressure of viscoelasitc fluids, flow patterns in the vicinity of static pressure measuring hole were photographically taken and observed graphically. The experiments to take photographs of flow patterns were performed by a parallel plate channel with the steady two-dimensional shear flow of viscoelastic fluids. Results of the experiment are classified as following three regions; (1) Arched symmetrical flow pattern region. (2) Asymmetrical flow pattern region. (3) Rectilinear symmetricl flow pattern region.

• Korea-Australia Rheology Journal
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• v.19 no.2
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• pp.67-73
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• 2007

A finite volume method (FVM) base on the SIMPLE algorithm as the pressure correction strategy and the traditional staggered mesh is used to investigate steady, fully developed flow of Oldroyd-3-constant fluids through a duct with square cross-section. Both effects of the two viscoelastic material parameters, We and ${\mu}$, on pattern and strength of the secondary flow are investigated. An amusing sixteen vortices pattern of the secondary flow, which has never been reported, is shown in the present work. The reason for the changes of the pattern and strength of the secondary flow is discussed carefully. We found that it is variation of second normal stress difference that causes the changes of the pattern and strength of the secondary flow.

• Journal of Mechanical Science and Technology
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• v.19 no.12
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• pp.2289-2295
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• 2005

Two-Phase flow pattern and pressure drop data were obtained for pure refrigerants R134a and R123 and their mixtures as test fluids in a horizontal tube. The flow pattern is observed through tubular sight glasses located at inlet and outlet of the test section. The flow map of Baker developed for air-water two-phase flow at atmospheric pressure failed to predict the observed flow patterns at the higher value of the mass velocity used in the present study. The map of Kattan et al. predicted the data well over the entire region of mass velocity selected in the present study. The measured pressure drop increased with an increase in vapor quality and mass velocity. A new two-phase multiplier was developed from a dimensional analysis of the frictional pressure drop data measured in the present experiment. This new multiplier was found successfully to correlate the frictional pressure drop.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.4
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• pp.263-269
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• 2007

A numerical algorithm for three-dimension laminar flow in an agitated vessel was established by using the spherical coordinates. Flow pattern for the double-stage paddle impeller was not dependent upon the distance of among the impeller in the agitated vessels. The numerical simulation of the flow pattern in spherical and cylindrical agitated vessel agree well with the visualization results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1348-1358
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• 2004

The filling pattern and an adaptive grid refinement based on the finite element method and Eulerian mesh advancement approach have been developed to analyze incompressible transient viscous flow with free surfaces. The governing equation fur flow analysis is Navier-Stokes equation including inertia and gravity effects. The mixed FE formulation and predictor-corrector method are used effectively for unsteady numerical simulation. The flow front surface and the volume inflow rate are calculated using the filling pattern technique to select an adequate pattern among seven filling patterns at each tetrahedral control volume. By adaptive grid refinement, the new flow field that renders better prediction in flow surface shape is generated and the velocity field at the flow front part is calculated more exactly. In this domain the elements in the surface region are made finer than those in the remaining regions for more efficient computation. The collapse of a water dam and the filling of a fluidity spiral have been analyzed. The numerical results have been in good agreement with the experimental results and the efficiency of the adaptive grid refinement and filling pattern techniques have been verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.3
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• pp.933-944
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• 1996

In this paper, two new techniques, the pattern filling and the refined flow field regeneration, based on the finite element method and Eulerian mesh advancement approach have been developed to analyze incompressible viscous flow with free surfaces. The gorerning equation for flow analysis is Navier-Stokes equation including inertia and gravity effects. The penalty and Newton-Raphson methods are used effectively for finite element formulation. The flow front surface and the volume inflow rate are calculated using the pattern filling technique to select an adequate pattern among five filling patterns at each quadrilateral control volume. By the refined flow field regeneration technique, the new flow field which renders better prediction in flow surface shape is generated and the velocity field at the flow front part is calculated more exactly. Using the new thchniques to be developed, the dam-breaking problem has been analyzed to predict flow phenomenon of fluid and the predicted front positions versus time have been compared with the reported experimental result.